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License and Collaboration Agreements - Schedule of Nippon Shinyaku Collaboration Agreement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues	$ 170,441	$ 83,328
Nippon Shinyaku Collaboration and License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues	84,725
Nippon Shinyaku Collaboration and License Agreement [Member] \| License and Royalty Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues	72,903
Nippon Shinyaku Collaboration and License Agreement [Member] \| Service Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues	$ 11,822

- Definition

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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+ Details

Summary of Significant Accounting Policies - Schedule of Revenue or Accounts Receivable by Major Customers (Detail) - Customer Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Revenue [Member] \| Customer A [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk percentage	49.00%	98.00%
Revenue [Member] \| Customer B [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk percentage	50.00%
Accounts Receivable \| Customer A [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk percentage	84.00%	97.00%
Accounts Receivable \| Customer B [Member]
Entity Wide Revenue Major Customer [Line Items]
Concentration risk percentage	14.00%

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References + Details

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Pay vs Performance Disclosure
Net Income (Loss)	$ (193,878)	$ (227,102)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Cybersecurity Risk Management, Strategy, and Governance	12 Months Ended
Cybersecurity Risk Management, Strategy, and Governance	Dec. 31, 2025
Cybersecurity Risk Management, Strategy, and Governance [Line Items]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	ITEM 1C. CYBERSECURITY We regularly assess risks from cybersecurity threats, monitor our information systems for potential vulnerabilities and test those systems pursuant to our cybersecurity policies, processes and practices. To protect our information systems from cybersecurity threats, we use security tools that are designed to help identify, escalate, investigate, resolve and recover from security incidents in a timely manner. We require annual information security training to be completed by our employees, and we maintain a limited cybersecurity liability insurance policy. Our Senior Vice President of Information Technology (SVP, IT) is responsible for the establishment and maintenance of our cybersecurity program, as well as the assessment and management of cybersecurity risks. Our current SVP, IT has over 25 years of experience in information technology and possesses the requisite education, skills and experience expected of an individual assigned to these duties. We also engage third-party consultants and auditors on an annual basis to assess the effectiveness of our cybersecurity prevention and response systems and processes. Where applicable, third-party service providers are contractually obligated to notify us of material incidents arising from cybersecurity events within their purview. We identify, assess and manage material risks from cybersecurity threats by following written policies and procedures, which are in compliance with the International Organization for Standardization (ISO) 27001 Information Security Management System. The output of this process is then integrated within our enterprise risk management (ERM) program. The ERM program is managed cross-functionally, with input from various senior management representatives across our business operations, and is used to assess risks to our business based on their potential likelihood and magnitude of impact. Our information technology organization provides the inputs to our ERM process related to material cybersecurity risks and mitigation plans. The information technology team is responsible for the prevention, detection, mitigation and remediation of cybersecurity incidents. Cybersecurity incidents are documented and triaged in accordance with a defined process. Incidents deemed to be significant are escalated to the Audit Committee of our Board of Directors after appropriate assessment by the information technology organization and other internal stakeholders. In the event an incident highlights an emerging or previously unidentified cybersecurity risk, such risk is then synthesized into the ERM process. The Audit Committee of our Board of Directors oversees our ERM program, including with respect to material risks arising from cybersecurity threats impacting our business. Management provides quarterly reporting on our material enterprise risks to the Audit Committee. In addition to material risks identified through the ERM process, our information technology management provides periodic reporting, at least semi-annually, on our cybersecurity risk profile and risk mitigation strategies to the Audit Committee. This reporting is also made available to the full Board of Directors. In the last three years, we have not identified any cybersecurity incidents which have materially affected, or are reasonably likely to materially affect, our business. For further information regarding cybersecurity risks, please refer to “Risk Factors – Risks Related to Our Business Operations” and other risks described in the “Risk Factors” section of this Annual Report on Form 10-K.
Cybersecurity Risk Management Processes Integrated [Flag]	true
Cybersecurity Risk Management Processes Integrated [Text Block]	The output of this process is then integrated within our enterprise risk management (ERM) program. The ERM program is managed cross-functionally, with input from various senior management representatives across our business operations, and is used to assess risks to our business based on their potential likelihood and magnitude of impact.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Board of Directors Oversight [Text Block]	The Audit Committee of our Board of Directors oversees our ERM program, including with respect to material risks arising from cybersecurity threats impacting our business. Management provides quarterly reporting on our material enterprise risks to the Audit Committee. In addition to material risks identified through the ERM process, our information technology management provides periodic reporting, at least semi-annually, on our cybersecurity risk profile and risk mitigation strategies to the Audit Committee. This reporting is also made available to the full Board of Directors.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	Management provides quarterly reporting on our material enterprise risks to the Audit Committee. In addition to material risks identified through the ERM process, our information technology management provides periodic reporting, at least semi-annually, on our cybersecurity risk profile and risk mitigation strategies to the Audit Committee. This reporting is also made available to the full Board of Directors.
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag]	false
Cybersecurity Risk Role of Management [Text Block]	Our Senior Vice President of Information Technology (SVP, IT) is responsible for the establishment and maintenance of our cybersecurity program, as well as the assessment and management of cybersecurity risks. Our current SVP, IT has over 25 years of experience in information technology and possesses the requisite education, skills and experience expected of an individual assigned to these duties. We also engage third-party consultants and auditors on an annual basis to assess the effectiveness of our cybersecurity prevention and response systems and processes. Where applicable, third-party service providers are contractually obligated to notify us of material incidents arising from cybersecurity events within their purview.
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	Our Senior Vice President of Information Technology (SVP, IT) is responsible for the establishment and maintenance of our cybersecurity program, as well as the assessment and management of cybersecurity risks.
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	Our current SVP, IT has over 25 years of experience in information technology and possesses the requisite education, skills and experience expected of an individual assigned to these duties.

Income Taxes - Additional Information (Detail)	12 Months Ended
Income Taxes - Additional Information (Detail)	Dec. 31, 2025 EUR (€)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Income Tax Disclosure [Line Items]
Provision for income taxes		$ 0	$ 0
Federal statutory income tax rate, percent	21.00%	21.00%	21.00%
Increase (decrease) in deferred tax assets valuation allowance		$ 36,100,000	$ 57,900,000
Research and development and orphan drug tax credit carryforwards		$ 94,867,000	87,030,000
Net of unrecognized tax benefits			100,000
Reserve for uncertain tax positions placed against credit carryforwards			$ 100,000
Cumulative changes in ownership Interest percentage threshold, subject to annual limitation of NOL and tax credit carryforwards		50.00%
Ownership interest change period	3 years	3 years
Research and Development Expense [Member]
Income Tax Disclosure [Line Items]
Increase (decrease) in deferred tax assets valuation allowance		$ 122,100,000
United States
Income Tax Disclosure [Line Items]
Amortization Period	5 years	5 years
Outside United States
Income Tax Disclosure [Line Items]
Amortization Period	15 years	15 years
Research and development expenses capitalized and amortized period	15 years	15 years
Domestic Country [Member]
Income Tax Disclosure [Line Items]
Research and development and orphan drug tax credit carryforwards		$ 95,100,000
BEPS Pillar 2 [Member]
Income Tax Disclosure [Line Items]
Global minimum tax rate	15.00%	15.00%
BEPS Pillar 2 [Member] \| Minimum [Member]
Income Tax Disclosure [Line Items]
Consolidated revenue \| €	€ 750,000,000

Commitments and Contingencies - Summary of Expenses Incurred by Company (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Cost of License and Royalty Revenues [Abstract]
Royalties on net sales of Zolgensma and Itvisma	$ 170,441	$ 83,328
Zolgensma Royalties [Member]
Cost of License and Royalty Revenues [Abstract]
Royalties on net sales of Zolgensma and Itvisma	82,536	81,505
GlaxoSmithKline LLC [Member]
Other Commitments [Line Items]
Total related party transaction expense	19,788	33,886
GlaxoSmithKline LLC [Member] \| Zolgensma Royalties Itvisma [Member]
Cost of License and Royalty Revenues [Abstract]
Royalties on net sales of Zolgensma and Itvisma	19,193	33,180
GlaxoSmithKline LLC [Member] \| Other [Member]
Other Commitments [Line Items]
Total related party transaction expense	399	337
GlaxoSmithKline LLC [Member] \| Cost of License and Royalty Revenues [Member]
Other Commitments [Line Items]
Total related party transaction expense	19,592	33,517
GlaxoSmithKline LLC [Member] \| General and Administrative [Member]
Other Commitments [Line Items]
Total related party transaction expense	196	369
License Fees [Member] \| The Trustees of the University of Pennsylvania [Member]
Other Commitments [Line Items]
Total related party transaction expense	817	911
License Fees [Member] \| The Trustees of the University of Pennsylvania [Member] \| General and Administrative [Member]
Other Commitments [Line Items]
Total related party transaction expense	461	299
License Fees [Member] \| The Trustees of the University of Pennsylvania [Member] \| Interest Expense [Member]
Other Commitments [Line Items]
Total related party transaction expense	$ 356	$ 612

License and Collaboration Agreements - Summary of Changes in Allowance For Credit Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Financing Receivable Allowance For Credit Losses [Line Items]
Changes in present value discount of receivables	$ 0	$ 413
Credit recoveries		(5,000)
Accounts Receivable
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	0	4,587
Ending Balance	$ 0	$ 0

- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

+ References + Details

Restructuring - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Restructuring Cost and Reserve [Line Items]
Percentage of reduction in workforce	15.00%
Restructuring costs		$ 0	$ 0	$ 3,700
Restructuring Charges, Statement of Income or Comprehensive Income [Extensible Enumeration]				General and Administrative Expense
Reductions in restructuring liability			(400)
Restructuring liability	$ 1,806		$ 0	$ 1,806

- Definition

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

+ References + Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Stock-based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 34,563	$ 38,463
Research and Development Expense [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	15,977	17,985
General and Administrative Expense [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 18,586	$ 20,478

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Summary of Significant Accounting Policies - Summary of Estimated Useful Lives of Assets (Detail)	Dec. 31, 2025
Computer Equipment and Software [Member]
Property Plant And Equipment [Line Items]
Property plant and equipment estimated useful lives	3 years
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Property plant and equipment estimated useful lives	5 years
Laboratory and Manufacturing Equipment [Member] \| Minimum [Member]
Property Plant And Equipment [Line Items]
Property plant and equipment estimated useful lives	5 years
Laboratory and Manufacturing Equipment [Member] \| Maximum [Member]
Property Plant And Equipment [Line Items]
Property plant and equipment estimated useful lives	15 years
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Property, Plant, and Equipment, Useful Life, Term, Description [Extensible Enumeration]	Shorter of Lease Term or Estimated Useful Life

Fair Value Measurements

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

Financial instruments reported at fair value on a recurring basis include cash equivalents and marketable securities. The following tables present the fair value of cash equivalents and marketable securities in accordance with the fair value hierarchy discussed in Note 2 (in thousands):


	Level 1		Level 2		Level 3		Total
December 31, 2025
Cash equivalents:
Money market mutual funds	$	—	$	21,418	$	—	$	21,418
U.S. government and agency securities		—		2,496		—		2,496
Total cash equivalents		—		23,914		—		23,914
Marketable securities:
U.S. government and agency securities		—		83,144		—		83,144
Corporate bonds		—		123,245		—		123,245
Total marketable securities		—		206,389		—		206,389
Total cash equivalents and marketable securities	$	—	$	230,303	$	—	$	230,303


	Level 1		Level 2		Level 3		Total
December 31, 2024
Cash equivalents:
Money market mutual funds	$	—	$	43,895	$	—	$	43,895
U.S. government and agency securities		—		2,498		—		2,498
Total cash equivalents		—		46,393		—		46,393
Marketable securities:
U.S. government and agency securities		—		44,215		—		44,215
Certificates of deposit		—		1,462		—		1,462
Corporate bonds		—		141,663		—		141,663
Total marketable securities		—		187,340		—		187,340
Total cash equivalents and marketable securities	$	—	$	233,733	$	—	$	233,733

Management estimates that the carrying values of its current accounts receivable, other current assets, accounts payable, accrued expenses and other current liabilities approximate fair value due to the short-term nature of those instruments. Certain non-current accounts receivable and non-current payables reported as other liabilities are recorded at their present values using a discount rate that is based on prevailing market rates on the date the amounts were initially recorded. Management does not believe there have been any significant changes in market conditions or credit quality that would cause the discount rates initially used to be materially different

from those that would be used as of December 31, 2025 to determine the present value of these instruments. Accordingly, management estimates that the carrying values of its non-current accounts receivable and other liabilities approximate the fair value of those instruments. Management estimates that the carrying values of its royalty monetization liabilities approximate fair value. As discussed in Note 7, the carrying values of royalty monetization liabilities are based on the Company’s estimate of future royalties, milestones and other consideration to be paid over the life of the arrangement, which are considered Level 3 inputs, as well as any remaining repayment obligations upon maturity of the instruments.

Long-lived assets, if determined to be impaired, are measured at fair value on a nonrecurring basis using Level 3 inputs. Please refer to Note 6 for further information on nonrecurring fair value measurements of long-lived assets during the years ended December 31, 2025 and 2024.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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+ Details

Net Loss Per Share

12 Months Ended

Dec. 31, 2025

Earnings Per Share [Abstract]

Net Loss Per Share

15. Net Loss Per Share

Since the Company incurred net losses for the years ended December 31, 2025 and 2024, common stock equivalents were excluded from the calculation of diluted net loss per share for such periods as their effect would be anti-dilutive. Accordingly, basic and diluted net loss per share were the same for such periods. The weighted-average number of common shares outstanding used in the basic and diluted net loss per share calculations includes the weighted-average effect of pre-funded warrants to purchase shares of the Company's common stock, as the pre-funded warrants are exercisable at any time for nominal cash consideration. The following potentially dilutive common stock equivalents outstanding at the end of the period were excluded from the computations of weighted-average diluted common shares for the periods indicated as their effects would be anti-dilutive (in thousands):


	Years Ended December 31,
	2025		2024
Stock options issued and outstanding		11,566		9,994
Unvested restricted stock units outstanding		2,850		2,042
Employee stock purchase plan		93		47
May 2025 Warrants outstanding		268		—
		14,777		12,083

Marketable Securities and Other Investments (Tables)

12 Months Ended

Dec. 31, 2025

Investments, Debt and Equity Securities [Abstract]

Summary of Marketable Securities and Other Investments

The following tables present a summary of the Company’s marketable securities, which consist solely of available-for-sale debt securities (in thousands):


	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
December 31, 2025
U.S. government and agency securities	$	83,085	$	59	$	—		$	83,144
Corporate bonds		123,131		131		(17	)		123,245
	$	206,216	$	190	$	(17	)	$	206,389


	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
December 31, 2024
U.S. government and agency securities	$	44,281	$	11	$	(77	)	$	44,215
Certificates of deposit		1,466		—		(4	)		1,462
Corporate bonds		141,474		234		(45	)		141,663
	$	187,221	$	245	$	(126	)	$	187,340

Summary of Fair Values and Unrealized Losses of Marketable Securities Held by the Company in an Unrealized Loss Position for Less Than 12 months and 12 Months or Greater

The following tables present the fair values and unrealized losses of available-for-sale debt securities held by the Company in an unrealized loss position for less than 12 months and 12 months or greater (in thousands):


	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
December 31, 2025
U.S. government and agency securities	$	4,676	$	—		$	—	$	—	$	4,676	$	—
Corporate bonds		32,289		(17	)		—		—		32,289		(17	)
	$	36,965	$	(17	)	$	—	$	—	$	36,965	$	(17	)


	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
December 31, 2024
U.S. government and agency securities	$	—	$	—		$	22,917	$	(77	)	$	22,917	$	(77	)
Certificates of deposit		—		—			1,221		(4	)		1,221		(4	)
Corporate bonds		21,317		(45	)		—		—			21,317		(45	)
	$	21,317	$	(45	)	$	24,138	$	(81	)	$	45,455	$	(126	)

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

+ Details

Supplemental Disclosures (Tables)

12 Months Ended

Dec. 31, 2025

Payables and Accruals [Abstract]

Schedule of Other Current Assets

Other current assets consisted of the following (in thousands):


	As of December 31,
	2025		2024
Net cost reimbursement due from AbbVie	$	10,871	$	11,304
Accrued interest on investments		1,004		1,094
Other		1,030		1,376
	$	12,905	$	13,774

Schedules of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	As of December 31,
	2025		2024
Accrued personnel costs	$	17,418	$	17,607
Accrued external research and development expenses		10,229		8,998
Accrued sublicense fees and royalties		8,652		8,658
Accrued external general and administrative expenses		1,301		2,002
Accrued purchases of property and equipment		33		156
Other		757		649
	$	38,390	$	38,070

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2025

The Trustees of the University of Pennsylvania [Member]

Summary of Expenses Incurred by Company

Expenses incurred by the Company related to the Penn License were recorded as follows (in thousands):


	Years Ended December 31,
	2025		2024
General and administrative	$	461	$	299
Interest expense		356		612
	$	817	$	911

GlaxoSmithKline LLC [Member]

Summary of Expenses Incurred by Company

Expenses incurred by the Company related to the GSK License were recorded as follows (in thousands):


	Years Ended December 31,
	2025		2024
Cost of license and royalty revenues:
Royalties on net sales of Zolgensma and Itvisma	$	19,193	$	33,180
Other		399		337
Total cost of license and royalty revenues		19,592		33,517
General and administrative		196		369
	$	19,788	$	33,886

Restructuring (Tables)

12 Months Ended

Dec. 31, 2025

Restructuring and Related Activities [Abstract]

Summary of Restructuring Liability

The following table presents the changes in the Company's restructuring liability (in thousands):


	Restructuring Liability
Balance at December 31, 2023	$	1,806
Restructuring charges		—
Cash payments		(1,370	)
Other adjustments		(436	)
Balance at December 31, 2024		—
Restructuring charges		—
Cash payments		—
Balance at December 31, 2025	$	—

License and Collaboration Agreements (Tables)

12 Months Ended

Dec. 31, 2025

Schedule Of Revenues Earned Under License and Collaboration Agreements

Revenues earned under license and collaboration agreements consisted of the following (in thousands):


	Years Ended December 31,
	2025		2024
License and royalty revenue:
Zolgensma and Itvisma royalties	$	83,177	$	81,505
Nippon Shinyaku licenses		72,903		—
Other		187		455
Total license and royalty revenue		156,267		81,960
Service revenue:
Nippon Shinyaku services		11,822		—
Other		2,352		1,368
Total service revenue		14,174		1,368
Total revenues	$	170,441	$	83,328

Summary of Accounts Receivable, Contract Assets and Deferred Revenue

The following table presents the balances of the Company’s accounts receivable, contract assets and deferred revenue, as well as other information regarding revenue recognized, during the periods presented (in thousands):


	Years Ended December 31,
	2025		2024
Accounts receivable, net, current and non-current:
Beginning of period	$	20,947	$	25,491
End of period	$	28,691	$	20,947

Contract assets:
Beginning of period	$	239	$	—
End of period	$	104	$	239

Deferred revenue, current and non-current:
Beginning of period	$	115	$	148
End of period	$	29,395	$	115

Revenue recognized during the period from:
Amounts included in deferred revenue at beginning of period	$	115	$	148
Performance obligations satisfied in previous periods	$	84,684	$	81,585

Summary of Accounts Receivables

Accounts receivable consisted of the following (in thousands):


	As of December 31,
	2025		2024
Current accounts receivable:
Billed to customers	$	557	$	65
Unbilled Novartis royalties		23,806		20,106
Unbilled Nippon Shinyaku services		1,997		—
Other unbilled		19		302
Current accounts receivable		26,379		20,473
Non-current accounts receivable:
Unbilled Nippon Shinyaku services		1,858		—
Other unbilled		454		474
Non-current accounts receivable		2,312		474
Total accounts receivable	$	28,691	$	20,947

Summary of Changes in Allowance For Credit Losses

The following table presents the changes in the allowance for credit losses related to accounts receivable and contract assets for the years ended December 31, 2025 and 2024 (in thousands):


	Allowance for Credit Losses
	Accounts Receivable			Contract Assets
Balance at December 31, 2023	$	4,587		$	—
Provision for credit losses		—			—
Changes in present value discount of receivables		413			—
Credit recoveries		(5,000	)		—
Balance at December 31, 2024		—			—
Provision for credit losses		—			—
Changes in present value discount of receivables		—			—
Credit recoveries		—			—
Balance at December 31, 2025	$	—		$	—

Novartis Gene Therapies [Member]

Schedule Of Revenues Earned Under License and Collaboration Agreements

The Company recognized the following amounts under the Novartis License (in thousands):


	Years Ended December 31,
	2025		2024
Zolgensma royalties	$	82,536	$	81,505
Itvisma royalties		641		—
Other license revenue		—		28
Total license and royalty revenue	$	83,177	$	81,533

Interest income from licensing	$	41	$	123

Abb Vie Collaboration And License Agreement [Member]

Schedule of Collaboration Agreement

The Company recognized the following amounts under the AbbVie Collaboration Agreement (in thousands):


	Years Ended December 31,
	2025			2024
Net cost reimbursement to (from) AbbVie included in:
Research and development expense	$	(60,222	)	$	(78,316	)
General and administrative expense		2,678			1,866
Total net cost reimbursement to (from) AbbVie	$	(57,544	)	$	(76,450	)

Nippon Shinyaku Collaboration and License Agreement [Member]

Schedule of Collaboration Agreement

The Company recognized the following amounts under the Nippon Shinyaku Collaboration Agreement (in thousands):


	Years Ended December 31,
	2025		2024
License and royalty revenue	$	72,903	$	—
Service revenue		11,822		—
Total revenues	$	84,725	$	—

Capitalization (Tables)

12 Months Ended

Dec. 31, 2025

Equity [Abstract]

Schedule of Shares of Common Stock Reserved for Future Issuance

Shares of common stock reserved for future issuance were as follows (in thousands):


	As of December 31,
	2025		2024
Reserved for issuance under equity incentive plans		20,133		13,548
Reserved for issuance under employee stock purchase plan		755		913
Reserved for exercise of warrants outstanding		1,138		1,325
		22,026		15,786

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(27))
-SubTopic 10
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
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-URI https://asc.fasb.org/1943274/2147481112/505-10-50-3

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI https://asc.fasb.org/1943274/2147481112/505-10-50-4

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI https://asc.fasb.org/1943274/2147481112/505-10-50-5

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI https://asc.fasb.org/1943274/2147481142/505-10-45-2

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-7

+ Details

Stock-based Compensation - Schedule of Fair Value of Options Granted on Weighted-Average Assumptions (Detail)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility	64.00%	64.00%
Expected term (years)	6 years	6 years
Risk-free interest rate	4.30%	4.00%
Expected dividend yield	0.00%	0.00%

Insider Trading Arrangements

3 Months Ended

Dec. 31, 2025

Trading Arrangements, by Individual

Material Terms of Trading Arrangement

Rule 10b5-1 Trading Plans

The adoption or termination of contracts, instructions or written plans for the purchase or sale of our securities by our Section 16 officers and directors for the three months ended December 31, 2025, each of which is intended to satisfy the affirmative defense of Rule 10b5-1(c) (Rule 10b5-1 Plan), were as follows:

        
       Rule 10b5-1 Trading Plan

       Aggregate # of

        
       Provides for

       Securities to be

       Name

       Title

       Action

       Date Adopted

       Expiration Date

       Purchase/Sale

       Purchased/Sold (a)

       Stephen Pakola, M.D.

       Executive Vice President, Chief Medical Officer

       Adoption

       11/12/2025

       12/31/2026

       Sale

       408,835

(a)

The aggregate number of shares in this column includes shares that may be forfeited or withheld to satisfy exercise price and/or tax withholding obligations at the time of vesting.

Other than as described above, during the three months ended December 31, 2025, none of our directors or Section 16 reporting officers adopted or terminated any Rule 10b5-1 trading arrangement or non-Rule 10b5-1 trading arrangement (as such terms are defined in Item 408 of the SEC's Regulation S-K).

Directors or Section 16 Reporting Officers [Member]

Trading Arrangements, by Individual

Title

directors or Section 16 reporting officers

Rule 10b5-1 Arrangement Adopted

false

Non-Rule 10b5-1 Arrangement Adopted

false

Rule 10b5-1 Arrangement Terminated

false

Non-Rule 10b5-1 Arrangement Terminated

false

Rule 10b51 Trading Plan Two [Member] | Stephen Pakola, M.D. [Member]

Trading Arrangements, by Individual

Name

Stephen Pakola, M.D.

Title

Executive Vice President, Chief Medical Officer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

11/12/2025

Expiration Date

12/31/2026

Aggregate Available

408,835

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2025

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment, net consists of the following (in thousands):


	As of December 31,
	2025			2024
Laboratory and manufacturing equipment	$	78,825		$	77,141
Computer equipment and software		4,573			4,244
Furniture and fixtures		7,039			7,031
Leasehold improvements		101,610			101,465
Total property and equipment		192,047			189,881
Accumulated depreciation and amortization		(87,192	)		(72,292	)
Property and equipment, net	$	104,855		$	117,589

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2025

Earnings Per Share [Abstract]

Schedules for Computation of Diluted Weighted-Average Shares Outstanding

The following potentially dilutive common stock equivalents outstanding at the end of the period were excluded from the computations of weighted-average diluted common shares for the periods indicated as their effects would be anti-dilutive (in thousands):


	Years Ended December 31,
	2025		2024
Stock options issued and outstanding		11,566		9,994
Unvested restricted stock units outstanding		2,850		2,042
Employee stock purchase plan		93		47
May 2025 Warrants outstanding		268		—
		14,777		12,083

Summary of Significant Accounting Policies - Summary of Reconciliation of Cash and Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Accounting Policies [Abstract]
Cash and cash equivalents	$ 34,466	$ 57,526
Restricted cash	2,030	2,030
Total cash and cash equivalents and restricted cash	$ 36,496	$ 59,556

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Summary of Reconciliation of Cash and Cash Equivalents and Restricted Cash

The following table provides a reconciliation of cash and cash equivalents and restricted cash as reported on the consolidated balance sheets to the total of these amounts as reported at the end of the period in the consolidated statements of cash flows (in thousands):


	As of December 31,
	2025		2024
Cash and cash equivalents	$	34,466	$	57,526
Restricted cash		2,030		2,030
Total cash and cash equivalents and restricted cash	$	36,496	$	59,556

Schedule of Revenue or Accounts Receivable by Major Customers

The following table summarizes those customers who represented at least 10% of revenues or total net accounts receivable for the periods presented:


	Revenues						Accounts Receivable
	Years Ended December 31,						As of December 31,
	2025			2024			2025			2024
Customer A		49	%		98	%		84	%		97	%
Customer B		50	%		—			14	%		—

Summary of Estimated Useful Lives of Assets

Depreciation and amortization is calculated using the straight-line method over the estimated useful lives of the assets, which are as follows:


	Estimated Useful Life
Computer equipment and software	3 years
Furniture and fixtures	5 years
Laboratory and manufacturing equipment	5 to 15 years
Leasehold improvements	Shorter of lease term or estimated useful life

Restructuring - Summary of Restructuring Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Restructuring and Related Activities [Abstract]
Beginning Balance	$ 0	$ 1,806
Restructuring charges	0	0	$ 3,700
Cash payments	$ 0	(1,370)
Other adjustments		(436)
Ending Balance		$ 0	$ 1,806

- Definition

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

+ References + Details

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($)	Aug. 31, 2019 USD ($)	Dec. 31, 2025 USD ($) Installment	Dec. 31, 2024 USD ($)	Apr. 30, 2019 USD ($)	Mar. 31, 2009 USD ($)
Other Commitments [Line Items]
Aggregate milestone payment for all the targets			$ 100,000	$ 100,000
Claims paid to date related to indemnification issues			0
Accruals or expenses related to indemnification issues			0	0
Maximum [Member]
Other Commitments [Line Items]
Aggregate milestone payment for all the targets			2,180,000,000
University of Pennsylvania [Member]
Other Commitments [Line Items]
Accrued expeses				5,800,000
Accounts payable accrued expenses and other current liabilities			$ 3,000,000
Accrued expenses, current				2,900,000
Accrued expenses, non current				2,900,000
University of Pennsylvania [Member] \| Maximum [Member]
Other Commitments [Line Items]
Upfront fee, milestone fees					$ 20,500,000
University of Pennsylvania [Member] \| Penn Letter Agreement [Member]
Other Commitments [Line Items]
Amount payable to agreement	$ 20,000,000			20,000,000
Number of equal annual installments \| Installment			4
Related party transaction expense	9,200,000
Sublicense fees previously recognized	8,100,000
Present value of cost of revenue	$ 17,300,000
Milestone payment obligation			$ 500,000
University of Pennsylvania [Member] \| Sublicense Fees Due Or Owed in Future [Member]
Other Commitments [Line Items]
Amount payable to agreement			8,000,000
University of Pennsylvania [Member] \| Other Past or Future Obligations to Pay Sublicense Fees [Member]
Other Commitments [Line Items]
Amount payable to agreement			12,000,000
University of Pennsylvania [Member] \| First Anniversary [Member]
Other Commitments [Line Items]
Amount payable to agreement			3,000,000
GlaxoSmithKline LLC [Member]
Other Commitments [Line Items]
Related party transaction expense			19,788,000	33,886,000
Accrued expeses			5,700,000	6,300,000
Accrued expenses, current			5,700,000	6,200,000
Accrued expenses, non current			100,000	$ 100,000
Milestone payment obligation						$ 1,500,000
Clearside Biomedical Inc. [Member]
Other Commitments [Line Items]
Milestone payment obligation			$ 3,000,000
Payments against exercise of license option		$ 1,600,000
Clearside Biomedical Inc. [Member] \| Maximum [Member]
Other Commitments [Line Items]
Milestone payment obligation		$ 136,000,000.0

License and Collaboration Agreements - Additional Information (Detail)	1 Months Ended					3 Months Ended	12 Months Ended
	Aug. 31, 2025 USD ($)	Mar. 31, 2025 USD ($)	Nov. 30, 2021 USD ($)	Jan. 31, 2018 USD ($)	Mar. 31, 2014 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2025 USD ($) ProductCandidate	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	May 31, 2018 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Aggregate milestone payment for all the targets							$ 100,000	$ 100,000
Milestone payment upon commencement of clinical trials in humans							546,700,000
Milestone payment upon submission of regulatory approval filings							106,300,000
Milestone payment upon achievement of specified sales targets for licensed products							1,530,000,000
Deferred revenue, current and non-current							29,395,000	115,000	$ 148,000
Aggregate transaction price of license agreements							$ 30,400,000
Aggregate transaction price of license agreements, expected satisfaction period							5 years
Revenue recognized upon achievement of development milestones							$ 1,500,000	0
Accounts receivable							28,691,000	20,947,000	25,491,000
Accounts receivable, Current							26,379,000	20,473,000
Accounts receivable, Non current							2,312,000	474,000
Provision for credit losses (recoveries)								(5,000,000)
Novartis Gene Therapies [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
License Fees				$ 180,000,000
Abb Vie Collaboration And License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Up-front fee paid			$ 370,000,000
Milestone fee payments upon achievement of various development and commercialization			1,380,000,000
Milestone due	$ 200,000,000
Milestone payment upon first patient dosed in the Phase IIb/III trial	100,000,000
Milestone payment upon first patient dosed in the subsequent Phase III trial	$ 100,000,000
Transaction price of license			370,000,000				370,000,000	370,000,000
Change in transaction price							0	0
Abb Vie Collaboration And License Agreement \| Other Current Assets [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Due from related parties, current							10,900,000	11,300,000
Nippon Shinyaku Collaboration and License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Up-front fee paid		$ 110,000,000
Accounts receivable							4,100,000
Accounts receivable, Current							2,300,000
Accounts receivable, Non current							1,900,000
Deferred revenue							29,400,000
Deferred revenue, Current							10,500,000
Deferred revenue, Noncurrent							18,900,000
Transaction price of license							110,000,000
Variable consideration							4,100,000
Novartis License Agreement [Member] \| Novartis Gene Therapies [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Up-front fee paid					$ 2,000,000
Cumulative payments										$ 12,300,000
Sales based milestone payments receivable						$ 80,000,000
Accounts receivable							24,100,000	20,400,000
Novartis License Agreement [Member] \| Zolgensma Royalties [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment upon achievement of specified sales targets for licensed products						$ 1,000,000,000
November Two Thousand Eighteen License Agreement \| Abeona Therapeutics Incorporation \| Contract Termination
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Settlement agreement payable							30,000,000
November Two Thousand Twenty One License Agreement \| Abeona Therapeutics Incorporation \| Contract Termination
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Settlement agreement payable							20,000,000
November Two Thousand Twenty Two License Agreement \| Abeona Therapeutics Incorporation \| Contract Termination
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Settlement agreement payable							5,000,000
November Two Thousand Twenty Four License Agreement \| Abeona Therapeutics Incorporation \| Contract Termination
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Settlement agreement payable							5,000,000
Settlement Agreement \| Abeona Therapeutics Incorporation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Allowance for credit losses									4,600,000
Accounts receivable									4,600,000
Due from related parties									$ 5,000,000
Provision for credit losses (recoveries)								(5,000,000)
Final payment collected								$ 5,000,000
Development Milestone \| Abb Vie Collaboration And License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone fee payments upon achievement of various development and commercialization			562,500,000
Transaction price of license							562,500,000
Development Milestone \| Nippon Shinyaku Collaboration and License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price of license							40,000,000
Milestone fee received upon achievement of specified development and sales based milestones		40,000,000
Sales Based Milestones \| Abb Vie Collaboration And License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone fee payments upon achievement of various development and commercialization			$ 820,000,000
Transaction price of license							820,000,000
Sales Based Milestones \| Nippon Shinyaku Collaboration and License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price of license							660,000,000
Milestone fee received upon achievement of specified development and sales based milestones		660,000,000
Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Aggregate milestone payment for all the targets							$ 2,180,000,000
Maximum [Member] \| Nippon Shinyaku Collaboration and License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone fee received upon achievement of specified development and sales based milestones		$ 700,000,000
N A V Technology Platform [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of commercial product candidates \| ProductCandidate							2
HCR [Member] \| Novartis License Agreement [Member] \| Novartis Gene Therapies [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accounts receivable, current							$ 18,300,000

Restructuring

12 Months Ended

Dec. 31, 2025

Restructuring and Related Activities [Abstract]

Restructuring

14. Restructuring

In November 2023, the Company implemented a strategic pipeline prioritization and corporate restructuring designed to reduce operating expenses and prioritize the development of ABBV-RGX-314, RGX-202 and RGX-121. The restructuring included a reduction in workforce and other planned operating expenses, primarily in rare neurodegenerative disease development, early research and other general and administrative areas. In connection with the restructuring, the Company implemented a reduction in workforce of approximately 15%, which was substantially completed in the fourth quarter of 2023. The Company recorded restructuring costs of $3.7 million during the year ended December 31, 2023, which primarily consisted of employee severance, continuing healthcare benefits and other employee-related costs. Restructuring costs associated with one-time termination benefits were recorded pursuant to ASC 420, while restructuring costs associated with ongoing benefit arrangements were recorded pursuant to ASC 712. During the year ended December 31, 2024, the Company recorded reductions in the restructuring liability of $0.4 million associated with changes in total estimated restructuring costs. As of December 31, 2024, all of the restructuring costs had been paid by the Company and no restructuring liability was recorded. No restructuring costs were recorded during the years ended December 31, 2025 and 2024.

The following table presents the changes in the Company's restructuring liability (in thousands):


	Restructuring Liability
Balance at December 31, 2023	$	1,806
Restructuring charges		—
Cash payments		(1,370	)
Other adjustments		(436	)
Balance at December 31, 2024		—
Restructuring charges		—
Cash payments		—
Balance at December 31, 2025	$	—

Supplemental Disclosures - Schedule of Other Current Assets (Details) (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Other Current Assets [Line Items]
Other Assets, Current, Total	$ 12,905	$ 13,774
Other Current Assets [Member]
Other Current Assets [Line Items]
Accrued Interest on Investments	1,004	1,094
Other	1,030	1,376
Other Current Assets [Member] \| Related Party [Member]
Other Current Assets [Line Items]
Due from related parties, current	$ 10,871	$ 11,304

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Components of Loss Before Income Taxes

The components of loss before income taxes were as follows (in thousands):


	Years Ended December 31,
	2025			2024
United States	$	(193,795	)	$	(227,022	)
Foreign		(83	)		(80	)
Total loss before income taxes	$	(193,878	)	$	(227,102	)

Schedule of Net Income Taxes Paid (Net Refunds Received)

Net income taxes paid (net refunds received) were as follows (in thousands):


	Years Ended December 31,
	2025		2024
Federal	$	280	$	—
State:
Maryland		—		(56	)
Illinois		—		(9	)
Other states		5		(7	)
Foreign		—		—
Total net income taxes paid (net refunds received):	$	285	$	(72	)

Schedule of Reconciliation of U.S. Federal Statutory Tax Rate to Effective Tax Rate

The following table presents a reconciliation of the U.S. federal statutory tax rate to the Company's effective tax rate for the years ended December 31, 2025 and 2024, presented in accordance with ASU 2023-09 (dollars in thousands):


	Year Ended December 31, 2025						Year Ended December 31, 2024
	Amount			Percent			Amount			Percent
U.S. federal statutory tax rate	$	(40,714	)		21.0	%	$	(47,692	)		21.0	%
State and local income tax benefit, net of federal tax effect		—			—	%		—			—	%
Foreign tax effects:
Ireland		17			0.0	%		17			0.0	%
Effect of changes in tax laws or rates enacted in the current period		—			—	%		—			—	%
Effects of cross-border tax laws		—			—	%		—			—	%
Tax credits:
Research and development and orphan drug tax credits		(7,492	)		3.9	%		(9,582	)		4.2	%
Other tax credits		(27	)		0.0	%		(35	)		0.0	%
Change in valuation allowance		40,418			(20.8	)%		51,658			(22.7	)%
Nontaxable or nondeductible items:
Stock-based compensation		5,385			(2.8	)%		3,171			(1.4	)%
Executive compensation		1,440			(0.7	)%		2,633			(1.2	)%
Other		1,137			(0.7	)%		3			0.0	%
Changes in unrecognized tax benefits		(148	)		0.1	%		—			—	%
Other adjustments		(16	)		0.0	%		(173	)		0.1	%
Effective tax rate	$	—			—	%	$	—			—	%

Components of Net Deferred Tax Assets

The significant components of the Company’s net deferred tax assets were as follows (in thousands):


	As of December 31,
	2025			2024
Deferred tax assets:
Net operating loss carryforwards	$	184,528		$	105,468
Research and development tax credits		94,867			87,030
Stock-based compensation		21,250			22,687
Lease liabilities		19,372			22,278
Liability related sale of future royalties		2,951			12,148
Capitalized research and development costs		77,147			122,082
Accruals and other		7,317			5,366
Total deferred tax assets before valuation allowance		407,432			377,059
Valuation allowance		(374,413	)		(338,352	)
Total deferred tax assets		33,019			38,707
Deferred tax liabilities:
Right-of-use assets		(12,193	)		(14,293	)
Depreciation and amortization		(20,826	)		(24,414	)
Total deferred tax liabilities		(33,019	)		(38,707	)
Net deferred tax assets	$	—		$	—

Schedule of U.S. Federal and State NOL and Tax Credit Carryforwards

The following table presents the Company's U.S. federal and state NOL and tax credit carryforwards which may be available to offset future income tax liabilities (in thousands):


	As of December 31, 2025		Expiration Date (if not utilized)
U.S. federal NOL carryforwards	$	754,390	Indefinite
U.S. federal tax credit carryforwards	$	94,143	Various dates between 2037 and 2045
U.S. state NOL carryforwards	$	6,857	Indefinite
U.S. state NOL carryforwards	$	388,008	Various dates between 2029 and 2045
U.S. state tax credit carryforwards	$	1,000	Various dates between 2029 and 2032

Capitalization - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended				12 Months Ended
	Nov. 30, 2024	May 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Sep. 30, 2023	Dec. 31, 2025	Dec. 31, 2024
Schedule of Capitalization [Line Items]
Common stock, shares authorized			100,000,000			100,000,000	100,000,000
Common stock, par value			$ 0.0001			$ 0.0001	$ 0.0001
Preferred stock, shares authorized			10,000,000			10,000,000	10,000,000
Preferred stock, par value			$ 0.0001			$ 0.0001	$ 0.0001
Warrants issued						$ 1,610
Percentage of common stock owned				9.99%
Percentage of voting power				9.99%
Common stock program, terminated date					Nov. 30, 2024
Maximum [Member]
Schedule of Capitalization [Line Items]
Percentage of common stock owned				19.99%
Minimum [Member]
Schedule of Capitalization [Line Items]
Percentage of common stock owned				4.99%
May 2025 Warrants [Member] \| HCR [Member] \| 2025 Royalty Bond
Schedule of Capitalization [Line Items]
Warrants contractual term		10 years
Warrants issued		$ 1,600
Warrants exercised						0
Warrants/Prefunded Warrants remained outstanding						268,096
Number of warrants issued		268,096
Exercise price of warrants		$ 14.92
Pre-funded warrants remained outstanding						268,096
March 2024 Public Offering [Member]
Schedule of Capitalization [Line Items]
Number of shares sold				4,565,260
Purchase price of share				$ 23
March 2024 Public Offering and Pre-funded Warrants [Member]
Schedule of Capitalization [Line Items]
Net proceeds from issuance of common stock				$ 131,100
March 2024 Public Offering and Pre-funded Warrants [Member] \| Pre Funded Warrants [Member]
Schedule of Capitalization [Line Items]
Purchase price of share				$ 22.9999
Number of warrants issued				1,521,740
Exercise price of warrants				$ 0.0001
March 2024 Public Offering and Pre-funded Warrants [Member] \| March 2024 Pre-funded Warrants [Member]
Schedule of Capitalization [Line Items]
Warrants/Prefunded Warrants remained outstanding						869,603
Pre-funded warrants remained outstanding						869,603
At-the-Market Offering Programs [Member]
Schedule of Capitalization [Line Items]
Aggregate offering price			$ 150,000		$ 150,000
Common Stock [Member] \| March 2024 Pre-funded Warrants [Member]
Schedule of Capitalization [Line Items]
Number of shares sold						455,137	197,000
Common Stock [Member] \| At-the-Market Offering Programs [Member]
Schedule of Capitalization [Line Items]
Number of shares sold	0					0

Marketable Securities and Other Investments - Additional Information (Detail) € in Millions	1 Months Ended		12 Months Ended
	Jul. 31, 2021 EUR (€)	Jul. 31, 2021 USD ($)	Dec. 31, 2025 EUR (€)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 EUR (€)	Dec. 31, 2024 USD ($) Security
Debt Securities, Available-for-Sale [Line Items]
Available for sale debt securities remaining maturities greater than three years				$ 0		$ 0
Realized gains or losses on available-for-sale securities				0		$ 0
Number of investment grade fixed income debt security \| Security						9
Non-marketable equity securities				0		$ 0
Remeasurements or impairment losses on non-marketable equity securities				0		0
Investment income				12,245,000		18,729,000
Uni Qure N V [Member]
Debt Securities, Available-for-Sale [Line Items]
Proceeds from acquiring business	€ 5.3	$ 6,100,000
Revenue recognition, milestone method, revenue recognized \| €	€ 37.1				€ 5.6
Investment income						$ 6,600,000
Revenue recognition, milestone method, revenue yet to be recognized			€ 29.7	$ 35,000,000

Royalty Monetization Liabilities

12 Months Ended

Dec. 31, 2025

Royalty Monetization Liabilities [Abstract]

Royalty Monetization Liabilities

7. Royalty Monetization Liabilities

Royalty monetization liabilities are accounted for as debt and consist of the following (in thousands):


	As of December 31,
	2025		2024
2020 Royalty Purchase Agreement	$	29,672	$	59,687
2025 Royalty Bond		157,345		—
Total	$	187,017	$	59,687

Current portion of royalty monetization liabilities	$	39,609	$	34,309
Non-current portion of royalty monetization liabilities		147,408		25,378
Total	$	187,017	$	59,687

2020 Royalty Purchase Agreement

In December 2020, the Company entered into a royalty purchase agreement (the 2020 Royalty Purchase Agreement) with HCR. Under the 2020 Royalty Purchase Agreement, HCR purchased the Company’s rights to a capped amount of Zolgensma and Itvisma royalty payments under the Company’s license agreement with Novartis Gene Therapies (the Novartis License), including $4.0 million of royalty payments received by the Company in the fourth quarter of 2020. In consideration for these rights, HCR paid the Company $200.0 million (the Purchase Price), less $4.0 million representing the payment of the royalties received in the fourth quarter of 2020 to HCR. Beginning upon the effective date of the 2020 Royalty Purchase Agreement, Zolgensma and Itvisma royalty payments, up to a specified threshold, shall be paid to HCR, net of upstream royalties payable by the Company to certain licensors in accordance with existing license agreements.

Pursuant to the 2020 Royalty Purchase Agreement, the total amount of Zolgensma and Itvisma royalty payments to be paid to HCR was subject to an increasing cap (the Cap Amount) equal to (i) $260.0 million applicable for the period from the effective date of the 2020 Royalty Purchase Agreement through November 7, 2024 (the First Cap Amount), and (ii) $300.0 million applicable for the period from November 8, 2024 through the effective date of termination of the Novartis License (the Second Cap Amount). If, on or prior to the defined dates for each Cap Amount, the total amount of royalties paid to HCR equals or exceeds the Cap Amount applicable to such date, the 2020 Royalty Purchase Agreement will automatically terminate. The First Cap Amount was not achieved prior to November 7, 2024, therefore the 2020 Royalty Purchase Agreement will remain in effect until the achievement of the Second Cap Amount or the termination of the Novartis License, if earlier. The Company has no obligation to repay any amounts to HCR under the 2020 Royalty Purchase Agreement if future Zolgensma and Itvisma royalty payments are not sufficient to achieve the applicable Cap Amount prior to the termination of the Novartis License.

The Company has a call option to repurchase its rights to the royalties under the 2020 Royalty Purchase Agreement for a repurchase price equal to, as of the option exercise date, $300.0 million minus the total amount of royalty payments paid to HCR.

The proceeds received from HCR under the 2020 Royalty Purchase Agreement of $196.0 million were recorded as a liability, net of transaction costs of $3.5 million, which is amortized over the estimated life of the arrangement using the effective interest method. In order to determine the amortization of the liability, the Company is required to estimate the total amount of future royalty payments to be paid to HCR, subject to the Cap Amount, over the life of the arrangement. The total amount of royalty payments paid to HCR, less the net proceeds received by the Company of $192.5 million, is recorded as interest expense over the life of the arrangement using the effective interest method. Due to its continuing involvement in the Novartis License, the Company continues to recognize royalty revenue on net sales of Zolgensma and Itvisma and records the royalty payments to HCR as a reduction of the liability when paid. As such payments are made to HCR, the balance of the liability will be effectively repaid over the life of the arrangement.

The Company estimates the effective interest rate used to record interest expense under the 2020 Royalty Purchase Agreement based on its estimate of total Zolgensma and Itvisma royalties to be paid HCR under the arrangement. At each reporting date, the Company reassesses its estimate of total future royalty payments to be paid to HCR at the applicable Cap Amount, and prospectively adjusts the effective interest rate and amortization of the liability as necessary. Over the life of the arrangement, the actual effective interest rate will be affected by the amount and timing of royalty payments actually paid to HCR, which may differ from the Company’s forecasts. The estimated effective interest rate in effect as of December 31, 2025 and 2024 was 85.2% and 65.5%, respectively, which was based on the amortized balance of the liability and the estimated remaining royalties to be paid to HCR under the arrangement. The estimated interest rate is subject to adjustments in the future based on actual royalties paid to HCR and changes in the royalty forecast. As of December 31, 2025, the estimated effective interest rate over the life of the 2020 Royalty Purchase

Agreement, taking into account actual royalties paid to date and the estimated remaining royalties to be paid under the arrangement, was 16.3%.

The following table presents the changes in the royalty monetization liability under the 2020 Royalty Purchase Agreement with HCR (in thousands):


	2020 Royalty
	Purchase Agreement
Balance at December 31, 2023	$	94,052
Novartis royalties paid to HCR		(46,413	)
Interest expense recognized		12,048
Balance at December 31, 2024		59,687
Novartis royalties paid to HCR		(60,095	)
Interest expense recognized		30,080
Balance at December 31, 2025		29,672
Current portion		(29,672	)
Non-current portion	$	—

2025 Royalty Bond

In May 2025, the Company entered into a loan agreement with HCR pursuant to which HCR will provide the Company with an aggregate limited recourse loan of up to $250.0 million (the 2025 Royalty Bond). The 2025 Royalty Bond is disbursable to the Company in three tranches, with $150.0 million funded on the closing date in May 2025, $50.0 million available to be funded if sales of a specified product exceed a specified threshold prior to December 31, 2026, and $50.0 million available to be funded if both parties exercise an option in 2027. Loan proceeds under the 2025 Royalty Bond are funded to the Company net of an original issue discount of 2.25% and reimbursement of certain expenses to HCR. Proceeds received by the Company from the initial funding tranche of the 2025 Royalty Bond in May 2025, net of discounts and transaction costs, were $144.5 million.

Prior to the maturity date, interest and principal under the 2025 Royalty Bond shall be paid quarterly to HCR solely using proceeds received from certain specified royalties, milestone payments, license fees and other consideration payable to the Company under specified license agreements (collectively, the Royalty Interest), including (i) the Novartis License for Zolgensma and Itvisma, (ii) the collaboration and license agreement with Nippon Shinyaku for RGX-121 and RGX-111, and (iii) NAV Technology Platform license agreements with Rocket Pharmaceuticals, Inc. and Ultragenyx Pharmaceutical Inc. Zolgensma and Itvisma royalties earned under the Novartis License shall only be included in the Royalty Interest after full repayment of the applicable Cap Amount under the 2020 Royalty Purchase Agreement with HCR. The Royalty Interest excludes, and the Company retains the rights to, certain other consideration payable under the license agreements including certain milestone payments, license fees and reimbursement of costs as applicable. The Royalty Interest is payable to HCR net of upstream royalty and sublicense fee obligations payable by the Company to applicable licensors. The 2025 Royalty Bond is collateralized by a security interest and lien on the Royalty Interest.

The 2025 Royalty Bond bears interest at a rate of 9.75% plus the 3-month secured overnight financing rate as administered by the Federal Reserve Bank of New York (SOFR), with a minimum interest rate of 14.0%. Interest payments are due quarterly using proceeds received under the Royalty Interest. At each payment date, any proceeds received under the Royalty Interest in excess of the interest payment due will be applied to outstanding principal. If the proceeds received under the Royalty Interest are insufficient to pay the interest due, unpaid interest will accrue to the principal balance.

The 2025 Royalty Bond matures in May 2035, subject to potential extension, unless repaid in full at an earlier date. The maturity date may be extended by two years to May 2037 subject to a potential patent term extension of a specific patent. Upon maturity, the outstanding principal and interest shall be due and payable to HCR. Additionally, upon repayment in full prior to the maturity date, or at the maturity date, the Company shall pay to HCR an additional amount equal to 5.0% of the total outstanding principal as of the applicable determination date. Other than through the payment of proceeds received under the Royalty Interest, the 2025 Royalty Bond may not be prepaid prior to maturity.

In connection with the loan agreement for the 2025 Royalty Bond, the Company also issued HCR warrants to purchase 268,096 shares of its common stock at an exercise price per share of $14.92 (the May 2025 Warrants). The May 2025 Warrants are exercisable upon issuance and expire 10 years from the closing date of the 2025 Royalty Bond. The Company evaluated the May 2025 Warrants and concluded the warrants are indexed to the Company's common stock and meet the criteria to be classified as equity. The net proceeds received by the Company under the loan agreement of $144.5 million were allocated between the 2025 Royalty Bond and

the May 2025 Warrants based on their relative fair values. The fair value of the 2025 Royalty Bond was determined based on the carrying amount of the loan on the closing date. The fair value of the May 2025 Warrants was determined using a Black-Scholes option-pricing model on the closing date, resulting in an estimated fair value of the warrants of $1.7 million. Based on the relative fair values of these instruments, $1.6 million of the net proceeds were allocated to the warrants and recorded as additional paid-in capital. The net proceeds allocated to the 2025 Royalty Bond were $142.9 million, resulting in a total debt discount of $7.1 million which is recorded as a reduction of the carrying value of the debt and will be amortized as interest expense over the life of the 2025 Royalty Bond.

The effective interest rate of the 2025 Royalty Bond is partially estimated based on the Company's estimate of future payments under the Royalty Interest to be paid HCR. At each reporting date, the Company reassesses its estimate of total future payments to HCR under the arrangement and prospectively adjusts the effective interest rate and amortization of the debt and associated discount as necessary. Over the life of the arrangement, the actual effective interest rate will be affected by the amount and timing of the actual Royalty Interest payments to HCR and fluctuations in the variable interest rate, which may differ from the Company’s forecasts. The estimated effective interest rate in effect as of December 31, 2025 was 15.1%, which was based on the amortized balance of the liability, the current coupon rate and the estimated remaining payments to HCR under the arrangement.

The following table presents the changes in the royalty monetization liability under the 2025 Royalty Bond with HCR (in thousands):


	2025 Royalty Bond
Balance at December 31, 2024	$	—
Proceeds from royalty bond, net of discount and issuance costs		142,883
Royalty interest paid to HCR		(109	)
Portion of payments representing interest		109
Unpaid interest accrued to principal		13,449
Amortization of debt discount and issuance costs		1,013
Balance at December 31, 2025		157,345
Current portion		(9,937	)
Non-current portion	$	147,408

Nature of Business - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ (1,126,027)	$ (932,149)
Cash, cash equivalents and marketable securities	$ 240,900	$ 244,900

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Royalty Monetization Liabilities - Schedule of Royalty Monetization Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Royalty Monetization Liabilities [Line Items]
Royalty monetization liabilities	$ 187,017	$ 59,687
Royalty monetization liabilities	39,609	34,309
Royalty monetization liabilities	147,408	25,378
2020 Royalty Purchase Agreement
Royalty Monetization Liabilities [Line Items]
Royalty monetization liabilities	29,672	59,687
2025 Royalty Bond
Royalty Monetization Liabilities [Line Items]
Royalty monetization liabilities	$ 157,345	$ 0

Property and Equipment, Net - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Property Plant And Equipment [Line Items]
Total property and equipment	$ 192,047	$ 189,881
Accumulated depreciation and amortization	(87,192)	(72,292)
Property and equipment, net	104,855	117,589
Laboratory and Manufacturing Equipment [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	78,825	77,141
Computer Equipment and Software [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	4,573	4,244
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	7,039	7,031
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Total property and equipment	$ 101,610	$ 101,465

Leases - Weighted-Average Remaining Lease Term and Weighted-Average Discount Rate of Operating Leases (Detail)	Dec. 31, 2025	Dec. 31, 2024
Leases [Abstract]
Weighted-average remaining lease term (years)	9 years 9 months 18 days	10 years 3 months 18 days
Weighted-average discount rate	5.70%	5.70%

Fair Value Measurements - Schedule of Fair Value of Cash Equivalents and Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Marketable securities:
Fair Value	$ 206,389	$ 187,340
Cash Equivalents and Marketable Securities [Member]
Marketable securities:
Total cash equivalents and marketable securities	230,303	233,733
Corporate Bonds [Member]
Marketable securities:
Fair Value	123,245	141,663
Cash Equivalents [Member]
Cash equivalents:
Total cash equivalents	23,914	46,393
US Government and Agency Securities [Member]
Cash equivalents:
Total cash equivalents	2,496	2,498
Marketable securities:
Fair Value	83,144	44,215
Certificates of Deposit [Member]
Marketable securities:
Fair Value		1,462
Money Market Mutual Funds [Member] \| Cash Equivalents [Member]
Cash equivalents:
Total cash equivalents	21,418	43,895
Level 2
Marketable securities:
Fair Value	206,389	187,340
Level 2 \| Cash Equivalents and Marketable Securities [Member]
Marketable securities:
Total cash equivalents and marketable securities	230,303	233,733
Level 2 \| Corporate Bonds [Member]
Marketable securities:
Fair Value	123,245	141,663
Level 2 \| Cash Equivalents [Member]
Cash equivalents:
Total cash equivalents	23,914	46,393
Level 2 \| US Government and Agency Securities [Member]
Cash equivalents:
Total cash equivalents	2,496	2,498
Marketable securities:
Fair Value	83,144	44,215
Level 2 \| Certificates of Deposit [Member]
Marketable securities:
Fair Value		1,462
Level 2 \| Money Market Mutual Funds [Member] \| Cash Equivalents [Member]
Cash equivalents:
Total cash equivalents	$ 21,418	$ 43,895

Leases

12 Months Ended

Dec. 31, 2025

Leases [Abstract]

Leases

6. Leases

9804 Medical Center Drive

In November 2018, the Company entered into an operating lease, which has been amended from time to time, for approximately 186,000 square feet of office, laboratory and manufacturing space at 9804 Medical Center Drive in Rockville, Maryland (the 9804 Medical Center Drive Lease), which now serves as the Company’s corporate, research and manufacturing headquarters. The initial construction of the building was performed by the landlord and the lease commenced in September 2020 upon delivery of the leased premises to the Company to make additional improvements to the building. Monthly payments under the lease began in September 2021 and escalate annually in accordance with the lease agreement. The lease expires in September 2036, subject to extension and termination options held by the Company. The Company has an option to extend the term of the lease for up to 10 additional years and an option to terminate the lease, with payment of an early termination fee, after 12 years from the delivery of the leased premises to the Company. As of December 31, 2025, the Company’s extension and termination options under the 9804 Medical Center Drive Lease were excluded from the measurement of the right-of-use assets and lease liabilities as they were not reasonably certain of exercise. As required by the 9804 Medical Center Drive Lease, the Company has provided the landlord with an irrevocable letter of credit of $1.1 million which the landlord may draw upon in the event of any uncured default by the Company under the terms of the lease.

Pursuant to the 9804 Medical Center Drive Lease, the Company received a $19.5 million tenant improvement allowance from the landlord to perform improvements to the leased premises. The tenant improvement allowance was recorded as a reduction of the right-of-use assets for the lease and is amortized on a straight-line basis as a reduction of lease expense over the term of the lease. The Company began occupation of a portion of the facility upon the completion of its construction in 2021. The remaining portion of the building, primarily associated with the manufacturing facility, was activated upon the completion of its construction in 2022.

As of December 31, 2025, the Company had recorded right-of-use assets of $40.8 million and lease liabilities of $65.6 million related to the 9804 Medical Center Drive Lease.

9712 Medical Center Drive

In March 2015, the Company entered into an operating lease for office space at 9712 Medical Center Drive in Rockville, Maryland (the 9712 Medical Center Drive Lease). The lease term commenced in April 2015, and monthly payments under the lease began in October 2015 and escalate annually in accordance with the lease agreement.

The 9712 Medical Center Drive Lease has been amended from time to time to include additional office and laboratory space at an adjacent building located at 9714 Medical Center Drive and extend the term of the lease, which expires in February 2027, subject to extension options held by the Company. The Company has an option to extend the term of the lease for three additional years, as well as an option to extend the lease term to be coterminous with the 9804 Medical Center Drive Lease, which expires in September 2036. As of December 31, 2025, the Company’s extension options under the 9712 Medical Center Drive Lease were excluded from the measurement of the right-of-use assets and lease liabilities as they were not reasonably certain of exercise. The Company received a $0.4 million tenant improvement allowance from the landlord which was recorded as a reduction of the right-of-use assets for the lease and is amortized on a straight-line basis as a reduction of lease expense over the term of the lease.

As of December 31, 2025, the Company had recorded right-of-use assets of $1.8 million and lease liabilities of $2.0 million related to the 9712 Medical Center Drive Lease.

New York Lease and Sublease

In May 2016, the Company entered into an operating lease for office space in New York, New York (the New York Lease), which has since been amended to include additional office space and extend the term of the lease. The lease term commenced in July 2016 and expires in April 2027. The Company received a $0.7 million tenant improvement allowance from the landlord which was recorded as a reduction of the right-of-use assets for the lease and is amortized on a straight-line basis as a reduction of lease expense over the term of the lease. As required by the New York Lease, the Company has provided the landlord with an irrevocable letter of credit of $0.2 million which the landlord may draw upon in the event of any uncured default by the Company under the terms of the lease.

In March 2024, the Company entered into an agreement to sublease its office space under the New York Lease (the New York Sublease) to a third-party subtenant. The sublease term commenced in April 2024 and expires in April 2027 concurrent with the expiration of the New York Lease. Monthly payments under the New York Sublease commenced in July 2024 and escalate annually in accordance with the sublease agreement. As of December 31, 2025, total undiscounted future minimum lease payments to be received by the Company over the term of the New York Sublease were $0.7 million. During the years ended December 31, 2025 and 2024, the Company recognized sublease income of $0.5 million and $0.3 million, respectively, under the New York Sublease.

The New York Sublease is classified as an operating lease and the Company was not relieved of its primary obligation under the New York Lease. The Company continues to account for the New York Lease as it did prior to the commencement of the sublease.

As a result of the New York Sublease, the Company determined an impairment indicator was present as of March 31, 2024 related to the long-lived asset group subject to the sublease, which included the right-of-use asset under the New York Lease, leasehold improvements and other property and equipment allocable to the New York Sublease. The Company concluded the carrying value of the asset group as of March 31, 2024 was not recoverable, as it exceeded the sum of the estimated undiscounted cash flows to be generated by the assets over their remaining lives. The Company estimated the fair value of the asset group as of March 31, 2024 using a discounted cash flow method, which incorporated unobservable inputs including the net identifiable cash flows over the term of the New York Sublease and an estimated borrowing rate of a market participant subtenant. The estimated fair value of the asset group as of March 31, 2024 represents a Level 3 nonrecurring fair value measurement. The Company concluded the carrying value of the asset group of $3.4 million exceeded its estimated fair value of $1.3 million as of March 31, 2024. As such, the Company recognized impairment losses of $2.1 million during the year ended December 31, 2024 on the long-lived asset group associated with the New York Sublease. The impairment losses were allocated to the various assets within the long-lived asset group based on their relative carrying values and consisted of $1.4 million recorded to the right-of-use assets and $0.7 million recorded to property and equipment. No impairment losses on long-lived assets were recorded during the year ended December 31, 2025.

As of December 31, 2025, the Company had recorded right-of-use assets of $0.3 million and lease liabilities of $1.4 million related to the New York Lease.

Other Leases

In October 2022, the Company entered into an operating lease for office space in Washington, D.C. (the DC Lease). The lease term commenced in October 2022 and expires in October 2027. The Company has an option to extend the term of the lease for five additional years. As of December 31, 2025, the Company’s extension option under the DC Lease was excluded from the measurement of the right-of-use assets and lease liabilities as it was not reasonably certain of exercise. As of December 31, 2025 the Company had recorded right-of-use assets of $2.7 million and lease liabilities of $2.8 million related to the DC Lease.

The Company leases additional office, laboratory and warehousing facilities, as well as laboratory and other equipment, under operating leases with various expiration dates through 2029, including leases which have been executed but have not yet commenced.

Operating Lease Information

All of the Company’s leases are classified as operating leases. The following table summarizes the Company’s lease costs and supplemental cash flow information related to its operating leases (in thousands):


	Years Ended December 31,
	2025			2024
Operating lease cost	$	11,256		$	11,168
Variable lease cost		3,064			2,725
Sublease income		(451	)		(319	)
Total lease cost	$	13,869		$	13,574

Cash paid for amounts included in operating lease liabilities	$	13,071		$	12,969
Right-of-use assets acquired through operating lease liabilities	$	93		$	826

Short-term lease expense for the years ended December 31, 2025 and 2024 was not material and is included in operating lease cost in the table above. Variable lease cost under the Company’s operating leases includes items such as common area maintenance, utilities, taxes and other charges.

The following table presents the weighted-average remaining lease term and weighted-average discount rate of the Company’s operating leases:


	As of December 31,
	2025			2024
Weighted-average remaining lease term (years)		9.8			10.3
Weighted-average discount rate		5.7	%		5.7	%

The following table presents a reconciliation of the undiscounted future minimum lease payments remaining under the Company’s operating leases to the amounts reported as operating lease liabilities on the consolidated balance sheet as of December 31, 2025 (in thousands):


	As of
	December 31, 2025
Undiscounted future minimum lease payments:
2026	$	12,237
2027		10,020
2028		7,943
2029		8,051
2030		8,134
Thereafter		50,855
Total undiscounted future minimum lease payments		97,240
Amount representing imputed interest		(23,739	)
Total operating lease liabilities		73,501
Current portion of operating lease liabilities		(8,286	)
Operating lease liabilities, non-current	$	65,215

The table above excludes future minimum lease payments for leases which were executed but had not yet commenced as of December 31, 2025, the total of which were not material.

Net Loss Per Share - Schedules for Computation of Diluted Weighted-Average Shares Outstanding (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted weighted average shares outstanding	14,777	12,083
Stock Options Issued and Outstanding [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted weighted average shares outstanding	11,566	9,994
Unvested Restricted Stock Units Outstanding [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted weighted average shares outstanding	2,850	2,042
Employee Stock Purchase Plan [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted weighted average shares outstanding	93	47
May 2025 Warrants Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted weighted average shares outstanding	268

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2025	Feb. 27, 2026	Jun. 30, 2025
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2025
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Trading Symbol	RGNX
Entity Registrant Name	REGENXBIO Inc.
Entity Central Index Key	0001590877
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		51,612,984
Entity Public Float			$ 385,010,782
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-37553
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-1851754
Entity Address, Address Line One	9804 Medical Center Drive
Entity Address, City or Town	Rockville
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20850
City Area Code	240
Local Phone Number	552-8181
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	Specified portions of the registrant’s definitive proxy statement with respect to the registrant’s 2026 Annual Meeting of Stockholders, which is to be filed pursuant to Regulation 14A within 120 days after the end of the registrant’s fiscal year ended December 31, 2025, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Washington, District of Columbia
Auditor Firm ID	238
Auditor Opinion [Text Block]	Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of REGENXBIO Inc. and its subsidiaries (the "Company") as of December 31, 2025 and 2024, and the related consolidated statements of operations and comprehensive loss, of stockholders’ equity and of cash flows for the years then ended, including the related notes (collectively referred to as the "consolidated financial statements"). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for the years then ended in conformity with accounting principles generally accepted in the United States of America. Substantial Doubt about the Company's Ability to Continue as a Going Concern The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. As discussed in Note 1 to the consolidated financial statements, the Company has incurred cumulative losses from operations since inception, an accumulated deficit of $1.13 billion and cash outflows from operating activities that raise substantial doubt about its ability to continue as a going concern. Management's plans in regard to these matters are also described in Note 1. The consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Marketable Securities and Other Investments - Summary of Company Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost / Cost	$ 206,216	$ 187,221
Unrealized Gains	190	245
Unrealized Losses	(17)	(126)
Fair Value	206,389	187,340
U.S. Government and Agency Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost / Cost	83,085	44,281
Unrealized Gains	59	11
Unrealized Losses		(77)
Fair Value	83,144	44,215
Certificates of Deposit [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost / Cost		1,466
Unrealized Losses		(4)
Fair Value		1,462
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost / Cost	123,131	141,474
Unrealized Gains	131	234
Unrealized Losses	(17)	(45)
Fair Value	$ 123,245	$ 141,663

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Capitalization

12 Months Ended

Dec. 31, 2025

Equity [Abstract]

Capitalization

9. Capitalization

As of December 31, 2025 and 2024, the authorized capital stock of the Company included 100,000,000 shares of common stock, par value $0.0001 per share, and 10,000,000 shares of preferred stock, par value $0.0001 per share. The Company’s restated certificate of incorporation and bylaws contain the rights, preferences and privileges of the Company’s stockholders and their respective shares.

Shares of common stock reserved for future issuance were as follows (in thousands):


	As of December 31,
	2025		2024
Reserved for issuance under equity incentive plans		20,133		13,548
Reserved for issuance under employee stock purchase plan		755		913
Reserved for exercise of warrants outstanding		1,138		1,325
		22,026		15,786

May 2025 Warrants

In May 2025, in connection with issuance of the 2025 Royalty Bond, the Company issued to HCR the May 2025 Warrants to purchase 268,096 shares of its common stock at an exercise price per share of $14.92. The May 2025 Warrants are exercisable upon issuance and have a contractual term of 10 years. The Company evaluated the May 2025 Warrants and concluded the warrants are indexed to the Company's common stock, meet the criteria to be classified as equity and are not subject to remeasurement. The Company allocated $1.6 million of the net proceeds from the 2025 Royalty Bond to the issuance of the May 2025 Warrants, which were recorded as additional paid-in capital. Please refer to Note 7 for further information on the May 2025 Warrants issued in connection with the 2025 Royalty Bond. As of December 31, 2025, none of the May 2025 Warrants had been exercised and 268,096 of the May 2025 Warrants remained outstanding.

March 2024 Public Offering and Pre-funded Warrants

In March 2024, the Company completed a public offering of 4,565,260 shares of its common stock at a price of $23.00 per share and 1,521,740 pre-funded warrants (the March 2024 Pre-funded Warrants) to purchase shares of its common stock at a price of $22.9999 per pre-funded warrant, which equaled the public offering price per share of the common stock less the $0.0001 exercise price of each pre-funded warrant. The aggregate net proceeds received by the Company from the offering were $131.1 million, net of underwriting discounts and commissions and offering expenses.

The rights and privileges of the March 2024 Pre-funded Warrants are set forth in the warrant agreement between the Company and each of the respective warrant holders. The March 2024 Pre-funded Warrants are exercisable at the option of the warrant holder at any time and do not expire. However, as set forth in the warrant agreements with each holder, the number of pre-funded warrants that may be exercised at any given time may be limited if, upon exercise, the warrant holder and any of its affiliates would beneficially own more than 9.99% of the Company’s common stock, or have voting power of more than 9.99% of the Company's common stock. The limitation threshold may be increased or decreased by the warrant holder, with advance notice to the Company, to any other percentage not less than 4.99% nor in excess of 19.99%. The March 2024 Pre-funded Warrants do not provide any of the rights or privileges provided by the Company's common stock, including any voting rights, until the pre-funded warrants are exercised and settled in underlying shares of common stock.

The Company evaluated the March 2024 Pre-funded Warrants and concluded the warrants are indexed to the Company's common stock, meet the criteria to be classified as equity and are not subject to remeasurement. The proceeds received from the issuance of the pre-funded warrants were recorded as additional paid-in capital. During the years ended December 31, 2025 and 2024, the Company issued 455,137 shares and 197,000 shares, respectively, of common stock upon the exercise of March 2024 Pre-funded Warrants. As of December 31, 2025, 869,603 of the March 2024 Pre-funded Warrants remained outstanding.

At-the-Market Offering Programs

In September 2023, the Company entered into an ATM Equity OfferingSM Sales Agreement with BofA Securities, Inc. (BofA) pursuant to which the Company may offer and sell shares of its common stock having an aggregate offering price of up to $150.0 million from time to time through BofA, acting as the Company's sales agent (the BofA ATM Program). The Company terminated the BofA ATM Program effective in November 2024. No shares of common stock were sold under the BofA ATM Program prior to its termination.

In December 2024, the Company entered into a Sales Agreement with Leerink Partners LLC (Leerink) pursuant to which the Company may offer and sell shares of its common stock having an aggregate offering price of up to $150.0 million from time to time through Leerink, acting as the Company's sales agent (the Leerink ATM Program). As of December 31, 2025, no shares of common stock had been sold under the Leerink ATM Program.

- Definition

The entire disclosure for equity.

+ References

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+ Details

Income Taxes - Components of Loss Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Income Tax Disclosure [Abstract]
United States	$ (193,795)	$ (227,022)
Foreign	(83)	(80)
Loss before income taxes	$ (193,878)	$ (227,102)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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+ Details

Marketable Securities and Other Investments - Summary of Fair Values and Unrealized Losses of Marketable Securities Held by the Company in an Unrealized Loss Position for Less Than 12 months and 12 Months or Greater (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Schedule Of Available For Sale Securities [Line Items]
Less than 12 Months, Fair Value	$ 36,965	$ 21,317
Less than 12 Months, Unrealized Losses	(17)	(45)
12 Months or Greater, Fair Value		24,138
12 Months or Greater, Unrealized Losses		(81)
Total, Fair Value	36,965	45,455
Total, Unrealized Losses	(17)	(126)
U.S. Government and Agency Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 Months, Fair Value	4,676	0
Less than 12 Months, Unrealized Losses		0
12 Months or Greater, Fair Value		22,917
12 Months or Greater, Unrealized Losses		(77)
Total, Fair Value	4,676	22,917
Total, Unrealized Losses		(77)
Certificates of Deposit [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 Months, Fair Value		0
Less than 12 Months, Unrealized Losses		0
12 Months or Greater, Fair Value		1,221
12 Months or Greater, Unrealized Losses		(4)
Total, Fair Value		1,221
Total, Unrealized Losses		(4)
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 Months, Fair Value	32,289	21,317
Less than 12 Months, Unrealized Losses	(17)	(45)
12 Months or Greater, Fair Value		0
12 Months or Greater, Unrealized Losses		0
Total, Fair Value	32,289	21,317
Total, Unrealized Losses	$ (17)	$ (45)

Income Taxes

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Income Taxes

13. Income Taxes

The components of loss before income taxes were as follows (in thousands):


	Years Ended December 31,
	2025			2024
United States	$	(193,795	)	$	(227,022	)
Foreign		(83	)		(80	)
Total loss before income taxes	$	(193,878	)	$	(227,102	)

Due to taxable losses and a full valuation allowance against its deferred tax assets, the Company did not record a provision for income taxes in the U.S. (federal or state) or any foreign jurisdictions for the years ended December 31, 2025 and 2024.

Net income taxes paid (net refunds received) were as follows (in thousands):


	Years Ended December 31,
	2025		2024
Federal	$	280	$	—
State:
Maryland		—		(56	)
Illinois		—		(9	)
Other states		5		(7	)
Foreign		—		—
Total net income taxes paid (net refunds received):	$	285	$	(72	)

Beginning in 2022, the Tax Cuts and Jobs Act of 2017 (the TCJA) eliminated the option to deduct research and development expenses currently and required taxpayers to amortize such costs over a period of five years for expenses incurred in the United States and a period of 15 years for expenses incurred outside the United States. This provision of the TCJA resulted in deferred tax assets of $122.1 million as of December 31, 2024 related to capitalized research and development expenses, net of amounts amortized to date.

The One Big Beautiful Bill Act (OBBBA) was enacted in July 2025. The OBBBA amended U.S. federal tax laws by restoring the option for immediate expense recognition of research and development expenses incurred in the United States and making permanent the ability to claim 100% bonus depreciation on qualified property, among other changes. The Company currently expects to elect these options and deduct U.S. research and development expenses incurred in the current period, along with 100% bonus depreciation on eligible property placed in service, beginning in 2025. Research and development expenses incurred outside the United States will continue to be capitalized and amortized over a period of 15 years for tax purposes. Unamortized U.S. research and development expenses incurred prior to 2025 may be amortized over their remaining life, or over a period of one or two years beginning in 2025. The Company currently expects to amortize these amounts over two years beginning in 2025. The enactment of the OBBBA resulted in a decrease in deferred tax assets for capitalized research and development expenses and an increase in deferred tax assets for net operating loss (NOL) carryforwards during the year ended December 31, 2025. However, due to taxable losses and a full valuation allowance against its deferred tax assets, the enactment of the OBBBA had no material impact to the Company's income tax provision for the year ended December 31, 2025. The Company continues to evaluate the impact the OBBBA will have on its consolidated financial statements in future periods.

The Organization for Economic Co-operation and Development (OECD) has introduced BEPS Pillar 2 rules that impose a global minimum tax rate of 15%. Numerous countries enacted corresponding legislation that is effective at various dates beginning as early as January 1, 2024. These rules generally apply to multinational companies with consolidated revenue of at least €750.0 million in at least two of the four preceding fiscal years. Based on the revenue thresholds established in the BEPS Pillar 2 rules, these changes do not have an impact on the Company’s income tax provision for the years ended December 31, 2025 and 2024. Further, under administrative guidance issued in January 2026, even if the Company were to exceed the applicable revenue threshold in future periods, it would be eligible to elect the Side-by-Side Safe Harbor, which is expected to mitigate the impact of the Pillar 2 rules on the Company’s income tax provision.


	Year Ended December 31, 2025						Year Ended December 31, 2024
	Amount			Percent			Amount			Percent
U.S. federal statutory tax rate	$	(40,714	)		21.0	%	$	(47,692	)		21.0	%
State and local income tax benefit, net of federal tax effect		—			—	%		—			—	%
Foreign tax effects:
Ireland		17			0.0	%		17			0.0	%
Effect of changes in tax laws or rates enacted in the current period		—			—	%		—			—	%
Effects of cross-border tax laws		—			—	%		—			—	%
Tax credits:
Research and development and orphan drug tax credits		(7,492	)		3.9	%		(9,582	)		4.2	%
Other tax credits		(27	)		0.0	%		(35	)		0.0	%
Change in valuation allowance		40,418			(20.8	)%		51,658			(22.7	)%
Nontaxable or nondeductible items:
Stock-based compensation		5,385			(2.8	)%		3,171			(1.4	)%
Executive compensation		1,440			(0.7	)%		2,633			(1.2	)%
Other		1,137			(0.7	)%		3			0.0	%
Changes in unrecognized tax benefits		(148	)		0.1	%		—			—	%
Other adjustments		(16	)		0.0	%		(173	)		0.1	%
Effective tax rate	$	—			—	%	$	—			—	%

The significant components of the Company’s net deferred tax assets were as follows (in thousands):


	As of December 31,
	2025			2024
Deferred tax assets:
Net operating loss carryforwards	$	184,528		$	105,468
Research and development tax credits		94,867			87,030
Stock-based compensation		21,250			22,687
Lease liabilities		19,372			22,278
Liability related sale of future royalties		2,951			12,148
Capitalized research and development costs		77,147			122,082
Accruals and other		7,317			5,366
Total deferred tax assets before valuation allowance		407,432			377,059
Valuation allowance		(374,413	)		(338,352	)
Total deferred tax assets		33,019			38,707
Deferred tax liabilities:
Right-of-use assets		(12,193	)		(14,293	)
Depreciation and amortization		(20,826	)		(24,414	)
Total deferred tax liabilities		(33,019	)		(38,707	)
Net deferred tax assets	$	—		$	—

The Company evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets as of December 31, 2025 and 2024. Based on the Company’s history of operating losses, and other relevant facts and circumstances, the Company concluded that it was more likely than not that the benefit of its deferred tax assets will not be realized. Accordingly, the Company provided a full valuation allowance for its deferred tax assets as of December 31, 2025 and 2024. The valuation allowance increased by $36.1 million and $57.9 million during the years ended December 31, 2025 and 2024, respectively. The increase in the valuation allowance during the year ended December 31, 2025 was due primarily to federal and state NOLs and research and development tax credits generated during the period, partially offset by a decrease in capitalized research and development expenses as a result of the enactment of the OBBBA. The increase in the valuation allowance during the year ended December 31, 2024 was

due primarily to an increase in capitalized research and development expenses, and federal and state NOLs and research and development tax credits generated during the period.

The following table presents the Company's U.S. federal and state NOL and tax credit carryforwards which may be available to offset future income tax liabilities (in thousands):


	As of December 31, 2025		Expiration Date (if not utilized)
U.S. federal NOL carryforwards	$	754,390	Indefinite
U.S. federal tax credit carryforwards	$	94,143	Various dates between 2037 and 2045
U.S. state NOL carryforwards	$	6,857	Indefinite
U.S. state NOL carryforwards	$	388,008	Various dates between 2029 and 2045
U.S. state tax credit carryforwards	$	1,000	Various dates between 2029 and 2032

As of December 31, 2025, the Company had U.S. federal and state research and development tax credit carryforwards of approximately $95.1 million which may be available to reduce future income tax liabilities. The calculation of these credits requires assumptions to be made by the Company to estimate qualified research expenses. The Company conducts formal studies to document the qualified activities and expenses used to calculate these credits however a portion of these credits may be subject to future examinations which have not yet occurred, the results of which may result in an adjustment to the Company’s credit carryforwards. The Company accounts for uncertain tax positions in accordance with the requirements of ASC 740, and recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. Further, a full valuation allowance has been provided against the net credit carryforwards and, if an adjustment is required upon the completion of the study, this adjustment would be offset by an adjustment to the deferred tax asset established for the research and development credit carryforwards and the valuation allowance. As of December 31, 2024, the Company had total unrecognized tax benefits of $0.1 million which were reserved against its research and development tax credit carryforwards as uncertain tax positions. The Company released all of its reserves for unrecognized tax benefits during the year ended December 31, 2025 due to the expiration of the associated statute of limitations, and had no unrecognized tax benefits as of December 31, 2025.

Under the provisions of the Internal Revenue Code, the Company’s NOL and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL and tax credit carryforwards may be subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has completed several financings since its inception which may have resulted in a change in control as defined by Sections 382 and 383 of the Internal Revenue Code, or could result in a change in control in the future.

The Company and its subsidiaries file income tax returns in the United States, at the federal level and in various states, and in foreign jurisdictions. The U.S. federal and state income tax returns are generally subject to tax examinations for the tax years ended December 31, 2021 onward. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service or state tax authorities to the extent utilized in a future period.

- Definition

The entire disclosure for income tax.

+ References

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+ Details

Segment and Geographical Information (Tables)

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Segment Information

The following table presents information about the Company's segment revenues, significant segment expenses regularly provided to the CODM, other segment items and consolidated net income (loss) (in thousands):


	Years Ended December 31,
	2025			2024
Revenues	$	170,441		$	83,328
Less:
Cost of license and royalty revenues		20,298			33,567
Research and development expense
Personnel		73,508			65,950
Direct development and support (a)		112,887			97,951
Facilities		11,276			11,410
Stock-based compensation		15,977			17,985
Depreciation and amortization		14,651			15,226
Total research and development expense		228,299			208,522
General and administrative expense
Personnel		22,793			20,816
Other general and administrative (b)		35,018			29,480
Facilities		5,502			4,856
Stock-based compensation		18,586			20,478
Depreciation and amortization		964			989
Total general and administrative expense		82,863			76,619
Other segment items (c)		(32,859	)		8,278
Net loss	$	(193,878	)	$	(227,102	)

(a)

Direct development and support includes external goods and services for the development of product candidates and early-stage research activities, laboratory costs, consulting, development cost reimbursement to and from collaborators and other expenses in support of research and development activities.

(b)

Other general and administrative expenses include professional and administrative services, consulting, commercial cost reimbursement to and from collaborators and other corporate overhead expenses.

(c)

Other segment items include credit losses (recoveries), impairment of long-lived assets, other operating expenses, interest income from licensing, investment income and interest expense.

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Significant Accounting Policies [Line Items]
Accrued interest or penalties related to uncertain tax positions	$ 0	$ 0
Unrecognized tax benefits	0	0
Accumulated deficit	(1,126,027,000)	(932,149,000)
Foreign currency transaction losses	$ (100,000)	(900,000)
Non-Marketable Equity Securities [Member]
Significant Accounting Policies [Line Items]
Percentage of ownership interest	20.00%
Software and Software Development Costs \| Cloud Computing Arrangements
Significant Accounting Policies [Line Items]
Amortization of capitalized costs		1,000,000
Capitalized costs net	$ 100,000
Maximum [Member] \| Software and Software Development Costs \| Cloud Computing Arrangements
Significant Accounting Policies [Line Items]
Amortization of capitalized costs	$ 100,000
Capitalized costs net		$ 100,000

Segment and Geographical Information - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Revenue, Major Customer [Line Items]
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]	srt:ChiefExecutiveOfficerMember
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description	The Company’s CODM, its Chief Executive Officer, views the Company’s operations and manages the business as one operating segment focused on the development and commercialization of gene therapies to treat an array of diseases.
Cash, cash equivalents and marketable securities	$ 240.9	$ 244.9
Interest income from investments	$ 12.2	$ 12.1
Customer Concentration Risk [Member] \| JAPAN \| Revenue [Member]
Revenue, Major Customer [Line Items]
Concentration risk percentage	44.00%
Customer Concentration Risk [Member] \| UNITED STATES \| Revenue [Member]
Revenue, Major Customer [Line Items]
Concentration risk percentage	25.00%	36.00%
Customer Concentration Risk [Member] \| GERMANY \| Revenue [Member]
Revenue, Major Customer [Line Items]
Concentration risk percentage		10.00%
Customer Concentration Risk [Member] \| UNITED ARAB EMIRATES \| Revenue [Member]
Revenue, Major Customer [Line Items]
Concentration risk percentage		10.00%
Customer Concentration Risk [Member] \| Other Countries \| Revenue [Member] \| Maximum [Member]
Revenue, Major Customer [Line Items]
Concentration risk percentage	10.00%	10.00%

License and Collaboration Agreements

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

License and Collaboration Agreements

10. License and Collaboration Agreements

License and Collaboration Revenues

As of December 31, 2025, the Company’s NAV Technology Platform was being applied by NAV Technology Licensees in two commercial products, Zolgensma and Itvisma, and in the development of various other licensed products. Additionally, the Company has licensed intellectual property rights to collaborators for the joint development and commercialization of certain product candidates. Consideration payable to the Company under its license and collaboration agreements may include: (i) up-front and annual fees, (ii) milestone payments based on the achievement of certain development and sales-based milestones, (iii) sublicense fees, (iv) royalties on sales of licensed products, (v) fees for services related to the development and manufacturing of licensed products and (vi) other consideration payable upon optional goods and services purchased by licensees and collaborators. Sublicense fees vary by license and range from a mid-single digit percentage to a low-double digit percentage of license fees received by licensees as a result of sublicenses. Royalties on net sales of commercialized products vary by license and range from a mid-single digit percentage to a low double-digit percentage of net sales by licensees.

Revenues earned under license and collaboration agreements consisted of the following (in thousands):


	Years Ended December 31,
	2025		2024
License and royalty revenue:
Zolgensma and Itvisma royalties	$	83,177	$	81,505
Nippon Shinyaku licenses		72,903		—
Other		187		455
Total license and royalty revenue		156,267		81,960
Service revenue:
Nippon Shinyaku services		11,822		—
Other		2,352		1,368
Total service revenue		14,174		1,368
Total revenues	$	170,441	$	83,328

Outstanding development milestone payments are evaluated each reporting period and are only included in the transaction price of each license to the extent the milestones are considered probable of achievement. Sales-based milestones are excluded from the transaction price of each license agreement and recognized as royalty revenue in the period of achievement. As of December 31, 2025, the Company’s license and collaboration agreements contained unachieved milestones which could result in aggregate milestone payments to the Company of up to $2.18 billion, including (i) $546.7 million upon the commencement of various stages of clinical trials, (ii) $106.3 million upon the submission of regulatory approval filings or upon regulatory approval of licensed products, and (iii) $1.53 billion upon the achievement of specified sales targets for licensed products, including milestones payable upon the first commercial sale of licensed products. To the extent the Company realizes the milestone payments, the Company may be obligated to pay sublicense fees to licensors based on a specified percentage of the fees earned by the Company. The achievement of these milestones is highly dependent on the successful development and commercialization of licensed products and it is at least reasonably possible that some or all of the milestone fees will not be realized by the Company.

Accounts Receivable, Contract Assets and Deferred Revenue


	Years Ended December 31,
	2025		2024
Accounts receivable, net, current and non-current:
Beginning of period	$	20,947	$	25,491
End of period	$	28,691	$	20,947

Contract assets:
Beginning of period	$	239	$	—
End of period	$	104	$	239

Deferred revenue, current and non-current:
Beginning of period	$	115	$	148
End of period	$	29,395	$	115

Revenue recognized during the period from:
Amounts included in deferred revenue at beginning of period	$	115	$	148
Performance obligations satisfied in previous periods	$	84,684	$	81,585

Revenue recognized from performance obligations satisfied in previous periods, as presented in the table above, was primarily attributable to Zolgensma and Itvisma royalties and changes in the transaction prices of the Company’s license agreements. Changes in transaction prices were primarily attributable to development milestones achieved or deemed probable of achievement during the periods, resulting in a cumulative catch-up adjustment to revenue. Revenue recognized during the year ended December 31, 2025, included $1.5 million in cumulative catch-up adjustments for changes in the probability of achievement of development milestones. No cumulative catch-up adjustments for development milestones were recorded in revenue during the year ended December 31, 2024.

As of December 31, 2025, the Company had recorded deferred revenue of $29.4 million which represents consideration received or unconditionally due from licensees and collaboration partners for performance obligations that have not yet been satisfied by the Company. Unsatisfied performance obligations as of December 31, 2025 consisted of (i) development services to be performed related to licensed products, which will be satisfied as the services are performed, and (ii) material rights granted to purchase commercial supply of licensed products, which will be satisfied upon delivery of the commercial supply. As of December 31, 2025, the aggregate transaction price of the Company’s license and collaboration agreements allocated to performance obligations not yet satisfied or partially satisfied was $30.4 million, primarily associated with development services under the Company's collaboration and license agreement with Nippon Shinyaku, the substantial majority of which is expected to be satisfied over a period of approximately five years.

Accounts receivable consisted of the following (in thousands):


	As of December 31,
	2025		2024
Current accounts receivable:
Billed to customers	$	557	$	65
Unbilled Novartis royalties		23,806		20,106
Unbilled Nippon Shinyaku services		1,997		—
Other unbilled		19		302
Current accounts receivable		26,379		20,473
Non-current accounts receivable:
Unbilled Nippon Shinyaku services		1,858		—
Other unbilled		454		474
Non-current accounts receivable		2,312		474
Total accounts receivable	$	28,691	$	20,947

The following table presents the changes in the allowance for credit losses related to accounts receivable and contract assets for the years ended December 31, 2025 and 2024 (in thousands):


	Allowance for Credit Losses
	Accounts Receivable			Contract Assets
Balance at December 31, 2023	$	4,587		$	—
Provision for credit losses		—			—
Changes in present value discount of receivables		413			—
Credit recoveries		(5,000	)		—
Balance at December 31, 2024		—			—
Provision for credit losses		—			—
Changes in present value discount of receivables		—			—
Credit recoveries		—			—
Balance at December 31, 2025	$	—		$	—

The Company’s allowance for credit losses during the year ended December 31, 2024 was related solely to accounts receivable from Abeona Therapeutics Inc. (Abeona). Please refer to the section below, "Settlement Agreement with Abeona Therapeutics," for further information regarding amounts due from Abeona and the associated allowance for credit losses.

Zolgensma and Itvisma License with Novartis Gene Therapies

In March 2014, the Company entered into an exclusive license agreement (as amended, the Novartis License) with Novartis Gene Therapies. Under the Novartis License, the Company granted Novartis Gene Therapies an exclusive, worldwide commercial license, with rights to sublicense, to the NAV Technology Platform, as well as other certain rights, for the treatment of SMA in humans by in vivo gene therapy.

In consideration for the rights granted under the license, Novartis Gene Therapies paid the Company (i) an up-front fee of $2.0 million upon the execution of the agreement in 2014, (ii) license fees totaling $180.0 million upon the amendment of the agreement in January 2018 and the subsequent acquisition of AveXis, Inc. (now Novartis Gene Therapies) by Novartis in May 2018, (iii) total cumulative payments of $12.3 million upon the achievement of various development milestones, and (iv) a sales-based milestone payment of $80.0 million upon the achievement of $1.0 billion in cumulative net sales of Zolgensma in 2020. In addition to the consideration above, Novartis Gene Therapies is obligated to pay to the Company fixed annual fees, royalties on net sales of licensed products and a percentage of any sublicense fees received by Novartis Gene Therapies from sublicensees for the licensed intellectual property rights. Royalties are payable by Novartis Gene Therapies at a mid-single to low double-digit percentage of net sales of licensed products using the NAV AAV9 vector, and a low double-digit percentage of net sales of licensed products using a licensed vector other than NAV AAV9, and are subject to reduction in specified circumstances. All development and sales-based milestones under the Novartis License have been achieved and there are no further milestone payments payable to the Company under the license agreement.

In 2019, Novartis Gene Therapies launched commercial sales of Zolgensma for the treatment of SMA in patients under the age of two years old. In the fourth quarter of 2025, Novartis Gene Therapies launched commercial sales of Itvisma for the treatment of SMA in patients two years and older. Zolgensma and Itvisma are licensed products under the Novartis License, pursuant to which the Company receives royalties on net sales of the licensed products.

The Company recognized the following amounts under the Novartis License (in thousands):


	Years Ended December 31,
	2025		2024
Zolgensma royalties	$	82,536	$	81,505
Itvisma royalties		641		—
Other license revenue		—		28
Total license and royalty revenue	$	83,177	$	81,533

Interest income from licensing	$	41	$	123

As of December 31, 2025 and 2024, the Company had recorded total accounts receivable of $24.1 million and $20.4 million, respectively, from Novartis Gene Therapies under the Novartis License, which consisted primarily of Zolgensma and Itvisma royalties receivable. Royalties receivable from Novartis recorded as of December 31, 2025 included $18.3 million expected to be paid to HCR in accordance with the 2020 Royalty Purchase Agreement discussed in Note 7.

Settlement Agreement with Abeona Therapeutics

In November 2021, the Company entered into a settlement agreement and mutual release with Abeona (the Settlement Agreement) related to claims associated with a license agreement between the parties which was terminated in May 2020. The Settlement Agreement resolved all arbitration and legal proceedings and mutually released each party from any and all claims under the terminated license agreement. Pursuant to the Settlement Agreement, Abeona paid the Company a total of $30.0 million as follows: (i) $20.0 million paid in November 2021, (ii) $5.0 million paid in November 2022, and (iii) $5.0 million paid in November 2024. As of December 31, 2025 and 2024, all amounts due from Abeona under the Settlement Agreement had been paid in full and no further amounts were due to the Company from Abeona.

As of December 31, 2023, the Company had recorded accounts receivable of $4.6 million associated with the remaining amounts due from Abeona under the Settlement Agreement, which consisted of the $5.0 million payment due by November 2024, net of discount to present value. Based on the Company's evaluation of Abeona's credit profile and financial condition, and its expectations regarding Abeona's future cash flows and ability to satisfy the contractual obligations of the Settlement Agreement, the Company recorded an allowance for credit losses of $4.6 million as of December 31, 2023 related to the accounts receivable due from Abeona. Prior to collection, the present value discount of the Abeona receivable was accreted as interest income from licensing through the contractual due date using the effective interest method. The Company elected to record increases in the allowance for credit losses associated with the accretion of the present value discount as a reduction of the associated interest income, resulting in no interest income recognized related to the accretion of the present value discount. The Company collected the final payment of $5.0 million due from Abeona under the Settlement Agreement upon its contractual due date in November 2024. As a result of the full collection of the receivable, the Company recorded a credit recovery of $5.0 million during the year ended December 31, 2024 against the associated allowance for credit losses.

Collaboration Agreements

AbbVie Collaboration and License Agreement

In September 2021, the Company entered into a collaboration and license agreement with AbbVie Global Enterprises Ltd. (AbbVie), a subsidiary of AbbVie Inc., to jointly develop and commercialize ABBV-RGX-314, the Company’s product candidate for the treatment of wet AMD, DR and other chronic retinal diseases (as amended, the AbbVie Collaboration Agreement). The AbbVie Collaboration Agreement became effective in November 2021.

Pursuant to the AbbVie Collaboration Agreement, the Company granted AbbVie a co-exclusive license to develop and commercialize ABBV-RGX-314 in the United States and an exclusive license to develop and commercialize ABBV-RGX-314 outside the United States. The Company and AbbVie will collaborate to develop ABBV-RGX-314 in the United States, and AbbVie will be responsible for the development of ABBV-RGX-314 in specified markets outside the United States. Global development expenses for ABBV-RGX-314 are shared by the parties in accordance with the AbbVie Collaboration Agreement, with AbbVie being responsible for the majority of total development expenses.

The Company will lead the manufacturing of ABBV-RGX-314 for clinical development and U.S. commercial supply, and AbbVie will lead the manufacturing of ABBV-RGX-314 for commercial supply outside the United States. Manufacturing expenses will be allocated between the parties in accordance with the terms of the AbbVie Collaboration Agreement and mutually agreed supply agreements. If requested by AbbVie, the Company will manufacture up to a specified portion of ABBV-RGX-314 commercial supply for sales outside the United States at a price specified in the agreement. AbbVie will lead the commercialization of ABBV-RGX-314 globally, and the Company will participate in U.S. commercialization efforts as provided under a commercialization plan determined in accordance with the agreement. The Company and AbbVie will share equally in the net profits and net losses associated with the commercialization of ABBV-RGX-314 in the United States. Outside the United States, AbbVie will be responsible, at its sole cost, for the commercialization of ABBV-RGX-314.

In consideration for the rights granted under the AbbVie Collaboration Agreement, AbbVie paid the Company an up-front fee of $370.0 million upon the effective date of the agreement in November 2021 and is required to pay to the Company up to $1.38 billion upon the achievement of specified development and sales-based milestones, of which $562.5 million are based on development milestones and $820.0 million are sales-based milestones. AbbVie is also required to pay to the Company tiered royalties on net sales of ABBV-RGX-314 outside the United States at percentages in the mid-teens to low twenties, subject to specified offsets and reductions.

In August 2025, the Company and AbbVie entered into an amendment to the AbbVie Collaboration Agreement which modified the development plan and milestone payment structure for the ABBV-RGX-314 DR program. Under the amendment, the Company will conduct the first registration enabling trial for DR suprachoroidal (SCS) treatment as a combined Phase IIb/III trial (NAAVIGATE) which will be performed in two parts (Part 1 and Part 2), and AbbVie will conduct the second registration enabling trial as a separate, standalone Phase III trial. In lieu of a $200.0 million development milestone payable to the Company under the original AbbVie Collaboration Agreement upon first patient dosed in the first registration enabling trial for DR SCS treatment, AbbVie will pay the Company $100.0 million upon first patient dosed in the NAAVIGATE trial and an additional $100.0 million upon first patient dosed in the subsequent Phase III trial. Also pursuant to the amendment, AbbVie will lead a new Phase III randomized controlled study (ACHIEVE) to assess the injection burden, adverse events, change in disease activity, and long-term preservation of visual acuity of ABBV-RGX-314 in adult participants with neovascular AMD. The Company will be responsible for its development expenses to conduct Part 1 of the NAAVIGATE trial and the parties will share the development expenses related to Part 2 of the NAAVIGATE trial and the subsequent Phase III trial for DR in accordance with the existing terms of the AbbVie Collaboration Agreement. AbbVie will be responsible for all development expenses related to the ACHIEVE study.

The AbbVie Collaboration Agreement contains provisions for termination, including termination for convenience by AbbVie. Contemporaneously with entering into the AbbVie Collaboration Agreement, the Company entered into a sublicense agreement with AbbVie (the AbbVie Sublicense Agreement) pursuant to which the Company granted AbbVie an exclusive sublicense to exploit licensed products in connection with the AbbVie Collaboration Agreement under specified patents licensed to the Company by Penn. The AbbVie Sublicense Agreement became effective contemporaneously with the AbbVie Collaboration Agreement in November 2021 and is coterminous with the AbbVie Collaboration Agreement.

The Company evaluated its various commitments under the AbbVie Collaboration Agreement and identified the following distinct units of account: (i) delivery of an intellectual property license for the rights to develop and commercialize ABBV-RGX-314 globally, (ii) development, manufacturing and commercialization activities for ABBV-RGX-314 in the United States, and (iii) manufacturing of commercial supply for sales of ABBV-RGX-314 outside the United States, if requested by AbbVie. In determining the distinct units of account, the Company concluded that the license granted to AbbVie to develop and commercialize ABBV-RGX-314 is distinct from the other goods and services promised under the agreement, as AbbVie can benefit from the license on a standalone basis and, based on the stage of development of ABBV-RGX-314, the underlying licensed products and know-how are not expected to be significantly modified as a result of other goods and services promised under the agreement.

For each of the distinct units of account identified under the AbbVie Collaboration Agreement, the Company determined whether the transactions should be accounted for as a contract with a customer within the scope of ASC 606 or as a collaborative arrangement within the scope of ASC 808. The Company concluded that the units of account for the delivery of the functional intellectual property license and the manufacturing of commercial supply for sales of ABBV-RGX-314 outside the United States should be accounted for as revenue under ASC 606, as AbbVie is deemed to be a customer for these transactions. The Company concluded that the unit of account for development, manufacturing and commercialization activities for ABBV-RGX-314 in the United States should be accounted for as a collaborative arrangement under ASC 808, as these represent joint operating activities for which the Company and AbbVie are both active participants and exposed to significant risks and rewards dependent on the commercial success of such activities.

The Company applied the requirements of ASC 606 to the AbbVie Collaboration Agreement for the units of account in which AbbVie was deemed to be a customer. The Company determined that there is only one material performance obligation under the agreement for the delivery of the intellectual property license to develop and commercialize ABBV-RGX-314 globally. The intellectual property licensed to AbbVie includes the rights to certain patents, data, know-how and other rights developed and owned by the Company, as well as other intellectual property rights exclusively licensed by the Company from various third parties. The Company evaluated options granted to AbbVie under the agreement and determined that the options do not represent material rights, and therefore are not considered separate performance obligations under the current arrangement. Specifically, the Company concluded that the option granted to AbbVie to purchase commercial supply of ABBV-RGX-314 from the Company for a portion of sales outside the United States does not convey a material right, as the option is not priced at an incremental discount to the standalone selling price of the underlying goods and services. Additionally, the Company identified various promises under the AbbVie Collaboration Agreement which were determined to be immaterial in the context of the contract and will not be accounted for as separate performance obligations.

As of December 31, 2025 and 2024, the transaction price of the AbbVie Collaboration Agreement was $370.0 million, which consisted solely of the up-front payment received from AbbVie in November 2021. The $370.0 million transaction price was fully recognized as revenue upon the delivery of the license to AbbVie in November 2021. Variable consideration under the AbbVie Collaboration Agreement, which has been excluded from the transaction price, includes $562.5 million in payments for development milestones that have not yet been achieved and were not considered probable of achievement. Additionally, the transaction price excludes sales-based milestone payments of $820.0 million and royalties on net sales of ABBV-RGX-314 outside the United States. Development milestones will be added to the transaction price and recognized as revenue upon achievement, or if deemed probable of achievement. In accordance with the sale- or usage-based royalty exception under ASC 606, royalties on net sales and sales-based milestones will be recognized as revenue in the period the underlying sales occur or milestones are achieved. There were no changes in the transaction price of the AbbVie Collaboration Agreement, and no revenue was recognized, during the years ended December 31, 2025 and 2024.

The Company applied the requirements of ASC 808 to the AbbVie Collaboration Agreement for the units of account which were deemed to be a collaborative arrangement. Both the Company and AbbVie will perform various activities related to the development, manufacturing and commercialization of ABBV-RGX-314 in the United States. Development costs are shared between the parties in accordance with the terms of the AbbVie Collaboration Agreement, and the parties will share equally in the net profits and losses derived from sales of ABBV-RGX-314 in the United States. The Company accounts for payments to and from AbbVie for the sharing of development and commercialization costs in accordance with its accounting policy for collaborative arrangements. Amounts owed to AbbVie for the Company’s share of development costs or commercialization costs incurred by AbbVie are recorded as research and development expense or general and administrative expense, respectively, in the period the costs are incurred. Amounts owed to the Company for AbbVie’s share of development costs or commercialization costs incurred by the Company are recorded as a reduction of research and development expense or general and administrative expense, respectively, in the period the costs are incurred. At the end of each reporting period, the Company records a net amount due to or from AbbVie as a result of the cost-sharing arrangement. As of December 31, 2025 and 2024, the Company had recorded $10.9 million and $11.3 million, respectively, due from AbbVie for net reimbursement of costs incurred for activities performed under AbbVie Collaboration Agreement, which was included in other current assets on the consolidated balance sheets.

The Company recognized the following amounts under the AbbVie Collaboration Agreement (in thousands):


	Years Ended December 31,
	2025			2024
Net cost reimbursement to (from) AbbVie included in:
Research and development expense	$	(60,222	)	$	(78,316	)
General and administrative expense		2,678			1,866
Total net cost reimbursement to (from) AbbVie	$	(57,544	)	$	(76,450	)

Nippon Shinyaku Collaboration and License Agreement

In January 2025, the Company entered into a collaboration and license agreement with Nippon Shinyaku for the development and commercialization of RGX-121, the Company’s product candidate for the treatment of MPS II, and RGX-111, the Company's product candidate for the treatment of MPS I (the Nippon Shinyaku Collaboration Agreement). The Nippon Shinyaku Collaboration Agreement became effective in March 2025.

Pursuant to the Nippon Shinyaku Collaboration Agreement, the Company granted Nippon Shinyaku a license to develop and exclusively commercialize RGX-121 and RGX-111 in the United States and certain countries in Asia. The Company is responsible for the development of RGX-121 and RGX-111 in the United States, and Nippon Shinyaku is responsible for development in licensed territories outside the United States. The Company is responsible for the manufacturing of RGX-121 and RGX-111 for clinical development and commercial supply, and manufacturing expenses will be allocated between the parties in accordance with the terms of the Nippon Shinyaku Collaboration Agreement and mutually agreed supply agreements. Nippon Shinyaku will be responsible, at its sole cost, for the commercialization of RGX-121 and RGX-111 in the licensed territories. The Company reserves the right to develop and commercialize RGX-121 and RGX-111 in countries outside the licensed territories. The Nippon Shinyaku Collaboration Agreement contains provisions for termination, including termination for convenience by Nippon Shinyaku.

In consideration for the rights granted and services to be performed under the Nippon Shinyaku Collaboration Agreement, Nippon Shinyaku paid the Company an up-front fee of $110.0 million upon the effective date of the agreement in March 2025 and is required to pay to the Company up to $700.0 million upon the achievement of specified development and sales-based milestones, of which $40.0 million are based on development milestones and $660.0 million are sales-based milestones. Nippon Shinyaku is also

required to pay to the Company double-digit royalties on net sales of RGX-121 and RGX-111 in the licensed territories, subject to specified offsets and reductions. The Company retains all rights to, and any proceeds related to the sale of, any priority review vouchers that may be issued upon the potential approvals of RGX-121 and RGX-111.

The Company evaluated its various commitments under the Nippon Shinyaku Collaboration Agreement and identified the distinct units of account under the arrangement. For each of the distinct units of account identified, the Company determined whether the transactions should be accounted for as a contract with a customer within the scope of ASC 606 or as a collaborative arrangement within the scope of ASC 808. The Company concluded that each of the distinct units of account identified should be accounted for as revenue under ASC 606, as Nippon Shinyaku is deemed to be a customer for each of the various transactions. The Company identified the following material performance obligations under the agreement: (i) delivery of intellectual property licenses to develop and commercialize RGX-121 and RGX-111 in the United States and Asia territories, (ii) development services for RGX-121 and RGX-111 in the United States, including manufacturing of clinical supply and commercial supply prior to regulatory approval, and (iii) material rights granted to Nippon Shinyaku to purchase commercial supply for sales in licensed territories.

The intellectual property licensed to Nippon Shinyaku includes the rights to certain patents, data, know-how and other rights developed and owned by the Company, as well as other intellectual property rights exclusively licensed by the Company from various third parties. In determining the distinct performance obligations under the agreements, the Company concluded that the licenses granted to Nippon Shinyaku to develop and commercialize RGX-121 and RGX-111 are distinct from the other goods and services promised under the agreement, as Nippon Shinyaku can benefit from the licenses on a standalone basis and, based on the stage of development of the product candidates, the underlying licensed products and know-how are not expected to be significantly modified as a result of other goods and services promised under the agreement. The Company evaluated all options granted to Nippon Shinyaku under the agreement to determine whether the options represent material rights. Management concluded the options to purchase commercial supply convey material rights granted to Nippon Shinyaku, and therefore are accounted for as separate performance obligations under the current arrangement. The Company identified various promises under the Nippon Shinyaku Collaboration Agreement which were determined to be immaterial in the context of the contract and will not be accounted for as separate performance obligations.

As of December 31, 2025, the transaction price of the Nippon Shinyaku Collaboration Agreement included fixed consideration of $110.0 million for the up-front payment and variable consideration of $4.1 million for estimated reimbursable costs of manufacturing and other services which are deemed not to be constrained. Variable consideration which has been excluded from the transaction price includes $40.0 million in payments for development milestones that have not yet been achieved and were not considered probable of achievement, and reimbursable costs of manufacturing and other services which are contingent on events occurring that are outside the Company’s control and are deemed to be constrained. The transaction price also excludes sales-based milestone payments of $660.0 million and royalties on net sales of RGX-121 and RGX-111 in the United States and Asia territories. Development milestones will be added to the transaction price upon achievement, or if deemed probable of achievement, and other variable consideration for manufacturing and other services may be added to the transaction price in the future as uncertainties regarding payment of the consideration are resolved. In accordance with the sale- or usage-based royalty exception under ASC 606, royalties on net sales and sales-based milestones will be recognized as revenue in the period the underlying sales occur or milestones are achieved. There were no changes in the fixed transaction price of the Nippon Shinyaku Collaboration Agreement between the effective date of the agreement and December 31, 2025.

The fixed transaction price of the Nippon Shinyaku Collaboration Agreement of $110.0 million was allocated to the various performance obligations based on their relative standalone selling prices, which requires significant judgment. The selling prices of the intellectual property licenses were determined based on discounted cash flow models for each of the licensed products in the respective licensed territories and were adjusted for the probability of developmental, regulatory and commercial success. Significant assumptions and judgments were required to estimate the future cash flows, including the addressable market, sales price per unit, discount rates and probabilities of success for each of the licensed products and territories. The selling prices of development services and commercial supply were determined based on the expected cost plus a reasonable margin. The selling prices of the material rights to purchase commercial supply were determined based on the incremental discount to the standalone selling prices of the commercial supply and were adjusted to consider the likelihood of exercise of the material rights. Significant assumptions and judgments were required to estimate the future costs of development and manufacturing, an appropriate margin for such services, and the likelihood of exercise of the material rights to purchase commercial supply. The $4.1 million of variable consideration included in the transaction price is allocated directly to performance obligations for the manufacturing of commercial supply prior to regulatory approval and other service obligations since the consideration is directly associated with the performance of such services and reimbursement of applicable costs. Consideration contingent upon the future exercise of options to purchase commercial supply is excluded from the transaction price until exercised.

The portion of the $110.0 million fixed transaction price allocated to the delivery of the intellectual property licenses was recognized as license and royalty revenue upon the delivery of the licenses to Nippon Shinyaku in March 2025. The portion of the fixed transaction price allocated to development services will be recognized as service revenue as the services are performed using an input method based on costs incurred versus total estimated costs to perform the services, which is re-assessed at each reporting date. The portion of the fixed transaction price allocated to material rights to purchase commercial supply will be recognized as revenue proportionally with the total expected commercial supply revenue expected to be recognized under the arrangement, which is re-assessed at each reporting date. Commercial supply revenue will be recognized as revenue upon delivery to Nippon Shinyaku, or otherwise upon transfer of control of commercial supply to Nippon Shinyaku as defined in the associated supply agreements.

The Company recognized the following amounts under the Nippon Shinyaku Collaboration Agreement (in thousands):


	Years Ended December 31,
	2025		2024
License and royalty revenue	$	72,903	$	—
Service revenue		11,822		—
Total revenues	$	84,725	$	—

As of December 31, 2025, the Company had recorded total accounts receivable of $4.1 million for reimbursable costs of manufacturing and other services under the Nippon Shinyaku Collaboration Agreement, of which $2.3 million was included in current assets and $1.9 million was included in non-current assets. As of December 31, 2025, the Company had recorded total deferred revenue of $29.4 million for development services and material rights which have not yet been satisfied under the Nippon Shinyaku Collaboration Agreement, of which $10.5 million was included in current liabilities and $18.9 million was included in non-current liabilities.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

Schedule of Fair Value of Cash Equivalents and Marketable Securities

The following tables present the fair value of cash equivalents and marketable securities in accordance with the fair value hierarchy discussed in Note 2 (in thousands):


	Level 1		Level 2		Level 3		Total
December 31, 2025
Cash equivalents:
Money market mutual funds	$	—	$	21,418	$	—	$	21,418
U.S. government and agency securities		—		2,496		—		2,496
Total cash equivalents		—		23,914		—		23,914
Marketable securities:
U.S. government and agency securities		—		83,144		—		83,144
Corporate bonds		—		123,245		—		123,245
Total marketable securities		—		206,389		—		206,389
Total cash equivalents and marketable securities	$	—	$	230,303	$	—	$	230,303


	Level 1		Level 2		Level 3		Total
December 31, 2024
Cash equivalents:
Money market mutual funds	$	—	$	43,895	$	—	$	43,895
U.S. government and agency securities		—		2,498		—		2,498
Total cash equivalents		—		46,393		—		46,393
Marketable securities:
U.S. government and agency securities		—		44,215		—		44,215
Certificates of deposit		—		1,462		—		1,462
Corporate bonds		—		141,663		—		141,663
Total marketable securities		—		187,340		—		187,340
Total cash equivalents and marketable securities	$	—	$	233,733	$	—	$	233,733

Supplemental Disclosures - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Supplemental Disclosures Of Noncash Investing And Financing Activities [Line Items]
Purchases of property and equipment included in accounts payable and accrued expenses and other current liabilities	$ 889	$ 339

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (GAAP) and include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

Foreign Currency Transactions

The functional currency of the Company and its consolidated subsidiaries is the U.S. dollar. Transaction gains and losses that arise from exchange rate fluctuations on transactions denominated in currencies other than the U.S. dollar are included in results of operations as incurred. During the years ended December 31, 2025 and 2024, the Company recorded aggregate net foreign currency transaction losses of $0.1 million and $0.9 million, respectively, which are included in other operating expenses in the consolidated statements of operations and comprehensive loss.

Use of Estimates

The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and related disclosure of contingent assets and liabilities for the periods presented. Management bases its estimates on historical experience and various other factors that it believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities, and other reported amounts, that are not readily apparent from other sources. Actual results may differ materially from these estimates. Estimates are used in the following areas, among others: revenue recognition, the allowance for credit losses, accrued research and development expenses and other accrued liabilities, stock-based compensation expense, interest expense under royalty monetization liabilities, income taxes and fair value measurements.

Reclassifications

Certain amounts reported in prior periods have been reclassified to conform to current period financial statement presentation, including separate presentation of service revenue in the statements of operations and comprehensive loss. As a result of the Company's collaboration and license agreement with Nippon Shinyaku Co., Ltd. (Nippon Shinyaku) which became effective in March 2025, the Company has modified the presentation of its revenues and now presents service revenues separately from license and royalty revenues. The modified presentation has been applied retrospectively to all prior periods presented. The reclassifications have no effect on previously reported financial position, results of operations and cash flows.

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with original maturities of 90 days or less at acquisition to be cash equivalents.

Restricted Cash

Restricted cash consists of deposits held at financial institutions that are used to collateralize irrevocable letters of credit required under the Company’s lease agreements and certain other agreements with third parties. The following table provides a reconciliation of cash and cash equivalents and restricted cash as reported on the consolidated balance sheets to the total of these amounts as reported at the end of the period in the consolidated statements of cash flows (in thousands):


	As of December 31,
	2025		2024
Cash and cash equivalents	$	34,466	$	57,526
Restricted cash		2,030		2,030
Total cash and cash equivalents and restricted cash	$	36,496	$	59,556

Marketable Securities

Marketable securities consist of available-for-sale debt securities and are carried at fair value. Marketable debt securities with remaining maturity dates exceeding 12 months which are not intended to be sold prior to maturity for use in current operations are classified as non-current assets. Unrealized gains and losses on available-for-sale debt securities, net of any related tax effects, are excluded from results of operations and are included in other comprehensive income and reported as a separate component of stockholders’ equity until realized. The Company uses the aggregate portfolio approach to release the tax effects of unrealized gains and losses on available-for-sale debt securities in accumulated other comprehensive loss. Purchase premiums and discounts on marketable debt securities are amortized or accreted into the cost basis over the life of the related security as adjustments to the yield using the effective-interest method. Interest income is recognized when earned. Realized gains and losses from the sale or maturity of marketable securities are based on the specific identification method and are included in results of operations as investment income.

At each reporting date, the Company evaluates available-for-sale debt securities which have an amortized cost basis in excess of the fair value of the security to determine if the unrealized loss or any potential credit losses should be recognized in results of operations. If the Company does not have the intent and ability to hold the security until recovery of the unrealized loss, the difference between the fair value and amortized cost basis of the security is charged to results of operations resulting in a new amortized cost basis of the security. If the Company has the intent and ability to hold the security until recovery of the unrealized loss, the security is evaluated for potential credit losses. If a credit loss is deemed to exist, the credit loss is recognized in results of operations and an allowance for credit losses is recorded against the amortized cost basis of the security. In determining whether a credit loss exists related to impaired available-for-sale debt securities, the Company considers, among other factors, the extent of the unrealized loss relative to the amortized cost basis, the credit rating of the issuer and any recent changes thereto, current and expected future

economic conditions, and any adverse events or other changes in circumstances that have occurred which may indicate a potential credit loss. The Company did not record an allowance for credit losses on its available-for-sale debt securities as of December 31, 2025 or 2024.

Accounts Receivable

Accounts receivable consist of consideration due to the Company resulting from its agreements with customers. Accounts receivable include amounts invoiced to customers as well as rights to consideration which have not yet been invoiced, including unbilled royalties and services, and for which payment is conditional solely upon the passage of time. If a licensee elects to terminate a license prior to the end of the license term, the licensed intellectual property is returned to the Company and any accounts receivable from the licensee which are not contractually payable to the Company are charged off as a reduction of revenue in the period of the termination. Accounts receivable which are not expected to be received by the Company within 12 months from the reporting date are stated net of a discount to present value and recorded as non-current assets on the consolidated balance sheets. The present value discount is recognized as a reduction of revenue in the period in which the accounts receivable balance is initially recorded and is accreted as interest income from licensing over the term of the receivables.

Accounts receivable are stated net of an allowance for credit losses, if deemed necessary based on the Company’s evaluation of collectability and potential credit losses. Management assesses the collectability of its accounts receivable using the specific identification of account balances and considers the credit quality and financial condition of its significant customers, historical information regarding credit losses and the Company’s evaluation of current and expected future economic conditions. If necessary, an allowance for credit losses is recorded against accounts receivable such that the carrying value of accounts receivable reflects the net amount expected to be collected. Accounts receivable balances are written off against the allowance for credit losses when the potential for collectability is considered remote. The Company did not record an allowance for credit losses on its accounts receivable as of December 31, 2025 or 2024.

Concentrations of Credit Risk and Off-balance Sheet Risk

Cash and cash equivalents, marketable debt securities and accounts receivable are financial instruments that are potentially subject to concentrations of credit risk. The Company’s cash and cash equivalents are deposited in accounts at multiple financial institutions, and amounts may exceed federally insured limits. The Company believes it is not exposed to significant credit risk due to the financial strength of the depository institutions in which the cash and cash equivalents are held. The Company’s marketable debt securities consist of investment grade securities and may be subject to concentrations of credit risk. The Company has adopted an investment policy which limits potential concentrations of investments and establishes minimum acceptable credit ratings, thereby reducing credit risk exposure. As of December 31, 2025, the Company believes that it is not exposed to significant credit risk related to accounts receivable due to the credit quality and history of collections from its significant customers, and the Company is unaware of any concentrations of credit risk related to accounts receivable from significant customers with deteriorated credit quality. The Company has no financial instruments with off-balance sheet risk of loss.

The following table summarizes those customers who represented at least 10% of revenues or total net accounts receivable for the periods presented:


	Revenues						Accounts Receivable
	Years Ended December 31,						As of December 31,
	2025			2024			2025			2024
Customer A		49	%		98	%		84	%		97	%
Customer B		50	%		—			14	%		—

Leases

The Company accounts for its lease arrangements in accordance with Accounting Standards Codification (ASC) 842, Leases (ASC 842). Under ASC 842, the Company classifies its leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the Company. Lease classification is evaluated at the inception of the lease agreement. Regardless of classification, the Company records a right-of-use asset and a lease liability for all leases with a term greater than 12 months. All of the Company’s leases are classified as operating leases. Operating lease expense is recognized on a straight-line basis over the term of the lease, with the exception of variable lease expenses which are recognized as incurred.

The Company identifies leases in its contracts if the contract conveys the right to control the use of identified property, plant or equipment for a period of time in exchange for consideration. The Company does not allocate lease consideration between lease and nonlease components and records a lease liability equal to the present value of the remaining fixed consideration under the lease. The interest rates implicit in the Company’s leases are generally not readily determinable. Accordingly, the Company uses its estimated incremental borrowing rate at the commencement date of the lease to determine the present value discount of the lease liability. The Company estimates its incremental borrowing rate for each lease based on an evaluation of its expected credit rating and the prevailing market rates for collateralized debt in a similar economic environment with similar payment terms and maturity dates commensurate with the term of the lease. The right-of-use asset for each lease is equal to the lease liability, adjusted for unamortized initial direct costs and lease incentives and prepaid or accrued rent. Initial direct costs of entering into a lease are included in the right-of-use asset and amortized as lease expense over the term of the lease. Lease incentives, such as tenant improvement allowances, are recorded as a reduction of the right-of-use asset and amortized as a reduction of lease expense over the term of the lease. The Company excludes options to extend or terminate leases from the calculation of the lease liability unless it is reasonably certain the option will be exercised.

The Company evaluates its right-of-use assets for impairment in accordance with its policy for long-lived assets. To the extent an impairment of a right-of-use asset is recognized, the remaining carrying value of the asset is subsequently amortized as lease expense on a straight-line basis from the date of impairment to the earlier of the end of the right-of-use asset’s useful life or the end of the lease term.

The Company determines the classification of subleases at the inception of the sublease, as well as whether the Company has been relieved of its primary obligation under the original lease. All of the Company's subleases are classified as operating leases and, in each case, the Company has not been relieved of its primary obligation under the original lease and continues to account for the original lease as it did prior to the commencement of the sublease. Sublease income is recognized on a straight-line basis over the term of the sublease as a reduction of the related lease expense of the original lease. Initial direct costs of entering into a sublease are deferred and amortized on a straight-line basis over the term of the sublease as a reduction of sublease income.

Property and Equipment

Property and equipment is stated at cost less accumulated depreciation and amortization. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed to operations as incurred. Upon disposal, the related cost and accumulated depreciation is removed from the accounts and any resulting gain or loss is included in the results of operations. Depreciation and amortization is calculated using the straight-line method over the estimated useful lives of the assets, which are as follows:


	Estimated Useful Life
Computer equipment and software	3 years
Furniture and fixtures	5 years
Laboratory and manufacturing equipment	5 to 15 years
Leasehold improvements	Shorter of lease term or estimated useful life

Cloud Computing Arrangements

The Company capitalizes certain costs associated with the implementation of cloud computing arrangements that are accounted for as service contracts. Once implementation activities are substantially complete and the cloud-based application is ready for its intended use, capitalization ceases and amounts capitalized are amortized on a straight-line basis over the term of the hosting arrangement. Capitalized implementation costs for cloud-based applications and associated amortization are classified on the consolidated balance sheets and statements of operations and comprehensive loss in the same manner as the costs of the associated hosting arrangement. As of December 31, 2025 and 2024, the Company had recorded capitalized costs, net of amounts amortized, of $0.1 million and less than $0.1 million, respectively, related to the implementation of cloud-based software applications, which were included in prepaid expenses and other assets on the consolidated balance sheets. Amortization of capitalized implementation costs for cloud-based applications recorded for the years ended December 31, 2025 and 2024 was less than $0.1 million and $1.0 million, respectively, and was included in general and administrative expenses in the consolidated statements of operations and comprehensive loss.

Impairment of Long-lived Assets

The Company's long-lived assets consist primarily of property and equipment and operating lease right-of-use assets. The Company evaluates its long-lived assets for impairment when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparison of the book values of the assets to estimated future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value, which is measured based on the projected discounted future net cash flows arising from the assets. Please refer to Note 5 and Note 6 for further information on impairment of long-lived assets.

Non-marketable Equity Securities

Non-marketable equity securities consist of equity investments in other entities in which the Company’s ownership interest is below 20% and the Company does not have significant influence over the operations of the entity, or for which the equity securities are not common stock or in-substance common stock. The Company’s non-marketable equity securities do not have readily determinable fair values and are measured at cost less impairment, adjusted for observable price changes for identical or similar investments of the same issuer. Please refer to Note 3 for further information on non-marketable equity securities.

Fair Value Measurements

The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. ASC 820, Fair Value Measurements and Disclosures, establishes a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below:

•

Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

•

Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly.

•

Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable.

To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for assets and liabilities categorized in Level 3. The level within the fair value hierarchy of an asset or liability measured at fair value is based on the lowest level of any input that is significant to the fair value measurement. The fair values of the Company’s Level 2 financial instruments are based on quoted market prices or broker or dealer quotations for similar assets. These investments are initially valued at the transaction price and subsequently valued utilizing third-party pricing providers or other market observable data. Please refer to Note 4 for further information on the Company's fair value measurements.

Royalty Monetization Liabilities

As discussed in Note 7, the Company has entered into multiple royalty monetization arrangements with entities managed by Healthcare Royalty Management, LLC (collectively and with other affiliated entities, HCR). Net proceeds received by the Company under these arrangements are recorded as liabilities and accounted for as debt since the return to HCR is explicitly capped under the agreements. The liabilities are amortized over the estimated life of the arrangements using the effective interest method. For arrangements in which there is no stated interest rate, the total amount of royalty and other payments paid to HCR under the arrangement, less the net proceeds received by the Company, is recorded as interest expense over the life of the arrangement. The Company estimates the effective interest rates of its royalty monetization liabilities based on its estimate of total payments to be paid to HCR under the arrangements. The Company reassesses these estimates at each reporting date and adjusts the effective interest rate and amortization of the liabilities on a prospective basis as necessary.

Due to its continuing involvement in the license and collaboration agreements underlying the royalty monetization arrangements with HCR, the Company continues to recognize license and royalty revenues under these license and collaboration agreements and records any payments to HCR as a reduction of the associated royalty monetization liability when paid. As such payments are made to HCR, the balance of the liability will be effectively repaid over the life of the royalty monetization agreement. The portion of royalty monetization liabilities representing principal that is expected to be paid within 12 months of the reporting date is recorded as a current liability, with the remaining portion of the liabilities recorded as non-current.

Warrants

Warrants are accounted for based on the specific terms of the warrant agreements. The Company's warrants, including pre-funded warrants, are indexed to the Company's common stock and meet the criteria to be classified as equity. Net proceeds received from the issuance of warrants are recorded within additional paid-in capital and are not subject to remeasurement. Please refer to Note 9 for further information regarding warrants issued by the Company.

Revenue Recognition

The Company recognizes revenue in accordance with ASC 606, Revenue from Contracts with Customers (ASC 606). ASC 606 requires entities to recognize revenue when control of the promised goods or services is transferred to customers at an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. The following five steps are performed to determine the appropriate revenue recognition for arrangements within the scope of ASC 606: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) the entity satisfies the performance obligations.

The Company applies the five-step model to contracts that are within the scope of ASC 606 only when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, for contracts within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations and whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to respective performance obligations when (or as) the respective performance obligations are satisfied.

The Company evaluates its contracts with customers for the presence of significant financing components. If a significant financing component is identified in a contract and provides a financing benefit to the customer, the transaction price for the contract is adjusted to account for the financing portion of the arrangement, which is recognized as interest income over the financing term using the effective interest method. In determining the appropriate interest rates for significant financing components, the Company evaluates the credit profile of the customer and prevailing market interest rates and selects an interest rate in which it believes would be charged to the customer in a separate financing arrangement over a similar financing term.

The Company licenses its NAV Technology Platform and other intellectual property rights to other biotechnology and pharmaceutical companies, including collaborators for the joint development and commercialization of its product candidates. The terms of the licenses vary, and licenses may be exclusive or non-exclusive and may be sublicensable by the licensee. Licenses may grant intellectual property rights for purposes of internal and preclinical research and development only, or may include the rights, or options to obtain future rights, to commercialize drug therapies for specific diseases using the Company’s NAV Technology Platform and other licensed rights. License agreements generally have a term at least equal to the life of the underlying patents, but are terminable at the option of the licensee. Consideration payable to the Company under its license and collaboration agreements may include: (i) up-front and annual fees, (ii) milestone payments based on the achievement of certain development and sales-based milestones, (iii) sublicense fees, (iv) royalties on sales of licensed products, (v) fees for services related to the development and manufacturing of licensed products and (vi) other consideration payable upon optional goods and services purchased by licensees and collaborators.

The Company evaluates its agreements with collaboration partners to determine whether they are within the scope of ASC 808, Collaborative Arrangements (ASC 808). For collaboration arrangements within the scope of ASC 808 that contain multiple elements, the Company identifies the various transactions with the counterparty and determines if any unit of account is more reflective of a transaction with a customer and therefore should be accounted for within the scope of ASC 606. For transactions that are accounted for pursuant to ASC 606, the Company applies the five-step model as described in its revenue recognition policies. For transactions that are accounted for pursuant to ASC 808, an appropriate method of recognition and presentation is determined and consistently applied in accordance with the Company's accounting policies for collaborative arrangements.

The Company’s license and collaboration agreements are accounted for as contracts with customers within the scope of ASC 606, with the exception of transactions for which the counterparty is determined not to be a customer. At the inception of each agreement, the Company determines the contract term for purposes of applying the requirements of ASC 606. Licenses are generally terminable at the option of the licensee with advance notice to the Company. For each license granted, the Company evaluates these termination rights to determine whether a substantive termination penalty would be incurred by the licensee upon termination. If the licensee incurs a substantive termination penalty upon termination, the contract term for revenue recognition purposes is generally equal to the stated term of the license, which is the life of the underlying licensed patents. Alternatively, if the licensee does not incur a substantive termination penalty upon termination, the contract term for revenue recognition purposes may be shorter than the stated term of the license, in which case the termination rights may be accounted for as contract renewal options.

Performance obligations under the Company’s license and collaboration agreements may include (i) the delivery of intellectual property licenses, (ii) development and manufacturing services to be performed by the Company related to licensed products and (iii) options granted to purchase additional goods and services, to the extent the options convey material rights. At the inception of each license agreement which contains performance obligations for development, manufacturing or other services, the Company evaluates whether the license is distinct from the services, which requires judgment. In making this determination, the Company considers, among other things, the stage of development of the licensed products and whether the services will significantly impact further development of the licensed products. If it is determined that the license is not distinct from the services, the license is combined with the services into a single performance obligation. Agreements may provide licensees and collaborators with options to purchase additional goods or other services, including options to purchase commercial supply of licensed products. Options are evaluated at the inception of the agreement to determine whether they provide material rights to the customer. In making this determination, the Company considers whether the options are priced at an incremental discount to the standalone selling price of the underlying goods or services, in which case the option is considered to be a material right. Material rights are accounted for as separate performance obligations under the current arrangement.

The Company evaluates the transaction price of its license and collaboration agreements at contract inception and at each reporting date. The transaction price includes the fixed consideration payable to the Company over the contract term, as well as any variable consideration to the extent that it is probable that a significant reversal of revenue will not occur in the future. Fixed consideration under the agreements may include up-front and annual fees payable over the contract term and fixed fees for development, manufacturing and other services performed by the Company. Variable consideration under the agreements may include development and sales-based milestone payments, payments for development, manufacturing and other services performed by the Company, sublicense fees and royalties on sales of licensed products. Consideration contingent upon the exercise of options by the customer is excluded from the transaction price and not accounted for as part of the arrangement until the option is exercised.

The transaction price of the Company's license and collaboration arrangements is allocated to the underlying performance obligations based on their relative standalone selling prices and recognized as revenue when (or as) the performance obligations are satisfied. Variable consideration payable based on services performed by the Company is allocated directly to the performance obligation for such services. Consideration allocated to performance obligations for the delivery of intellectual property licenses is recognized as license and royalty revenue in full upon the delivery of the license. Consideration allocated to performance obligations for development, manufacturing and other services is recognized as service revenue as the services are performed by the Company. Consideration allocated to performance obligations for material rights to purchase additional goods and services is recognized as revenue upon the satisfaction of the performance obligations underlying the optional goods and services purchased by the customer. Service revenue is recognized using a measure of progress that best reflects the pattern of satisfaction of the performance obligations. At each reporting date, the Company re-evaluates the measure of progress and adjusts service revenue on a cumulative catch-up basis to reflect its best estimate of the services performed to date versus the total services to be performed under the arrangement.

Development milestone payments are payable to the Company upon the achievement of specified development milestones. At the inception of each license agreement that contains development milestone payments, the Company evaluates whether the milestones are probable of achievement and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal will not occur in the future, milestone payments are included in the transaction price. Milestone payments contingent on the achievement of development milestones that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved and are excluded from the transaction price until the milestone is achieved. At each reporting date, the Company re-evaluates the probability of achievement of each outstanding development milestone and, if necessary, adjusts the transaction price for any milestones for which the probability of achievement has changed due to current facts and circumstances. The increase to the transaction price as a result of any such adjustments is then allocated to the underlying performance obligations in a manner similar to the allocation of the initial transaction price and, to the extent the performance obligations are satisfied, recognized as revenue on a cumulative catch-up basis in the period of the adjustment.

Royalties on sales of licensed products, sales-based milestone payments, including milestones payable upon first commercial sales of licensed products, and sublicense fees based on the receipt of certain fees by licensees from any sublicensees are excluded from the transaction price of each license and recognized as license and royalty revenue in the period that the related sales or sublicenses occur, provided that the associated license has been delivered to the licensee.

Royalty revenue to date consists primarily of royalties on net sales of Zolgensma and Itvisma, which are licensed products under the Company’s license agreement with Novartis Gene Therapies, Inc. (Novartis Gene Therapies), a wholly owned subsidiary of Novartis AG (Novartis), for the development and commercialization of treatments for spinal muscular atrophy (SMA). The Company recognizes royalty revenue from net sales of Zolgensma and Itvisma in the period in which the underlying products are sold by Novartis Gene Therapies, which in certain cases may require the Company to estimate royalty revenue for periods of net sales which have not yet been reported to the Company. Estimated royalties are reconciled to actual amounts reported in subsequent periods, and any differences are recognized as an adjustment to royalty revenue in the period the royalties are reported.

The Company receives payments from licensees and collaborators based on the billing schedules established in the associated agreements. Amounts recognized as revenue which have not yet been received from the customer are recorded as accounts receivable when the Company’s rights to the consideration are conditional solely upon the passage of time. Amounts recognized as revenue which have not yet been received from customers are recorded as contract assets when the Company’s rights to the consideration are not unconditional. Contract assets are recorded as other current assets on the consolidated balance sheets if the consideration is expected to be realized within 12 months from the reporting date, or as other assets if the consideration is expected to be realized in periods beyond 12 months from the reporting date. If a licensee elects to terminate a license prior to the end of the license term, the licensed intellectual property is returned to the Company and any consideration recorded as accounts receivable or contract assets which is not contractually payable by the licensee is charged off as a reduction of revenue in the period of the termination. Amounts received by the Company prior to the delivery of underlying performance obligations are deferred and recognized as revenue upon the satisfaction of the performance obligations by the Company. Deferred revenue which is not expected to be recognized within 12 months from the reporting date is recorded as non-current on the consolidated balance sheets.

Collaborative Arrangements

The Company evaluates its agreements with collaboration partners to determine whether they are within the scope of ASC 808. Such arrangements are within the scope of ASC 808 if they involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This evaluation is performed throughout the life of the arrangement based on any changes in the roles and responsibilities of the parties under the arrangement. For collaboration arrangements within the scope of ASC 808 that contain multiple elements, the Company identifies the various transactions with the counterparty and determines if any unit of account is more reflective of a transaction with a customer and therefore should be accounted for within the scope of ASC 606. For transactions that are accounted for pursuant to ASC 606, the Company applies the five-step model as described in its revenue recognition policies. For transactions that are accounted for pursuant to ASC 808, an appropriate method of recognition and presentation is determined and consistently applied.

For transactions accounted for as collaborative arrangements under ASC 808, payments to and from collaboration partners associated with multiple activities in a collaboration arrangement are classified based on the nature of each separate activity. Payments associated with development activities performed are recorded as research and development expense when owed to collaboration partners, or as a reduction of research and development expense when due from collaboration partners. Payments associated with commercialization activities performed are recorded as general and administrative expense when owed to collaboration partners, or as a reduction of general and administrative expense when due from collaboration partners. At the end of each reporting period, the Company records a net amount due to or from collaboration partners for activities performed by the parties under the collaboration.

Cost of License and Royalty Revenues

Cost of license and royalty revenues consists primarily of sublicense fees and royalties on net sales of licensed products as specified in the Company’s agreements with its licensors. Sublicense fees are based on a percentage of license fees received by the Company from licensees and are recognized in the period that the underlying revenue is recognized. Royalties are based on a percentage of net sales of licensed products by licensees and are recognized in the period that the underlying sales occur. Amounts which are payable to licensors in periods beyond 12 months from the reporting date are recorded as non-current liabilities on the consolidated balance sheets.

Research and Development Expenses

Research and development costs are expensed as incurred in performing research and development activities. Advance payments for goods or services related to research and development activities are deferred and expensed as the goods are delivered or the services are performed. Research and development costs include salaries, wages, benefits and other personnel-related costs, laboratory and facilities costs, allocated overhead costs, license and milestone fees, and costs of goods and services associated with preclinical research and clinical trial activities, associated manufacturing-related activities, regulatory activities and other related services performed by third parties. At the end of each reporting period, the Company compares payments made to third-party service providers to the estimated expenses incurred based on the services provided and progress toward completion of the research or development objectives. Such estimates are subject to change as additional information becomes available. Depending on the timing of payments to the service providers and the estimated expenses incurred, the Company may record net prepaid or accrued research and development expenses relating to these costs. Up-front fees incurred in obtaining technology licenses, as well as milestone payments to licensors, are charged to research and development expense as incurred if the technology licensed has no alternative future use.

Stock-based Compensation

The Company accounts for its stock-based compensation awards in accordance with ASC 718, Compensation—Stock Compensation (ASC 718). ASC 718 requires all stock-based awards to employees and nonemployees to be recognized as expense based on the grant date fair value of the awards. The Company’s stock-based awards include stock options and restricted stock units granted to employees and nonemployees and shares issued to employees under its employee stock purchase plan.

The Company’s stock-based awards may be subject to either service or performance-based vesting conditions. Compensation expense related to awards with service-based vesting conditions is recognized on a straight-line basis based on the estimated grant date fair value over the requisite service period of the award, which is generally the vesting term. Compensation expense related to awards with performance-based vesting conditions is recognized based on the estimated grant date fair value over the requisite service period using the accelerated attribution method to the extent achievement of the performance condition is probable.

The Company has elected to not estimate forfeitures of stock-based awards and accounts for forfeitures as they occur.

The Company estimates the fair value of its stock option awards using the Black-Scholes option-pricing model, which requires the input of subjective assumptions, including (i) the fair value of the underlying common stock, (ii) the expected stock price volatility, (iii) the expected term of the award, (iv) the risk-free interest rate and (v) expected dividends. The Company estimates expected stock price volatility based on the historical volatility of its common stock over a period of time commensurate with the expected term of its stock option awards. Due to the lack of sufficient historical data, the Company estimates the expected term of its employee stock options using the “simplified” method, whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option. For stock options granted to nonemployees, the Company uses the contractual term of the award rather than expected term to estimate the fair value of the award. The Company estimates the risk-free interest rates for periods within the expected term of its options based on the rates of U.S. Treasury securities with maturity dates commensurate with the expected term of the associated awards. The Company assumes a dividend yield of zero for its common stock as it has never paid dividends and does not expect to pay dividends for the foreseeable future.

The Company estimates the fair value of restricted stock units based on the fair value of the Company’s common stock on the date of the grant.

Income Taxes

Income taxes are accounted for in accordance with ASC 740, Income Taxes (ASC 740), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided, if based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.

The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances.

The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2025 and 2024, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company’s consolidated statements of operations and comprehensive loss.

Restructuring Expenses

The Company records costs and liabilities associated with exit and disposal activities in accordance with ASC 420, Exit or Disposal Cost Obligations (ASC 420) and ASC 712, Compensation – Nonretirement Postemployment Benefits (ASC 712). Such costs are based on estimates of fair value in the period liabilities are incurred. The Company evaluates and adjusts these costs as appropriate for changes in circumstances as additional information becomes available. Please refer to Note 14 for further information regarding restructuring expenses.

Net Loss Per Share

Basic net loss per share is calculated by dividing net loss applicable to common stockholders by the weighted-average common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by adjusting the weighted-average common shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of computing both basic and diluted net loss per share, pre-funded warrants are considered outstanding shares upon issuance because the underlying shares may be issued for nominal consideration and are exercisable after the original issuance date. Contingently convertible shares in which conversion is based on non-market-priced contingencies are excluded from the calculations of both basic and diluted net loss per share until the contingency has been fully met. For purposes of the diluted net loss per share calculation, common stock equivalents are excluded from the calculation of diluted net loss per share if their effect would be anti-dilutive.

Comprehensive Loss

Comprehensive loss includes net loss as well as unrealized gains and losses on available-for-sale debt securities, net of income tax effects and reclassification adjustments for realized gains and losses.

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In November 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which enhances certain interim and annual disclosure requirements of reportable segment information, including information about significant segment expenses. Additionally, the standard requires entities with a single reportable segment to provide all disclosures required by ASC 280, Segment Reporting. The Company adopted this standard for annual reporting periods beginning January 1, 2024 and interim reporting periods beginning January 1, 2025, on a retrospective basis for all periods presented. Please refer to Note 16 for further information regarding reportable segment information, including the information required to be disclosed pursuant to this standard.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which enhances the disclosure of an entity's effective tax rate reconciliation and requires the disclosure of income taxes paid to be disaggregated by jurisdiction. The Company adopted this standard for annual reporting periods beginning January 1, 2025, on a retrospective basis for all periods presented. Please refer to Note 13 for further information regarding income taxes, including the information required to be disclosed pursuant to this standard.

Recent Accounting Pronouncements Not Yet Adopted

In November 2024, the FASB issued ASU 2024-03, Income Statement – Reporting Comprehensive Income – Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses. The new standard requires disclosures about specific types of expenses included in the expense captions presented on the face of the income statement as well as disclosures about selling expenses. In January 2025, the FASB issued ASU 2025-01, which clarifies the effective date of ASU 2024-03 with respect to interim periods. The standard is effective for the Company for annual periods beginning January 1, 2027 and interim periods beginning January 1, 2028, with early adoption permitted. The standard may be applied either prospectively to financial statements issued for reporting periods after the effective date or retrospectively to any or all prior periods presented in the financial statements. The Company is currently in the process of evaluating the impact of this standard on its consolidated financial statements and related disclosures.

Capitalization - Schedule of Shares of Common Stock Reserved for Future Issuance (Detail) - shares shares in Thousands	Dec. 31, 2025	Dec. 31, 2024
Schedule of Capitalization [Line Items]
Reserved common shares	22,026	15,786
Equity Incentive Plans [Member]
Schedule of Capitalization [Line Items]
Reserved common shares	20,133	13,548
Employee Stock Purchase Plan [Member]
Schedule of Capitalization [Line Items]
Reserved common shares	755	913
Pre Funded Warrants [Member]
Schedule of Capitalization [Line Items]
Reserved common shares	1,138	1,325

Income Taxes - Schedule of Net Income Taxes Paid (Net Refunds Received) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Income Taxes Paid, Net [Abstract]
Federal	$ 280
Total net income taxes paid (net refunds received):	285	$ (72)
Maryland
Income Taxes Paid, Net [Abstract]
State		(56)
Illinois
Income Taxes Paid, Net [Abstract]
State		(9)
Other states
Income Taxes Paid, Net [Abstract]
State	$ 5	$ (7)

Income Taxes - Components of Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Deferred tax assets:
Net operating loss carryforwards	$ 184,528	$ 105,468
Research and development tax credits	94,867	87,030
Stock-based compensation	21,250	22,687
Lease liabilities	19,372	22,278
Liability related sale of future royalties	2,951	12,148
Capitalized research and development costs	77,147	122,082
Accruals and other	7,317	5,366
Total deferred tax assets before valuation allowance	407,432	377,059
Valuation allowance	(374,413)	(338,352)
Total deferred tax assets	33,019	38,707
Deferred tax liabilities:
Right-of-use assets	(12,193)	(14,293)
Depreciation and amortization	(20,826)	(24,414)
Total deferred tax liabilities	$ (33,019)	$ (38,707)

Fair Value Measurements - Additional Information (Detail) € in Millions	1 Months Ended		12 Months Ended
	Jul. 31, 2021 EUR (€)	Jul. 31, 2021 USD ($)	Dec. 31, 2025 EUR (€)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 EUR (€)	Dec. 31, 2024 USD ($)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Non-marketable equity securities				$ 0		$ 0
Remeasurements or impairment losses on non-marketable equity securities				0		0
Investment income				12,245,000		18,729,000
Uni Qure N V
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Proceeds from acquiring business	€ 5.3	$ 6,100,000
Revenue recognition, milestone method, revenue recognized \| €	€ 37.1				€ 5.6
Investment income						$ 6,600,000
Revenue recognition, milestone method, revenue yet to be recognized			€ 29.7	$ 35,000,000

License and Collaboration Agreements - Schedule Of Revenues Earned Under License and Collaboration Agreements (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues	$ 170,441	$ 83,328
Other	187	455
Total license and royalty revenue	156,267	81,960
Zolgensma and Itvisma Royalties [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues	83,177	81,505
Nippon Shinyaku Licenses [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues	72,903
Nippon Shinyaku Services [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues	11,822
Other [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues	2,352	1,368
Total Service Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenues	$ 14,174	$ 1,368

- Definition

+ References

+ Details

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense		$ 15,615	$ 16,215
Impairment of property and equipment			$ 2,101
Furniture Fixtures and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Impairment of property and equipment	$ 700

Leases - Additional Information (Detail)	1 Months Ended					12 Months Ended
Leases - Additional Information (Detail)	Mar. 31, 2024 USD ($)	Oct. 31, 2022	Nov. 30, 2018 USD ($) ft²	May 31, 2016 USD ($)	Mar. 31, 2015	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Other Commitments [Line Items]
Property and equipment, net						$ 104,855,000	$ 117,589,000
Operating lease right-of-use assets						47,156,000	53,716,000
Lease liabilities						73,501,000
Total undiscounted payments						97,240,000
Sublease income						$ 451,000	319,000
Impairment losses of long-lived assets							$ 2,101,000
Rockville, Maryland [Member]
Other Commitments [Line Items]
Operating lease expiration year						2029
Washington, D.C. Lease [Member]
Other Commitments [Line Items]
Lease expiration date		Oct. 31, 2027
Operating lease right-of-use assets						$ 2,700,000
Lease liabilities						$ 2,800,000
Operating lease, option to extend description						The Company has an option to extend the term of the lease for five additional years.
Operating Lease Commencement Year		2022-10
9804 Medical Center Drive [Member]
Other Commitments [Line Items]
Tenant improvement allowance received						$ 19,500,000
Operating lease right-of-use assets						40,800,000
Lease liabilities						$ 65,600,000
9804 Medical Center Drive [Member] \| Rockville, Maryland [Member]
Other Commitments [Line Items]
Number of square feet to be constructed \| ft²			186,000
Construction completion, description						The initial construction of the building was performed by the landlord and the lease commenced in September 2020 upon delivery of the leased premises to the Company to make additional improvements to the building.
Lease commenced date			2020-09
Lease expiration date			Sep. 30, 2036
Lease not yet commenced, option to terminate the lease							true
Lease not yet commenced, option to terminate the lease, description						The Company has an option to extend the term of the lease for up to 10 additional years and an option to terminate the lease, with payment of an early termination fee, after 12 years from the delivery of the leased premises to the Company.
Lease not yet commenced, additional lease term			10 years
Minimum release term for option to terminate			12 years
Letters of credit			$ 1,100,000
Operating lease right-of-use assets						$ 1,800,000
9712 Medical Center Drive [Member] \| Rockville, Maryland [Member]
Other Commitments [Line Items]
Lease commenced date					2015-04
Lease expiration date						Sep. 30, 2036
Tenant improvement allowance received						$ 400,000
Lease liabilities						$ 2,000,000
Lease term						February 2027, subject to extension options held by the Company.
Operating lease, existence of option to extend the lease							true
Operating lease, option to extend description						The Company has an option to extend the term of the lease for three additional years, as well as an option to extend the lease term to be coterminous with the 9804 Medical Center Drive Lease, which expires in September 2036.
Additional lease term under option to extend						3 years
400 Madison Avenue [Member] \| 400 Madison Lease [Member]
Other Commitments [Line Items]
Lease expiration date				Apr. 30, 2027
Letters of credit				$ 200,000
Operating lease right-of-use assets						$ 300,000
Lease liabilities						1,400,000
Operating Lease Commencement Year				2016-07
Tenant improvement allowance entitled to received				$ 700,000
New York Sublease [Member]
Other Commitments [Line Items]
Lease expiration date	Apr. 30, 2027
Operating Lease Commencement Year	2024-04
Total undiscounted payments						700,000
Sublease income						500,000	$ 300,000
Carrying value of the asset	$ 3,400,000
Estimated fair value of asset	$ 1,300,000
Impairment losses of long-lived assets						0	$ 2,100,000
Impairment losses recorded to right-of-use assets						1,400,000
Impairment losses recorded to property and equipment						$ 700,000

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Current assets
Cash and cash equivalents	$ 34,466	$ 57,526
Marketable securities	195,604	177,161
Accounts receivable	26,379	20,473
Prepaid expenses	11,927	9,067
Other current assets	12,905	13,774
Total current assets	281,281	278,001
Marketable securities	10,785	10,179
Accounts receivable	2,312	474
Property and equipment, net	104,855	117,589
Operating lease right-of-use assets	47,156	53,716
Restricted cash	2,030	2,030
Other assets	4,613	4,000
Total assets	453,032	465,989
Current liabilities
Accounts payable	21,358	22,798
Accrued expenses and other current liabilities	38,390	38,070
Deferred revenue	10,452	115
Operating lease liabilities	8,286	7,902
Royalty monetization liabilities	39,609	34,309
Total current liabilities	118,095	103,194
Deferred revenue	18,943
Operating lease liabilities	65,215	74,131
Royalty monetization liabilities	147,408	25,378
Other liabilities	638	3,635
Total liabilities	350,299	206,338
Commitments and contingencies (Note 8)
Stockholders’ equity
Preferred stock; $0.0001 par value; 10,000 shares authorized, no shares issued and outstanding at December 31, 2025 and 2024
Common stock; $0.0001 par value; 100,000 shares authorized at December 31, 2025 and 2024; 50,892 and 49,549 shares issued and outstanding at December 31, 2025 and 2024, respectively	5	5
Additional paid-in capital	1,229,442	1,192,536
Accumulated other comprehensive loss	(687)	(741)
Accumulated deficit	(1,126,027)	(932,149)
Total stockholders’ equity	102,733	259,651
Total liabilities and stockholders’ equity	$ 453,032	$ 465,989

Leases - Reconciliation of Undiscounted Future Minimum Lease Payments Remaining Operating Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Undiscounted future minimum lease payments:
2026	$ 12,237
2027	10,020
2028	7,943
2029	8,051
2030	8,134
Thereafter	50,855
Total undiscounted future minimum lease payments	97,240
Amount representing imputed interest	(23,739)
Total operating lease liabilities	73,501
Current portion of operating lease liabilities	(8,286)	$ (7,902)
Operating lease liabiliies, noncurrent	$ 65,215	$ 74,131

License and Collaboration Agreements - Summary of Accounts Receivables (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Current accounts receivable:
Billed to customers	$ 557	$ 65
Other unbilled	19	302
Current accounts receivable	26,379	20,473
Non-current accounts receivable:
Other unbilled	454	474
Non-current accounts receivable	2,312	474
Total accounts receivable	28,691	20,947
Novartis Royalties [Member]
Current accounts receivable:
Unbilled	23,806	$ 20,106
Nippon Shinyaku Services [Member]
Current accounts receivable:
Unbilled	1,997
Non-current accounts receivable:
Unbilled	$ 1,858

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Revenues
Revenues	$ 170,441	$ 83,328
Operating Expenses
Cost of license and royalty revenues	20,298	33,567
Research and development	228,299	208,522
General and administrative	82,863	76,619
Credit losses (recoveries)		(5,000)
Impairment of long-lived assets		2,101
Other operating expenses	179	865
Total operating expenses	331,639	316,674
Loss from operations	(161,198)	(233,346)
Other Income (Expense)
Interest income from licensing	83	174
Investment income	12,245	18,729
Interest expense	(45,008)	(12,659)
Total other income (expense)	(32,680)	6,244
Net loss	(193,878)	(227,102)
Other Comprehensive Income (Loss)
Unrealized gain on available-for-sale securities, net	54	3,688
Total other comprehensive income	54	3,688
Comprehensive loss	$ (193,824)	$ (223,414)
Net loss per share, basic	$ (3.76)	$ (4.59)
Net loss per share, diluted	$ (3.76)	$ (4.59)
Weighted-average common shares outstanding, basic	51,573	49,509
Weighted-average common shares outstanding, diluted	51,573	49,509
License and royalty [Member]
Revenues
Revenues	$ 156,267	$ 81,960
Service [Member]
Revenues
Revenues	$ 14,174	$ 1,368

Property and Equipment, Net

12 Months Ended

Dec. 31, 2025

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

5. Property and Equipment, Net

Property and equipment, net consists of the following (in thousands):


	As of December 31,
	2025			2024
Laboratory and manufacturing equipment	$	78,825		$	77,141
Computer equipment and software		4,573			4,244
Furniture and fixtures		7,039			7,031
Leasehold improvements		101,610			101,465
Total property and equipment		192,047			189,881
Accumulated depreciation and amortization		(87,192	)		(72,292	)
Property and equipment, net	$	104,855		$	117,589

During the years ended December 31, 2025 and 2024, the Company recorded depreciation and amortization expense of $15.6 million and $16.2 million, respectively.

In March 2024, the Company entered into an agreement to sublease its office facilities in New York, New York. In connection with the sublease, the Company recorded impairment of property and equipment of $0.7 million in the first quarter of 2024 related to furniture and fixtures and leasehold improvements located at the subleased facility. Please refer to Note 6 for further information regarding the sublease agreement and associated impairment of long-lived assets.

Stock-based Compensation - Additional Information (Detail) - USD ($)		1 Months Ended	12 Months Ended
	Sep. 16, 2015	Jan. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	May 31, 2025
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance			22,026,000	15,786,000
Unrecognized stock-based compensation expense			$ 47,700,000
Unrecognized stock-based compensation, weighted-average period			2 years 2 months 12 days
Proceeds from exercise of stock options			$ 318,000	$ 1,512,000
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units vested			743,000
Total intrinsic values vested			$ 6,000,000	$ 6,700,000
2015 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance			20,133,416
Additional shares authorized for issuance		1,981,975
Stock options expiration date			10 years
Stock plan expiration date			2025-06
Weighted-average fair values of options granted			$ 4.96	$ 9.98
Exercise of stock options, net of tax, shares			67,735	290,753
Total intrinsic value of options exercised			$ 300,000	$ 3,100,000
2015 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares authorized for issuance			1,426,994
Shares available for future grants			755,306
Share-based compensation arrangement by share-based payment award, description			The number of authorized shares reserved for issuance under the 2015 ESPP automatically increases on the first business day of each fiscal year
Share-based compensation arrangement by share-based payment award, percentage of outstanding stock minimum	1.00%
Common stock shares issued to participants			157,658	105,400
2025 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares authorized for issuance					5,500,000
Common stock reserved for issuance			5,717,654
Stock options expiration date			10 years
Stock options vesting period			1 year
Stock plan expiration date			2035-05
2014 Plan, 2015 Plan and 2025 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options expiration date			10 years

Stock-based Compensation - Summary of Unvested RSUs Activity Under Equity Incentive Plans (Details) - Restricted Stock Units (RSUs)	12 Months Ended
	Dec. 31, 2025 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested balance at December 31, 2024 \| shares	2,042,000
Shares, Granted \| shares	1,724,000
Vested \| shares	(743,000)
Forfeited \| shares	(173,000)
Unvested balance at December 31, 2025 \| shares	2,850,000
Weighted-average Grant Date Fair Value, Unvested Beginning Balance \| $ / shares	$ 19.95
Weighted-average Grant Date Fair Value, Granted \| $ / shares	8.62
Weighted-average Grant Date Fair Value, Vested \| $ / shares	21.27
Weighted-average Grant Date Fair Value, Forfeited \| $ / shares	14.57
Weighted-average Grant Date Fair Value, Unvested Ending Balance \| $ / shares	$ 13.08

Marketable Securities and Other Investments

12 Months Ended

Dec. 31, 2025

Investments, Debt and Equity Securities [Abstract]

Marketable Securities and Other Investments

3. Marketable Securities and Other Investments

The following tables present a summary of the Company’s marketable securities, which consist solely of available-for-sale debt securities (in thousands):


	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
December 31, 2025
U.S. government and agency securities	$	83,085	$	59	$	—		$	83,144
Corporate bonds		123,131		131		(17	)		123,245
	$	206,216	$	190	$	(17	)	$	206,389


	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
December 31, 2024
U.S. government and agency securities	$	44,281	$	11	$	(77	)	$	44,215
Certificates of deposit		1,466		—		(4	)		1,462
Corporate bonds		141,474		234		(45	)		141,663
	$	187,221	$	245	$	(126	)	$	187,340

As of December 31, 2025 and 2024, no available-for-sale debt securities had remaining maturities greater than two years. The amortized cost of marketable debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, or to the earliest call date for callable debt securities purchased at a premium.

As of December 31, 2025 and 2024, the balance in accumulated other comprehensive loss consisted solely of unrealized gains and losses on available-for-sale debt securities, net of reclassification adjustments for realized gains and losses and income tax effects. The Company did not recognize any realized gains or losses on available-for-sale securities during the years ended December 31, 2025 and 2024, and no income tax effects or reclassification adjustments were recorded in accumulated other comprehensive loss during the periods.


	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
December 31, 2025
U.S. government and agency securities	$	4,676	$	—		$	—	$	—	$	4,676	$	—
Corporate bonds		32,289		(17	)		—		—		32,289		(17	)
	$	36,965	$	(17	)	$	—	$	—	$	36,965	$	(17	)


	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
December 31, 2024
U.S. government and agency securities	$	—	$	—		$	22,917	$	(77	)	$	22,917	$	(77	)
Certificates of deposit		—		—			1,221		(4	)		1,221		(4	)
Corporate bonds		21,317		(45	)		—		—			21,317		(45	)
	$	21,317	$	(45	)	$	24,138	$	(81	)	$	45,455	$	(126	)

As of December 31, 2025, available-for-sale debt securities held by the Company in an unrealized loss position consisted of nine investment grade security positions. The Company has the intent and ability to hold such securities until recovery, and based on the credit quality of the issuers and low severity of each unrealized loss position relative to its amortized cost basis, the Company did not identify any credit losses associated with its available-for-sale debt securities. The Company did not recognize any impairment or credit losses on available-for-sale debt securities during the years ended December 31, 2025 and 2024.

Non-marketable Equity Securities

Non-marketable equity securities are measured at cost less impairment, adjusted for observable price changes for identical or similar investments of the same issuer. The Company did not hold any non-marketable equity securities as of December 31, 2025 and 2024. No remeasurements or impairment losses were recorded on non-marketable equity securities during the years ended December 31, 2025 and 2024.

Prior to the acquisition of Corlieve Therapeutics SAS (Corlieve) by uniQure N.V. (uniQure) in July 2021, the Company held non-marketable equity securities of Corlieve which were originally acquired by the Company in June 2020 as consideration under a license and collaboration agreement with Corlieve. In connection with the acquisition of Corlieve by uniQure in July 2021, the Company received proceeds of €5.3 million ($6.1 million) from uniQure in exchange for its ownership interest in Corlieve. As additional consideration, the Company became eligible to receive payments of up to €37.1 million from uniQure contingent upon the achievement of various development and regulatory milestones. During the year ended December 31, 2024, the Company received €5.6 million in milestone payments from uniQure and recognized investment income of $6.6 million, respectively, related to the achievement of the milestones during the period. No milestones were achieved or paid by uniQure during the year ended December 31, 2025. As of December 31, 2025, there were €29.7 million ($35.0 million as of December 31, 2025) in remaining milestones which have not been paid or achieved and have not been recognized in the consolidated financial statements. Proceeds contingent upon the achievement of the remaining milestones will be recognized as investment income in the period in which any uncertainty regarding realization is substantially resolved, which may not occur until the achievement of the underlying milestones. It is at least reasonably possible that some or all of the proceeds contingent upon these milestones will not be realized by the Company.

Supplemental Disclosures - Schedules of Accrued Expenses and Other Current Liabilities (Detail) - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Payables and Accruals [Abstract]
Accrued personnel costs	$ 17,418,000	$ 17,607,000
Accrued external research and development expenses	10,229,000	8,998,000
Accrued sublicense fees and royalties	8,652,000	8,658,000
Accrued external general and administrative expenses	1,301,000	2,002,000
Accrued purchases of property and equipment	33,000	156,000
Other accrued expenses and current liabilities	757,000	649,000
Accrued expenses and other current liabilities	$ 38,390,000	$ 38,070,000

Retirement Plan

12 Months Ended

Dec. 31, 2025

Postemployment Benefits [Abstract]

Retirement Plan

12. Retirement Plan

The Company sponsors a defined-contribution retirement plan under Section 401(k) of the Internal Revenue Code (the 401(k) Plan). The 401(k) Plan covers all employees who meet defined minimum age and service requirements, and allows participants to defer a portion of their annual compensation. The Company matches employee deferrals up to a specified percentage of eligible compensation. For the years ended December 31, 2025 and 2024, the Company incurred expenses of $3.4 million and $3.1 million, respectively, for matching contributions to the 401(k) Plan.

Royalty Monetization Liabilities - Schedule of Changes in Royalty Monetization Liability (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Royalty Monetization Liabilities [Line Items]
Beginning balance	$ 59,687
Ending balance	187,017	$ 59,687
Current portion	(39,609)	(34,309)
Non-current portion	147,408	25,378
2020 Royalty Purchase Agreement
Royalty Monetization Liabilities [Line Items]
Beginning balance	59,687
Ending balance	29,672	59,687
2020 Royalty Purchase Agreement \| HCR [Member]
Royalty Monetization Liabilities [Line Items]
Beginning balance	59,687	94,052
Novartis royalties paid to HCR	(60,095)	(46,413)
Interest expense recognized	30,080	12,048
Ending balance	29,672	59,687
Current portion	(29,672)
Non-current portion	(0)
2025 Royalty Bond
Royalty Monetization Liabilities [Line Items]
Beginning balance	0
Ending balance	157,345	0
2025 Royalty Bond \| HCR [Member]
Royalty Monetization Liabilities [Line Items]
Beginning balance	0
Proceeds from royalty bond, net of discount and issuance costs	142,883
Royalty interest paid to HCR	(109)
Portion of payments representing interest	109
Unpaid interest accrued to principal	13,449
Amortization of debt discount and issuance costs	1,013
Ending balance	157,345	$ 0
Current portion	(9,937)
Non-current portion	$ 147,408

Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2025

Stock-Based Compensation Expense by Award Type

The Company’s stock-based compensation expense by award type was as follows (in thousands):


	Years Ended December 31,
	2025		2024
Stock options	$	18,622	$	23,518
Restricted stock units		15,278		14,455
Employee stock purchase plan		663		490
	$	34,563	$	38,463

Stock-Based Compensation Expense

The Company recorded aggregate stock-based compensation expense in the consolidated statements of operations and comprehensive loss as follows (in thousands):


	Years Ended December 31,
	2025		2024
Research and development	$	15,977	$	17,985
General and administrative		18,586		20,478
	$	34,563	$	38,463

Schedule of Fair Value of Options Granted on Weighted-Average Assumptions

The fair values of options granted were estimated at each grant date using the Black-Scholes valuation model with the following weighted-average assumptions:


	Years Ended December 31,
	2025			2024
Expected volatility		64	%		64	%
Expected term (years)		6.0			6.0
Risk-free interest rate		4.3	%		4.0	%
Expected dividend yield		0.0	%		0.0	%

Summary of Unvested RSUs Activity Under Equity Incentive Plans

The following table summarizes restricted stock unit activity under the Company's equity incentive plans (in thousands, except per share data):


				Weighted-average
				Grant Date
	Shares			Fair Value
Unvested balance at December 31, 2024		2,042		$	19.95
Granted		1,724		$	8.62
Vested		(743	)	$	21.27
Forfeited		(173	)	$	14.57
Unvested balance at December 31, 2025		2,850		$	13.08

2014 and 2015 Equity Incentive Plan [Member]

Summary of Stock Option Activity

The following table summarizes stock option activity under the Company's equity incentive plans (in thousands, except per share data):


						Weighted-
						average
				Weighted-		Remaining
				average		Contractual		Aggregate
				Exercise		Life		Intrinsic
	Shares			Price		(Years)		Value (a)
Outstanding at December 31, 2024		9,994		$	29.48		5.9	$	240
Granted		2,441		$	8.02
Exercised		(68	)	$	4.70
Cancelled or forfeited		(801	)	$	27.12
Outstanding at December 31, 2025		11,566		$	25.26		6.0	$	17,523
Exercisable at December 31, 2025		7,953		$	31.37		4.8	$	2,495
Vested and expected to vest at December 31, 2025		11,566		$	25.26		6.0	$	17,523

(a)

The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the common stock for the options that were in the money at the dates reported.

Royalty Monetization Liabilities (Tables)

12 Months Ended

Dec. 31, 2025

Royalty Monetization Liabilities [Line Items]

Schedule of Royalty Monetization Liabilities

Royalty monetization liabilities are accounted for as debt and consist of the following (in thousands):


	As of December 31,
	2025		2024
2020 Royalty Purchase Agreement	$	29,672	$	59,687
2025 Royalty Bond		157,345		—
Total	$	187,017	$	59,687

Current portion of royalty monetization liabilities	$	39,609	$	34,309
Non-current portion of royalty monetization liabilities		147,408		25,378
Total	$	187,017	$	59,687

2020 Royalty Purchase Agreement

Royalty Monetization Liabilities [Line Items]

Schedule of Changes in Royalty Monetization Liability

The following table presents the changes in the royalty monetization liability under the 2020 Royalty Purchase Agreement with HCR (in thousands):


	2020 Royalty
	Purchase Agreement
Balance at December 31, 2023	$	94,052
Novartis royalties paid to HCR		(46,413	)
Interest expense recognized		12,048
Balance at December 31, 2024		59,687
Novartis royalties paid to HCR		(60,095	)
Interest expense recognized		30,080
Balance at December 31, 2025		29,672
Current portion		(29,672	)
Non-current portion	$	—

2025 Royalty Bond

Royalty Monetization Liabilities [Line Items]

Schedule of Changes in Royalty Monetization Liability

The following table presents the changes in the royalty monetization liability under the 2025 Royalty Bond with HCR (in thousands):


	2025 Royalty Bond
Balance at December 31, 2024	$	—
Proceeds from royalty bond, net of discount and issuance costs		142,883
Royalty interest paid to HCR		(109	)
Portion of payments representing interest		109
Unpaid interest accrued to principal		13,449
Amortization of debt discount and issuance costs		1,013
Balance at December 31, 2025		157,345
Current portion		(9,937	)
Non-current portion	$	147,408

Stock-based Compensation - Stock-Based Compensation Expense by Award Type (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 34,563	$ 38,463
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	18,622	23,518
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	15,278	14,455
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 663	$ 490

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Royalty Monetization Liabilities - Additional Information (Details)	1 Months Ended	12 Months Ended
	May 31, 2025 USD ($) Tranche $ / shares shares	Dec. 31, 2025 USD ($)	Dec. 31, 2024
Royalty Monetization Liabilities [Line Items]
Warrants issued		$ 1,610,000
2020 Royalty Purchase Agreement
Royalty Monetization Liabilities [Line Items]
Repurchase of call option amount		$ 300,000,000
Interest Rate, Effective Percentage		16.30%
HCR [Member] \| 2020 Royalty Purchase Agreement
Royalty Monetization Liabilities [Line Items]
Proceeds from Royalties Received		$ 4,000,000
Purchase Agreement		200,000,000
Proceeds from sale of future royalties		196,000,000
Deferred Transaction Cost		3,500,000
Interest expense		$ 192,500,000
Interest Rate, Effective Percentage		85.20%	65.50%
HCR [Member] \| 2020 Royalty Purchase Agreement \| November 7, 2024
Royalty Monetization Liabilities [Line Items]
Royalty Payment Cap Amount		$ 260,000,000
HCR [Member] \| 2020 Royalty Purchase Agreement \| November 8, 2024
Royalty Monetization Liabilities [Line Items]
Royalty Payment Cap Amount		$ 300,000,000
HCR [Member] \| 2025 Royalty Bond
Royalty Monetization Liabilities [Line Items]
Interest Rate, Effective Percentage	9.75%	15.10%
Number of tranches of debt disbursal \| Tranche	3
Description of debt disbursal		The 2025 Royalty Bond is disbursable to the Company in three tranches, with $150.0 million funded on the closing date in May 2025, $50.0 million available to be funded if sales of a specified product exceed a specified threshold prior to December 31, 2026, and $50.0 million available to be funded if both parties exercise an option in 2027.
First disbursal of loan amount	$ 150,000,000
Second disbursal of loan amount	50,000,000
Third disbursal of loan amount	$ 50,000,000
Debt issuance discount percentage	2.25%
Proceeds received, net of discounts and transaction costs	$ 144,500,000
Interest rate terms		The 2025 Royalty Bond bears interest at a rate of 9.75% plus the 3-month secured overnight financing rate as administered by the Federal Reserve Bank of New York (SOFR), with a minimum interest rate of 14.0%. Interest payments are due quarterly using proceeds received under the Royalty Interest.
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]	us-gaap:SecuredOvernightFinancingRateSofrMember
Debt instrument, maturity date	May 31, 2035
Debt instrument extended maturity date	May 31, 2037
Additional percentage of amount payable upon repayment of debt	5.00%
Net proceeds allocated to Royalty Bond		$ 142,883,000
HCR [Member] \| 2025 Royalty Bond \| Maximum [Member]
Royalty Monetization Liabilities [Line Items]
Aggregate amount	$ 250,000,000
HCR [Member] \| 2025 Royalty Bond \| Minimum [Member]
Royalty Monetization Liabilities [Line Items]
Interest Rate, Effective Percentage	14.00%
May 2025 Warrants [Member] \| HCR [Member] \| 2025 Royalty Bond
Royalty Monetization Liabilities [Line Items]
Proceeds received, net of discounts and transaction costs	$ 144,500,000
Number of warrants issued \| shares	268,096
Exercise price of warrants \| $ / shares	$ 14.92
Warrants contractual term	10 years
Estimated fair value of warrants	$ 1,700,000
Warrants issued	1,600,000
Net proceeds allocated to Royalty Bond	142,900,000
Debt discount	$ 7,100,000

Retirement Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Retirement Benefits [Abstract]
Employer matching contribution expense	$ 3.4	$ 3.1

Nature of Business

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Business

1. Nature of Business

REGENXBIO Inc. (the Company) is a clinical-stage biotechnology company seeking to improve lives through the curative potential of gene therapy. The Company's investigational gene therapies use adeno-associated virus (AAV) vectors from its proprietary gene delivery platform (NAV Technology Platform). The NAV® Technology Platform has consisted of exclusive rights to a large portfolio of proprietary AAV vectors. The Company has developed a broad pipeline of gene therapy product candidates using the NAV Technology Platform as a one-time treatment to address an array of diseases. The Company's lead product candidates include ABBV-RGX-314 for the treatment of wet age-related macular degeneration (wet AMD) and diabetic retinopathy (DR), RGX-202 for the treatment of Duchenne muscular dystrophy, RGX-121 for the treatment of Mucopolysaccharidosis Type II (MPS II) and RGX-111 for the treatment of Mucopolysaccharidosis Type I (MPS I). In addition to its internal product development efforts, the Company has also selectively licensed the NAV Technology Platform and other intellectual property rights to other leading biotechnology and pharmaceutical companies (NAV Technology Licensees). As of December 31, 2025, the NAV Technology Platform was being applied by NAV Technology Licensees in two commercial products, Zolgensma® and Itvisma®, and in the preclinical and clinical development of various other licensed products. Additionally, the Company has licensed intellectual property rights to collaborators for the joint development and commercialization of certain product candidates. The Company was formed in 2008 in the State of Delaware and is headquartered in Rockville, Maryland.

Liquidity

The Company has incurred cumulative losses since inception and as of December 31, 2025, had generated an accumulated deficit of $1.13 billion. The Company's ability to transition to recurring profitability is dependent upon achieving a level of revenues adequate to support its cost structure, which depends heavily on the successful development, approval and commercialization of its product candidates. The Company may never achieve recurring profitability, and unless and until it does, will continue to need to raise additional capital through equity offerings, licensing and collaboration arrangements, or other non-dilutive financings. There is no assurance that the Company will be able to raise sufficient capital or obtain financing on favorable terms, or at all.

As of December 31, 2025, the Company had cash, cash equivalents and marketable securities of $240.9 million, which management believes is sufficient to fund operations into early 2027. This estimate is based on the Company's current operating plan, and excludes the potential effects of any future financings or material milestone payments that may be received under the Company's licensing and collaboration arrangements. The Company has based this estimate on assumptions that may prove to be wrong, and it could exhaust its capital resources sooner than expected. These conditions raise substantial doubt about the Company's ability to continue as a going concern within 12 months from the date these consolidated financial statements were issued. The Company’s ability to continue as a going concern will depend heavily on the successful development, approval and commercialization of its product candidates and its ability to raise additional capital to fund its operations. If the Company is unable to raise capital sufficient to meet its working capital needs in the future, it may be forced to delay expenditures, reduce the scope of its development activities or make other changes to its operating plans.

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Cash flows from operating activities
Net loss	$ (193,878)	$ (227,102)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation expense	34,563	38,463
Depreciation and amortization	15,615	16,215
Provision for credit losses (recoveries)		(5,000)
Net accretion of discounts on marketable debt securities	(5,479)	(4,144)
Net realized gain on investments	(62)	(6,616)
Impairment of long-lived assets		2,101
Non-cash interest expense	12,901	6,101
Other non-cash adjustments	597	1,324
Changes in operating assets and liabilities
Accounts receivable	(7,661)	9,707
Prepaid expenses	(2,860)	5,453
Other current assets	658	6,511
Operating lease right-of-use assets	6,653	6,196
Other assets	(613)	807
Accounts payable	(2,284)	(292)
Accrued expenses and other current liabilities	229	(12,124)
Deferred revenue	29,280	(33)
Operating lease liabilities	(8,625)	(8,083)
Other liabilities	(2,997)	(2,609)
Net cash used in operating activities	(123,963)	(173,125)
Cash flows from investing activities
Purchases of marketable debt securities	(332,630)	(190,139)
Maturities of marketable debt securities	319,114	290,238
Sales of equity securities	62	5,783
Purchases of property and equipment	(2,414)	(2,436)
Net cash provided by (used in) investing activities	(15,868)	103,446
Cash flows from financing activities
Proceeds from exercise of stock options	318	1,512
Taxes paid related to net settlement of stock-based awards	(633)	(910)
Proceeds from issuance of common stock under employee stock purchase plan	1,048	1,191
Proceeds from public offering of common stock and pre-funded warrants, net of issuance costs		131,067
Expenses related to at-the-market offering programs	(357)	(323)
Proceeds from issuance of royalty bond and warrants, net of transaction costs	144,493
Repayments under royalty monetization liabilities, net of interest	(28,098)	(39,854)
Net cash provided by financing activities	116,771	92,683
Net increase (decrease) in cash and cash equivalents and restricted cash	(23,060)	23,004
Cash and cash equivalents and restricted cash
Beginning of period	59,556	36,552
End of period	36,496	59,556
Supplemental cash flow information
Cash paid (received) for income taxes	285	(72)
Cash paid for interest under royalty monetization liabilities	32,107	6,559
Supplemental disclosures of non-cash investing and financing information
Purchases of property and equipment in accounts payable and accrued expenses and other current liabilities	889	339
Deferred equity offering costs in accounts payable and accrued expenses and other current liabilities	153	222
Deferred equity offering costs reclassified	$ 499	$ 628

Segment and Geographical Information - Shedule of Information about Company's Segment Revenues, Significant Segment Expenses Regularly Provided to CODM, Other Segment Items and Consolidated Net Income (loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Segment Reporting Information [Line Items]
Revenues	$ 170,441	$ 83,328
Less:
Cost of license and royalty revenues	20,298	33,567
Total research and development expense	228,299	208,522
Total general and administrative expense	82,863	76,619
Other segment items	(32,859)	8,278
Net loss	(193,878)	(227,102)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	170,441	83,328
Less:
Cost of license and royalty revenues	20,298	33,567
Total research and development expense	228,299	208,522
Total general and administrative expense	82,863	76,619
Operating Segments [Member] \| Personnel
Less:
Total research and development expense	73,508	65,950
Total general and administrative expense	22,793	20,816
Operating Segments [Member] \| Direct development and support
Less:
Total research and development expense	112,887	97,951
Operating Segments [Member] \| Other general and administrative
Less:
Total general and administrative expense	35,018	29,480
Operating Segments [Member] \| Facilities
Less:
Total research and development expense	11,276	11,410
Total general and administrative expense	5,502	4,856
Operating Segments [Member] \| Stock-based compensation
Less:
Total research and development expense	15,977	17,985
Total general and administrative expense	18,586	20,478
Operating Segments [Member] \| Depreciation and amortization
Less:
Total research and development expense	14,651	15,226
Total general and administrative expense	$ 964	$ 989

Consolidated Statements of Stockholders' Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($)
Common Stock [Member] \| Public Offering [Member]
Issuance of Stock, transaction costs	$ 534

License and Collaboration Agreements - Schedule of AbbVie Collaboration Agreement (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Net cost reimbursement to (from) AbbVie included in:
Total net cost reimbursement to (from) AbbVie	$ (57,544)	$ (76,450)
Abb Vie Collaboration And License Agreement \| Research and Development Expense [Member]
Net cost reimbursement to (from) AbbVie included in:
Total net cost reimbursement to (from) AbbVie	(60,222)	(78,316)
Abb Vie Collaboration And License Agreement \| General and Administrative Expense [Member]
Net cost reimbursement to (from) AbbVie included in:
Total net cost reimbursement to (from) AbbVie	$ 2,678	$ 1,866

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2025	Dec. 31, 2024
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	50,892,000	49,549,000
Common stock, shares outstanding	50,892,000	49,549,000

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Basis of Presentation and Principles of Consolidation

Foreign Currency Transactions

Use of Estimates

Reclassifications

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with original maturities of 90 days or less at acquisition to be cash equivalents.

Restricted Cash


	As of December 31,
	2025		2024
Cash and cash equivalents	$	34,466	$	57,526
Restricted cash		2,030		2,030
Total cash and cash equivalents and restricted cash	$	36,496	$	59,556

Marketable Securities

Accounts Receivable

Concentrations of Credit Risk and Off-balance Sheet Risk

The following table summarizes those customers who represented at least 10% of revenues or total net accounts receivable for the periods presented:


	Revenues						Accounts Receivable
	Years Ended December 31,						As of December 31,
	2025			2024			2025			2024
Customer A		49	%		98	%		84	%		97	%
Customer B		50	%		—			14	%		—

Leases

Property and Equipment


	Estimated Useful Life
Computer equipment and software	3 years
Furniture and fixtures	5 years
Laboratory and manufacturing equipment	5 to 15 years
Leasehold improvements	Shorter of lease term or estimated useful life

Cloud Computing Arrangements

Impairment of Long-lived Assets

Non-marketable Equity Securities

Fair Value Measurements

•

Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

•

Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly.

•

Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable.

Royalty Monetization Liabilities

Warrants

Revenue Recognition

Collaborative Arrangements

Cost of License and Royalty Revenues

Research and Development Expenses

Stock-based Compensation

The Company has elected to not estimate forfeitures of stock-based awards and accounts for forfeitures as they occur.

The Company estimates the fair value of restricted stock units based on the fair value of the Company’s common stock on the date of the grant.

Income Taxes

Restructuring Expenses

Net Loss Per Share

Comprehensive Loss

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recent Accounting Pronouncements Not Yet Adopted

Segment and Geographical Information

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Segment and Geographical Information

16. Segment and Geographical Information

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker (CODM), or decision-making group, in making decisions on how to allocate resources and assess performance. The Company’s CODM, its Chief Executive Officer, views the Company’s operations and manages the business as one operating segment focused on the development and commercialization of gene therapies to treat an array of diseases. The determination of a single operating segment is consistent with the consolidated financial information regularly provided to the CODM.

The CODM reviews and evaluates consolidated net income (loss) for purposes of assessing performance, making operating decisions and allocating resources. The CODM uses net income (loss) to assess performance versus operating budgets and in the preparation of near-term and long-range operating plans to inform decisions on resource and capital allocation. The CODM reviews consolidated cash, cash equivalents and marketable securities as a measure of segment assets. As of December 31, 2025 and 2024, the Company’s cash, cash equivalents and marketable securities were $240.9 million and $244.9 million, respectively.


	Years Ended December 31,
	2025			2024
Revenues	$	170,441		$	83,328
Less:
Cost of license and royalty revenues		20,298			33,567
Research and development expense
Personnel		73,508			65,950
Direct development and support (a)		112,887			97,951
Facilities		11,276			11,410
Stock-based compensation		15,977			17,985
Depreciation and amortization		14,651			15,226
Total research and development expense		228,299			208,522
General and administrative expense
Personnel		22,793			20,816
Other general and administrative (b)		35,018			29,480
Facilities		5,502			4,856
Stock-based compensation		18,586			20,478
Depreciation and amortization		964			989
Total general and administrative expense		82,863			76,619
Other segment items (c)		(32,859	)		8,278
Net loss	$	(193,878	)	$	(227,102	)

(a)

(b)

Other general and administrative expenses include professional and administrative services, consulting, commercial cost reimbursement to and from collaborators and other corporate overhead expenses.

(c)

Other segment items include credit losses (recoveries), impairment of long-lived assets, other operating expenses, interest income from licensing, investment income and interest expense.

The Company’s interest income during the years ended December 31, 2025 and 2024 included interest income from licensing as presented in the consolidated statements of operations and comprehensive loss, as well as interest income from investments of $12.2 million and $12.1 million, respectively, which is included within investment income in the consolidated statements of operations and comprehensive loss.

For the year ended December 31, 2025, 44% and 25% of the Company’s revenues were attributed to Japan and the United States, respectively, and no other countries accounted for 10% or more of the Company’s revenues. For the year ended December 31, 2024, 36%, 10% and 10% of the Company’s revenues were attributed to the United States, Germany and United Arab Emirates, respectively, and no other countries accounted for 10% or more of the Company’s revenues. The country of origin for license revenue is determined based on the country of domicile of the licensee. The country of origin for royalty revenue is determined based on the location of the underlying net sales of licensed products. The country of origin for service revenue is determined based on the location where the Company principally performs the services.

The substantial majority of the Company’s assets reside in the United States.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

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+ Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2025

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

8. Commitments and Contingencies

In-licensed Technology

The Company in-licenses intellectual property from third parties for technology and know-how used in its product candidates and development programs, some of which is further sublicensed to NAV Technology Licensees and collaboration partners. In-licenses may require the Company to make future payments relating to sublicense fees, milestone fees and royalties on future sales of licensed products. Additionally, the Company may be responsible for the cost of the maintenance of the intellectual property as incurred by its licensors. Up-front fees to obtain licensed technology, as well as associated milestone fees, are recorded as research and development expenses if the technology has no alternative future use. Sublicense fees are based on a specified percentage of license fees earned by the Company as a result of sublicensing the technology to third parties and are recorded as cost of revenues. Royalties due to licensors on sales of licensed products, including sales by NAV Technology Licensees, are recorded as cost of revenues. Patent maintenance costs are recorded as general and administrative expenses.

Please refer to Note 10 for information on licenses granted by the Company and collaboration agreements with third parties.

The Trustees of the University of Pennsylvania

In February 2009, the Company entered into a license agreement, which has been amended from time to time (as amended, the Penn License), with The Trustees of the University of Pennsylvania (Penn) for exclusive, worldwide rights to certain patents owned by Penn underlying the Company’s NAV Technology Platform, as well as exclusive rights to certain data, results and other information. Pursuant to the originally agreed upon Penn License, the Company was obligated to pay Penn royalties on net sales of licensed products and sublicense fees. Additionally, the Company was obligated to reimburse Penn for certain costs incurred related to the maintenance of the licensed patents.

In April 2019, the Penn License was amended to include exclusive license rights to certain patent rights and know-how, including research data and other information, relating to the treatment of late-infantile neuronal ceroid lipofuscinosis type 2 (CLN2) disease. In consideration for the additional licensed rights, and in addition to any consideration owed under the license prior to the amendment, the Company paid Penn an up-front fee and is obligated to pay milestone fees of up to $20.5 million upon the achievement of various development and sales-based milestones and additional royalties on net sales of licensed products for the treatment of CLN2 disease. From the inception of the agreement through December 31, 2025, the Company had incurred $0.5 million for development milestones achieved, or deemed probable of achievement, under the Penn License.

In March 2022, the Company and Penn entered into a letter agreement (the Penn Letter Agreement) pursuant to which the Company will pay to Penn a total of $20.0 million, consisting of (i) $8.0 million paid in April 2022 to satisfy payment of any sublicense fees due or owed in the future under the Penn License as a result of the Company’s collaboration and license agreement with AbbVie Global Enterprises Ltd., and (ii) $12.0 million to satisfy any other past or future obligations of the Company to pay sublicense fees under the Penn License, which is payable in four equal annual installments of $3.0 million beginning in March 2023. The Penn Letter Agreement amended the Penn License to remove the Company’s obligations to pay sublicense fees under the license agreement. The Company remains obligated to pay Penn royalties on net sales of licensed products, milestone fees and reimbursement of certain patent maintenance costs in accordance with the Penn License.

The Company recognized a charge of $9.2 million as cost of revenues upon the execution of Penn Letter Agreement in March 2022, which consisted of $17.3 million representing the present value of the $20.0 million payable under the Penn Letter Agreement, less $8.1 million in sublicense fees previously recognized as expense by the Company in prior periods and accrued as liabilities prior to the effectiveness of the Penn Letter Agreement. The present value discount is accreted as interest expense over the contractual payment period using the effective interest method.

Expenses incurred by the Company related to the Penn License were recorded as follows (in thousands):


	Years Ended December 31,
	2025		2024
General and administrative	$	461	$	299
Interest expense		356		612
	$	817	$	911

As of December 31, 2025, the Company had recorded $3.0 million payable under the Penn License, net of present value discount, which was included in accounts payable and accrued expenses and other current liabilities on the consolidated balance sheet. As of December 31, 2024, the Company had recorded $5.8 million payable under the Penn License, net of present value discount, of which $2.9 million was included in accrued expenses and other current liabilities, and $2.9 million was included in other liabilities on the consolidated balance sheet.

GlaxoSmithKline

In March 2009, the Company entered into a license agreement, which was amended in April 2009 (as amended, the GSK License), with GlaxoSmithKline LLC (GSK) for exclusive, worldwide rights to certain patents underlying the Company’s NAV Technology Platform which are owned by Penn and exclusively licensed to GSK. Pursuant to the GSK License, the Company is obligated to pay GSK royalties on net sales of licensed products and sublicense fees. Additionally, the Company is obligated to reimburse GSK for certain costs incurred related to the maintenance of the licensed patents. The Company was also obligated to pay $1.5 million to GSK upon the achievement of various milestones, all of which have been achieved and paid.

In connection with the execution of the Penn Letter Agreement in March 2022, the Company’s royalty obligations under the GSK License were assigned by GSK to Penn. Beginning upon the effective date of the Penn Letter Agreement in March 2022, any royalties payable by the Company under the GSK License shall be paid to Penn rather than GSK. The Company remains obligated to pay GSK sublicense fees and reimbursement of certain patent maintenance costs in accordance with the GSK License.

Expenses incurred by the Company related to the GSK License were recorded as follows (in thousands):


	Years Ended December 31,
	2025		2024
Cost of license and royalty revenues:
Royalties on net sales of Zolgensma and Itvisma	$	19,193	$	33,180
Other		399		337
Total cost of license and royalty revenues		19,592		33,517
General and administrative		196		369
	$	19,788	$	33,886

As of December 31, 2025, the Company had recorded $5.7 million payable under the GSK License, of which $5.7 million was included in accrued expenses and other current liabilities, and less than $0.1 million was included in other liabilities on the consolidated balance sheet. As of December 31, 2024, the Company had recorded $6.3 million payable under the GSK License, of which $6.2 million was included in accrued expenses and other current liabilities, and $0.1 million was included in other liabilities on the consolidated balance sheet.

The Company has been notified of a dispute with GSK over the amount of sublicense fees paid by the Company to GSK under the GSK License. GSK claims there has been a significant underpayment by the Company as they are entitled to a sublicense payment on all amounts received by the Company from sublicensees, including royalties, and not just amounts received for GSK's sublicensed patents. The Company disagrees with GSK's interpretation of the GSK License and engaged in non-binding mediation with GSK but the dispute has not yet been resolved. The Company does not believe that a loss is probable, and no reasonable range of loss is estimable, related to this matter. No liabilities related to this matter were recorded as of December 31, 2025 and 2024.

Emory University

In August 2018, the Company entered into a license agreement (the Emory License) with Emory University (Emory) for an exclusive license to Emory’s interest in certain patent rights, which are co-owned by Emory and the Company, to commercialize products covered by the licensed patent rights in any country or territory. Patent rights licensed under the Emory License include certain rights which have been sublicensed by the Company to Novartis and are applicable to Itvisma for the treatment of certain patients with SMA. Pursuant to the Emory License, the Company is obligated to reimburse Emory for patent prosecution and maintenance expenses and pay Emory annual maintenance fees under certain circumstances, royalties on net sales, sublicense fees and fees upon the achievement of various milestones for the first licensed product. During the years ended December 31, 2025 and 2024, the Company incurred $0.1 million and $0.1 million, respectively, under the Emory License for milestone payments and patent maintenance costs.

Clearside Biomedical

In August 2019, the Company entered into an option and license agreement with Clearside Biomedical, Inc. (Clearside) pursuant to which the Company was granted an option to exclusively license the worldwide rights to certain patents related to Clearside’s proprietary, in-office SCS Microinjector® for the delivery of ABBV-RGX-314 to the suprachoroidal space to treat wet AMD, DR and other diseases. The Company exercised its license option in October 2019, resulting in a payment of $1.6 million to Clearside payable under the license agreement. Additionally, the Company is obligated to pay milestone fees of up to $136.0 million upon the achievement of various development and sales-based milestones, as well as royalties on net sales of licensed products using the SCS Microinjector. Clearside is responsible for supplying the SCS Microinjector to the Company to support all preclinical, clinical and commercial needs. From the inception of the agreement through December 31, 2025, the Company had incurred $3.0 million for development milestones achieved, or deemed probable of achievement, under the agreement.

In November 2025, Clearside announced that it filed a voluntary petition under Chapter 11 of the U.S. Bankruptcy Code in the District of Delaware and that it was seeking authorization to sell all or substantially all of its assets in a court-supervised auction and sale process under Section 363 of the U.S. Bankruptcy Code. Clearside subsequently announced that it entered into an asset purchase agreement with a stalking horse bidder, Health Ocean Pharma (Eye) Limited, for the sale of substantially all of its assets, including its remaining rights with respect to the SCS Microinjector. The sale process is still ongoing and is subject to pending objections by parties in interest, and, therefore, the ultimate outcome of that process is unknown.

Other Licenses

In November 2014, the Company entered into a license agreement, which has been amended from time to time, with Regents of the University of Minnesota (Minnesota), for an exclusive license to Minnesota’s interest in certain patent rights which are co-owned by Minnesota and the Company to commercialize products covered by the licensed patent rights in any country or territory in which a licensed patent has been issued and is unexpired, or a licensed patent application is pending. Pursuant to the license agreement, the Company is obligated to pay Minnesota annual maintenance fees, royalties on net sales, sublicense fees and fees upon the achievement of various milestones. Additionally, the Company is obligated to pay for certain costs incurred related to the maintenance of the licensed patents.

In June 2022, the Company entered into a license agreement with Johns Hopkins University (JHU) for an exclusive license to JHU's interest in certain patent rights which are co-owned by JHU and the Company to commercialize products covered by the licensed patent rights in any country or territory. Pursuant to the license agreement, the Company paid JHU an upfront fee and is obligated to pay JHU royalties on net sales, minimum annual royalties, sublicense fees and fees upon the achievement of various milestones for the first two licensed products. Additionally, the Company is obligated to pay for certain costs incurred related to the maintenance of the licensed patents.

Other Funding Commitments

In the normal course of business, the Company enters into agreements with contract research organizations, contract manufacturing organizations and other third parties for services to be provided to the Company. Generally, these agreements provide for termination upon notice, with specified amounts due upon termination based on the timing of termination and the terms of the agreement. The actual amounts and timing of payments under these agreements are uncertain and contingent upon the initiation and completion of services to be provided to the Company.

Guarantees and Indemnifications

In the normal course of business, the Company enters into agreements that contain a variety of representations and provide for general indemnification. The Company’s potential exposure under these agreements is unknown because it involves claims that may be made against the Company in the future. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. As of December 31, 2025 and 2024, the Company did not have any material indemnification claims that were probable or reasonably possible and consequently had not recorded any related liabilities.

Litigation

On or about February 13, 2026, a putative securities class action complaint was filed by Andre Kuik against the Company and certain of its current officers and directors in the United States District Court for the District of Maryland. The complaint asserts claims under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder, on behalf of a putative class of persons who purchased or otherwise acquired the Company's securities during the period from February 9, 2022 through January 27, 2026. The complaint alleges that the Company misled investors concerning the viability and safety of RGX-111 study, and that the Company's stock price declined following the announcement of the clinical holds imposed by the FDA on the Company’s RGX-111 and RGX-121 programs on January 28, 2026. The plaintiff seeks unspecified compensatory damages, attorneys' fees, expert fees and other costs, and other relief as the court may deem just and proper. The Company believes that it has meritorious defenses to the claims asserted and intends to vigorously defend against them. The Company does not believe that a loss is probable, and no reasonable range of loss is estimable, related to this matter. No liabilities related to this matter were recorded as of December 31, 2025.

Supplemental Disclosures

12 Months Ended

Dec. 31, 2025

Payables and Accruals [Abstract]

Supplemental Disclosures

17. Supplemental Disclosures

Other Current Assets

Other current assets consisted of the following (in thousands):


	As of December 31,
	2025		2024
Net cost reimbursement due from AbbVie	$	10,871	$	11,304
Accrued interest on investments		1,004		1,094
Other		1,030		1,376
	$	12,905	$	13,774

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	As of December 31,
	2025		2024
Accrued personnel costs	$	17,418	$	17,607
Accrued external research and development expenses		10,229		8,998
Accrued sublicense fees and royalties		8,652		8,658
Accrued external general and administrative expenses		1,301		2,002
Accrued purchases of property and equipment		33		156
Other		757		649
	$	38,390	$	38,070

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Public Offering [Member]	Common Stock [Member]	Common Stock [Member] Public Offering [Member]	Additional paid in capital [Member]	Additional paid in capital [Member] Public Offering [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Balances at Dec. 31, 2023	$ 311,742		$ 4		$ 1,021,214		$ (4,429)	$ (705,047)
Balances (Shares) at Dec. 31, 2023			44,046
Vesting of restricted stock units, net of tax, shares			345
Vesting of restricted stock units, net of tax	(910)				(910)
Exercise of stock options, net of tax, shares			291
Exercise of stock options, net of tax	1,512				1,512
Issuance of common stock under employee stock purchase plan, shares			105
Issuance of common stock under employee stock purchase plan	1,191				1,191
Issuance of common stock and pre-funded warrants, shares				4,565
Issuance of common stock and pre-funded warrants		$ 131,067		$ 1		$ 131,066
Exercise of pre-funded warrants, shares			197
Stock-based compensation expense	38,463				38,463
Unrealized gain (loss) on available-for-sale securities, net	3,688						3,688
Net loss	(227,102)							(227,102)
Balances at Dec. 31, 2024	259,651		$ 5		1,192,536		(741)	(932,149)
Balances (Shares) at Dec. 31, 2024			49,549
Vesting of restricted stock units, net of tax, shares			662
Vesting of restricted stock units, net of tax	(633)				(633)
Exercise of stock options, net of tax, shares			68
Exercise of stock options, net of tax	318				318
Issuance of common stock under employee stock purchase plan, shares			158
Issuance of common stock under employee stock purchase plan	1,048				1,048
Issuance of warrants, net of transaction costs	1,610				1,610
Exercise of pre-funded warrants, shares			455
Stock-based compensation expense	34,563				34,563
Unrealized gain (loss) on available-for-sale securities, net	54						54
Net loss	(193,878)							(193,878)
Balances at Dec. 31, 2025	$ 102,733		$ 5		$ 1,229,442		$ (687)	$ (1,126,027)
Balances (Shares) at Dec. 31, 2025			50,892

Stock-based Compensation - Summary of Stock Option Activity (Detail) - Equity Incentive Plans [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Shares Outstanding, Beginning Balance	9,994
Shares, Granted	2,441
Shares, Exercised	(68)
Shares, Cancelled or forfeited	(801)
Shares Outstanding, Ending Balance	11,566	9,994
Shares, Exercisable	7,953
Shares, Vested and expected to vest	11,566
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-average Exercise Price Outstanding, Beginning Balance	$ 29.48
Weighted-average Exercise Price, Granted	8.02
Weighted-average Exercise Price, Exercised	4.70
Weighted-average Exercise Price, Cancelled or forfeited	27.12
Weighted-average Exercise Price, Outstanding, Ending Balance	25.26	$ 29.48
Weighted-average Exercise Price, Exercisable	31.37
Weighted-average Exercise Price, Vested and expected to vest	$ 25.26
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-average Remaining Contractual Life (Years) Outstanding	6 years	5 years 10 months 24 days
Weighted-average Remaining Contractual Life (Years), Exercisable	4 years 9 months 18 days
Weighted-average Remaining Contractual Life (Years), Vested and expected to vest	6 years
Aggregate Intrinsic Value Outstanding	$ 17,523	$ 240
Aggregate Intrinsic Value, Exercisable	2,495
Aggregate Intrinsic Value, Vested and expected to vest	$ 17,523

Income Taxes - Schedule of Reconciliation of U.S. Federal Statutory Tax Rate to Effective Tax Rate (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Amount
U.S. federal statutory tax rate	$ (40,714,000)	$ (47,692,000)
State and local income tax benefit, net of federal tax effect	0	0
Effect of changes in tax laws or rates enacted in the current period	0	0
Effects of cross-border tax laws	0	0
Tax credits:
Research and development and orphan drug tax credits	(7,492,000)	(9,582,000)
Other tax credits	(27,000)	(35,000)
Change in valuation allowance	40,418,000	51,658,000
Nontaxable or nondeductible items:
Stock-based compensation	5,385,000	3,171,000
Executive compensation	1,440,000	2,633,000
Other	1,137,000	3,000
Changes in unrecognized tax benefits	(148,000)	0
Other adjustments	(16,000)	(173,000)
Effective tax rate	$ 0	$ 0
Percent
U.S. federal statutory tax rate	21.00%	21.00%
State and local income tax benefit, net of federal tax effect	0.00%	0.00%
Effect of changes in tax laws or rates enacted in the current period	0.00%	0.00%
Effects of cross-border tax laws	0.00%	0.00%
Tax credits:
Research and development and orphan drug tax credits	3.90%	4.20%
Other tax credits	0.00%	0.00%
Change in valuation allowance	(20.80%)	(22.70%)
Nontaxable or nondeductible items:
Stock-based compensation	(2.80%)	(1.40%)
Executive compensation	(0.70%)	(1.20%)
Other	(0.70%)	0.00%
Changes in unrecognized tax benefits	0.10%	0.00%
Other adjustments	0.00%	0.10%
Effective tax rate	0.00%	0.00%
Ireland
Amount
Foreign tax effects	$ 17,000	$ 17,000
Percent
Foreign tax effects	0.00%	0.00%

Leases (Tables)

12 Months Ended

Dec. 31, 2025

Leases [Abstract]

Summary of Lease Costs and Supplemental Cash Flow Information of Operating Leases

The following table summarizes the Company’s lease costs and supplemental cash flow information related to its operating leases (in thousands):


	Years Ended December 31,
	2025			2024
Operating lease cost	$	11,256		$	11,168
Variable lease cost		3,064			2,725
Sublease income		(451	)		(319	)
Total lease cost	$	13,869		$	13,574

Cash paid for amounts included in operating lease liabilities	$	13,071		$	12,969
Right-of-use assets acquired through operating lease liabilities	$	93		$	826

Weighted-Average Remaining Lease Term and Weighted-Average Discount Rate of Operating Leases

The following table presents the weighted-average remaining lease term and weighted-average discount rate of the Company’s operating leases:


	As of December 31,
	2025			2024
Weighted-average remaining lease term (years)		9.8			10.3
Weighted-average discount rate		5.7	%		5.7	%

Reconciliation of Undiscounted Future Minimum Lease Payments Remaining Operating Leases


	As of
	December 31, 2025
Undiscounted future minimum lease payments:
2026	$	12,237
2027		10,020
2028		7,943
2029		8,051
2030		8,134
Thereafter		50,855
Total undiscounted future minimum lease payments		97,240
Amount representing imputed interest		(23,739	)
Total operating lease liabilities		73,501
Current portion of operating lease liabilities		(8,286	)
Operating lease liabilities, non-current	$	65,215

License and Collaboration Agreements - Schedule Of License Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total license and royalty revenue	$ 170,441	$ 83,328
Other license revenue		28
Interest income from licensing	83	174
Novartis Gene Therapies [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total license and royalty revenue	83,177	81,533
Interest income from licensing	41	123
Zolgensma Royalties [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total license and royalty revenue	82,536	$ 81,505
Itvisma Royalties [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total license and royalty revenue	$ 641

- Definition

+ References

+ Details

Leases - Summary of Lease Costs and Supplemental Cash Flow Information of Operating Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Leases [Abstract]
Operating lease cost	$ 11,256	$ 11,168
Variable lease cost	3,064	2,725
Sublease income	(451)	(319)
Total lease cost	13,869	13,574
Cash paid for amounts included in operating lease liabilities	13,071	12,969
Right-of-use assets acquired through operating lease liabilities	$ 93	$ 826

License and Collaboration Agreements - Summary of Accounts Receivable, Contract Assets and Deferred Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Accounts receivable, net, current and non-current:
Balance, beginning of period	$ 20,947	$ 25,491
Balance, end of period	28,691	20,947
Contract assets:
Balance, beginning of period	239
Balance, end of period	104	239
Deferred revenue, current and non-current:
Balance, beginning of period	115	148
Balance, end of period	29,395	115
Revenue recognized during the period from:
Amounts included in deferred revenue at beginning of period	115	148
Performance obligations satisfied in previous periods	$ 84,684	$ 81,585

Income Taxes - Schedule of U.S. Federal and State NOL and Tax Credit Carryforwards (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2025 USD ($)
Domestic Country [Member]
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 754,390
Tax credit carryforwards	$ 94,143
NOL carryforwards, Expiration Date	Indefinite
Tax credit carryforwards, Expiration Date	Various dates between 2037 and 2045
U. S State Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 6,857
Tax credit carryforwards	$ 1,000
NOL carryforwards, Expiration Date	Indefinite
Tax credit carryforwards, Expiration Date	Various dates between 2029 and 2032
U. S State Tax Authority One [Member]
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 388,008
NOL carryforwards, Expiration Date	Various dates between 2029 and 2045

Stock-based Compensation

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Stock-based Compensation

11. Stock-based Compensation

In September 2014, the Company adopted the 2014 Stock Plan (the 2014 Plan). In June 2015, the Company adopted the 2015 Equity Incentive Plan (the 2015 Plan), which replaced the 2014 Plan effective upon the Company’s initial public offering in September 2015. Upon the effective date of the 2015 Plan, no further awards may be granted under the 2014 Plan. As of December 31, 2025, there were no awards outstanding under the 2014 Plan.

Effective in January 2025, an additional 1,981,975 shares were authorized for issuance under the 2015 Plan. The 2015 Plan expired in June 2025, upon which no further awards may be granted under the plan. Any awards outstanding under the 2015 Plan as of the plan expiration date shall remain outstanding and effective pursuant to the contractual terms of the awards.

In May 2025, the Company adopted the 2025 Equity Incentive Plan (the 2025 Plan), which replaced the 2015 Plan upon its expiration in June 2025. The total number of shares of common stock authorized for issuance under the 2025 Plan upon its adoption was 5,500,000. The number of shares authorized for issuance under the 2025 Plan shall automatically increase for any shares of common stock underlying awards outstanding under the 2015 Plan, as of the adoption date of the 2025 Plan, which are not issued due to forfeiture, expiration, termination or cancellation of the award. Shares of common stock that are withheld, tendered, or otherwise not issued in connection with the settlement of awards outstanding under the 2015 Plan do not increase the number of shares authorized for issuance under the 2025 Plan. As of December 31, 2025, the total number of shares of common stock reserved for issuance under the 2025 Plan and 2015 Plan was 20,133,416, of which 5,717,654 remained available for future grants under the 2025 Plan.

The 2014 Plan, 2015 Plan and 2025 Plan provide for the issuance of stock options, stock appreciation rights, restricted and unrestricted stock and unit awards, and performance cash awards to employees, members of the Board of Directors and consultants of the Company. As of December 31, 2025, the Company has issued only stock options and restricted stock units under the plans. Stock options generally expire 10 years following the date of grant. Stock options typically vest over a four-year period, but vesting provisions can vary by award based on the discretion of the Board of Directors. Stock options have an exercise price at least equal to the estimated fair value of the Company’s common stock on the date of grant. Restricted stock units typically vest over a four-year period, but vesting provisions can vary by award based on the discretion of the Board of Directors. Upon vesting, restricted stock units are settled in common stock of the Company. Awards granted under the 2025 Plan generally have a minimum vesting requirement of one year from the grant date.

Shares of common stock underlying awards granted under the 2025 Plan which are not issued due to forfeiture, expiration, termination or cancellation of the award are added to the number of shares of common stock available for issuance under the 2025 Plan, except for shares that are withheld, tendered or otherwise not issued in connection with the settlement of the award. Shares available for issuance under the 2025 Plan and 2015 Plan may be either authorized but unissued shares of the Company’s common stock or common stock reacquired by the Company and held in treasury. The 2025 Plan expires in May 2035, 10 years from its adoption date, unless earlier terminated.

Stock-based Compensation Expense

The Company’s stock-based compensation expense by award type was as follows (in thousands):


	Years Ended December 31,
	2025		2024
Stock options	$	18,622	$	23,518
Restricted stock units		15,278		14,455
Employee stock purchase plan		663		490
	$	34,563	$	38,463

As of December 31, 2025, the Company had $47.7 million of unrecognized stock-based compensation expense related to stock options, restricted stock units and the 2015 Employee Stock Purchase Plan (the 2015 ESPP), which is expected to be recognized over a weighted-average period of 2.2 years.

The Company recorded aggregate stock-based compensation expense in the consolidated statements of operations and comprehensive loss as follows (in thousands):


	Years Ended December 31,
	2025		2024
Research and development	$	15,977	$	17,985
General and administrative		18,586		20,478
	$	34,563	$	38,463

Stock Options

The following table summarizes stock option activity under the Company's equity incentive plans (in thousands, except per share data):


						Weighted-
						average
				Weighted-		Remaining
				average		Contractual		Aggregate
				Exercise		Life		Intrinsic
	Shares			Price		(Years)		Value (a)
Outstanding at December 31, 2024		9,994		$	29.48		5.9	$	240
Granted		2,441		$	8.02
Exercised		(68	)	$	4.70
Cancelled or forfeited		(801	)	$	27.12
Outstanding at December 31, 2025		11,566		$	25.26		6.0	$	17,523
Exercisable at December 31, 2025		7,953		$	31.37		4.8	$	2,495
Vested and expected to vest at December 31, 2025		11,566		$	25.26		6.0	$	17,523

(a)

The weighted-average grant date fair value per share of options granted during the years ended December 31, 2025 and 2024 was $4.96 and $9.98, respectively. During the years ended December 31, 2025 and 2024, the total number of stock options exercised was 67,735 and 290,753, respectively, resulting in total proceeds of $0.3 million and $1.5 million, respectively. The total intrinsic value of options exercised during the years ended December 31, 2025 and 2024 was $0.3 million and $3.1 million, respectively.

The fair values of options granted were estimated at each grant date using the Black-Scholes valuation model with the following weighted-average assumptions:


	Years Ended December 31,
	2025			2024
Expected volatility		64	%		64	%
Expected term (years)		6.0			6.0
Risk-free interest rate		4.3	%		4.0	%
Expected dividend yield		0.0	%		0.0	%

Restricted Stock Units

The following table summarizes restricted stock unit activity under the Company's equity incentive plans (in thousands, except per share data):


				Weighted-average
				Grant Date
	Shares			Fair Value
Unvested balance at December 31, 2024		2,042		$	19.95
Granted		1,724		$	8.62
Vested		(743	)	$	21.27
Forfeited		(173	)	$	14.57
Unvested balance at December 31, 2025		2,850		$	13.08

The total intrinsic value of restricted stock units vested during the years ended December 31, 2025 and 2024 was $6.0 million and $6.7 million, respectively.

Employee Stock Purchase Plan

In June 2015, the Board of Directors adopted the 2015 ESPP, which became effective upon the Company’s initial public offering in September 2015. The number of authorized shares reserved for issuance under the 2015 ESPP automatically increases on the first business day of each fiscal year by the lesser of (i) 1% of the shares of common stock outstanding on the last business day of the prior fiscal year; or (ii) the number of shares determined by the Board of Directors. Unless otherwise determined by the administrator of the 2015 ESPP, two offering periods of six months’ duration will begin each year on January 1 and July 1. As of December 31, 2025, the total number of shares of common stock authorized for issuance under the 2015 ESPP was 1,426,994, of which 755,306 remained available for future issuance. During the years ended December 31, 2025 and 2024, 157,658 and 105,400 shares of common stock, respectively, were issued under the 2015 ESPP.