Washington, D.C. 20549


Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
OMB Number: 3235-0287
Estimated average burden
hours per response: 0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
1. Name and Address of Reporting Person*

(Last) (First) (Middle)


(City) (State) (Zip)
2. Issuer Name and Ticker or Trading Symbol
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
Director 10% Owner
X Officer (give title below) Other (specify below)
Chief Medical Officer
3. Date of Earliest Transaction (Month/Day/Year)
4. If Amendment, Date of Original Filed (Month/Day/Year)
6. Individual or Joint/Group Filing (Check Applicable Line)
X Form filed by One Reporting Person
Form filed by More than One Reporting Person
Rule 10b5-1(c) Transaction Indication

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 03/05/2024 M(1) 12,878 A $22.25 120,070 D
Common Stock 03/05/2024 S(1) 12,878 D $28.36 107,192 D
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 6. Date Exercisable and Expiration Date (Month/Day/Year) 7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Stock Options (Right to Buy) $22.25 03/05/2024 M(1) 12,878 (2) 01/03/2033 Common Stock 12,878 $0.00 31,277 D
Explanation of Responses:
1. This transaction was effected pursuant to a Rule 10b5-1 trading plan.
2. The previously granted option, representing a right to purchase a total of 44,155 shares, became exercisable as follows: 25% of the shares subject to this option vested on January 3, 2024, and the balance vests in equal monthly installments over the 36 months thereafter while the optionee provides continuous service to the Issuer
/s/ Patrick J. Christmas as attorney-in-fact 03/07/2024
** Signature of Reporting Person Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

The undersigned individual (the "Reporting Person") hereby constitutes
and appoints each of Patrick J. Christmas, Kenneth T. Mills and Vittal
K. Vasista, signing singly, with full power of substitution, as the
Reporting Person's true and lawful attorney in fact to:

(1) prepare and file on behalf of such Reporting Person any and all
reports, notices, communications and other documents (including, but
not limited to, reports on Schedule 13D, Schedule 13G, Form 13-F,
Form 3, Form 4 and Form 5) that such Reporting Person may be
required to file with the Securities and Exchange Commission (the
"SEC") pursuant to the Securities Act of 1933, as amended and the
Securities Exchange Act of 1934, as amended (together with the
implementing regulations thereto, the "Exchange Act") (collectively, the
"Reports") with respect to the Reporting Person's ownership of, or
transactions in, the securities of REGENXBIO Inc. (the "Company")
(whether directly or indirectly owned) by such Reporting Person;

(2) do and perform any and all acts for and on behalf of the Reporting
Person which may be necessary or desirable to complete and execute
any such Reports, complete and execute any amendment or amendments
thereto, and timely file such form with the SEC and any stock exchange
or similar authority; and

(3) take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney in fact, may be of
benefit to, in the best interest of, or legally required by, the Reporting
Person, it being understood that the documents executed by such
attorney in fact on behalf of the Reporting Person pursuant to this Power
of Attorney shall be in such form and shall contain such terms and
conditions as such attorney in fact may approve in such attorney in
fact's discretion.

The Reporting Person hereby grants to such attorney in fact full power
and authority to do and perform any and every act and thing whatsoever
requisite, necessary or proper to be done in the exercise of any of the
rights and powers herein granted, as fully to all intents and purposes as
the Reporting Person might or could do if personally present, with full
power of substitution or revocation, hereby ratifying and confirming all
that such attorney in fact, or such attorney in fact's substitute or
substitutes, shall lawfully do or cause to be done by virtue of this power
of attorney and the rights and powers herein granted. The Reporting
Person acknowledges that the foregoing attorney in fact, in serving in
such capacity at the request of the Reporting Person, is not assuming
any of the Reporting Person's responsibilities to comply with Section 16
of the Exchange Act.

This Power of Attorney with respect to the Reporting Person shall
remain in full force and effect until such Reporting Person is no longer
required to file any Reports with respect to the Reporting Person's
ownership of, or transactions in, the securities of the Company, unless
earlier revoked in a signed writing delivered to the foregoing attorney in

IN WITNESS WHEREOF, the undersigned has caused this Power of
Attorney to be executed as of this 15th day of April, 2019.

/s/ Steve Pakola
Steve Pakola