REGENXBIO Receives FDA Fast Track Designation for RGX-121 Gene Therapy for the Treatment of Mucopolysaccharidosis Type II
The FDA Fast Track program is designed to facilitate the development and expedite the review of new drugs that are intended to treat serious or life-threatening conditions and that demonstrate the potential to address unmet medical needs. Fast Track-designated drugs often qualify for priority review, thereby expediting the
"Children living with MPS II have limited treatment options, making this Fast Track designation tremendously important," said
"My family has seen firsthand the unmet needs of children with MPS II," said
Leading international gene therapy and lysosomal storage disease centers will participate in the Phase I/II clinical trial for RGX-121 for the treatment of MPS II.
About the Phase I/II Clinical Trial of RGX-121
RGX-121 will be evaluated in a Phase I/II, multi-center, open-label, multiple-cohort, dose-escalation study in pediatric subjects with MPS II. Eligible patients must have documented evidence of early-stage neurocognitive deficit due to MPS. Approximately six male subjects with MPS II greater than or equal to four months old and less than five years old will be treated in two dose cohorts (1.3 × 1010 GC/g brain mass and 6.5 × 1010 GC/g brain mass), and will receive a single dose of RGX-121 administered by an injection directly in the cerebrospinal fluid (CSF). Patients will receive immunosuppression for the first year after RGX-121 is administered. The primary purpose of the clinical study is to assess the safety and tolerability of RGX-121 at 24 weeks. The primary endpoint will be a safety assessment. The secondary and exploratory endpoints include the effect of RGX-121 on biomarkers of I2S activity in the CSF, serum and urine and effect of RGX-121 on neurocognitive deficits, as well as other outcome measures. Following completion of the primary study period, subjects will continue to be assessed for a total of 104 weeks following treatment with RGX-121 and then be asked to participate in a long-term follow-up.
RGX-121 is being developed as a novel, one-time, direct-to-CNS treatment for MPS II that includes the NAV AAV9 vector encoding for human I2S. Delivery of the enzyme that is deficient within cells in the CNS could provide a permanent source of secreted I2S beyond the blood-brain barrier, allowing for long-term cross-correction of cells throughout the CNS. This strategy could also provide rapid I2S delivery to the brain, potentially preventing the progression of cognitive deficits that otherwise occurs in MPS II patients.
Treatment with RGX-121 has been shown to restore I2S enzyme activity in animal models of MPS II to levels equivalent to or greater than those in non-affected animals. The extent of CNS correction in animal studies suggests that RGX-121 has the potential to be an important and suitable therapeutic option for MPS II patients.
About Mucopolysaccharidosis Type II (MPS II)
MPS II is a rare X-linked recessive genetic disease caused by deficiency of I2S, an enzyme required for the breakdown of polysaccharides in the lysosomes. These polysaccharides, called glycosaminoglycans (GAGs), accumulate in tissues of MPS II patients, resulting in characteristic storage lesions and diverse clinical signs and symptoms including in the central nervous system (CNS), which can include neural cell death, excessive accumulation of fluid in the brain, spinal cord compression and cognitive impairment. MPS II is estimated to occur in approximately 1 in 100,000 to 1 in 170,000 births. The current disease-modifying therapy for MPS II is enzyme replacement therapy with a recombinant form of human I2S administered intravenously. However, intravenous enzyme therapy does not treat the CNS manifestations of MPS II.
REGENXBIO is a leading clinical-stage biotechnology company seeking to improve lives through the curative potential of gene therapy.
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