Regenxbio provides update from Phase I/II AFFINITY DUCHENNE trial of RGX-202

Regenxbio announced that enrollment has completed at dose level 2 and reported additional interim safety and efficacy in the Phase I/II AFFINITY DUCHENNE trial of RGX-202 in patients with Duchenne muscular dystrophy ages 4 to11 years old. As of February 6, 2024, RGX-202 has been well tolerated with no drug-related serious adverse events in five patients, aged 4.4 to 12.1 at dose level 1 and dose level 2. Time of post-administration follow up ranges from approximately three weeks to over nine months. All patients who reached three-month follow-up have completed the immunosuppression regimen per study protocol. In new data from the third patient, aged 6.6 years, who received RGX-202 at dose level 1, RGX-202 microdystrophin expression was measured to be 83.4% compared to control at three months. A reduction from baseline in serum creatinine kinase (CK) levels of 93% was observed at ten weeks. All three patients, at dose level 1, who completed three-month trial assessments indicate encouraging increases in expression of RGX-202 microdystrophin and reduction from baseline in serum CK levels, supporting evidence of clinical improvement. REGENXIO expects to make a pivotal dose determination in mid-2024. The Company also expects to share initial strength and functional assessment data for both dose levels and the initiation of a pivotal trial in the second half of 2024. The Company plans to use RGX-202 microdystrophin expression as a surrogate endpoint to support a Biologics License Application filing using the accelerated approval pathway.