REGENXBIO Inc. has shared new, positive interim safety and efficacy data in the Phase I/II AFFINITY DUCHENNE® trial of RGX-202 in participants with Duchenne ages 1 to 11 years old. RGX-202 utilizes a novel adeno-associated virus (AAV8) to transport a shortened version of the dystrophin gene (micro-dystrophin) that may provide benefit in place of the missing full-length dystrophin protein.

REGENXBIO shared that in the two participants aged 5.8 and 8.5 who received RGX-202 at dose level 2, RGX-202 microdystrophin expression was measured to be 77.2%, and 46.5%, respectively, compared to control at three months.

Additionally, REGENEXBIO reported that as of July 8, 2024, RGX-202 has been well tolerated with no serious adverse events. The company indicated that all seven patients who completed three-month trial assessments indicate meaningful increases in expression of RGX-202 microdystrophin and reduction from baseline in serum creatinine kinase levels, supporting evidence of clinical improvement.

Program Updates

According to REGENXBIO, the company expects to complete enrollment in the dose level 2 expansion cohort early in the third quarter of 2024 and has initiated enrollment in the cohort for boys aged 1-3. Initiation of the pivotal trial is expected in the fourth quarter of 2024. REGENXBIO also expects to share initial strength and functional assessment data for both dose levels of the AFFINITY DUCHENNE trial in the second half of 2024.

Additionally, REGENXBIO reported that the company recently held a successful End-of-Phase II (EOP2) meeting with the U.S. FDA and is moving forward with plans to initiate a pivotal trial in Q4 2024. According to REGENXBIO, discussions with the FDA continue to support use of microdystrophin as a surrogate endpoint likely to predict clinical benefit for accelerated approval. The company expects to share the trial design of the pivotal trial in late Q3 to early Q4.

PPMD has requested a webinar with REGENXBIO and we will share additional information as it becomes available.

Read REGENXBIO’s press release here.