REGENXBIO Inc. has announced that the AFFINITY DUCHENNE® open-label trial of RGX-202 has advanced to pivotal stage and dosed its first patient. The company also announced new, positive efficacy and safety data from the Phase I/II portion of the study, including the first functional data. RGX-202 utilizes a new, modified  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. 

According to REGENXBIO, functional results from the first five participants in the Phase I/II portion of the ongoing AFFINITY DUCHENNE trial indicate that RGX-202 demonstrates evidence of positively impacting disease progression, with participants demonstrating stable or improved function on the North Star Ambulatory Assessment (NSAA) and other timed function tests. The AFFINITY DUCHENNE study is open-label, meaning all participants are aware of the dose of the gene therapy they receive and there is no placebo control. 

REGENXBIO also announced new biomarker data, which measure the amount of microdystrophin protein being produced after receiving RGX-202, that continue to support consistent, high expression and transduction of RGX-202 microdystrophin. Additionally, they reported that RGX-202 was well tolerated with no serious safety events, though they did report common drug-related adverse events typically seen with gene therapy administration such as nausea and vomiting. 

The AFFINITY DUCHENNE trial has been expanded into a multicenter, open-label pivotal Phase I/II/III trial which will evaluate the efficacy of RGX-202 at dose level 2 (2×1014 GC/kg) in approximately 30 ambulatory patients aged 1 and older. A pivotal trial provides critical evidence to support the FDA approval of a new drug or biologic product, and is typically the final step in the clinical trial process before a product is submitted for approval to the FDA. While a pivotal trial can be a separate clinical trial, REGENXBIO has consolidated their development of RGX-202 into one ongoing trial. REGENXBIO indicated that the pivotal trial phase of AFFINITY DUCHENNE is expected to support filing RGX-202 for FDA approval using the accelerated approval pathway in 2026.

PPMD is pleased to learn this update from REGENXBIO and we look forward to learning more about the ongoing AFFINITY DUCHENNE trial during our upcoming community webinar on Wednesday, November 20th, 2024, at 1:00 PM ET. Register here and submit questions in advance here.

Read REGENXBIO’s press release here.