RegenXBio Reports Functional Gains and Safety in Phase 1/2 Duchenne Muscular Dystrophy Gene Therapy Trial

RegenXBio has released an update on its Phase 1/2 clinical trial evaluating the gene therapy RGX-202 in boys diagnosed with Duchenne muscular dystrophy (DMD). The new data highlight functional improvements in a group of older patients who received what RegenXBio refers to as the pivotal dose.
The update encompasses five patients who were between the ages of 6 and 12 at the time of treatment with RGX-202. This age range is significant, as individuals with DMD typically begin to lose physical abilities, including walking and other basic movements, during these years. RegenXBio gathered follow-up data at both nine and 12 months after administration of the therapy.

The company observed mean improvements in three core functional tests: time to stand, the 10-meter walk-run, and time to climb. All five patients had reached the nine-month mark, and four had been evaluated at 12 months. In addition to these measures, RegenXBio also recorded progress on a broader functional motor ability scale commonly used to assess children with DMD.
When comparing these results to a natural history external control group, RegenXBio reported that the treated patients performed better, both relative to their pre-treatment baseline and in contrast to expected disease progression. Although the company presented a pooled analysis, Steve Pakola, M.D., the company’s chief medical officer, emphasized during a call with analysts that the improvements observed were both “robust and consistent.” According to Pakola, each patient in the cohort showed gains across a variety of functional benchmarks and surpassed expectations based on historical data.
While the observed functional gains at the pivotal dose were slightly lower than those seen in an earlier lower-dose group reported late last year, RegenXBio noted that differences in patient characteristics may account for this variation. Specifically, the average age at treatment for the first dose group was 7.1 years, whereas patients in the second cohort had a mean age of 8.7 years at the time of dosing.
Regarding safety outcomes, the company reported no serious adverse events among patients in either dosing group. There were no instances of central or peripheral neurotoxicity, no cases of drug-induced liver injury, and no reports of thrombocytopenia. This safety profile stands out, especially in light of a recent fatality associated with a different DMD gene therapy, Elevidys, developed by Sarepta Therapeutics. RegenXBio has pointed to the absence of serious adverse effects as a distinguishing feature of RGX-202.

Looking ahead, RegenXBio plans to complete enrollment in its pivotal trial within the current year. This timeline could allow the company to submit a regulatory approval application in 2026, aiming for a potential market launch of RGX-202 by 2027.