RegenXBio has shared updated phase 1/2 data on its Duchenne muscular dystrophy (DMD) gene therapy, providing evidence that its pivotal dose improves functional outcomes in older boys with the disease.
The data update looked at five patients who were 6 to 12 years old when they received the gene therapy RGX-202. Untreated, people with DMD can start to lose the ability to walk and perform other tasks over those years. Data captured nine and 12 months after treatment with RGX-202 suggest the gene therapy may be able drive improvements in functional outcomes.
Mean scores on tests of time to stand, 10-meter walk-run and time to climb improved in the five patients with nine months of follow-up and the four patients with 12 months of follow-up. RegenXBio also tracked improvements on a scale that measures the functional motor abilities of children with DMD.
The biopharma compared the improvements to the deterioration seen in a natural history external control group. RegenXBio only provided a pooled analysis of the data but, speaking on a call with analysts about the update, the company’s chief medical officer Steve Pakola, M.D., called the improvements “robust and consistent.”
“All the patients are doing better than external natural history and also doing better than baseline, even when you look across a broad range of functional endpoints,” Pakola said. “These are boys that you would definitely be anticipating would be declining. Not only are we seeing stabilization, but we're actually seeing improvement.”
The level of improvement on some of the tests is lower than the changes RegenXBio saw at a lower dose late last year. However, differences between the baseline characteristics of the patients could explain the results. The first dose cohort enrolled (PDF) kids with a mean age of 7.1 years at baseline. The average age in the second dose cohort was 8.7 years.
No patients at either dose had serious adverse events, central or peripheral neurotoxicity, drug-induced liver injury or thrombocytopenia. The safety of DMD gene therapies was thrust into the spotlight earlier this year when a patient died after receiving Sarepta Therapeutics’ Elevidys. RegenXBio has identified safety as a potential differentiator of RGX-202.
The biopharma is racing toward pivotal data that could support its argument. RegenXBio expects to wrap up enrollment in the pivotal trial this year, putting it on track to file for approval in 2026 and bring the gene therapy to market in 2027.