By Padmanabhan Ananthan
May 14 (Reuters) – Regenxbio said on Thursday that its experimental gene therapy for a muscle-wasting disorder met the main goal in a late-stage study, but its shares plunged 31% in morning trading over safety concerns.
Regenxbio’s therapy, RGX-202, to treat Duchenne Muscular Dystrophy produced statistically significant results in 93% of patients in the study, which also reported two serious adverse events.
Leerink Partners analyst Mani Foroohar said the data is more mixed than the brokerage had hoped as the adverse events and lack of certainty on the U.S. Food and Drug Administration’s position will likely become a source of debate.
Wall Street has been closely watching whether the safety profile of RGX-202 could help differentiate it from approved rivals, given the liver safety concerns tied to Sarepta’s gene therapy Elevidys, including two deaths from liver failure.
Regenxbio said one case of subacute myocarditis, an inflammatory condition of the heart muscle, was reported in an 8-year-old participant. Another case of asymptomatic liver injury was reported in a 10-year-old participant.
Both were easily managed and resolved within weeks, the company said.
The therapy produced statistically high levels of a muscle protein, called microdystrophin, in 93% of patients after 12 weeks, in the study that enrolled 31 boys aged 1 year and older who were still able to walk independently.
The protein is usually missing or defective in people with the genetic disorder, characterized by muscle degeneration and weakness.
Microdystrophin expression averaged 71.1% across all participants, and 41.6% in boys aged more than 8 years, the company said.
“These data support the potential of RGX-202 to become a best-in-class gene therapy for Duchenne patients,” said Chief Medical Officer Steve Pakola.
The company plans to discuss the data with the FDA at a future meeting, and is preparing for a potential launch next year.
(Reporting by Padmanabhan Ananthan in Bengaluru; Editing by Sahal Muhammed)
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