(Reuters) -Sarepta said on Monday that its late-stage study testing two gene-targeted therapies for Duchenne muscular dystrophy did not meet the main goal, sending its shares plummeting over 27% in extended trading.
The study took nine years to complete and enrolled 225 patients aged 6 to 13 with Duchenne, a rare genetic disorder that causes progressive muscle weakness and mostly affects boys.
The trial was designed to evaluate the therapies, casimersen and golodirsen, which belong to a class of drugs called phosphorodiamidate morpholino oligomers, or PMOs.
These therapies help certain patients produce a shorter but functional version of the dystrophin protein.
The main goal was to show a statistically significant improvement in how quickly patients could climb four steps after 96 weeks of treatment.
While patients on the drugs showed a numerical improvement over those on placebo, the difference did not reach statistical significance.
Sarepta reported an observed difference of 0.05 steps per second on the primary endpoint.
The company said the therapies were well tolerated, with no new safety concerns. It also noted that the COVID-19 pandemic disrupted trial participation and data collection, adding complexity to the study and potentially affecting the results.
Despite the setback, Sarepta said it plans to meet with the U.S. Food and Drug Administration to discuss converting the drugs’ current accelerated approvals into full approvals.
Duchenne muscular dystrophy usually begins in early childhood and worsens over time, making walking, breathing and other daily activities increasingly difficult.
Sarepta has lost about 80% of its market value this year, as mounting regulatory scrutiny and three patient deaths linked to its separate gene therapy, Elevidys, have triggered clinical trial holds and raised concerns about the company’s safety oversight.
(Reporting by Kamal Choudhury in Bengaluru; Editing by Alan Barona)
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