Trouble may be brewing for Sarepta Therapeutics, which suspended a U.K. study of its next-generation Duchenne muscular dystrophy drug, golodirsen.
The temporary halt in dosing, mandated by U.K.-specific rules, was “triggered by one serious adverse event that could possibly be related to the investigational drug product,” Sarepta said in an emailed statement. No direct connection has yet been made between the drug and the event, and an independent committee reviewed safety data for the trial, saying dosing could continue for all patients.
This could just be a hiccup for Sarepta, as it expects to resume dosing once it gets approval from the U.K.’s Medicine and Healthcare products Regulatory Agency. But it appears the biotech tried to keep the hold under wraps—not a good look.
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EP Vantage first reported the halt in the study, dubbed Essence, citing a Facebook post from the parent of a child involved in the study:
“My son was due his biopsy and first dose of 45 skip [in] Essence last week. They have temporarily stopped dosing in the UK ... I understand due to rhabdomyolysis side effects,” the parent wrote.
Sarepta’s shares fell 6% as the news made its rounds.
Sarepta ushered Exondys 51 through FDA approval in 2016, with CDER Director Janet Woodcock going to bat for the treatment against apprehension from elsewhere in the FDA. The approval was based on data using a surrogate endpoint and that did not demonstrate “a clinical benefit,” which necessitated a follow-up trial.
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Shortly after bagging approval, Sarepta inked a pact with Summit Therapeutics, picking up rights to the latter’s utrophin modulator pipeline in Europe, Turkey and the Commonwealth of Independent States. Sarepta also has the option of grabbing the Latin American rights to the assets under the deal, which could be worth more than $584 million.
As Exondys 51 is only indicated for patients whose disease is amenable to exon 51 skipping—about 13%—Sarepta pivoted to golodirsen, which is being tested in the Essence study in patients whose DMD is amenable to skipping exons 45 or 53.