- Sarepta Therapeutics will not release the rejection letter that set back its efforts to win U.S. approval for a second Duchenne muscular dystrophy treatment, CEO Doug Ingram told patient advocates Wednesday, citing the company's respect for the Food and Drug Administration.
- Ingram reaffirmed, however, that the agency's refusal to approve Vyondys 53 was related to safety risks. Sarepta remains committed to securing clearance for Vyondys as well as a similar drug called casimersen, the executive said, and won't shift resources toward a promising DMD gene therapy.
- The FDA's rejection of Vyondys on Tuesday took the biotech sector by surprise, knocking $1.4 billion from the valuation of the Cambridge, Massachusetts-based company.
The FDA's Complete Response Letter to Sarepta really was about infection risk and preclinical data hinting at kidney toxicity, Ingram told a webinar put on by the advocacy group Parent Project Muscular Dystrophy (PPMD). But patients as well as investors will have to take his word for it, because he won't release the letter.
Releasing the text "might not look like we're being as respectful as we'd like to be," he said. "The basis for the CRL is exactly as I've said it."
Ingram also repeated what his executive team told analysts in the immediate aftermath of the rejection: that the company was not given any hint by the FDA that these two issues could interfere with approval. Company representatives had even been invited to review a draft approval press release for Vyondys 53 (golodirsen).
This claim has stimulated debate over whether the FDA's decision was political, since Sarepta had not begun the confirmatory trial for its marketed drug Exondys 51 (eteplirsen) as required under accelerated approval. The FDA rejects that claim.
Ingram said the company will ask in the next week to schedule a meeting to review the letter with agency officials, which should take place in the next 60 days. This likely means regulatory next steps for Vyondys will become clear later this year, Cantor Fitzgerald analyst Alethia Young wrote in a Thursday note to clients.
Answering patient advocates' questions during the webinar, Ingram said the company intends to press forward with development of Vyondys and a related drug called casimersen, which together with Exondys could treat about 30% of DMD patients.
By comparison, Sarepta's emerging gene therapy, which has shown promise in early results, should in theory cover all patients.
The DMD patient community is highly active, and played a large role in the 2016 approval of Exondys. Advocates testified at length at an advisory committee meeting which ultimately recommended against approval of the drug. In the run-up to its eventual approval, however, Sarepta clashed with the agency, and some observers believe the involvement of advocacy groups could risk resumption of that conflict.
"We worry that over-involvement from advocacy groups could make the road more difficult for Sarepta," Cantor's Young wrote.
On the Wednesday webinar, advocates asked Sarepta how they could help speed the new FDA review of Vyondys and casimersen, but Ingram demurred.
"It really is our responsibility. It is not your responsibility," he said.
Sarepta is a corporate sponsor of the PPMD.