Sarepta Saga Drags On as FDA Delays Decision on Duchenne Drug

Xconomy Boston — 

The multi-year saga of eteplirsen, a Duchenne muscular dystrophy drug from Cambridge, MA-based Sarepta Therapeutics, will continue to drag on.

Sarepta (NASDAQ: SRPT) said today that the FDA won’t complete its review of its drug, eteplirsen, by the established May 26 deadline. As a result, rather than approve or reject eteplirsen—which has the chance to be the first marketed drug ever for Duchenne—the FDA will simply continue its review for an undetermined period of time. Sarepta said that the FDA will “strive to complete their work in as timely a manner as possible,” though no specific timeline was provided.

Investors are taking this development as a positive, sending shares up more than 25 percent in pre-market trading.

By and large, the expectation has been that the FDA will reject eteplirsen because its scientists skewered the data supporting the company’s case, and an advisory panel voted against approval of the drug at a meeting last month. In a recent research note, for instance, RBC Capital Markets analyst Simos Simeonidis gave the drug a roughly 20 percent chance of getting approved.

The major issue: Eteplirsen’s case is based on a tiny, flawed study of only 12 patients. Approving the drug risks effectively setting a new standard for drug approvals. On the other hand, rejecting the drug means more time will go by without treatment for a patient group that is in a battle against time. Duchenne is a genetic disease that affects about 300,000 people worldwide, primarily boys. It robs patients of their ability to walk, puts most in wheelchairs by their teens, and typically kills them—usually from heart or lung complications—by their mid 20s.

Sarepta’s biggest hope is that the delay means that the FDA is displaying the type of “flexibility” that Janet Woodcock, the director of the FDA’s center for drug evaluation, mentioned at the April meeting. Though the majority of a group of medical experts voted against approval of eteplirsen, Woodcock openly talked about the consequences of a “type 2 error,” which means rejecting a drug that works. “In devastating diseases the consequences of [an unwarranted rejection] can be extreme,” she said. “But most of these cons are borne by the patients.”

The FDA has already rejected two Duchenne drugs this year—from BioMarin Pharmaceutical (NASDAQ: BMRN) and PTC Therapeutics (NASDAQ: PTCT). Sarepta’s drug is the only potential near-term option for patients, and that has led to a lot of pressure from patient advocacy groups and politicians lobbying for approval of eteplirsen despite the limitations of the clinical data. Eteplirsen is meant for roughly 13 percent of patients with Duchenne.

Check out these stories for more on Sarepta, Duchenne, and the eteplirsen saga.