- The FDA on Friday strongly questioned the persuasiveness of Sarepta's clinical trial data for its investigational Duchenne muscular dystrophy (DMD) therapy eteplirsen, sending the firm's shares tumbling more than 56% in early Friday trading.
- The news comes just one day after the agency rejected BioMarin's competing DMD treatment Kyndrisa (drisapersen). DMD is a genetic degenerative muscular disease which mainly affects male children and adolescents. Maximum life expectancy for those with the condition is generally less than 30 years.
- The FDA rejected approval of Kyndrisa because, according to the agency, evidence for its effectiveness was inadequate. However, Kyndrisa is still under review in the E.U. One major challenge for BioMarin was the size of its studies.
- Friday's critical review bodes poorly for Sarepta's ambitions to outshine its competitor considering that the FDA similarly scrutinized BioMarin's drug before that medication's advisory committee hearing last fall, in which an independent panel ruled the company's trial data unpersuasive and helped set up Thursday's Kyndrisa rejection.
All told, it's shaping up to be a devastating week for the Duchenne patient community.
DMD affects approximately 1 in every 3,500 live male births, and a great deal of hope has been building around the availability of a treatment for these patients. BioMarin and Sarepta has many supporters who agree with the companies' reasoning that even if the therapies failed to meet all endpoints, the totality of the evidence justifies approval. Apparently, the FDA disagreed.
Sarepta's advisory committee for eteplirsen is scheduled for January 22. While it had been clear for a while that BioMarin's drug was headed for likely failure, some had hoped that Sarepta's would be a different story considering comparatively better efficacy data such as notable comparative improvements in the 6-minute walk test (6MWT) in eteplirsen-treated patients and data showing changes in key biomarker production and respiratory function in these patients. Furthermore, there had not been any major safety-related adverse events among treated patients.
In the review released on Friday, regulators said that Sarepta's 6-minute walk test results were unreliable; expressed concerns about the extremely small clinical trial size; noted a lack of efficacy at higher doses early on in the treatment process (suggesting even less efficacy at lower doses and later on in the process); and highlighted the failure to meet the primary endpoint.
There is still the possibility that Kyndrisa will be approved by the European Medicine Agency. But the Duchenne patient advocate community has an uphill battle in convincing the FDA advisory committee and, ultimately, the agency itself that an approval is warranted considering a lack of treatments for the devastating condition despite data that regulators clearly find unconvincing.