A majority of The Food and Drug Administration’s (FDA) Advisory Committee voted against recommending eteplirsen, which in its New Drug Application (NDA), proposes to become the first drug to treat Duchenne muscular dystrophy.
The Advisory Committee’s recommendations are based on results from the Phase 2b clinical program for eteplirsen; ‘Study 201′ and ‘Study 202′. Study 201, a randomized-controlled study, compared three groups of four patients, for 24 weeks (12 patients in total). One group was administered 50mg/kg of eteplirsen, 1 administered 30mg/kg, and 1 placebo. Study 202 was an open label extension of Study 201, in which each patient received eteplirsen 30mg/kg, weekly.
Results of Study 201/202 6-minute walk test (6MW) test showed significant superiority in eteplirsen-treated patients. There was a greater difference of 148 meters at Year 3, and 162 meters at Year 4, for etepilrsen patients compared to the control group.
However, the committee voted 7 to 5 against whether decisions to administer the 6MW test were free of bias and subjective decision making by patients and caregivers to allow for a legitimate comparison between patients in the study, and the control group (FDA Question #4).
Seven to 3 (with 3 abstentions) voted that the data from the studies did not meet FDA requirements that are needed for approval. The chief issue is the low number of participating patients in the study. Additionally, the FDA indicated that the improved walking ability displayed by the 12 eteplirsen patients was within the range of natural variation for Duchenne muscular dystrophy; thus cannot be used to prove the drug worked.
With no current treatment for DMD, patients, parents, and clinicians have been lobbying the FDA for years to gain approval for the treatment. Pharmacist Richard P. Hoffman, who acted as the consumer representative on the committee, was 1 of the 3 who abstained from the FDA requirements vote, he told the New YorkTimes, “I was just basically torn between my mind and my heart.”
An advisory committee meeting on eteplirsen was opened by the director of the FDA’s division of neurology products, Billy Dunn, stating the FDA was “highly sensitive to the urgency” of gaining a DMD treatment, but they were restricted by law to only approve drugs which had “substantial evidence”.
The panel also voted 7 to 6 against the Accelerated Approval for the drug, finding no substantial evidence – based on Study 201/202 – to prove that eteplirsen induces production of dystrophin to a level reasonably likely to predict clinical benefit.
Eteplirsen is designed to address the cause of DMD by restoring mRNA reading frame, which enables the production of a shorter, functional form of the dystrophin protein. The action date for completion of the FDA review of eteplirsen is May 26, 2016. Although not bound by the Advisory Committee’s recommendation, the FDA takes its advice into consideration when reviewing New Drug and Biologic License Applications.
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