Sarepta plummets on eteplirsen delay

Sarepta Therapeutics Inc. (NASDAQ:SRPT) fell $23.40 (64%) to $13.16 on Tuesday on news that FDA now considers an NDA submission for the company's eteplirsen to treat Duchenne muscular dystrophy (DMD) "premature." Sarepta, which had planned to submit an NDA seeking accelerated approval next half, said on a conference call the news could delay approval of the phosphorodiamidate morpholino oligomer (PMO) targeting exon 51 by at least two years.

According to Sarepta, FDA said it has "considerable doubt" about the use of dystrophin as a surrogate endpoint as well as the six-minute walk test (6MWT) data from Sarepta's open-label Phase IIb trial of eteplirsen. The agency said it questions using dystrophin in light of the recent "failed" Phase III trial of drisapersen, a competing DMD compound from Prosensa Holding N.V. (NASDAQ:RNA) and GlaxoSmithKline plc (LSE:GSK; NYSE:GSK) that did not significantly improve 6MWT vs. placebo "despite increased expression of dystrophin." In July, Sarepta fell $8.75 (19%) to $37.68 after announcing that FDA "would not commit to declaring dystrophin an acceptable surrogate endpoint" for accelerated approval of eteplirsen (see BioCentury, Sept. 30). ...