Shares of Cambridge, Massachusetts-based Sarepta Therapeutics Inc. (SRPT) are soaring today on reports that its experimental drug eteplirsen improved walking ability in patients with Duchenne Muscular Dystrophy (DMD) in a phase IIb clinical trial. DMD is a rare genetic disorder with no approved treatments that causes severe and progressive muscle loss in boys. The crippling disease is caused by a gene mutation in the protein dystrophin, which is critical to muscle fiber function.
Sarepta, formerly AVI Biopharma until a name and ticker change in July, said that the boys treated with 50mg/kg of eteplirsen were able to walk an average of 89.4 meters further than boys in the placebo arm of the study. The results were measured in a standard six-minute walk test after 48 weeks of treatment. In addition to walking further than controls, patients on eteplirsen actually walked 21 meters further at the end of the study than they could walk at the beginning.
In the 12-patient trial, eteplirsen administered once weekly at either 30 mg/kg or 50 mg/kg for 48 weeks (n=8) resulted in a statistically significant increase in dystrophin-positive fibers to 47 percent of what is considered normal. The placebo/delayed treatment cohort, which had received 24 weeks of eteplirsen at either 30 mg/kg or 50 mg/kg following 24 weeks of placebo (n=4), also showed a statistically significant increase in dystrophin-positive fibers to 38.3% of normal.
No safety concerns were cited in the study.
It’s a small trial, but the results are very promising. “We are extremely excited about these data, as they demonstrate that longer-term treatment with eteplirsen is translating to continued and unprecedented increases in both dystrophin production and clinical benefit across various subgroups of DMD patients involved in this study,” said Sarepta CEO Chris Garabedian.
Shares of Sarepta had been crushed earlier this year as preliminary data did not show much of a statistical improvement in dystrophin levels or walking distance. Shares – upwardly adjusted for a 1 for six reverse stock split – fell to just over $3 per share on the lackluster data.
Shares have been on the mend ever since and closed Tuesday trading at $14.99. With today’s data, shares have surged more than 100 percent to above $30 per share in early trading.