Sarepta spikes on disputed report of adverse events for rival GSK drug

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Shares of Sarepta ($SRPT)--already swelled by the positive response that followed upbeat results from its early-stage study of a new therapy for Duchenne muscular dystrophy--climbed sharply this afternoon after TheStreet's biotech analyst raised alarms about a series of adverse events recorded during clinical studies of a competing therapy in late-stage development by GlaxoSmithKline ($GSK).

GSK has already disclosed that several patients taking drisapersen, which GSK in-licensed from Prosensa, suffered from "moderate cases of proteinuria (excess protein in the urine) and decreased thrombocytes, which play a role in blood clotting," Adam Feuerstein at TheStreet reported. A scientist for GSK discussed the adverse events at a meeting in Rome over the weekend, Feuerstein wrote, adding that while the company had earlier reviewed some of the safety data, "the adverse events attributed to drisapersen, also known as GSK-2402968, escalated with Sunday's disclosure of hospitalized patients."

TheStreet attributed the remarks to Dr. Rohit Batta, global medical leader in Glaxo's neuromuscular rare disease unit, who said four Duchenne muscular dystrophy patients "required hospitalization due to thrombocytopenia and that 'several' patients with 'severe proteinuria'" were also hospitalized. Feuerstein also noted that a GSK spokesperson confirmed the remarks.

That was all Sarepta enthusiasts needed. In a quick response, the biotech's shares shot up about 9%, to $31.51, giving the small biotech a market cap of $802 million.

But Melinda Stubbee, a spokesperson for GSK, took exception with the way TheStreet characterized the adverse event discussion in Rome as an escalation of the story.

"There have been adverse events that included hospitalization to facilitate patient treatment and recovery, but the subjects discussed by Dr. Batta have all recovered," said Stubbee in a prepared statement to FierceBiotech. "As part of GSK's commitment to transparency we have shared safety information on our clinical program at the Parent Project Meeting in Italy, as we have done in the past," she says, adding that the events have been recorded--and discussed--for a small number of the 300 patients tested.

"Maintaining the safety of subjects is of prime importance to GSK, and in all the drisapersen clinical trials, safety is closely monitored," Stubbee added. "Adverse events occur in all clinical trials, and our large clinical trial program has been ongoing for more than two years. All clinical trials are progressing as planned, and boys are continuing to receive medicine per protocol."

Feuerstein is a sharp student of biotech and has been reporting for TheStreet for more than a decade, earning lots of love and hate from the legion of investors who follow every word he writes. He's been paying close attention to Sarepta as its stock price escalated on very positive results from its small, early-stage study for eteplirsen, which has encouraged some of its investors to believe that the company can gain a very early approval with the data in hand. Over the months Feuerstein has frequently praised the company's work, remarking in an interview at the end of last summer, for instance, that Sarepta might be on to "what might be a groundbreaking treatment."

Hans Schikan, the CEO of the Dutch biotech Prosensa, did not immediately respond to a query from FierceBiotech. Prosensa was one of FierceBiotech's Fierce 15 companies in 2012.

- here's the report from TheStreet  

Special Report: Prosensa – 2012 Fierce 15

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