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Buzz on Sarepta's Eteplirsen From London Duchenne Meeting

Tickers in this article: SRPT GSK

NEW YORK ( TheStreet) -- Duchenne muscular dystrophy (DMD) patients treated with Sarepta Therapeutics' (SRPT) eteplirsen continue to do well on therapy, according to the company's chief medical officer speaking at the Action Duchenne meeting held this weekend in London.

JMP Securities analyst Liisa Bayko was in London attending the meeting, where Sarepta's chief medical officer Dr. Ed Kaye discussed results from the eteplirsen phase II study. In a note to clients this morning, Bayko writes:

The next catalyst for Sarepta will be 62-week data, which we believe may be presented in January in San Francisco, and Dr. Kaye noted that the patients continue to do well on therapy with no decline in function nor missed infusions or discontinuations.

Bayko also learned that GlaxoSmithKline (GSK) and Prosensa won't release results from controlled studies of their competing DMD drug drisapersen until the third quarter 2013. Again, Bayko:

GSK disclosed that it is committed to a full development program and will not release data from the Phase 2 placebo controlled study until 3Q13 at the earliest, and it is targeting 2014-15 for approval. In our view, this removes some risk from Sarepta -- in the event that it is enrolling a Phase 3 program in 2014, drisapersen will not yet be commercially available and competing for patients.

Glaxo and Prosensa's larger drisapersen phase III study is also ongoing with data not expected until the fourth quarter 2013, according to Bayko's account of Glaxo's presentation at the Action Duchenne meeting.

More from Bayko's note on drisapersen:

GSK provided an update on the ongoing long-term extension (LTE) study from the original cohort of 12 patients. Whereas the study originally evaluated weekly intramuscular dosing, the LTE utilizes an eight weeks on/four-weeks off schedule to alleviate key side effects, including proteinura (observed in 100% of the boys including increased urinary alpha 1 microglobin, which is a marker for proximal tubule kidney dysfunction) thrombocytopenia (observed in 1/3 of the boys) and difficult injection site reactions (ISRs) from the intramuscular injection (separately, concerns were raised about a potential un-blinding effect). Dr. Padraig Wright from GSK relayed that the drug holiday seems to be helping and that no patient has discontinued this or any other global study, which speaks to the commitment of the DMD community and the potential benefit provided by drisapersen.

On eteplirsen:

Importantly, we learned that nNOS, an important marker in muscle cells, was reconstructed, which further validates the drug candidate. Eteplirsen is cleared unmetabolized via the kidney and shows no signs of toxicity. Moreover, the intravenous delivery seems to be associated with less severe injection site reactions than drisapersen. No patient has yet to miss an infusion which speaks to the dedication, as well as the benefit of the compound.