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FDA rejects BioMarin's muscle wasting drug; Sarepta drug in focus

* Kyndrisa had received negative FDA review in Nov

* Kyndrisa also under review in Europe

* Sarepta's rival drug to be reviewed next week (Recasts; adds analyst comments)

By Amrutha Penumudi and Natalie Grover

Jan 14 (Reuters) - The U.S. Food and Drug Administration rejected BioMarin Pharmaceutical Inc's drug to treat a rare muscle-wasting disorder, shifting investor focus to Sarepta Therapeutics Inc's rival drug in development.

The rejection caps months of uncertainty surrounding the drug, Kyndrisa, which was billed to be the first treatment in the United States for Duchenne muscular dystrophy (DMD).

DMD is a progressive, degenerative genetic disorder that hampers muscle movement and affects one in 3,600 newborn boys. Most patients die by the age of 30. DMD has no cure.

A panel of independent advisers to the FDA had in November indicated that Kyndrisa's effectiveness in trials was not enough to warrant approval. Sarepta's drug, eteplirsen, is up for review next week.

WBB Securities analyst Steve Brozak said Kyndrisa's rejection effectively crowned Sarepta the U.S. DMD winner and that pressure to approve a treatment would mount.

Analysts said BioMarin will likely need another late-stage study for Kyndrisa in the United States. Kyndrisa is also under review in Europe.

Sarepta's eteplirsen, like BioMarin's Kyndrisa, skips a faulty section of the gene to produce dystrophin, the lack of which is believed to cause DMD.

Both drugs target a particular subset of DMD patients, which translates into an addressable population of about 1,800 boys in the United States and about 5,000 outside, according to Wedbush Securities analyst Heather Behanna.

The U.S. rejection, however, is not end of the road for Kyndrisa. BioMarin expects to hear back from the European regulatory advisory committee in April or May, with a final decision in the third quarter.

While a U.S. approval would have given BioMarin first-mover advantage in the market, a European approval is perhaps more significant as the drug will target a larger patient population.

Evercore ISI's Mark Schoenebaum expects BioMarin make its next move only after the FDA's decision on Sarepta, and European regulators' decision on Kyndrisa.

BioMarin said on Thursday it would work with the FDA to determine its next step.

PTC Therapeutics Inc's DMD drug, Translarna, won conditional European approval in 2014, to treat a different subset of patients.

Last year, PTC said it had enough data to submit a U.S. marketing application, despite the drug failing a U.S. late-stage study.

Shares of BioMarin, which bought Prosensa Holding NV for $840 million last year to acquire Kyndrisa, dipped about 1 percent in late morning trading. Sarepta fell nearly 6 percent.

(Reporting by Amrutha Penumudi and Natalie Grover in Bengaluru; Editing by Savio D'Souza and Saumyadeb Chakrabarty)