Sept 26 (Reuters) - PTC Therapeutics Inc has not supplied persuasive evidence that its experimental drug to treat a form of Duchenne muscular dystrophy is effective, a preliminary review by scientists at the U.S. Food and Drug Administration concluded.

The review, posted on the FDA's website on Tuesday, said data to establish the effectiveness of the drug, ataluren, "are not persuasive."

The FDA's comments come two days ahead of a meeting of outside advisors who will discuss ataluren. The agency has asked its advisors to decide whether or not the drug is effective or whether the data is inconclusive.

The FDA is not obliged to follow the recommendation of its advisors but typically does. (Reporting by Toni Clarke in Washington; Editing by Chizu Nomiyama)