Scientists dispute PTC's claim on muscular dystrophy drug mechanism

Right on the heels of a $125 million IPO, PTC Therapeutics ($PTCT) has another public relations problem on its hands. The Scientist is reporting that a group of investigators have completed an in vitro study of their lead treatment and came to a startling conclusion: It doesn't work the way PTC has said it does.

As The Scientist explains, PTC Therapeutics has said that ataluren--or PTC124--can effectively treat a subset of cystic fibrosis or Duchenne muscular dystrophy patients by correcting the translation of specific proteins, a read-through process deemed critical in treating these diseases.

"From a basic mechanistic standpoint, it doesn't look like [PTC124 is causing] translational read-through, certainly in our assays," Stuart McElroy, a scientist at the University of Dundee in Scotland and an author of the paper, tells The Scientist.

The company, however, defended its work.  

"Numerous independent laboratories have provided confirmation of our results, demonstrating ataluren's read-through activity in studies using reporters as well as multiple animal and cell-based nonsense mutation disease models," notes a company statement.

David Bedwell at the University of Alabama, who's done consultancy work for PTC, also said that mouse studies have shown that there's a read-through.

PTC has already had to contend with some discomforting revelations in its S-1. After touting the fact that PTC had filed for a European approval late last year, company officials stayed mum when regulators came back to say that their first review led them to conclude that the company didn't have the necessary efficacy data. And the company has had to concede that a Phase IIb as well as a Phase III study both failed primary endpoints, leaving the biotech at work on new Phase III trials for CF and DMD.

This isn't the first time investigators have failed to repeat key research work backing a lead program. But for PTC--which now has a stock price to defend--it comes at a particularly bad time.

- here's the article from The Scientist

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