Headed for failure, Osiris ends trial enrollment

Osiris Therapeutics has ended enrollment in a late-stage trial of Prochymal for Crohn's disease, saying that it believes that a design flaw spurred an unexpected placebo response. And that placebo response, the company said in a statement this morning, would have prevented its therapy from achieving its primary endpoint.

Now Osiris is looking for a do-over on the closely watched stem cell trial. Last November Genzyme paid $130 million upfront and promised up to $1.3 billion more to gain commercialization rights to Prochymal and Chondrogen outside the U.S.

"We had a situation where we were experiencing a much higher than expected placebo response rate," says C. Randal Mills, the CEO of Osiris. "As we looked into possible causes, we discovered what we believe to be a systemic design flaw in the trial that would likely affect the utility of the data for purposes of registration. After careful discussion with the FDA, we elected to discontinue enrollment rather than attempt to re-power the trial. We will keep the trial blinded and expect a solid data package for use in designing future trials in Crohn's disease and to bolster Prochymal's safety database."

David Meeker, an executive vice president for Genzyme, agreed with the decision, calling it a prudent decision that would create a more efficient development path going forward. Investors, though, were clearly unimpressed. Osiris' shares plunged 22 percent on the news. 

- check out Osiris' release

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