Osiris Therapeutics, Inc has successfully completed patient enrolment in its pivotal, phase-III trial evaluating Prochymal as a first-line treatment for acute graft vs. host disease (GvHD), a life-threatening complication of bone-marrow transplantation. The double-blind, placebo-controlled trial enrolled 190 patients from 52 leading transplant centers across the United States, Canada and Australia. Osiris has now completed enrolment in two pivotal stem cell trials in GvHD and expects top-line data from both studies in the second half of 2009.

Additionally, the company announced that it has confirmed with the US Food and Drug Administration, receipt of the first portions of its Biological License Application or BLA for Prochymal as part of a rolling submission. A BLA is a comprehensive regulatory submission prepared by a biologic drug's sponsor to obtain full marketing approval from the FDA. Rolling submission is an FDA provision available to drug candidates that have received Fast Track designation, which allows for completed sections of a BLA to be submitted on an ongoing basis. It can facilitate the process by allowing FDA to initiate review of sections as soon as they are available.

"Completing patient enrolment in this second trial and initiating the application process with FDA are two important milestones for Osiris," said Lode Debrabandere, senior vice president of Therapeutics at Osiris. "GvHD has a very high mortality rate and today there are no approved treatments. With over 400 patients participating between the two studies, we are compiling the largest data set ever assembled for this devastating disease. We appreciate all of the efforts of the Food & Drug Administration in the development of this first-in-class stem cell therapy."

"We sincerely appreciate the participation of clinicians and patients in this trial, who share Osiris' commitment to address the needs of this underserved population," said Rod Monroy, senior director of the acute GvHD programme at Osiris Therapeutics. "We are now focused, along with our partners at Genzyme, on preparing for world-wide registration activities."

Prochymal is a preparation of mesenchymal stem cells specially formulated for intravenous infusion. The stem cells are obtained from the bone marrow of healthy adult donors. Prochymal is currently being evaluated in phase-III trials for steroid refractory GvHD, acute GvHD, and Crohn's disease.

Osiris Therapeutics is the leading stem cell therapeutic company focused on developing products to treat serious medical conditions in the inflammatory, orthopedic and cardiovascular areas.