Osiris shares sink on disappointing stem cell data

Shares of Osiris Therapeutics slid nearly 10 percent in after-hours trading after the developer announced that interim data on Prochymal--a cutting-edge adult stem cell therapy--failed to demonstrate an improvement in pulmonary function in COPD patients enrolled in a mid-stage study. Researchers said that the data did provide additional evidence of safety, though, which had been a closely-watched aspect of the clinical study.

Prochymal also demonstrated significantly decreased inflammation in patients with COPD, says Osiris, which released six-month data from the study. Researchers are following 62 patients in a placebo-controlled trial for two years.

"Mild pulmonary effects may be acceptable particularly given the gravity of this population's existing pulmonary disease," analysts at the private equity firm Wedbush said in a statement, noting the significance of safety data. And the developer added a positive spin of its own on the interim results.

"Importantly, we are gratified to obtain clear, objective data that helps bolster our understanding of the anti-inflammatory effects of these remarkable cells," said CEO C. Randal Mills in a statement. "Short-term, these anti-inflammatory effects did not appear to improve pulmonary function in patients with advanced destructive changes of the lung. Collectively however, these findings add to our confidence about the safety and effectiveness of the drug."

- check out Osiris' release
- read the story from Dow Jones