One-year positive data released Tuesday by Osiris Therapeutics (OSIR - Get Report) from an ongoing study of its stem-cell treatment for knee repair should raise concerns about the results' reliability.
Surgical patients with osteoarthritis injected with the stem-cell therapy known as Chrondrogen experienced a statistically significant reduction in knee pain compared with control patients given an injection of hyaluronic acid, according to Osiris' analysis of one-year data from a phase II study.
But data from this same study were decidedly more
Osiris chose not to disclose Tuesday that the osteoarthritis patients who appear to have benefited from Chrondrogen make up just more than half of the 55 patients originally enrolled in this phase II study. The company also failed to mention that measurement of pain reduction was a secondary endpoint, not the primary endpoint, of the study.That didn't stop Osiris shares from jumping more than 15% on Tuesday to $11.84. Osiris' announcement also comes after the departure of its chief financial officer, which was disclosed the day after Thanksgiving. Osiris is developing therapies derived from mesenchymal stem cells (MSCs), a form of adult stem cell capable of differentiating into tissues that provide rigidity or stability in the body -- bone, cartilage, fat, tendon or muscle. MSCs may also possess anti-inflammatory properties and appear not to activate an immune response when transplanted into an unrelated or unmatched host.