Osiris Therapeutics, Inc (COLUMBIA, Maryland), a leading stem cell therapeutic company focused on developing and marketing products to treat medical conditions in the inflammatory, orthopedic, and cardiovascular areas announced positive 1-year interim results in the evaluation of Chondrogenâ„¢, a preparation of mesenchymal stem cells obtained from the bone marrow of healthy adult donors and formulated for direct injection into the knee. The 1-year data showed improvement in joint condition that correlated with a clinically and statistically significant improvement in pain in patients with osteoarthritis (OA) who received Chondrogen as compared with those treated with the control, hyaluronic acid (HA).

The randomized, prospective, double-blind, controlled phase I/II study of 55 patients enrolled at seven leading sports medicine centers in the US is evaluating the safety and preliminary efficacy of the drug to impact tissue regeneration and the development of OA in patients undergoing meniscectomy. In patients with OA at the time of surgery, a statistically significant 20 mm reduction in pain, as measured by the visual analog scale (VAS), was observed in patients receiving a single injection of Chondrogen into the joint capsule versus patients receiving an injection of HA at 1 year (Chondrogen 48 mm vs control 28 mm, P = .05). The reduction in pain increased even further to 37 mm with more severe OA changes in the patient's joint (Chondrogen 56 mm vs control 19 mm, P = .004). For comparison, according to Osiris, currently available treatments for OA, such as HA which requires multiple injections, were approved by the US FDA based upon improvements of 9 mm to 23 mm compared with placebo.

The clinical effects were dose dependent and pain scores improved from 6 months to 1 year following treatment, suggesting the drug treatment caused a biological modification of OA and may promise a durable effect. The beneficial effects of Chondrogen were also seen in physical measures of joint condition. Bony changes associated with OA, such as subchrondral sclerosis and osteophyte formation, were reported in 21% of patients receiving the control, but only 6% of Chondrogen-treated patients. Joint condition was determined from MRI analysis using centralized, independent, blinded orthopaedic radiologists. Chondrogen was well tolerated at both dose levels and there were no serious adverse events associated with administration, and no evidence of abnormal tissue formation.

One of the goals of the study was to assess the ability of MRI to detect the volume of meniscus regeneration following meniscectomy. The MRI volume analysis method was deemed unsuitable for computational analysis because of the high level of variability seen between readings. As a result, no meaningful evaluation of meniscus regeneration can be made.

Patients in the study underwent standard meniscectomy surgery to remove torn or damaged tissue in their meniscus. One week following surgery, patients were given a single injection of either HA or a low dose (50 million cells) or high dose (150 million cells) of Chondrogen. Neither the patients nor the surgeons knew what was given for the duration of the study. Patients will be followed for safety and additional preliminary efficacy such as pain, cartilage damage, and tissue repair for 2 years under the current study protocol.

Osiris currently markets and sells OsteocelR for regenerating bone in orthopaedic indications. Prochymalâ„¢ is in phase III clinical trials for both graft versus host disease and Crohn's disease and is the only stem cell therapeutic currently designated by the US FDA as both an Orphan Drug and a Fast Track product.