Osiris Therapeutics (BALTIMORE, Maryland), a leader in adult stem cell therapy, announced that 6-month interim results from its phase I/II clinical study of Chondrogenâ„¢, a preparation of mesenchymal stem cells obtained from the bone marrow of healthy adult donors and specially formulated for direct injection into the knee for the regeneration of the meniscus in the knee and prevention of osteoarthritis, failed to demonstrate significant amounts of meniscal regeneration. However, some of the patients treated with Chondrogen demonstrated an improvement in their baseline cartilage and joint condition, while no patients in the placebo group demonstrated similar improvement.

The study was designed to assess the safety of an injection of mesenchymal stem cells into the joint capsule and to gain preliminary efficacy data on the extent of tissue regeneration using magnetic resonance imaging (MRI). A total of 55 patients were treated in the double-blind study. Patients underwent standard meniscectomy surgery to remove torn or damaged tissue in their meniscus. One week following surgery, the patients were given a single injection of either placebo or a low dose (50 million cells) or high dose (150 million cells) of Chondrogen. At the 6-month time point, Chondrogen met its primary endpoint, demonstrating product safety, and was well tolerated. However, MRI results show the trial did not demonstrate that treatment with Chondrogen resulted in a statistically significant increase in the volume of meniscus as compared to placebo.

Eighteen of the patients treated with Chondrogen had shown signs of arthritis upon entry into the study; six of these patients showed at least slight improvement in the signs of arthritis, while none of the patients who had signs of arthritis and were given placebo showed a reduction in arthritis symptoms. The company did not provide any detailed data in support of these observations.

Neither the patients nor the surgeons will know what treatment was given for the duration of the study. Patients will be followed for safety and additional preliminary efficacy, such as pain, cartilage damage, and changes in the meniscus, for 2 years under the current study protocol.

—A. Techman

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