Experimental Drug Rebuilds Cartilage in Knee Osteoarthritis Patients

By Pat Anson, PNN Editor

An experimental treatment shows promise in slowing the progression of knee osteoarthritis by increasing the thickness of cartilage in the knee joint, according to results of an early clinical trial published in the Journal of the American Medical Association (JAMA).

Researchers at the University of Maryland School of Medicine gave 549 volunteers with knee osteoarthritis injections of the drug sprifermin or a placebo. Sprifermin is a disease modifying drug that stimulated the production of cartilage-producing cells in animal studies.

The researchers found that participants who received a 100 microgram dose of sprifermin either twice or once yearly experienced a statistically significant but slight gain in joint cartilage thickness after two years.  Those given smaller doses had smaller gains in cartilage that were not statistically or clinically significant.

"While the increase in cartilage thickness is a positive sign, we do not know at this point whether it has any clinical significance," said lead investigator Marc Hochberg, MD, a Professor of Medicine at UMSOM. "It is not known whether those who experience increased cartilage thickness over time will be able to avoid or delay knee replacement surgery."

Interestingly, patients treated with a high dose of sprifermin did not experience any significant improvement in their arthritis symptoms – such as pain and stiffness -- compared to those given lower doses or placebo injections.

All of the injections were stopped after 18 months. The Phase 2 study is designed to continue for a total of five years and future analyses of the findings are planned.

About 10 percent of Americans over age 60 have knee osteoarthritis, a progressive condition caused by the breakdown of joint cartilage. Knee osteoarthritis causes pain, physical disability, lower quality of life and is associated with early death and cardiovascular problems.

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The pain is usually treated with over-the-counter pain relievers, anti-inflammatory drugs, steroid injections, and sometimes surgery. No disease-modifying osteoarthritis drugs have been approved in the United States or Europe.

Arthroscopic and knee replacement surgeries are increasingly being used to treat knee osteoarthritis. But a number of recent studies have found the arthroscopic surgery does not relieve knee pain any better than physical therapy or over-the-counter pain relievers. Researchers have also found that about a third of patients who had knee replacement surgery continued to have pain after the procedure.