By Pat Anson, Editor

Pfizer and Eli Lilly have announced positive findings in treating osteoarthritis pain with an experimental non-opioid drug that has a history of safety concerns.  

Tanezumab is a humanized monoclonal antibody that targets nerve growth factor (NGF), a protein that increases in the body because of injury, inflammation or chronic pain. Tanezumab binds to NGF and inhibits pain signals from muscles, skin and organs from reaching the brain.

In the 16-week clinical study, osteoarthritis patients who were given two injections of tanezumab had significant improvement in their pain, physical function and assessment of their symptoms compared to a placebo. Osteoarthritis is a joint disorder that leads to thinning of cartilage and progressive joint damage.

“There is a substantial need for innovative new treatment options for osteoarthritis, as many patients are unable to find relief with currently available medicines and continue to suffer,” Ken Verburg of Pfizer Global Product Development said in a statement.

“We are encouraged by these results, which speak to the potential of tanezumab as a non-opioid treatment option for pain reduction and improvement in physical function.”

Preliminary safety data showed that tanezumab was generally well tolerated, with about 1% of patients discontinuing treatment due to adverse events. Rapidly progressive osteoarthritis was observed in about 1.5% tanezumab-treated patients, but none in the placebo arm.

The U.S. Food and Drug Administration granted “fast track” designation to tanezumab last year to help speed its development as a new treatment for osteoarthritis and chronic low back pain.

Ironically, it was the FDA that slowed the development of NGF inhibitors in 2010 after Pfizer reported some osteoarthritis patients receiving tanezumab experienced worsening of their disease and needed joint replacements. Another safety issue arose in 2012 because the drug caused “adverse changes in the sympathetic nervous system of mature animals.”  Most clinical studies of tanezumab did not resume until 2015.

“We look forward to continuing to advance tanezumab in our ongoing global Phase 3 development program, which includes six studies in approximately 7,000 patients with osteoarthritis, chronic low back pain and cancer pain,” said Christi Shaw, senior vice president of Eli Lilly. In studies to date, tanezumab has not demonstrated a risk of addiction, misuse or dependence.

Regeneron recently halted high-dose trials of fasinumab, another NGF inhibitor, because the risk of harm outweighed the benefits of the drug. There is some concern that NGF antibodies work too well and encourage osteoarthritis patients to become more active, which accelerates joint deterioration.