By Pat Anson, PNN Editor

Two FDA advisory committees have voted against recommending an experimental non-opioid pain reliever as a new treatment for osteoarthritis, dealing a potential death blow to a drug that’s been under development for 15 years.

On a nearly unanimous 19 to 1 vote, the FDA’s Arthritis Advisory Commitee and Drug Safety and Risk Management Advisory Committee decided that the benefits of tanezumab do not outweigh its possible safety risks, which include the acceleration of osteoarthritis in some patients.  Advisory committee recommendations are not binding on the FDA, but they are likely to carry a good deal of weight when the agency makes a final decision on tanezumab.

Pfizer and Eli Lilly are jointly developing tanezumab, an injectable humanized monoclonal antibody that targets nerve growth factor (NGF), a protein that increases in the body due to injury, inflammation or chronic pain. Tanezumab binds to NGF and inhibits pain signals from muscles, skin and organs from reaching the brain.

FDA reviewers released a report this week saying tanezumab works as a pain reliever, but the effect “is modest, and there is no convincing evidence of a superior efficacy” over non-steroidal anti-inflammatory drugs (NSAIDs), the current standard treatment for osteoarthritis.

More concerning are the potential side effects of tanezumab, the most serious being rapidly progressing osteoarthritis that is so severe some patients need total joint replacements. Investigators say tanezumab also appears to affect healthy joints and causes “abnormal peripheral sensation” similar to carpal tunnel syndrome.

The side effects of tanezumab have been known for over a decade. The FDA slowed the development of tanezumab and other NGF inhibitors in 2010 because of concerns they make osteoarthritis worse in some patients.

Under pressure to approve more non-opioid pain relievers, the FDA allowed clinical studies of tanezumab to resume in 2015 and two years later gave it “fast track” designation to help speed its development.

Pfizer and Eli Lilly have conducted dozens of clinical trials evaluating the safety and efficacy of tanezumab on more than 18,000 patients. The companies at one time considered, but then abandoned plans to develop tanezumab as a treatment for chronic low back pain after 10% of patients given high doses developed joint pain and other side effects.

Critics say its time to finally throw in the towel on tanezumab.

“The drug is unsafe. It accelerates the underlying joint disease. And according to the FDA, even if you stop the drug early on, there’s evidence you can still progress to having these joint problems,” Michael Carome, director of Public Citizen’s Health Research Group, told PNN.  “The decision here is clear cut. The drug should not be approved. And in our view, no further studies on this drug should be done. Because it would be unethical to continue to expose people to this drug where the harm is clear and there’s no real benefit.”

A Pfizer spokesman said the company would continue to seek approval for tanezumab, despite the committees’ recommendation.

“While we are disappointed in today’s outcome, we continue to believe that the clinical data presented for tanezumab supports its benefit-risk profile,” Jim Rusnak, chief development officer for Pfizer, said in a statement. “The patients whom we aim to help with tanezumab are suffering from significant, debilitating osteoarthritis pain and have exhausted available medical therapies and are hopeful for new, non-opioid treatments. We will continue to work with the FDA to determine next steps.”

Osteoarthritis is a progressive joint disorder caused by painful inflammation of soft tissue, which leads to thinning of cartilage and joint damage in the knees, hips, fingers and spine. The World Health Organization estimates that about 10% of men and 18% of women over age 60 have some form of osteoarthritis.