By Pat Anson, Editor

The U.S. Food and Drug Administration has granted “fast track” designation to a new, non-opioid pain medication for patients with osteoarthritis and chronic low back pain -- even though the drug has a history of safety issues.

Tanezumab is an investigational humanized monoclonal antibody that targets nerve growth factor (NGF), a protein that increases in the body as a result of injury, inflammation or chronic pain. Tanezumab binds to NGF and inhibits pain signals from reaching the spinal cord and brain.

Tanezumab is the first NGF inhibitor to receive fast track designation from the FDA, a process that speeds up the development and review of new therapies to treat serious conditions with unmet medical needs.

“If approved, tanezumab would be the first in a new class of non-opioid chronic pain medications,” said Ken Verburg, Chief Development Officer, Neuroscience & Pain, Pfizer Global Product Development. “We believe it would represent an important medical advance in the treatment of debilitating osteoarthritis and chronic low back pain for patients who do not experience adequate pain relief or cannot tolerate currently available pain medications.”

Pfizer is jointly developing tanezumab with Eli Lilly. The two drug makers are currently recruiting patients for Phase 3 studies of tanezumab in 7,000 patients with osteoarthritis, low back pain or cancer pain. Participants will be injected with tanezumab once every eight weeks for treatment periods ranging from 16 to 56 weeks, followed by a 24-week safety follow-up period.  Results from the clinical trials are not expected until next year.

"It is estimated that there are more than 27 million Americans currently living with osteoarthritis and 23 million living with chronic low back pain, many of whom fail to achieve adequate pain relief despite treatment with various types of pain medications,” said Christi Shaw, Senior Vice President and President, Lilly Bio-Medicines.

“We are committed to offering innovative solutions to people suffering from chronic pain conditions, and look forward to working closely with the FDA to facilitate the development of tanezumab.”

Ironically, it was the FDA that slowed the development of NGF inhibitors in 2010 because of safety concerns. The agency ordered a partial halt to clinical studies after Pfizer said a small number of 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. Pfizer says the current Phase 3 studies include risk mitigation measures for joint safety and sympathetic nervous system safety.

A clinical study of fasinumab, another nerve growth factor drug being developed by Teva and  Regeneron Pharmaceuticals, was stopped by the FDA last year after a patient showed signs of severe joint disease. Regeneron and Teva said they would redesign the study of patients with chronic low back pain to exclude participants with advanced osteoarthritis.