Pfizer and Eli Lilly have announced that they will seek FDA approval by 2018 for a new type of pain drug that could be an alternative to opioids for osteoarthritis (OA), chronic back pain, and cancer pain. The drug, tanezumab, is administered by injection every eight weeks.
Tanezumab is a humanized monoclonal immunoglobulin G2 (IgG2) antibody that selectively targets nerve growth factor (NGF), a regulator of pain processing and sensitivity. NGF levels increase as a result of injury or inflammation and in chronic pain states. Tanezumab selectively binds to NGF, thereby inhibiting the protein from activating pain-signaling neurons.
In clinical studies involving more than 11,000 patients, tanezumab demonstrated clinically meaningful efficacy compared with placebo and commonly used pain medications. It was shown to be more effective than oxycodone, a widely used opioid, and naproxen, the active ingredient of the over-the-counter painkiller Aleve (Bayer).
Although tanezumab has been well tolerated so far, some patients taking it have developed swelling of the extremities and other adverse effects.
Pfizer and Lilly agreed in 2013 to jointly develop and market tanezumab for several pain-related conditions, including OA and cancer.
In March 2015, the FDA lifted a partial clinical hold on the tanezumab development program after reviewing nonclinical data characterizing the sympathetic nervous system response to the drug. A partial clinical hold had been in place for all anti-NGF antibodies since December 2012 because of adverse changes in the sympathetic nervous system of mature animals. Studies in terminal cancer pain were allowed to proceed.
In addition, the FDA had concerns about the joint-related safety of tanezumab in patients with OA. Eighty-seven cases of osteonecrosis were reported among 386 OA patients who received joint replacements. An adjudication committee determined, however, that only two of the investigator reports of osteonecrosis were correctly diagnosed.
Opioids caused 18,893 overdose deaths in the United States in 2014, according to the American Society of Addiction Medicine.