A federal advisory panel unanimously said a class of experimental arthritis-pain drugs from Pfizer Inc. and other companies should continue to be developed, although some panel members suggested limiting study to patients who failed other therapies.
The bulk of clinical studies involving the drugs, known as antinerve growth factors, were put on hold in 2010 following reports that some patients' osteoarthritis rapidly worsened to the point of requiring joint replacement surgeries.
According to the U.S. Food and Drug Administration, there are three companies that have conducted studies involving anti-NGF agents—with Pfizer the furthest along in development with its drug called tanezumab. A unit of Johnson & Johnson and Regeneron Pharmaceuticals Inc. each have similar drugs in development.
The drugs, designed to be given by injection, either intravenously or by needle, work by blocking a protein called nerve growth factor, which is believed to contribute to pain.
In 2010, the FDA asked Pfizer to temporarily suspend testing of tanezumab after data from clinical studies of the drug in osteoarthritis patients showed some patients had their condition rapidly worsen to the point they needed a joint replacement. Most studies from Regeneron and Johnson & Johnson were also put on hold, although the FDA did allow cancer-related pain studies to continue.
It isn't clear if the drugs actually caused joint destruction to worsen. One theory is that the drugs masked the pain in some patients so well that they increased their activity and accelerated the rate of damage to their knees or hips, for example.
The agency's arthritis drugs advisory panel, which is made up of non-FDA medical experts, said clinical data collected to date suggests there is a warning signal showing a certain type of rapid joint destruction among some patients exposed to the drugs, but that it wasn't enough to end development. The panel also said it is possible that nonsteroidal anti-inflammatory drugs, or NSAIDS, added to the risk of rapid joint destruction.
Several panel members also said there is a need for new kinds of pain medicines.
"The risk of currently used available agents—NSAIDS and opioids—is very high," said Lenore Buckley the chair of the panel and an internal medicine professor at Virginia Commonwealth University School of Medicine in Richmond. "Not many people want to say, let's just give up on this class of medications at this point."
The panel voted 21-0 in favor of a question that asked whether there was a role for continued development of the drugs. The panel then voted 20-1 in favor of a question that asked whether development of the drugs should be continued for pain conditions that currently don't have good treatments like chronic pancreatitis.
FDA officials said if they allow development of the drugs to continue more broadly that they would hold advisory panel meetings before any drug would be allowed to be marketed.
Pfizer said it believes studies of tanezumab in osteoarthritis should be allowed but has proposed certain restrictions such as using a lower dose and discontinuing use of tanezumab in patients who may not initially respond to treatment. The company is also proposing to study the product as a single therapy and not combined with nonsteroidal anti-inflammatory drugs, or NSAIDs.
