The U.S. Food and Drug Administration Arthritis Advisory Committee on Monday has unanimously agreed to let companies like Pfizer Inc. and Regeneron Pharmaceuticals Inc. resume clinical trials with their anti–nerve growth factor (NGF) drugs, despite past cases of bone decay and joint deterioration being linked to their use.

The panel voted 21-0 that federal regulators should lift its hold on clinical trials of the pain drugs.

“There’s significant risk but there are probably patient populations where there will be significant benefit,” Lenore Buckley, chairwoman of the FDA advisory panel and professor of internal medicine and pediatrics at Virginia Commonwealth University School of Medicine in Richmond, according to Bloomberg.

However, while FDA usually follows the panel’s recommendations, the federal agency is not required to submit to their advice.

The NGF drugs are being developed to treat a variety of chronic painful conditions, including osteoarthritis, chronic lower back pain, diabetic peripheral neuropathy, postherpetic neuralgia, chronic pancreatitis, endometriosis, interstitial cystitis, vertebral fracture, thermal injury, and cancer pain.

Doctors have treated pain with common drugs like aspirin and Advil, or powerful opiate-based drugs for more than a century. However both of these current pain medications carry health risks. Anti-inflammatory painkillers like Advil can cause internal and stomach bleeding, while opiates are highly addictive.

The FDA stopped almost all clinical trials of the NGF drugs in 2010 after an “unusually high incidence in the populations studied” reported joint-related destruction or side effects that were “usually severe” compared to joint-related problems that occur in the patient population, and nearly 500 people taking the drugs had to have joint replaced.

The only people who companies were still allowed to keep on clinical trials were patients with terminal cancer and had severe pain in their bodies because the benefits in this population were judged to outweigh the risks.

The drugs block a protein called nerve growth factor (NGF), which plays a part in promoting the survival and development of sensory and sympathetic neurons, and may also help repair wounds and the growth of new blood vessels, the FDA said in a memo earlier this month.

The joint problems associated with the drug may be that it blocks the beneficial growth effects of the NGF protein, an FDA reviewer had said.

The panel said that the drugs provide a meaningful benefit to help people treat pain, particularly for those who have fewer alternative options, but they said that the companies developing the anti-nerve drugs should find out which patients would benefit most, and to try to exclude those who may be more inclined to joint problems.

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