FDA panel says antidepressant looks effective for back pain, but not osteoarthritis

FDA panel mixed on approving Cymbalta for pain

WASHINGTON — A group of federal health experts narrowly voted to expand approval of a best-selling antidepressant on Thursday, though panelists disagreed over which types of pain the pill effectively treats.

The Food and Drug Administration is considering whether to broaden approval of Elli Lilly & Co.’s Cymbalta to treat chronic pain, a major expansion of a drug already used by 15 million U.S. patients.

An FDA panel of outside physicians voted 8-6 in favor of the broader indication, though they separately ruled that the drug did not appear effective for arthritis-related pain.

The FDA gives weight to the panel’s recommendations but is not required to follow them.

Indianapolis-based company has asked the FDA to approve its drug for chronic pain, a broad indication that encompasses more than 30 million American patients. The drug is already approved to treat depression, diabetic nerve pain and fibromyalgia.

But FDA panelists picked apart five clinical studies submitted by the company, which showed conflicting results for the drug’s effectiveness in different pain disorders and patient groups.

For osteoarthritis, one study that showed a significant reduction in pain, while another failed to reach statistical significance. Panelists voted 9-4 that the data did not support Cymbalta’s effectiveness for the condition.

Three studies in lower back pain were more convincing, and panelists voted 8-5 in favor of expanding the drug for that indication. One panelists abstained from each vote.

“I think there’s more to be done to identify the patient populations who might most benefit from this drug, but I think it’s a valuable treatment for patients,” said Dr. John Markman of the University of Rochester Medical Center.

Many panelists complained that Lilly’s studies were primarily composed of older, Caucasian patients, raising questions about the drug’s effectiveness in different age groups and ethnicities.

Eli Lilly global development leader Dr. Robert Baker said the panel meeting was “an important step toward approval.”

“We do want to work with the FDA and will continue discussions with them as they decide about how to best frame the indication,” Baker said.

Cymbalta is part of a class of drugs called serotonin-norepinephrine reuptake inhibitors, which includes antidepressants Effexor and Pristiq. The mechanism of action through which Cymbalta decreases pain is not entirely understood, though the company says it likely involves the brain chemical serotonin, which affects mood.

The drug was Eli Lilly’s second best seller last year with sales of $3 billion, behind the anti-psychotic Zyprexa.

An FDA approval will allow Lilly to begin marketing Cymbalta for chronic pain. But Leerink Swann analyst Rick Wise said the approval may not result in a major expansion in Cymbalta sales since the drug is already used off-label, or without FDA approval. In a recent research note, Wise estimates that 14 percent of Cymbalta prescriptions are for chronic pain.

Doctors are free to prescribe drugs for off-label uses, though drug companies are prohibited from publicizing those uses.