Neuropathy Patch Rejected by FDA

By a vote of 12-0, the Food and Drug Administration's (FDA's) Anesthetic and Analgesic Drug Products Advisory Committee decided a capsaicin skin patch (Qutenza) did not relieve neuropathic pain from HIV, according to a February 9 report in MedPage Today.

The committee concluded that the benefits of the 8% capsaicin patch did not outweigh its risks as a treatment for HIV-associated peripheral neuropathy. The patient representative on the panel abstained from voting.

All panelists expressed major disappointment in voting down the drug, which would have been the first approved treatment of a condition that affects up to 40% of patients with HIV, but they concluded that the available data did not support an approval and many panel members blamed a poor study design for the lack of persuasive data.

During its February 9 meeting, the panel examined the company's two Phase 3, 12-week randomized, double-blinded, controlled trials, both of which enrolled about 800 patients with HIV peripheral neuropathy pain (generally in the feet). The mostly male participants randomly received either the 8% capsaicin patch, or a low-dose (0.04%) capsaicin control patch. The patches were applied for either 30, 60, or 90 minutes in one trial and either 30 or 60 minutes in the other trial. The study endpoint in both was a change in baseline in the "average pain for the past 24 hours."

The results were mixed, and the panelists expressed confusion at how to interpret them. One might expect an effective patch applied for 30 minutes would work even better when applied for 60 minutes, and to work best when applied for 90 minutes, and that all applications of the 8% dose would be better at easing pain than the very low dose placebo patch.

But instead, one study found that the 8% patch applied for 30 minutes worked best at reducing pain, followed by the 90 minute patch, while the 60 minute application wasn't more effective than the very low-dose patch.

In the other study, while the 8% patch applied for 60 minutes appeared to ease pain better than the 30-minute patch, the 60-minute patch had almost identical results as the 60-minute 0.04% capsaicin patch, suggesting a placebo effect.

"All us recognize the importance of this drug," said panelist James Ramsay, M.D., an anesthesiologist at Emory University Hospital in Atlanta. "But there was obvious agreement of lack of efficacy."

Bob Rappaport, M.D., director of the FDA's Division of Anesthesia, Analgesia, and Addiction Products, called the disappointing results from the trials "heartbreaking" and said the meeting was "the most difficult" of the advisory committee he's attended.