Dive Brief:

• Merck doesn’t yet have enough data to support use of Keytruda ahead of surgery in a difficult-to-treat form of breast cancer, a Food and Drug Administration advisory committee said Tuesday.

• The panel of outside experts voted 10-0 that the FDA’s decision on the new use of Keytruda should be deferred until more data and analysis is available from the trial, called Keynote-522.

• Merck’s chief medical officer, Roy Baynes, said the company was disappointed in the panel’s decision but still has confidence Keytruda can help patients with triple-negative breast cancer. “We look forward to continuing to work with the FDA,” Baynes said in a Feb. 9 release.

Dive Insight:

The vote is a rare speed bump for Keytruda, which is approved to treat a range of cancers and ranks as one of the world’s best-selling drugs, with $14.4 billion in revenue last year. The FDA doesn’t have to follow the recommendations of its advisory committees but usually does.

Merck doesn’t expect new data from the Keynote-522 trial until the third quarter of this year, well after the FDA’s March 29 target action date on the company’s application.

The study focuses on the use of Keytruda in patients with high-risk, early-stage triple-negative breast cancer, an aggressive type that isn’t fueled by estrogen, progesterone or the HER2 protein targeted by drugs like Roche’s Herceptin.

The triple negative form affects 15% to 20% of all breast cancer patients, and Keytruda is already approved for patients with advanced forms of the disease that can’t be surgically removed. The new application is aimed at expanding the medicine’s use to treating patients in earlier stages of their disease.

Researchers in the trial compared Keytruda against a placebo, in combination with chemotherapy before surgery, then as the only treatment after surgery. The main goals were pathological complete response, or the disappearance of invasive cancer, and survival without worsening or new cancer. The study also assessed overall survival as a secondary measure.

While the most recent analysis of the study found that more patients given Keytruda had pathological complete responses, there weren’t yet enough complications and deaths in the trial to give a reliable gauge of comparative “event-free” survival and overall survival rates. More patients on Keytruda also suffered from side effects and potentially problematic autoimmune responses, the FDA said in documents prepared for the advisory committee.

Merck’s Baynes said the event-free survival data was “encouraging” in the interim analysis of the study. “We believe Keytruda can help meet the significant unmet medical need for these patients,” he said