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FDA Issues Complete Response Letter to Merck for Keytruda in Early TNBC Asking for More Data

NEW YORK – Merck said after the close of the market on Monday that the US Food and Drug Administration has, at this time, decided not to approve pembrolizumab (Keytruda) as a neoadjuvant and adjuvant treatment for high-risk, early-stage triple-negative breast cancer (TNBC).

The drugmaker had filed a supplemental biologics license application seeking approval for its PD-1 inhibitor in combination with chemotherapy in the neoadjuvant setting and then as a single agent in the adjuvant setting. The FDA issued a complete response letter indicating that it would need more data to make its decision.

Merck had submitted data from an interim analysis of the Phase III Keynote-522 trial, which showed that adding pembrolizumab to chemotherapy before surgery could result in a greater percentage of patients experiencing pathologic complete response compared to those receiving just chemo. The ongoing trial is designed to evaluate pathologic complete response and event-free survival times among patients who are treated with the neoadjuvant pembrolizumab-chemo combination to shrink tumors, then receive surgery, and continue on adjuvant single-agent pembrolizumab.

More than 1,000 TNBC patients are randomized in the study to receive the combination treatment, surgery, then pembrolizumab versus chemo plus placebo, surgery, then placebo. Researchers are also tracking overall survival and quality of life data as secondary endpoints.

The FDA's complete response letter follows the advice of its Oncologic Drugs Advisory Committee, which in February unanimously recommended that the agency await more mature data on event-free and overall survival endpoints before making its decision on this application. Merck submitted interim event-free survival data as part of its sBLA, though the company said it is continuing to evaluate this endpoint. According to the firm, the next interim analysis from Keynote-522 is slated for the third quarter of 2021.

FDA's complete response letter on this indication has no bearing on existing pembrolizumab approvals, Merck said, including the accelerated approval for pembrolizumab plus chemo in PD-L1-positive, locally recurrent, unresectable, or metastatic TNBC.

In Tuesday morning trading on the Nasdaq, Merck's stock price was down around 1 percent at $77.23.