FDA Grants Accelerated Approval to Keytruda-Chemotherapy Combination for TNBC

The Food and Drug Administration (FDA) granted an accelerated approval for the combination of Keytruda (pembrolizumab) and chemotherapy for patients with locally recurrent unresectable or metastatic triple-negative breast cancer (TNBC) with a PD-L1 expression. Along with the treatment, the PD-L1 IHC 22C3 pharmDx companion diagnostic test was also approved by the FDA to select appropriate patients with TNBC for this therapy.

The accelerated approval was based on results of the multicenter, double-blind, randomized, placebo-controlled KEYNOTE-355 trial that looked at patients with TNBC who were not treated with chemotherapy in the metastatic setting previously, according to an alert from the FDA. Looking at progression-free survival (PFS), the length of time the patient would live with TNBC not progressing any further, the study found significant results in favor of the combination therapy. Median PFS was 9.7 months in the Keytruda and chemotherapy arm compared with 5.6 months in the placebo arm. Chemotherapy treatments included in the approval were paclitaxel protein-bound, paclitaxel, and gemcitabine plus carboplatin.

The most common side effects found in the trial were fatigue, nausea, diarrhea, constipation, vomiting, alopecia (patchy hair loss), rash, cough, decreased appetite and headache for patients on Keytuda and chemotherapy. Other side effects observed in the trial included anemia, leukopenia (low white blood cell count), neutropenia (low number of a white blood cell called neutrophils), lymphopenia (low levels of lymphocytes, another type of white blood cell) and thrombocytopenia (low number of platelets). In addition, researchers observed some other side effects such as elevated ALT and AST (indicators of abnormal liver function), hyperglycemia (high glucose levels), hypoalbuminemia (low albumin levels in blood), increased alkaline phosphatase (indicator of liver damage or a bone disorder), hypocalcemia (low levels of calcium in plasma), hyponatremia (low sodium in blood), hypophosphatemia (low phosphates in blood) and hypokalemia (low potassium levels in blood).

“These acceptances mark the first U.S. applications for Keytruda in breast cancer, and we look forward to working closely with the FDA to bring these new options to patients as quickly as possible,” said Dr. Roy Baynes, senior vice president and head of global clinical development, chief medical officer, Merck Research Laboratories, in July when Keynote-355 was accepted for review by the FDA.

The recommended dosing for adult patients with locally recurrent unresectable or metastatic TNBC is 200 mg every -three weeks or 400 mg every six weeks administered prior to chemotherapy, according to the alert.

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