On November 13, 2020, the FDA granted accelerated approval to pembrolizumab in combination with chemotherapy for the treatment of patients with locally recurrent unresectable or metastatic triple-negative breast cancer (TNBC) whose tumors express PD-L1 (as determined by an FDA test) based on progression-free survival (PFS).
The FDA also approved a companion diagnostic, PD-L1 IHC 22C3 pharmDx, on this date.
This approval was based on data from the KEYNOTE-355 trial, a multicenter-double-blind, randomized, placebo-controlled trial, where patients who had not been previously treated with chemotherapy in a metastatic setting were randomized in a 2:1 ratio to receive pembrolizumab or placebo in combination with different chemotherapy treatments (paclitaxel, paclitaxel-protein bound, or gemcitabine plus carboplatin).
The main end point was PFS, independently reviewed according to RECIST 1.1. In the pembrolizumab plus chemotherapy arm, median PFS was 9.7 months (95%CI, 7.6-11.3) versus 5.6 months (95% CI, 5.3-7.5) in the placebo arm.
The most common (≥20%) adverse reactions associated with pembrolizumab treatment were fatigue, nausea, diarrhea, constipation, vomiting, alopecia, rash, cough, decreased appetite and headache.—Kaitlyn Manasterski
