Keytruda (pembrolizumab) received accelerated approval from FDA in combination with chemotherapy for the treatment of locally recurrent unresectable or metastatic triple-negative breast cancer whose tumors express PD-L1 (CPS ≥10) as determined by an FDA approved test.
Keytruda is sponsored by Merck.
FDA also approved the PD-L1 IHC 22C3 pharmDx (sponsored by Dako North America Inc.) as a companion diagnostic for selecting patients with TNBC for pembrolizumab.
Approval was based on KEYNOTE-355 (NCT02819518), a multicenter, double-blind, randomized, placebo-controlled trial in patients with locally recurrent unresectable or metastatic TNBC, who had not been previously treated with chemotherapy in the metastatic setting. Patients were randomized (2:1) to receive pembrolizumab 200 mg on day one every every weeks or placebo in combination with different chemotherapy treatments (paclitaxel protein-bound, or paclitaxel, or gemcitabine plus carboplatin) via intravenous infusion.
The main efficacy outcome measure was progression-free survival as assessed by blinded independent review according to RECIST 1.1, tested in the subgroup of patients with CPS ≥10. Median PFS was 9.7 months (95% CI: 7.6, 11.3) in the pembrolizumab plus chemotherapy arm and 5.6 months (95% CI:5.3, 7.5) in the placebo arm (HR 0.65; 95% CI: 0.49, 0.86; one-sided p-value=0.0012).
