Overall survival with pembrolizumab plus chemotherapy for advanced triple-negative breast cancer

Interim analysis of the multinational phase 3 KEYNOTE-355 trial found that the addition of pembrolizumab to investigator’s choice of chemotherapy resulted in longer PFS than placebo plus chemotherapy among patients with advanced triple-negative breast cancer whose tumors expressed PD-L1 with a CPS of 10 or more (CPS-10 subgroup). Final overall survival analysis of the trial has now been published. In the CPS-10 subgroup, the median OS was 23.0 months with pembrolizumab-chemotherapy versus 16.1 months with placebo-chemotherapy (HR 0.73; p=0.0185). In the CPS-1 subgroup the median OS was 17.6 versus 16.0 months (p=0.1125) and in the ITT-population the median OS was 17.2 versus 15.5 months (significance not tested). Adverse event of grade 3 or higher were seen in 68.1% of patients with pembrolizumab-chemotherapy and 66.9% with placebo-chemotherapy, including death in 0.4% and 0, respectively (quick take video summary).