Keytruda met one of its primary endpoints in Phase III KEYNOTE 355 trial + chemotherapy for metastatic triple-negative breast cancer.- Merck Inc.

Merck announced that the pivotal Phase III KEYNOTE-355 trial investigating Keyrtuda, Merck’s anti-PD-1 therapy, in combination with chemotherapy met one of its dual primary endpoints of progression-free survival (PFS) in patients with metastatic triple-negative breast cancer (mTNBC) whose tumors expressed PD-L1 (Combined Positive Score [CPS] ?10). Based on an interim analysis conducted by an independent Data Monitoring Committee (DMC), first-line treatment with Keytruda in combination with chemotherapy (nab-paclitaxel, paclitaxel or gemcitabine/carboplatin) demonstrated a statistically significant and clinically meaningful improvement in PFS compared to chemotherapy alone in these patients. Based on the recommendation of the DMC, the trial will continue without changes to evaluate the other dual primary endpoint of overall survival (OS). The safety profile of Keytruda in this trial was consistent with that observed in previously reported studies; no new safety signals were identified. The Keytruda breast cancer clinical development program encompasses several internal and external collaborative studies. In addition to KEYNOTE-355, in TNBC these include the ongoing registration-enabling studies KEYNOTE-242 and KEYNOTE-522. Comment: Keytruda is a humanized monoclonal antibody that blocks the interaction between PD-1 and its ligands, PD-L1 and PD-L2, thereby activating T lymphocytes which may affect both tumor cells and healthy cells.