US pharmaceutical company Merck & Co Inc (NYSE:MRK), known as MSD outside the US and Canada, announced on Thursday that the US Food and Drug Administration (FDA) has approved Keytruda (pembrolizumab) and Keytruda Qlex (pembrolizumab and berahyaluronidase alfa-pmph), each in combination with Trodelvy (sacituzumab govitecan-hziy), for the first-line treatment of adults with unresectable locally advanced or metastatic PD-L1-positive (CPS ≥10) triple-negative breast cancer (TNBC).

This approval marks the first use of a PD-1 inhibitor combined with a Trop-2-directed antibody-drug conjugate (ADC) in advanced TNBC.

The decision was supported by Phase 3 KEYNOTE-D19/ASCENT-04 trial data showing that Keytruda plus Trodelvy reduced the risk of disease progression or death by 35% compared with Keytruda plus chemotherapy.

Patients receiving the Keytruda-Trodelvy regimen achieved median progression-free survival of 11.2 months versus 7.8 months for those treated with Keytruda plus chemotherapy. The combination also delivered a higher objective response rate of 61% compared with 55% for the chemotherapy-based regimen, while complete response rates were 12% and 8%, respectively.

The effectiveness of Keytruda Qlex was established through studies of Keytruda and additional data demonstrating comparable pharmacokinetic, efficacy, and safety profiles between the two therapies.