Merck, known as MSD outside of the United States and Canada, today announced that Keytruda (pembrolizumab) plus Trodelvy (sacituzumab govitecan-hziy) reduced the risk of disease progression or death by 35% versus Keytruda plus chemotherapy for the first-line treatment of patients with PD-L1+ inoperable (unresectable) locally advanced or metastatic triple-negative breast cancer (TNBC), as determined by an FDA-approved test. 

Keytruda, when given in combination with Gilead’s TROP2 antibody-drug conjugate (ADC) Trodelvy, resulted in a median progression-free survival (PFS) of 11.2 months versus 7.8 months when Keytruda was given in combination with chemotherapy. 

“These results have the potential to be an important advancement for patients with PD-L1–positive metastatic triple-negative breast cancer, a population for whom first-line options remain limited,” said Sara Tolaney, MD, MPH, Dana-Farber Cancer Institute and primary investigator of the ASCENT-04/KEYNOTE-D19 study. “By combining sacituzumab govitecan with pembrolizumab, we’re seeing meaningful gains in progression-free survival and a promising trend in overall survival—findings that could support a new frontline standard of care for this aggressive disease.” 

The safety profile of Keytruda plus Trodelvy in this study was consistent with the known safety profile of each agent. No new safety signals were identified with the combination. The two companies plan to share these results with regulatory authorities worldwide. 

“We’re committed to building on the established role of Keytruda as a foundational treatment for people with TNBC to provide new options in earlier lines of treatment, in the hope of improving outcomes for people living with this disease,” said Dr. Marjorie Green, senior vice president and head of oncology, global clinical development, Merck Research Laboratories. “These data support the addition of this TROP2-directed ADC to Keytruda, demonstrating the potential to help people with TNBC and to give doctors another option to treat this disease.” 

Merck has a comprehensive clinical development program in various subtypes of breast cancer including evaluating Keytruda in combination with investigational TROP2 ADCs (trophoblast cell-surface antigen-directed antibody-drug conjugates) in metastatic and early-stage cancers. The company has four ongoing Phase 3 studies in breast cancer, with two being in metastatic disease. 

As announced, data spanning more than 25 types of cancer are being presented from Merck’s broad oncology portfolio and investigational pipeline at the 2025 ASCO Annual Meeting.