RAHWAY, N.J. — October 26, 2026

Merck & Co., Inc. (NYSE: MRK), known as MSD outside the United States and Canada, announced positive results from the Phase 3 TroFuse-005 trial evaluating sacituzumab tirumotecan (sac-TMT), an investigational TROP2-directed antibody-drug conjugate (ADC), in patients with advanced or recurrent endometrial cancer previously treated with platinum-based chemotherapy and anti-PD-1/L1 immunotherapy. Compared with physician’s choice of chemotherapy, sac-TMT reduced the risk of death by 32% (HR=0.68; P<0.0001) and the risk of disease progression or death by 41% (HR=0.59; P<0.0001). Median overall survival (OS) was 19.0 months versus 12.1 months, while median progression-free survival (PFS) was 7.2 months versus 3.9 months. The objective response rate (ORR) was 35.1% with sac-TMT compared with 17.3% with chemotherapy. The results were presented at the European Society for Medical Oncology (ESMO) Congress 2026 and published simultaneously in The Lancet. The U.S. Food and Drug Administration (FDA) has accepted Merck’s Biologics License Application for priority review, with a target action date of June 15, 2027. Although the findings demonstrate significant survival improvements, Grade 3 or higher treatment-related adverse events occurred in 54.4% of sac-TMT recipients. Sac-TMT remains investigational.

TroFuse-005 Demonstrates Improved Survival Outcomes

The randomized, open-label TroFuse-005 trial enrolled 776 patients who received sac-TMT or physician’s choice of doxorubicin or paclitaxel. At a median follow-up of 14 months, sac-TMT improved median OS by 6.9 months and median PFS by 3.3 months. Median duration of response was 11.1 months with sac-TMT versus 6.9 months with chemotherapy. Complete responses occurred in 6.1% and 4.5% of patients, respectively. These results establish statistically significant improvements in the trial’s dual primary endpoints and support further regulatory evaluation in previously treated advanced or recurrent endometrial cancer.

Safety Profile and Treatment Tolerability

Treatment-related adverse events occurred in 97.1% of patients receiving sac-TMT and 89.6% receiving chemotherapy. Grade 3 or higher treatment-related adverse events occurred in 54.4% and 41.4%, respectively. The most common severe events with sac-TMT were anemia (23.7%), neutropenia (20.1%) and oral mucositis/stomatitis (9.9%). Treatment discontinuation rates were 3.1% with sac-TMT and 4.9% with chemotherapy. Health-related quality of life was maintained over time, and no new safety signals were reported. These findings indicate that the survival benefit must be assessed alongside the higher incidence of severe treatment-related adverse events.

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FDA Priority Review and Further Clinical Development

The FDA accepted Merck’s application for priority review for adults with endometrial cancer previously treated with platinum-containing chemotherapy and PD-1 or PD-L1 inhibitor therapy, separately or in combination. The target action date is June 15, 2027. Developed by Kelun-Biotech, sac-TMT uses a TROP2-targeting antibody linked to a belotecan-derived topoisomerase I inhibitor payload. Merck is evaluating the candidate in 18 ongoing global Phase 3 trials across multiple tumor types. TroFuse-005 represents a significant clinical milestone, although regulatory approval and continued evaluation will determine its role in treatment.

Source:Merck,a,Press release