On Oct. 26, 2026, Merck announced the first results from the pivotal Phase 3 TroFuse-005 trial evaluating sacituzumab tirumotecan (sac-TMT), an investigational TROP2-directed antibody-drug conjugate (ADC) being developed in collaboration with Kelun-Biotech, in patients with advanced or recurrent endometrial cancer who have received prior platinum-based chemotherapy and anti-PD-1/L1 immunotherapy. At a pre-specified interim analysis, the study demonstrated statistically significant and clinically meaningful improvement in its dual primary endpoints of overall survival (OS) and progression-free survival (PFS) as well as its key secondary endpoint of objective response rate (ORR) compared with treatment of physician’s choice (TPC; doxorubicin or paclitaxel).

TroFuse-005 is the first global Phase 3 trial and the first ADC to demonstrate statistically significant improvement in both OS and PFS compared to chemotherapy for these patients with advanced or recurrent endometrial cancer. These late-breaking data will be presented for the first time today during a Presidential Symposium session at the European Society for Medical Oncology (ESMO) Congress 2026 [Presentation #LBA11], were selected for an official ESMO press briefing, and were published simultaneously in The Lancet.

At the time of analysis, with a median follow-up of 14.0 months, sac-TMT reduced the risk of death by 32%, extending median OS by 6.9 months compared with TPC (19.0 months vs. 12.1 months). Sac-TMT also reduced the risk of disease progression or death by 41%, extending median PFS by 3.3 months compared with TPC (7.2 months vs. 3.9 months). The study improved ORR by 17.8%, double what was observed in the TPC arm (35.1% vs. 17.3%), and complete responses occurred in 6.1% of patients on the sac-TMT arm and 4.5% of patients on the chemotherapy. Responses were durable, with a median duration of response of 11.1 months (95%) in the sac-TMT arm and 6.9 months (95%) in the TPC arm.

The safety profile was consistent with what has been observed in previously reported studies of sac-TMT; no new safety signals were observed. Treatment-related adverse events (TRAEs) of any grade occurred in 97.1% of patients treated with sac-TMT and 89.6% of patients receiving TPC. These AEs were mostly low grade and manageable with supportive care and dose modifications, with low discontinuation rates. Grade ≥3 TRAEs occurred in 54.4% and 41.4% of patients, respectively. The most common Grade ≥3 clinical safety events with sac-TMT were anemia (23.7%), neutropenia (20.1%) and oral mucositis/stomatitis (9.9%). Treatment discontinuation rate in the sac-TMT arm was 3.1% and in the TPC arm was 4.9%. Health-related quality of life was maintained over time with sac-TMT. TRAEs led to death in 0.8% of patients (N=3) in each arm.

Based on data from the TroFuse-005 trial, the U.S. Food and Drug Administration (FDA) has accepted for priority review a Biologics License Application (BLA) seeking approval of sac-TMT for the treatment of adult patients with endometrial cancer who have previously received platinum containing chemotherapy and a programmed death receptor 1 (PD 1) or programmed death ligand 1 (PD L1) inhibitor, separately or in combination. The FDA has set a Prescription Drug User Fee Act (PDUFA), or target action date, of June 15, 2027. Merck will also discuss these data with global regulatory authorities.