Sacituzumab Tirumotecan (Sac-TMT) Reduced the Risk of Death by 32% and the Risk of Disease Progression or Death by 41% Compared to Chemotherapy in Certain Patients With Advanced or Recurrent Endometrial Cancer

RAHWAY, N.J.--(BUSINESS WIRE)-- Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced the first presentation of 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% (HR=0.68; 95% CI, 0.55-0.84; P<0.0001), 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% (HR=0.59; 95% CI, 0.50-0.70; P<0.0001), extending median PFS by 3.3 months compared with TPC (7.2 months vs. 3.9 months). The study improved ORR by 17.8% (95% CI, 11.6–23.9; P <0.00001), 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% CI, 9.2–13.0) in the sac-TMT arm and 6.9 months (95% CI, 5.4–9.1) in the TPC arm.

“Sac-TMT is the first TROP2 ADC to demonstrate an improvement in overall survival in advanced or recurrent endometrial cancer in this setting compared to chemotherapy in a global Phase 3 trial. In addition, TroFuse-005 found a higher response rate and longer duration of response among patients treated with sac-TMT compared to chemotherapy,” said Dr. Domenica Lorusso, the study’s global lead investigator, lead investigator for ENGOT and professor of Obstetrics and Gynecology at Humanitas University and Humanitas San Pio X, Milan. “The incidence and mortality rates of endometrial cancer are increasing worldwide, and the results from TroFuse-005 have the potential to change the way we treat patients who have received prior platinum-based chemotherapy and anti-PD-1/L1 immunotherapy.”

“Sac-TMT demonstrated an improvement in overall survival of almost seven months for women with endometrial cancer who progress following treatment with platinum-based chemotherapy and anti-PD-1 therapy, a meaningful advancement for these women who face a median survival of less than a year with current therapies,” said Dr. Dean Y. Li, president, Merck Research Laboratories. “We believe sac-TMT, with its unique bifunctional linker, can become a cornerstone for the treatment of certain patients with advanced or recurrent endometrial cancer. Based on discussions with the U.S. FDA, the company is hopeful for an approval before the PDUFA date to bring sac-TMT to patients as quickly as possible.”

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.

Merck’s TroFuse clinical development program for sac-TMT currently consists of 18 ongoing global Phase 3 trials across multiple tumor types, the broadest range of disease and treatment settings compared to any TROP2-directed ADC to date. Ten of the Phase 3 trials are in women’s cancers, building on Merck’s deep expertise and commitment to women’s cancers research. This includes the ongoing TroFuse-033 trial in first line mismatch repair proficient endometrial cancer. The program is evaluating sac-TMT across a diverse range of tumor types, including endometrial, bladder, breast, cervical, gastric, non-small cell lung and ovarian cancers, and it spans early-to-late-stage disease as both monotherapy and in combination with immunotherapies. TroFuse-005 is among the 14 of these Phase 3 studies which aim to address unmet medical need with first-in-class opportunities.

About TroFuse-005
TroFuse-005 is a randomized, active-controlled, open-label, multicenter, global Phase 3 trial (ClinicalTrials.gov, NCT06132958) evaluating sac-TMT versus TPC in patients with endometrial carcinoma who have received prior platinum-based chemotherapy and anti-PD-1/anti-PD-L1 immunotherapy either together or separately. The trial enrolled 776 patients who were randomized to receive either sac-TMT or TPC, consisting of doxorubicin or paclitaxel. Sac-TMT (4 mg/kg) was administered on Day 1 of each two-week treatment cycle. Doxorubicin (60 mg/m²) was administered on Day 1 of each three-week treatment cycle and paclitaxel (80 mg/m²) was administered on Days 1, 8 and 15 of each four-week treatment cycle.

The study has dual primary endpoints: PFS by blinded independent central review (BICR), defined as the time from randomization to the first documented disease progression or death from any cause, and OS, defined as the time from randomization to death from any cause. A key secondary endpoint is ORR, and other secondary endpoints include duration of response, incidence of adverse events, treatment discontinuation due to adverse events and change from baseline in global health status/quality-of-life scores.

About sacituzumab tirumotecan (sac-TMT)
Sac-TMT is an investigational TROP2-directed ADC with a belotecan-derived topoisomerase I inhibitor payload and a unique bifunctional linker designed with the potential to maximize payload delivery to tumor cells and minimize payload loss while circulating in the body.

TROP2 is overexpressed on tumor cells compared to healthy cells in many common cancers, and through the TroFuse clinical development program, Merck is evaluating sac-TMT in 18 ongoing global Phase 3 trials across multiple tumor types, the broadest range of disease and treatment settings compared to any TROP2-directed ADC to date. The TroFuse development program spans early-to-late-stage disease in more than nine disease areas and includes more than 15,000 patients worldwide. Numerous Phase 3 trials are exploring sac-TMT as monotherapy and in combination with immunotherapies, aiming to improve survival and quality of life for patients with advanced and earlier-stage cancers.

About endometrial cancer
Endometrial cancer (also referred to as endometrial carcinoma) begins in the inner lining of the uterus, which is known as the endometrium, and is the most common type of cancer in the uterus. More than 90% of uterine body cancers occur in the endometrium. In the U.S., it is estimated there will be approximately 68,270 patients diagnosed with endometrial cancer and approximately 14,450 patient deaths from the disease in 2026. Globally, endometrial cancer is the sixth most common cancer in women and the 15th most common cancer overall. Following primary treatment, patients face a risk of their cancer returning, often as distant metastasis, which is associated with poorer outcomes.

About Merck’s research in women’s cancers
Merck is advancing research aimed at expanding treatment options for certain breast and gynecologic (ovarian, cervical and endometrial) cancers, with a goal of improving outcomes for more patients affected by these diseases. Breast cancer and gynecologic cancers are the first and second most commonly occurring cancer types among women worldwide, respectively, and Merck aims to provide options to patients facing these devastating diseases. With more than 30 clinical trials in more than 20,000 patients around the world, Merck is driving innovative research to purposefully advance standards of care in women’s cancers. Merck’s research efforts include trials focused on evaluating its medicines in earlier stages, as well as identifying novel mechanisms and new combinations with these treatments. Through our portfolio and pipeline, Merck is working to address the impact of women’s cancers on patients, their families and communities globally.

About the Merck and Kelun-Biotech strategic collaboration
Sac-TMT was developed by Kelun-Biotech. Kelun-Biotech (6990.HK) is a holding subsidiary of Kelun Pharmaceutical (002422.SZ), which focuses on the R&D, manufacturing, commercialization and global collaboration of innovative biological drugs and small molecule drugs. Under a collaboration agreement, Kelun-Biotech has granted Merck the exclusive rights to develop, manufacture and commercialize sac-TMT in all territories outside of Greater China (which includes Mainland China, Hong Kong, Macau and Taiwan).

Merck’s focus on cancer
Every day, we follow the science as we work to discover innovations that can help patients, no matter what stage of cancer they have. As a leading oncology company, we are pursuing research where scientific opportunity and medical need converge, underpinned by our diverse pipeline of more than 20 novel mechanisms. With one of the largest clinical development programs across more than 25 tumor types, we strive to advance breakthrough science that will shape the future of oncology. By addressing barriers to clinical trial participation, screening and treatment, we work with urgency to reduce disparities and help ensure patients have access to high-quality cancer care. Our unwavering commitment is what will bring us closer to our goal of bringing life to more patients with cancer. For more information, visit https://www.merck.com/research/oncology.

About Merck
At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.merck.com and connect with us on X (formerly Twitter), Facebook, Instagram, YouTube and LinkedIn.

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