ESMO 2026: Merck’s Kelun-partnered ADC cuts death risk by over 30% in endometrial cancer

News Drug Development ESMO 2026: Merck’s Kelun-partnered ADC cuts death risk by over 30% in endometrial cancer October 26, 2026 | 3 min read | Heather McKenzie Twitter LinkedIn Facebook Email Print Sac-TMT significantly extended overall and progression-free survival for patients with advanced or recurrent endometrial cancer by 6.9 months over chemotherapy in a Phase 3 trial—becoming the first TROP2-directed ADC to do so in this setting, Merck told BioSpace. In a late-stage trial, Merck’s Kelun-Biotech–partnered TROP2 antibody-drug conjugate sacituzumab tirumotecan, better known as sac- TMT, slashed the risk of death by 32% in a particularly challenging type of endometrial cancer—the first ADC to significantly improve overall survival and progression-free survival vs. chemotherapy in this patient population.“It’s also the first new therapy that we can offer patients post [immuno-oncology] because the standard in that setting currently is chemotherapy, which has very dismal outcomes,” Bhavana Pothuri, professor in the Departments of Ob/gyn and Medicine and medical director of the Perlmutter Cancer Center Clinical Trials Office, told BioSpace prior to the Monday data release at the 2026 European Society for Medical Oncology (ESMO) meeting in Madrid.Pothuri serves as a principal investigator on the Phase 3 TroFuse-005 trial, which enrolled around 776 patients who had previously been treated with a platinum-based chemotherapy and anti-PD-1/L1 immunotherapy.

In TroFuse-005, sac-TMT hit both primary endpoints, according to a Monday afternoon press release. The ADC extended overall survival in patients with advanced or recurrent endometrial cancer by 6.9 months, with participants on Merck’s ADC living an average of 19 months vs. 12.1 for those in the chemo cohort.

Sac-TMT also cut the risk of disease progression or death by 41%, achieving progression-free survival (PFS) of 7.2 months for patients taking the ADC vs. 3.9 months for those on chemotherapy for a difference of 3.3 months.The overall response rate (ORR) was twice as high for patients receiving sac-TMT compared with those on chemotherapy, Merck said, at 35.1% vs. 17.3%, meeting the trial’s key secondary endpoint.“These patients have a median overall survival of less than a year on current therapies, so extending survival by almost 7 months is incredibly meaningful,” Shweta Jain, a vice president at Merck, told BioSpace in an email prior to the data release.

“Importantly, this is the first time a TROP2-directed ADC has demonstrated statistically significant improvements in both overall survival and progression-free survival compared with chemotherapy in this setting.”As for safety, 97.1% of patients treated with sac-TMT experienced a treatment-related adverse event (TREA) compared to 89.6% of participants on chemotherapy alone, Merck said. Severe TREAs were seen in 54.4% of patients who received sac-TMT and 41.4% of those on chemo. The most common severe adverse events were anemia and neutropenia, a condition that results in low levels of infection-fighting white blood cells called neutrophils.

Pothuri said she has used a range of TROP2 ADCs to treat patients with endometrial cancer “and this one by far was better tolerated, and obviously, the efficacy speaks for itself.”The data were presented during a Presidential Symposium session at ESMO and simultaneously published in The Lancet.“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,” Dean Li, president of Merck Research Laboratories, said in a prepared statement on Monday.Pothuri agreed that this bifunctional linker differentiates sac-TMT and “really maximizes” the delivery of the topoisomerase I (TOP1) payload into the tumor cells. antibody-drug conjugate (ADC) ESMO 2026: Merck’s Kelun-partnered ADC hits the ‘Goldilocks zone,’ VP says At the European Society for Medical Oncology meeting this weekend, Merck will showcase three late-stage trials of its Kelun-Biotech–partnered TROP2-directed antibody sac-TMT that VP of Chemistry Alan Northrup says gets the payload release “just right.” October 22, 2026 · 5 min read · Heather McKenzie Read more With ADC linker payloads, “You’re trying to find that Goldilocks zone,” Merck Vice President of Chemistry Alan Northrup told BioSpace earlier this month. Some linker payloads are “too hot,” so the payload is released throughout the body, causing myriad issues including anemia and neutropenia, and some are “too cold,” meaning their release is slow once they hit the tumor, he explained.

Sac-TMT, he added, gets it “just right.”Indeed, the ADC has also shown signs of efficacy beyond endometrial cancer. In the Phase 3 OptiTROP-Lung04 trial—which pitted sac-TMT against platinum chemotherapy in EGFR-mutated non-small cell lung cancer (NSCLC) after progression on a treatment that blocks the EGFR tyrosine kinase domain—the ADC reduced the risk of disease progression or death by 51%, Kelun reported in October 2025.Then, in July 2026, sac-TMT plus Merck’s PD-1 blockbuster Keytruda meaningfully improved PFS vs. standard of care (immunotherapy plus chemotherapy) in first-line non-small cell lung cancer in the Phase 3 OptiTROP-Lung06 Study trial—representing the first direct proof-of-concept for an ADC replacing platinum-based chemo in this setting, according to Leerink Partners.Kelun presented additional data from the trial at ESMO showing that sac-TMT reduced the risk of disease progression or death by 51%, a result BMO Capital Markets said in a Sunday note “likely exceeds” investors’ already-high expectations.

Lung cancer Kelun’s Merck-partnered ADC notches late-stage NSCLC win alongside Keytruda The Phase 3 results are the first direct proof-of-concept for an ADC replacing platinum-based chemo in a first-line standard-of-care regimen for non-small cell lung cancer, according to Leerink Partners. The readout also represents the second late-stage win for the Merck and Kelun-Biotech asset, called sac-TMT. July 15, 2026 · 2 min read · Michael Gibney Read more Twitter LinkedIn Facebook Email Print Cancer Women’s health Antibody-drug conjugate (ADC) Phase 3 ESMO Merck & Co.

Heather McKenzie Heather McKenzie is senior editor at BioSpace and curator of the ClinicaSpace newsletter. She is an award-winning journalist specializing in rare disease and neuroscience, in addition to her extensive coverage of the FDA and regulatory science. You can reach her at heather.mckenzie@biospace.com.

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