A drug that delivers a chemotherapy-like payload directly to cancer cells lowered the risk of death in a large trial in advanced endometrial cancer, according to news coverage published on October 26 and 27. Endometrial cancer starts in the tissues lining the inside of the uterus (womb).1 The drug is sacituzumab tirumotecan, shortened to sac-TMT, and Merck is developing it outside China.2
Trade publication Scrip, covering ESMO 2026, reported that the drug “cut risk of death by 32% in advanced endometrial cancer in the TroFuse-005 trial.” ESMO 2026 is the 2026 congress of the European Society for Medical Oncology, a major cancer meeting.32 Health and Me reported that the drug extended survival by nearly 7 months.4 This is the first Biohack article on this drug.
What happened
The trial compared sac-TMT with chemotherapy in women whose endometrial cancer had already been treated with two standard approaches: platinum-based chemotherapy and immunotherapy, which helps the immune system fight cancer.5 Its stated goal was to learn whether people on sac-TMT “live longer overall and without the cancer getting worse” than people on chemotherapy.5
The two main reports describe the result in different words. Scrip’s summary says the drug cut the risk of death by 32%.3 Health and Me’s summary says the drug “increased survival rate in patients by at least 32%,” and its headline says survival was extended by nearly 7 months.4 “Risk of death” usually means how likely a patient was to die at any point during follow-up compared with the other group, not the share of patients still alive. The sources do not give the underlying numbers, so readers cannot yet check how those two descriptions fit together.
Scrip’s headline said Merck is “close to sealing its first approval” for the drug.3 That is the publication’s reading of the situation, not a regulatory decision.
How the trial was set up
The trial’s public registry record lists it under Merck’s code MK-2870-005. It is a Phase 3 study, the last large stage of testing before a drug is usually submitted for approval.5 Key features from the registry:
- Randomized: patients were assigned by chance to sac-TMT or to a chemotherapy chosen by their doctor (doxorubicin, paclitaxel or nab-paclitaxel).5
- Open-label: patients and doctors knew which treatment was given.5
- Size: an estimated 710 participants.5
- Timeline: started December 6, 2023; it is no longer recruiting, and its primary completion date is listed as January 10, 2028.5
- Main goals: how long patients lived without their cancer growing, judged on scans by reviewers who did not know the treatment, and how long patients lived overall.5
Only adult women could join.6 The trial excluded people who had received more than three earlier lines of treatment, people with a history of lung inflammation that needed steroids, people with active or past inflammatory bowel disease, and people with severe dry eye or serious corneal disease.6 People who had already received a similar drug aimed at the same target were also excluded.6 Sites listed by University of California Health include UCLA in Los Angeles and California Pacific Medical Center in San Francisco.6
How the drug is meant to work
Sac-TMT is an antibody-drug conjugate. Merck’s trial pages describe this as a drug that “attaches to specific targets on cancer cells and delivers treatment to destroy those cells.”1 Its target is a protein called TROP2 on the surface of tumor cells.2
According to Kelun-Biotech, the Chinese company that created the drug, the antibody is taken up into the tumor cell and releases a payload that blocks an enzyme called topoisomerase I. This causes DNA damage that stops the cell from dividing and leads it to die.2 The company says the payload can pass through cell membranes, so it may also kill neighboring tumor cells, which it calls a “bystander effect.”2 Each antibody carries an average of 7.4 payload molecules, according to the company.2 These are the developer’s descriptions of how the drug is designed, not trial findings.
What the reports do not show yet
The available sources leave a lot out:
- Full numbers: the reports give neither the median survival in each group nor how many patients were analyzed.
- Cancer growth: the trial also measured how long patients lived without their cancer getting worse,5 but the reports give no figure for that.
- Side effects: none of the sources describe the drug’s safety in this trial.
- Peer review: the registry shows no posted results,5 and the sources do not mention a published paper.
- Who benefits most: there is no breakdown by cancer subtype or prior treatment.
Because the trial was open-label, patients and doctors knew who got which drug.5 Survival is less open to that kind of bias than measures based on judgment. The trial also had scans read by reviewers who did not know the treatment.5
Who is behind it
Merck Sharp & Dohme is the trial’s sponsor.5 The drug was developed by Sichuan Kelun-Biotech Biopharmaceutical. In May 2022, Kelun-Biotech licensed exclusive rights to Merck (known as MSD outside the US and Canada) to develop, make and sell the drug everywhere outside Greater China.2 The trial’s official title also names two research groups that work on gynecologic cancers (GOG-3095 and ENGOT-en23).5 Both companies have a financial stake in the outcome. The early reports come from news coverage rather than an independent analysis of the data.
How it fits the wider picture
In China, the drug is already approved for two uses: a form of breast cancer called triple-negative breast cancer after at least two earlier treatments, and a type of lung cancer with an EGFR mutation after earlier targeted pills and platinum chemotherapy.2 The endometrial result would be Merck’s first approval for the drug if regulators agree, according to Scrip’s framing.3
The company has been testing the drug in womb cancer for some time. At the 2025 ESMO congress, Kelun-Biotech presented a poster with results from an earlier, smaller study of the drug alone in advanced or metastatic endometrial cancer.2 At ESMO 2026, Scrip also reported on a large trial in Chinese patients with a type of lung cancer, in which the drug combined with Keytruda is positioned to replace chemotherapy.3
What to watch next
Merck is already running a second large womb cancer trial, called TroFuse-033. It compares sac-TMT plus pembrolizumab against pembrolizumab alone as ongoing “maintenance” treatment after first therapy.7 It enrolls people with advanced or recurrent endometrial cancer of the “mismatch repair proficient” type, meaning certain normal DNA-repair proteins are present in the cancer cells.1 It aims to enroll about 1,123 people, started in May 2025 and is still recruiting. Its primary completion date is listed as May 2032.7
For the current trial, the next steps to watch are a full presentation or published paper with survival numbers and side effects, and any filing with regulators. Those will show how large the benefit is, who it applies to, and what it costs patients in side effects.
