MSD's Sac-TMT Delivers in First Phase 3 Readout

Why It Matters

The results address a high‑unmet‑need population that has exhausted platinum and immunotherapy, positioning Merck for a lucrative new indication and a competitive edge over Gilead’s Trodelvy and AstraZeneca/Daiichi’s Datroway.

Key Takeaways

• Sac‑TMT improves PFS and OS in advanced endometrial cancer.
• Trial beats physician’s choice chemo with statistically significant survival gain.
• Merck licensed sac‑TMT for up to $1.4 billion in 2022.
• First anti‑TROP2 ADC showing benefit in post‑platinum, post‑immunotherapy setting.
• Could give Merck first‑to‑market advantage before rivals launch.

Pulse Analysis

TROP2‑directed antibody‑drug conjugates have emerged as a fast‑growing class in oncology, leveraging a tumor‑associated antigen to deliver cytotoxic payloads directly to cancer cells. Merck’s decision to license sac‑TMT from Kelun‑Biotech in 2022—under a deal valued at up to $1.4 billion—reflects the strategic importance of expanding its ADC pipeline beyond existing assets such as Kadcyla. By securing rights to a molecule already approved in China for lung and breast cancers, Merck positioned itself to rapidly test the drug across multiple indications, culminating in the TroFuse‑005 phase 3 trial for endometrial cancer.

Endometrial cancer is one of the few major solid tumors with rising incidence and mortality, and patients who progress after platinum‑based chemotherapy and PD‑1/PD‑L1 immunotherapy have limited options. The TroFuse‑005 study enrolled heavily pre‑treated patients and compared sac‑TMT to physician’s choice chemotherapy, demonstrating statistically significant improvements in both progression‑free survival and overall survival. These outcomes not only meet a critical clinical need but also validate the bifunctional linker technology designed to maximize tumor payload while sparing healthy tissue, a differentiator that could influence future ADC design.

The competitive landscape now includes Gilead’s Trodelvy and AstraZeneca/Daiichi’s Datroway, both TROP2 ADCs approved for breast and lung cancers but not yet for endometrial disease. Merck’s early success may grant it a first‑to‑market advantage, allowing the company to establish brand recognition and reimbursement pathways before rivals expand into this niche. As the data are shared with global regulators, a positive filing could unlock a multi‑billion‑dollar revenue stream and reinforce Merck’s standing as a leader in next‑generation oncology therapeutics.