Merck’s $1.4 billion gamble on Kelun-Biotech’s antibody-drug conjugate pipeline just delivered its first Phase 3 win. The TroFuse-005 trial hit both primary endpoints at an interim analysis: overall survival and progression-free survival for sacituzumab tirumotecan (sac-TMT) in patients with advanced or recurrent endometrial cancer who’d already received platinum-based chemotherapy and anti-PD-1 therapy.
Merck called it the first global Phase 3 trial to demonstrate statistically significant improvement in both OS and PFS compared to chemotherapy in this patient population. The 776-patient study compared sac-TMT to physician’s choice of doxorubicin or paclitaxel. Sac-TMT also cleared the secondary endpoint of objective response rate.
Sac-TMT targets TROP2, a protein highly expressed in many cancers and linked to tumor survival, rapid growth, and metastasis. The drug carries a belotecan-derived topoisomerase I inhibitor, and a proprietary linker Merck says maximizes payload delivery to target cells while cutting off-target effects. The numbers aren’t out yet. Full data is expected at the European Society for Medical Oncology congress in October.
The $1.4B sac-TMT entry price looks different now that the Phase 3 reads out. Merck placed a second, larger bet on Kelun in December 2022: $9.3 billion for seven investigational ADCs, with $175 million upfront. A first Phase 3 win out of 17 ongoing TroFuse studies, spanning women’s cancers including ovarian, cervical, and breast, validates the portfolio thesis beyond just this single asset. No regulatory filing timeline was announced, but TroFuse-005 was designed as a pivotal trial.
ESMO in October.
— Sarah Chen