Merck & Co Inc. announced a strategic $700 million funding agreement with Blackstone Life Sciences to accelerate development of sacituzumab tirumotecan (sac-TMT), an investigational antibody-drug conjugate (ADC) targeting trophoblast cell-surface antigen 2 (TROP2). The partnership supports one of the most extensive Phase 3 programs in oncology, with the ADC currently being evaluated across 15 global trials spanning six tumor types.
Comprehensive Phase 3 Development Program
Sac-TMT is being studied across multiple cancer indications, including breast, endometrial, and lung cancers. The extensive clinical program represents a significant investment in TROP2-targeting therapy, with TROP2 being a protein found on the surface of various cancer cells that is highly expressed in epithelial-derived tumors and can promote tumor cell proliferation, invasion, and metastasis.
"This agreement positions Merck to harness the potential of sac-TMT, a promising ADC candidate targeting TROP2, while we continue to advance our broad and expansive pipeline," said Caroline Litchfield, chief financial officer at Merck. "We are making important investments to drive patient impact and revenue growth, and to sustain our business for the future while remaining disciplined towards maintaining an appropriate financial profile."
Financial Structure and Royalty Terms
Under the agreement terms, Blackstone will provide $700 million in non-refundable funding to cover a portion of sac-TMT's development costs expected through 2026. In return, Blackstone is eligible to receive low-to-mid single-digit royalties on net sales of sac-TMT across all approved indications in Merck's marketing territories. The royalty payments are contingent upon receipt of U.S. regulatory approval for first-line treatment of triple-negative breast cancer based on findings from the TroFuse-011 clinical trial.
Dr. Nicholas Galakatos, global head of Blackstone Life Sciences, emphasized the therapeutic potential: "Sac-TMT is an innovative asset that has the potential to improve patient care across many forms of cancer. We are excited to be collaborating with Merck to realize the full value of this high priority product and contribute to our partner's revenue growth by leveraging our scale capital and expertise."
Advanced ADC Technology Platform
Sac-TMT represents a sophisticated ADC design consisting of three key components: a TROP2-targeting monoclonal antibody called sacituzumab, a cytotoxic payload from the topoisomerase 1 inhibitor class, and a novel, irreversible but hydrolyzable linker that joins the antibody and payload using proprietary linker conjugation technology. The ADC features an average drug-to-antibody ratio of 7.4, which allows for enhanced cytotoxic delivery to TROP2-expressing tumor cells.
TROP2 ADCs specifically target TROP2-expressing tumor cells to deliver cytotoxic effects and have demonstrated encouraging anti-tumor activity in clinical studies, according to Merck's announcement.
Strategic Partnership Structure
The funding agreement maintains Merck's operational control over the asset. Merck will retain decision-making authority and control over the development, manufacturing, and commercialization of sac-TMT, while Blackstone will not receive any rights to the compound itself.
Sac-TMT was originally developed by Kelun-Biotech, a holding subsidiary of Sichuan Kelun Pharmaceutical Co, Ltd. Under an existing collaboration agreement, Kelun-Biotech has granted Merck 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. The Blackstone funding agreement does not alter this existing partnership structure.
