Blackstone Life Sciences agreed to provide roughly $700 million to underwrite Merck’s development of a Trop2-targeting antibody‑drug conjugate, shifting a large portion of clinical and commercial risk to the private-equity group. Merck simultaneously spent about $150 million to regain control of an early‑phase asset tied to the same program, according to company filings. The financing structures were reported by BioCentury and other outlets and represent the growing use of external risk‑sharing to fund expensive oncology Phase III programs. ADCs require expensive pivotal studies and manufacturing scale; risk‑sharing deals like this enable big pharmas to accelerate programs while limiting balance‑sheet exposure. The pact underscores private markets’ growing willingness to co-fund late‑stage oncology bets.