Merck and Moderna’s late-stage melanoma study met primary endpoints, boosting Merck’s market value by $43 billion in a single session.
Merck’s stock jumped 12.5% on August 19 after its personalized cancer vaccine, developed with Moderna, succeeded in a Phase 3 melanoma trial. The rally added $43 billion to Merck’s market capitalization, marking one of its largest single-day gains ever.
The INTerpath-001 trial tested the vaccine, Intismeran, alongside Merck’s immunotherapy Keytruda in 1,137 high-risk melanoma patients. The combination outperformed Keytruda alone in delaying cancer recurrence and metastasis, according to the companies’ release.
The result addresses investor concerns over Merck’s 2028 patent cliff for Keytruda, its top-selling drug. Analysts now debate whether the surge reflects long-term value or a short-lived reaction.