Merck & Co., Inc. (NYSE:MRK) jumped 12.6% to a record $152.20 on August 19 after a pivotal melanoma trial validated intismeran autogene, the individualized mRNA cancer therapy developed with Moderna.
In the 1,137-patient Phase 3 INTerpath-001 study, intismeran plus Keytruda produced statistically significant and clinically meaningful improvements in recurrence-free survival and distant-metastasis-free survival compared with Keytruda alone
No new safety concerns emerged. Investors are now asking whether intismeran can turn Keytruda from a drug approaching a patent cliff into the foundation of a personalized-cancer platform. That distinction matters because Merck & Co., Inc. (NYSE:MRK) generated $31.68 billion from Keytruda and Keytruda Qlex in 2025, nearly half of the company’s sales.
In the U.S., biosimilar competition could begin after Keytruda’s primary compound patent expires in December 2028, although biosimilars have already entered some smaller international markets. A successful combination could support continued use of the franchise without removing the need for other growth engines. Bull Case: A New Layer for the Keytruda Franchise The bullish case for Merck & Co., Inc. (NYSE:MRK) is that intismeran adds a personalized immune response to a checkpoint inhibitor already embedded across oncology.