Merck & Co. shares rose 6.2% in pre-market trading on Monday, lifting the stock to $143.52—a new 52-week high and well above its prior peak of $137.98.
The advance followed positive results from the Phase 3 INTerpath-001 trial, which tested Intismeran autogene in combination with Merck’s Keytruda in 1,137 patients with completely resected stage IIB-IV melanoma. The trial met its primary endpoint of recurrence-free survival and a key secondary endpoint of distant metastasis-free survival. The data marks the first large-scale Phase 3 confirmation of an mRNA-based individualized neoantigen therapy platform, according to the companies.
The trial builds on earlier Phase 2b findings that showed a 49% reduction in the risk of recurrence or death when Intismeran autogene was used alongside Keytruda, compared with Keytruda alone. Merck and Moderna are also conducting additional Phase 3 studies in non-small cell lung cancer, though enrollment remains ongoing.
Analysts moved quickly to reflect the trial’s significance. Daiwa upgraded Merck to Outperform from Neutral on August 17, citing pipeline progress, while Wells Fargo reiterated a Buy rating the same day. The broader market showed little movement, with the S&P 500 up just 0.1% and the Nasdaq slightly lower, underscoring that Merck’s rally was driven entirely by company-specific news. Pfizer and AbbVie, among other pharmaceutical peers, did not report comparable catalysts on the same day.
