Moderna and Merck vaccine plus Keytruda cuts melanoma relapse risk by 42% in late-stage trial

A late-stage adjuvant study of Moderna’s experimental melanoma vaccine, intismeran autogene, combined with Merck’s Keytruda showed a 42% reduction in the risk of relapse or death compared with Keytruda alone.

The trial met its primary endpoint at an early, pre-planned data review, and analysts described the outcome as a landmark moment for the vaccine’s commercial prospects.

Despite the positive data, both companies’ shares fell after the announcement, with analysts noting a "sell-the-news" reaction that outweighed the clinical upside in the market.

Moderna’s stock had previously surged more than four-fold on earlier news, and the results will be presented at the upcoming European Society for Medical Oncology meeting.