Moderna Plunges 25% as Leaked Phase 3 Cancer Vaccine Data Meets Reality

Partial Phase 3 data for Moderna and Merck's experimental mRNA cancer vaccine, intismeran autogene, leaked on an oncology website ahead of its official ESMO Congress presentation. The combination with Merck's Keytruda cut the risk of recurrence or death by 42% in melanoma patients after surgery, leaving 82.2% of patients cancer-free after two years compared to 70% on Keytruda alone. Despite the positive clinical benchmark, Moderna's stock plunged up to 25% intraday before closing down 17.57% at $202.63, as investors had anchored on higher efficacy expectations from an earlier Phase 2b study. The companies plan to file for US regulatory approval with an anticipated launch in 2027, and are actively testing the combination in kidney, bladder, and lung cancers. "From the beginning, we believed mRNA technology could make it possible to develop cancer treatments uniquely matched to each patient’s tumor. The INTerpath-001 results mark a defining moment for that vision and show what’s possible when we rethink how medicines are made." — Stéphane Bancel