Moderna and Merck’s melanoma mRNA vaccine trial hit its Phase 3 goal, but key data are still missing

Moderna and Merck said an interim Phase 3 analysis of their personalized mRNA cancer therapy, intismeran autogene, used with Keytruda in melanoma patients, met both its primary and key secondary endpoints. The update sent Moderna shares up 176.97% on Aug. 19 to $174.38, lifting the company’s market value from about $25 billion to roughly $69 billion in a single session, while Merck rose more than 9% intraday. The regimen is designed as adjuvant therapy after surgery for resected stage IIB to IV cutaneous melanoma, aiming to reduce recurrence and distant metastasis rather than treat widely metastatic end-stage disease. The trial, INTerpath-001, enrolled 1,137 patients in a 2:1 randomized, double-blind design. Still, the companies have not yet released hazard ratios, confidence intervals, p-values, event counts, absolute recurrence rates, or Kaplan-Meier survival curves from the Phase 3 readout. Earlier Phase 2 data from KEYNOTE-942 showed a 49% reduction in recurrence or death risk and a 59% reduction in distant metastasis or death risk, but overall survival was not statistically significant. Questions around durability, manufacturing scale, pricing, reimbursement, expansion into other tumor types, and long-term safety remain unresolved.