Moderna Surges Record 177% After Melanoma Vaccine Succeeds in Phase 3 Trial With Merck

Moderna and Merck reported positive topline results Wednesday from the Phase 3 INTerpath-001 trial of intismeran autogene, a personalized mRNA-based individualized neoantigen therapy, combined with Merck's immunotherapy Keytruda. The trial, which enrolled more than 1,100 patients with completely resected Stage IIB-IV melanoma, met both its primary endpoint of recurrence-free survival and its secondary endpoint of distant metastasis-free survival, with the combination significantly outperforming Keytruda alone. The study was halted at its first interim analysis following those positive results, which mark the first time any mRNA-based personalized cancer vaccine has succeeded in a late-stage trial.

Moderna shares, which closed Tuesday at $62.96, surged as high as roughly $125 in premarket trade before closing the day up approximately 177%, adding about $44 billion in market capitalization and marking the stock's best single-day gain on record. Moderna co-founder Robert Langer became a billionaire again on the move. Merck shares rose about 12.4%.

The broader biopharma sector rallied in sympathy, with Amgen up 3.7%, Eli Lilly up 4.0%, and AbbVie up 2.6%. William Blair upgraded Moderna to Outperform following the announcement. CEO Stephane Bancel said the company is targeting regulatory approval by 2027.

Personalis, which sequences tumors to design neoantigen vaccines, also rose on the news as investors identified it as a key enabler of such therapies.