Modera and Merck report Phase 3 melanoma vaccine cuts recurrence risk, stock surges

Pharmaceutical companies Moderna and Merck announced on August 19, 2026, that a Phase 3 clinical trial of their personalized mRNA cancer vaccine successfully met its primary goals, significantly reducing the risk of melanoma recurrence and spread in high-risk patients. The positive interim results triggered a dramatic surge in Moderna's stock price, which more than doubled in early trading.

The trial, named INTerpath-001, enrolled 1,137 patients with stage IIB to stage IV melanoma whose tumors had been surgically removed. Participants were randomly assigned to receive either the experimental vaccine, called intismeran, in combination with Merck's immunotherapy drug Keytruda, or Keytruda alone. The companies reported that the combination therapy significantly extended recurrence-free survival and reduced the risk of metastasis to distant parts of the body. Based on the strength of these results, the trial was stopped early at its first analysis.

"This is a landmark moment for adjuvant melanoma treatment," said Professor Georgina Long, the study's principal investigator. She noted it is the first Phase 3 study to demonstrate that a treatment designed based on a patient's unique...