Moderna, Merck vaccine cuts recurrence and spread of melanoma,
raising new treatment hope

Aug 19 (Reuters) - Moderna (MRNA), and Merck (MRK), said on Wednesday that a personalized mRNA cancer vaccine reduced the ​risk of recurrence and spread of melanoma in a late-stage trial, a major success in a new field of cancer treatment that sent Moderna's shares surging as much ‌as 160%.

The companies tested the vaccine together with Merck's immunotherapy drug Keytruda, a widely used melanoma treatment. Thousands of patients who have undergone surgery to remove high-risk melanoma tumors could benefit as soon as next year if regulators approve the vaccine, Moderna President Stephen Hoge said in an interview.

Karen Knudsen, ​CEO of the Parker Institute for Cancer Immunotherapy, said the Moderna results could signal a new era for treating solid-tumor cancers.

"The positive hit here leads us ⁠into truly this next phase in immunotherapy," Knudsen said. "This is an auspicious start — this is where things begin."

Reuters, August 19, 2026