Get you up to speed: Moderna, Merck unveil mRNA-based cancer vaccine that cuts spread

What remains unclear — Detailed results of the late-stage trial are yet to be released.

Moderna and Merck announce mRNA cancer vaccine Intismeran reduces melanoma spread

News|HealthModerna, Merck unveil mRNA-based cancer vaccine that cuts spread

Moderna’s mRNA vaccine Intismeran shows promise, reducing melanoma recurrence and spread in late-stage trials.

Published On 19 Aug 202619 Aug 2026

Moderna and Merck have announced that a personalised mRNA cancer vaccine called Intismeran 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 percent.

Interim results of the study released on Wednesday found that the treatment met both goals of reducing cancer recurrence and preventing the spread of tumours. Detailed results of the study have not been released but are expected to be shared at an upcoming medical meeting, according to the drugmaker.

Moderna President Stephen Hoge said thousands of patients who have had high-risk melanoma tumours removed in surgery could benefit by next year if the vaccine is approved by regulators. According to the National Cancer Institute, there were more than 1.5 million people in the US living with melanoma in 2023.

Developed alongside pharmaceutical giant Merck, Moderna tested the vaccine with immunotherapy drug Keytruda.

A nurse loads a syringe with a vaccine at an inoculation station [File: Rogelio V Solis/AP Photo]

The experimental vaccine trains the patient’s immune system to fight tumours by targeting mutations in cancer cells. Similar approaches are being tested to combat other cancers such as lung, breast and pancreatic cancers.

Previous studies have suggested that mRNA vaccines could help immune systems recognise and attack cancer cells in mice and in analyses of medical records of cancer patients. Findings from the studies came at a time when the administration of United States President Donald Trump cut funding for mRNA research.

The development is the first positive late-stage trial result for an mRNA cancer vaccine. Merck said the companies are already in talks ⁠with regulators about the treatment.

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