Merck and Moderna say cancer vaccine shows promise in preventing recurrence of melanoma

Pharmaceutical giants Moderna and Merck said Wednesday that an experimental vaccine treatment has shown signs of preventing cancer from returning or spreading in a study of high-risk melanoma patients.

The companies have not published their results in a peer-reviewed journal or released the new data, saying instead that it will be presented at an upcoming medical meeting and shared with regulators.

According to a news release, the mRNA-based vaccine was tested in a late-stage trial involving people who’d already had surgery to remove a melanoma, the deadliest form of skin cancer. The study involved a personalized cancer vaccine called Intismeran, produced by Merck and Moderna, administered in combination with Merck’s cancer immunotherapy Keytruda.

Interim results from the trial show that the vaccine-drug combo appeared to extend the time before cancer returned in high-risk patients, according to the release, though the companies did not say for how long.

In June, Merck and Moderna presented research on the experimental melanoma vaccine at the American Society of Clinical Oncology’s annual meeting, saying at the time that it halved the risk of melanoma returning after five years. Those findings were also published in the Journal of Clinical Oncology.

Merck and Moderna described the new results as the first breakthrough of its kind. They said the study would continue to examine overall survival rates following the treatment.

“These Phase 3 findings represent a pivotal moment for the field of cancer research,” Stéphane Bancel, CEO of Moderna, said in the release. “For many years, the idea of creating an mRNA treatment designed specifically for an individual patient’s cancer was aspirational. We are now helping turn that vision into a reality.”

Covid shots were the first mRNA vaccines to hit the market, and the Food and Drug Administration this month approved the first flu shot that uses mRNA technology , also from Moderna. Decades before those vaccines became available, scientists were exploring the technology as a way to treat cancer.

Merck and Moderna have been working on the melanoma vaccine for about a decade. It’s designed to train the immune system to identify and kill cancer cells. The vaccine targets abnormal proteins called neoantigens that appear on the surface of cancer cells.

Moderna shares soared as much as 106% in premarket trading Wednesday. Merck shares were up 7%.

The future of mRNA research has been uncertain under the Trump administration. Health Secretary Robert F. Kennedy Jr. has repeatedly criticized mRNA technology, and he slashed $500 million in contracts last year for mRNA vaccine research and development. Under the FDA’s former vaccine chief, Dr. Vinay Prasad, the agency initially rejected Moderna’s application for the mRNA-based flu vaccine but later reversed course.