An experimental mRNA cancer drug has been found to stop the spread and return of melanoma for the first time, a potentially game-changing breakthrough for people with life-threatening skin cancer.

The therapy called intismeran, which is personalized for each patient, succeeded in preventing melanoma from coming back or spreading in people who had surgery to remove the cancer when combined with another cancer drug Keytruda, the drugmakers Merck and Moderna announced Wednesday.

“These Phase 3 findings represent a pivotal moment for the field of cancer research,” Moderna CEO Stéphane Bancel said in a statement. “Together with Merck, we have started to demonstrate the transformative potential of this technology to address critical unmet needs in the adjuvant melanoma setting.”

Melanoma is the deadliest form of skin cancer. About 112,000 new melanomas are expected to be diagnosed in the U.S. this year, and more than 8,500 Americans will die, according to the American Cancer Society.

Only around a third of patients with the worst form of the disease live for five years after diagnosis, researchers say.

The companies did not say how long patients taking drug combination lived without their cancer progressing. More details are expected to be shared at a medical conference later this year, according to The Wall Street Journal.

The study followed more than 1,000 patients who either took a combination of intismeran and Keytruda or just Keytruda for nearly a year.

Previous trials using the drug cut the risk of recurrence or death nearly in half compared with just taking Keytruda.

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