Merck, Moderna say melanoma vaccine meets goals in large trial

Shares of Moderna rose 40%, while Merck climbed 2% in premarket trading.

Melanoma is the deadliest form of skin cancer. In 2023, there were more than 1.5 million people in the U.S. living with melanoma, according to the National Cancer Institute.

Merck MRK.N and Moderna MRNA.O said on Wednesday a study of a personalized mRNA vaccine combined with the immunotherapy drug Keytruda reduced skin cancer recurrence and spread compared with Keytruda alone, the first positive late-stage trial results for an mRNA cancer vaccine.

The trial is ongoing, but interim results found the treatment, known as Intismeran, met both its primary target of reducing cancer recurrence and its secondary goal of keeping cancers from spreading to other parts of the body.

The treatment combines Merck's Keytruda with a made-to-order mRNA vaccine from Moderna that is based on an analysis of mutations found in the patients' own tumors.

The trial enrolled 1,137 high-risk patients with stage IIB-IV melanoma that had been surgically removed.

Volunteers were randomized to receive up to nine doses of Keytruda plus the personalized vaccine or Keytruda alone for about one year. The companies said no new safety signals have emerged in the trial.

In January, the companies announced results of a mid-stage trial of the treatment showing that it reduced the risk of recurrence or death by 49% after five years.

The companies said they will present their results at an upcoming medical meeting and share them with regulators.