Moderna and Merck said their personalized mRNA cancer vaccine, intismeran autogene, showed promising results in a late-stage clinical trial involving more than 1,000 patients. Used after surgery for localized melanoma, the vaccine reduced the risk of cancer recurrence or spread to other parts of the body. Full trial data have not yet been released, but researchers and cancer specialists see the result as a possible breakthrough for patient-specific therapeutic vaccines.

The companies formally partnered on cancer vaccines in 2016, with Merck investing $200 million that year and another $250 million in 2022. The vaccine was used with Keytruda, which helps immune T-cells become active against cancer cells. Researchers say the treatment analyzes a patient’s tumor genetics and trains the immune system to recognize up to 34 cancer targets.

US approval could be possible next year if the vaccine is successfully cleared. Researchers are also examining whether the method can work in cancers with fewer genetic mutations, including lung, kidney and pancreatic cancers. Moderna and Merck are further analyzing melanoma data to improve effectiveness, while Moderna’s chief executive said the current version is not the final version.