The first personalized cancer vaccine

It is produced specifically for each patient's cancer.

An experimental cancer vaccine developed individually for each patient has reached a major milestone in the United States; Moderna and Merck announced that their personalized mRNA-based therapy met the primary endpoints of a large Phase 3 clinical trial involving patients with melanoma—one of the most dangerous forms of skin cancer. The treatment, called Intismaran Autogen (formerly known as mRNA-4157 or V940), does not function exactly like a traditional vaccine designed to prevent a person from developing a disease.

The procedural steps are as follows: first, a tumor sample undergoes genetic analysis to identify unique mutations present in the cancer cells. Based on that information, a synthetic mRNA molecule is created that is capable of encoding up to 34 neoantigens specific to that tumor. When administered to the patient, the goal is to prime the immune system to recognize those specific characteristics and attack cells carrying the same mutations.

The new study involved 1,137 patients with cutaneous melanoma—all of whom had undergone surgery to completely remove their tumors—and yielded positive initial Phase 3 results. According to Moderna and Merck, adding the personalized therapy to Keytruda resulted in a statistically significant and clinically meaningful improvement in recurrence-free survival. The study also met a key secondary endpoint regarding the time patients remained free of distant metastasis.

In other words, among patients treated with the combination, it took longer for the cancer to return or spread compared to treatment with Keytruda alone. The companies have not yet released the full Phase 3 figures, so the exact magnitude of the benefit observed in this new study remains unknown; however, earlier results had already attracted significant attention. In the Phase 2 trial, which involved a smaller group of patients, the combination reduced the risk of recurrence or death by 49% after approximately five years of follow-up compared to Keytruda alone.

Detailed results are expected to be presented at a medical conference and submitted for scientific publication, while Moderna and Merck plan to discuss the data with regulatory authorities.