Merck, Moderna’s Personalized mRNA Cancer Vaccine Succeeds in Phase 3 Trial

Intismeran, a personalized mRNA cancer vaccine jointly developed by Merck and Moderna, met its primary endpoints in a phase 3 clinical trial.

Merck announced on the 19th local time that, in the phase 3 INTerpath-001 trial conducted with Moderna, the combination of intismeran and Keytruda met both the recurrence-free survival (RFS) and distant metastasis-free survival (DMFS) endpoints.

The trial enrolled 1,137 patients with stage IIB to IV cutaneous melanoma who had undergone complete surgical removal but remained at high risk of recurrence. The combination of intismeran and Keytruda showed a clinically meaningful improvement compared with Keytruda monotherapy.

Intismeran is an mRNA therapy designed based on mutations unique to each patient’s tumor. It consists of synthetic mRNA encoding up to 34 neoantigens and induces neoantigen-specific T-cell responses in the body to attack cancer cells.

Keytruda is an immune checkpoint inhibitor that blocks cancer’s immune evasion mechanisms. It prevents the PD-1 receptor on T cells from binding to ligands on cancer cells, thereby activating the T cells’ ability to attack.

The companies advanced to phase 3 after confirming in the phase 2 KEYNOTE-942 trial a 44% reduction in the risk of recurrence or death and a 65% reduction in the risk of distant metastasis or death compared with Keytruda alone. The effect was maintained at approximately 3- and 5-year follow-up.

The announcement reported topline results from a prespecified interim analysis. The safety profile of the combination was consistent with previous studies, and no new safety signals were observed.

Merck plans to present the data at an upcoming international medical meeting and consult with regulatory authorities regarding a marketing application. The remaining endpoints, including overall survival (OS), will continue to be evaluated according to the protocol.