Phase 3 INTerpath-001 Trial: Personalized mRNA Vaccine Cuts Melanoma Recurrence Risk 42% With Pembrolizumab

The phase 3 INTerpath-001 trial randomized 757 patients to pembrolizumab plus the vaccine and 380 to pembrolizumab plus placebo after surgery. Tumor sequencing identified up to 34 neoantigens per patient to encode in mRNA. At median 24.6-month follow-up the combination improved 2-year recurrence-free survival to 82.2% versus 70.0% and distant-metastasis-free survival to 88.5% versus 80.2%. Grade 3+ adverse events rose modestly to 23.6% from 20.3%.

Prior phase 3 attempts to add a second checkpoint inhibitor failed to improve on anti-PD-1 monotherapy, making the neoantigen-specific approach a mechanistic departure. The absolute 12.2-point gain in recurrence-free survival at two years is clinically meaningful for patients, yet overall survival remains immature (HR 0.77) and the trial has not yet reported melanoma-specific survival or long-term durability.

Ongoing trials in lung, bladder, and kidney cancer will test whether the same platform extends beyond melanoma. Key open questions are whether the early benefit persists across all subgroups, which patients derive the largest absolute gain, and whether the reduction in recurrence ultimately converts to a survival advantage.

Longer follow-up and mature overall-survival data are required before routine adoption can be recommended.