Neoadjuvant ipilimumab plus nivolumab in melanoma: 5-year survival and biomarker analysis from the phase 2 PRADO-trial.

Neoadjuvant ipilimumab plus nivolumab has become standard therapy for stage III melanoma based on the NADINA trial, although long-term data are lacking. In the phase 2 PRADO cohort of OpACIN-neo, 99 patients with stage III macroscopic melanoma received this regimen. Here we report first-time 5-year survival data: 71% event-free survival, 74% relapse-free survival, 79% distant metastasis-free survival and 86% overall survival. Ongoing grade 1-2 immune-related adverse events occurred in 69% of patients alive, predominantly vitiligo and hypothyroidism. Major pathologic response (MPR), high tumor mutational burden (TMB), high interferon-gamma (IFNγ) signature and programmed cell death ligand 1 (PD-L1) expression of 1% or higher were associated with favorable outcomes. Combined high TMB, IFNγ and PD-L1 expression yielded 100% MPR and 100% 5-year event-free survival, whereas triple low expression had only 18% MPR and 41% event-free survival. Our findings demonstrate favorable long-term outcomes for patients with an MPR and identify IFNγ and PD-L1 as promising baseline biomarkers. ClinicalTrials.gov identifier: NCT02977052 .