Personalized neoantigen-targeting cancer vaccines in ovarian cancer: a phase 1 trial.

A personalized neoantigen long-peptide vaccine (NeoVax with poly-ICLC), combined with delayed anti-PD-1 antibody, was feasible and safe in ten patients with platinum-sensitive high-grade epithelial ovarian cancer after platinum doublet chemotherapy. Nine of twelve evaluable Cohort B patients were vaccinated (75%, 90% CI 47-93%), over 70% of targets remained detectable in cell-free DNA despite a median 6.5-month biopsy-to-vaccine interval, and biomarker analysis suggested biologic activity in six of ten patients. Resistant tumor clones showed defects in antigen presentation, consistent with vaccine-driven immune pressure.