Phase 1 NeoVax trial: personalised neoantigen vaccines feasible in ovarian cancer

Nature Medicine on 14 October 2026 published a phase 1 clinical trial (ClinicalTrials.gov NCT04024878) of personalised neoantigen-targeting vaccines (NeoVax) for high-grade epithelial ovarian cancer, led by investigators at Dana-Farber Cancer Institute and collaborators.

Study design (type and size)

NeoVax used pools of synthetic long peptides targeting patient-specific neoantigens mixed with the immunostimulant poly-ICLC, combined with delayed anti-PD-1 (nivolumab). Ten patients were treated: one newly diagnosed (Cohort A) and nine at first recurrence (Cohort B) with platinum-sensitive disease after standard platinum doublet chemotherapy. Vaccination was completed in 9 of 12 evaluable Cohort B patients (75%, 90% CI 47–93%) and 1 of 9 Cohort A patients (11%, 90% CI 0.6–43%).

Safety and signals

Authors report no unexpected safety signals and no discontinuations due to toxicity. Across patients, more than 70% of selected vaccine targets remained detectable by noninvasive cell-free DNA despite a median 6.5 months from diagnostic biopsy to vaccination during chemotherapy. Biomarker analyses were suggestive of biologic activity in six of ten patients and associated with broader tumour- and vaccine-specific immune responses; progressing clones showed diverse antigen-presentation escape mechanisms.

Limitations (important)

This is an early, small, non-randomised phase 1 feasibility/safety study — not powered to prove clinical efficacy or change standard care. Manufacturing success differed sharply between cohorts; immune “activity” markers are not the same as proven survival benefit. Resistant clones highlight immune-evasion challenges. Results need larger controlled trials. This summary is not personal medical advice.