Vaccination with Folate Receptor-Alpha Peptides in Patients with Ovarian Cancer Following Response to Platinum-Based Therapy: A Randomized, Multicenter Clinical Trial

Objective Folate receptor alpha (FRα) is overexpressed on >90% of high-grade epithelial ovarian cancers (EOC). Targeting FRα with antibody-drug conjugates has proven utility in the platinum-resistant setting. It is also a potential therapeutic target for immuno-oncologic agents, such as peptide vaccines that work primarily via adaptive and humoral immunity. We tested the hypothesis that FRα peptide immunization could improve outcomes in patients with EOC following response to platinum-based therapy. Methods We conducted a randomized, double-blind, multicenter, phase II study to evaluate the safety and efficacy of TPIV200 (a multi-epitope FRα peptide vaccine admixed with GM-CSF) versus GM-CSF alone in 120 women who did not have disease progression after at least 4 cycles of first-line platinum-based therapy. Patients were vaccinated intradermally once every 4 weeks up to 6 times, followed by a boosting period of 6 vaccinations at 12-week intervals. Primary endpoints included safety, tolerability, and progression free survival (PFS). Results At study termination with a median follow-up of 15.2 months (range 1.2–28.4 months), 68 of 119 intention-to-treat patients had disease progression (55% in TPIV200 + GM-CSF arm and 59% in GM-CSF alone arm). The median PFS was 11.1 months (95% CI 8.3–16.6 months) with no significant difference between the treatment groups (10.9 months with TPIV200 + GM-CSF versus 11.1 months with GM-CSF, HR, 0.85; upper 90% CI 1.17]. No patient experienced a ≥ grade 3 drug-related adverse event. Conclusion TPIV200 was well tolerated but was not associated with improved PFS. Additional studies are required to uncover potential synergies using multiepitope vaccines targeting FRα.Trial RegistrationNLM/NCBI Registry, NCT02978222, https://clinicaltrials.gov/search?term=NCT02978222.