Multinational phase 1-2 trial of maveropepimut-S, pembrolizumab and low-dose cyclophosphamide for metastatic ovarian cancer

Maveropepimut-S is a survivin-targeting vaccine. The multinational phase 1-2 PESCO trial evaluated the combination of maveropepimut-S with pembrolizumab and low-dose cyclophosphamide of recurrent epithelial ovarian cancer. The primary endpoints were safety and clinical efficacy measured by overall response rate (ORR) and disease control rate (DCR). Secondary endpoints included recommended phase 2 dose (RP2D), progression-free survival (PFS), and survivin-specific immune response. Of 47 enrolled patients, 44 were evaluable. Most treatment-related adverse events were grade 1 or 2, most commonly injection site reactions. The RP2D was established to be 0.25 ml. The ORR was 23% and the DCR was 67%, with greater activity in platinum-sensitive disease. Median PFS was 6.3 months in platinum-sensitive disease and 12 months in platinum-resistant disease. Survivin-specific immune responses occurred in 62.5% of tested patients and correlated with clinical benefit. The authors conclude that the combination demonstrated tolerability and sustained clinical activity.