Introduction Oregovomab, a murine IgGκ1 MAb, with high affinity binding (1.16 x 10¹⁰/M⁻¹) to the tumor associated antigen CA125, acts as a therapeutic vaccine inducing indirect immunization by cellular and humoral immune responses directed against CA125. In a randomized phase II study in patients with previously untreated EOC, immunization with oregovomab in a schedule-dependent combination with paclitaxel and carboplatin (PC) demonstrated significant improvement in mPFS (months) 41.8 for PCO and 12.2 for PC (p = 0.0027, HR 0.46) and mOS has not yet been reached (NE) for PCO and was 43.2 months for PC (p = 0.043, HR 0.35).

Methods This is a single arm Phase 2 evaluation of the combination of oregovomab and niraparib in subjects who have been previously treated with 1 to 3 lines of platinum-based chemotherapy and have platinum sensitive EOC. All subjects will receive the combination of niraparib and oregovomab. The daily dose of niraparib will be 300 mg taken orally from Day 1 Week 1 to at least the end of Week 12. For subjects whose baseline weight is <77 kg or baseline platelet count is <150,000 µL the daily dose of niraparib will be 200 mg. Oregovomab (2 mg) will be administered at Day 1 of Weeks 1, 4, 7, 12, and 20. This study will assess DCR, ORR, early humoral response, and safety of concomitant administration of oregovomab and niraparib.

Current Trial Status At the time of abstract submission, 10 subjects were enrolled, and the target enrollment was completed.