Objectives This phase IB study assessed safety of Oregovomab (O) indirect immunization (monoclonal antibody for CA125) and TLR3 stimulation with H (polyICLC) in PROC. Secondary endpoints were RECIST response, immune response, response to subsequent therapies, and overall survival.

Methods Patients with PROC (median 5 prior Rx) received 4 IV infusions with 2 mg O followed by 2 mg H IM 30 min & 48 hours post-O at weeks 0, 3, 6 and 9. Week 12, imaging was performed, and elective chemotherapy was allowed post-progression. A final O infusion was given at week-16 and patients were followed.

Results 17 patients were enrolled at 2 centers; 15 were dosed and 13 completed the minimum 3 infusions. Treatment phase safety analysis is complete & post IT follow-up is ongoing. Local site reactions to H and mild fatigue/flulike symptoms were reported in 13(87%) patients. Serious adverse events were reported in 5 (33%) patients, attributed to underlying disease. No new safety signals were observed. Six (40%) had stable disease through the 12-week immunization period. Four patients with persistent/progressive disease stopped IT prior to infusion 4. Early humoral response by week-6 was observed in 7 of 9 (77%) patients with the available time points. 14 patients took additional cancer Rx, 5 died of disease and 5 with persistent/progressive disease are stable on Rx.

Conclusions Safety, compatibility of combining O with H, and early humoral responsiveness to indirect immunization by week-6 have been established. The potential to enhance activity of chemotherapy using O indirect immunization is proposed.