The Immune adjuvant properties of front-line carboplatin-paclitaxel: a randomized phase 2 study of alternative schedules of intravenous oregovomab chemoimmunotherapy in advanced ovarian cancer.

Oregovomab is a monoclonal antibody that recognizes CA125 and forms circulating immune complexes that can elicit immunity against both tumor antigen and tumor. This study was designed to assess combining this immunotherapy at 2 dosing schedules with front-line chemotherapy in patients with advanced ovarian cancer. Forty patients with stage III/IV carcinomas were randomized to receive a 2 mg oregovomab infusion either the same day [simultaneous infusion (SIM)] or 1 week after [1-week delayed (OWD)] standard carboplatin-paclitaxel chemotherapy at cycles 1, 3, and 5, then quarterly for up to 11 antibody doses. The primary end point was antibody response to oregovomab. Secondary end points included cellular immune response, response rate to front-line treatment, and progression-free survival. A different immune response pattern was observed between the SIM arm and the OWD arm, baseline plasma cytokines were balanced. Humoral immunity occurred more rapidly (P=0.0033) and with greater magnitude in the SIM arm. Absolute lymphocyte counts decreased in the SIM arm at cycles 3 and 5 compared with baseline. Treatment emergent CA125-specific cellular immunity was measured more commonly with SIM (P=0.04) and clinical parameters directionally favored this schedule. The immune responses were stronger than those measured in a previous maintenance monoimmunotherapy protocol. Immunotherapy-associated toxicity was minimal in this study. Front-line chemotherapy with carboplatin-paclitaxel has immune adjuvant properties when combined with oregovomab immunotherapy; however, schedule is important. SIM strategies of carboplatin and paclitaxel should be further studied with oregovomab and other antigen-specific cancer immunotherapy approaches.