Oregovomab maintenance monoimmunotherapy does not improve outcomes in advanced ovarian cancer

PURPOSE

This phase III study tested the hypothesis that the CA-125-specific murine monoclonal antibody, oregovomab, administered as a monoimmunotherapy after front-line therapy in a selected ovarian cancer population would prolong time to relapse (TTR) and, ultimately, survival.

PATIENTS AND METHODS

Patients with stage III to IV ovarian cancer with preoperatively elevated CA-125 and objectively defined characteristics were randomly assigned 4 to 12 weeks after front-line carboplatin and paclitaxel chemotherapy to maintenance monoimmunotherapy in a fully blinded protocol. Two mg of oregovomab or placebo was infused over 20 minutes at weeks 0, 4, and 8 and then 12 weeks until recurrence or up to year 5. Patients were evaluated with serial imaging and clinical evaluation for evidence of recurrence at quarterly visits. TTR was the primary end point.

RESULTS

Three hundred seventy-three patients were accrued at more than 60 centers; 251 patients were assigned to oregovomab and 120 patients were assigned to placebo. The treatment arms were well balanced. There were no differences in the clinical outcomes between treatment groups. Median TTR measured from randomization after completion of chemotherapy for the integrated study was 10.3 months (95% CI, 9.7 to 13.0 months) for oregovomab and 12.9 months (95% CI, 10.1 to 17.4 months) for placebo (P = .29, log-rank test). The treatment was well tolerated. Grade 3 to 4 toxicity was reported in 24.6% of patients in the placebo group and 20.1% of patients in the oregovomab group, respectively.

CONCLUSION

Although oregovomab has demonstrated bioactivity, the strategy of monoimmunotherapy is not effective as maintenance therapy after front-line treatment of a favorable subset of patients with advanced ovarian cancer. Future studies of this or other tumor-antigen specific immunization strategies should seek ways to further augment induced immunity.

Paclitaxel maintenance chemotherapy following intraperitoneal chemotherapy for ovarian cancer

The aim of this study was to determine the feasibility of two treatment regimens for ovarian cancers: (1) combined intraperitoneal/intravenous (IP/IV) cisplatin/paclitaxel; or (2) IV only carboplatin/paclitaxel; both followed by 12 cycles of maintenance paclitaxel. A total of 102 subjects were identified who underwent surgery for stage III ovarian cancer. All subjects received either IV or IV/IP chemotherapy, and had a complete response. The subjects were then prescribed maintenance paclitaxel IV for an additional 12 months. Demographic and clinical data were analyzed. Forty-five subjects received combined IP/IV chemotherapy versus 57 who received IV therapy alone. IP/IV versus IV administration was not associated with differences in age, ethnicity, tumor histology, or incidence of intestinal surgery. Toxicities included fatigue, neuropathy, myelosuppression, and nausea/vomiting in both groups. In the IP/IV group, 29/47 subjects (61.7%) completed 12 cycles of maintenance paclitaxel versus 18/55 (32.7%) in the IV group (P = 0.006). The mean number completed by the IP/IV group was 8.6, while the IV group completed 5.8 cycles (P = 0.002). In subjects who received <12 cycles, the mean number of cycles completed by the IP/IV group was 3.1 versus 2.8 in the IV group. The reasons for stopping included neuropathy (33), fatigue (8), myelosuppression (7) and disease progression (6). Patients who received combined IP/IV chemotherapy were more likely to complete maintenance therapy than those who only received IV chemotherapy. Patients who stop maintenance therapy usually do so early in the course. Additional resources directed at physical and emotional support during early cycles of maintenance chemotherapy may allow more to complete the regimen.