Human Anti-mouse IgM and IgG Responses in Ovarian Cancer Patients after Radioimmunotherapy with 90Y-muHMFG1

Background: Human anti-mouse antibody (HAMA)- IgM and IgG in ovarian cancer patients treated with intraperitoneal (i.p.) 90 Y-muHMFG1 as consolidating therapy were analyzed for a relationship with outcome of disease. Patients and Methods: Serial serum samples from 208 ovarian cancer patients participating in a phase III trial of i.p. 90 Y-muHMFG1 and 25 controls were analyzed for HAMA-IgM and HAMA-IgG. Results were correlated with time to, and location of, disease recurrence. Results: Patients receiving i.p. 90 Y-muHMFG1 developed a rapid HAMA-IgM peak (week 4 to 8), followed by a HAMA-IgG peak 2-4 weeks later. HAMA levels in the control group remained unchanged. Early maximum HAMA-IgG peaks were associated with early relapse (hazard ratio (HR), 0.975; 95% confidence interval (CI) 0.956 to 0.995; p=0.012). Patients with a HAMA-IgG maximum before or at 8 weeks were at significantly higher risk for disease recurrence (HR, 1.6; 95% CI 1.1 to 2.5; p=0.021) as compared to patients with a HAMA-IgG maximum after 8 weeks. Conclusion: Besides time point of maximum HAMA-IgG, no evident relation could be found between HAMA-IgM or HAMA-IgG development and time to relapse or location of recurrence. Despite advances in the treatment of ovarian cancer, it is still the leading cause of death from gynecological malignancies (1). New strategies to improve overall survival are needed and radioimmunotherapy (RIT) could be one of the options.