Therapeutic efficacy of α-radioimmunotherapy with different activity levels of the 213Bi-labeled monoclonal antibody MX35 in an ovarian cancer model

Therapeutic efficacy of α-radioimmunotherapy with different activity levels of the 213Bi-labeled monoclonal antibody MX35 in an ovarian cancer model

EJNMMI Research, April 2017

28439844

Anna Gustafsson-Lutz, Tom Bäck, Emma Aneheim, Ragnar Hultborn, Stig Palm, Lars Jacobsson, Alfred Morgenstern, Frank Bruchertseifer, Per Albertsson, Sture Lindegren

The aim of this study was to compare the therapeutic efficacy of two different activity levels of the (213)Bi-labeled monoclonal antibody MX35 in an ovarian cancer model. Sixty female BALB/c (nu/nu) mice were inoculated intraperitoneally with human ovarian cancer cells (OVCAR-3). Two weeks later, 40 mice were injected intraperitoneal (i.p.) with 1 ml of (213)Bi-MX35, 3 MBq/mL (n = 20), or 9 MBq/mL (n = 20). An additional 20 mice received unlabeled MX35. Incidence of tumors and ascites was investigated 8 weeks after therapy. Body weight and white blood cell counts were monitored after treatment for possible signs of toxicity. The tumor-free fraction of the animals treated with 3 MBq/mL of (213)Bi-MX35 was 0.55, whereas that of animals treated with 9 MBq/mL of (213)Bi-MX35 was 0.78. The control group treated with unlabeled MX35 had a tumor-free fraction of 0.15. No significant reduction in white blood cell counts or weight loss was observed. Tumor growth after i.p. treatment with (213)Bi-MX35 was significantly reduced compared to treatment with unlabeled MX35. Treatment with 9 MBq/mL of (213)Bi-MX35 resulted in higher tumor-free fraction compared with 3 MBq/mL of (213)Bi-MX35, but this difference was not statistically significant. No signs of toxicity were observed in the treated animals.