TY - JOUR A2 - Markman, Maurie M. AU - Elgqvist, Jörgen AU - Andersson, Håkan AU - Jensen, Holger AU - Kahu, Helena AU - Lindegren, Sture AU - Warnhammar, Elisabet AU - Hultborn, Ragnar PY - 2010 DA - 2009/10/25 TI - Repeated Intraperitoneal 𝛼 -Radioimmunotherapy of Ovarian Cancer in Mice SP - 394913 VL - 2010 AB - The aim of this study was to investigate the therapeutic efficacy of α-radioimmunotherapy of ovarian cancer in mice using different fractionated treatment regimens. The study was performed using the monoclonal antibody MX35 F(ab)2 labeled with the α-particle emitter A211t. Methods. Nude mice were intraperitoneally inoculated with ~1×107 cells of the cell line NIH:OVCAR-3. Four weeks later 6 groups of animals were given 400 kBq  211At-MX35 F(ab)2 as a single or as a repeated treatment of up to 6 times (n=18 in each group). The fractionated treatments were given every seventh day. Control animals were treated with unlabeled MX35 F(ab)2 (n=12). Eight weeks posttreatment the animals were sacrificed and the presence of macro- and microscopic tumors and ascites was determined. Results. The tumor-free fractions (TFFs) of the animals, defined as the fraction of animals with no macro- and microtumors and no ascites, were 0.17, 0.11, 0.39, 0.44, 0.44, and 0.67 when treated with 400 kBq  211At-MX35 F(ab)2 once or 2, 3, 4, 5, or 6 times, respectively. Repeated treatment 3 times or more resulted in a significantly higher (P<.05) TFF than compared to treatment once or twice. The presence of ascites decreased from 15 out of 18 animals in the group given only one treatment to zero for the 2 groups given 5 or 6 fractions. Treatment with unlabeled MX35 F(ab)2 resulted in a TFF of zero. Conclusion. Weekly repeated intraperitoneal injections of tolerable amounts of activity of A211t-MX35 F(ab)2 of up to 6 times produced increased therapeutic efficacy without observed toxicity, indicating a potential increase of the therapeutic index. SN - 1687-8450 UR - https://doi.org/10.1155/2010/394913 DO - 10.1155/2010/394913 JF - Journal of Oncology PB - Hindawi Publishing Corporation KW - ER -