TY - JOUR T1 - Antitumor Effects of a Human Dimeric Antibody Fragment <sup>131</sup>I-AFRA-DFM5.3 in a Mouse Model for Ovarian Cancer JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1938 LP - 1946 DO - 10.2967/jnumed.110.086819 VL - 52 IS - 12 AU - Alberto Zacchetti AU - Franck Martin AU - Elena Luison AU - Angela Coliva AU - Emilio Bombardieri AU - Marcello Allegretti AU - Mariangela Figini AU - Silvana Canevari Y1 - 2011/12/01 UR - http://jnm.snmjournals.org/content/52/12/1938.abstract N2 - AFRA-DMF5.3 is a human antibody fragment that, as a dimer, specifically binds to the α-folate receptor (FR) on ovary cancer cells. Pharmacokinetic and biodistribution parameters of 131I-AFRA-DFM5.3 after intravenous administration in animal models support its potential therapeutic use. We evaluated its preclinical specificity and therapeutic efficacy in tumor models. Methods: A negative control, AFRA-DFM6.1, was obtained by protein engineering. The activity and specificity of 131I-AFRA-DFMs were evaluated by systemic administration (intravenous) in subcutaneous tumor xenograft–bearing nude mice. Pharmacokinetics, biodistribution, and efficacy were assessed by intraperitoneal administration of 131I-AFRA-DFM5.3 in nude mice bearing 2 different intraperitoneal ovarian carcinoma xenografts. Treatments were tested at different doses and as single or double administrations 1 wk apart. Results: In subcutaneous models, 131I-AFRA-DFM5.3, but not the negative control, was found to reside on FR-positive tumor masses and significantly reduced tumor growth. In intraperitoneal models, early accumulation on free-floating clumps of ovarian cancer cells and solid peritoneal masses was evident after 1 h, and tumor uptake was stable for up to 3 h. The high tumor uptake determined the efficacy of 131I-AFRA-DFM5.3. The best antitumor activity, with more than 50% of treated animals cured, was achieved with 2 locoregional treatments of intraperitoneally growing tumors on days 2 and 9. Conclusion: These results suggest that radioimmunotherapy with 131I-AFRA-DFM5.3 is feasible and leads to significantly prolonged survival. These preclinical data provide the basis for the rationale design of therapeutic treatments of ovarian cancer patients with a radiolabeled anti-FR antibody fragment. ER -