TY - JOUR T1 - Development of an anti-claudin-3 and -4 bispecific monoclonal antibody for cancer diagnosis and therapy JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther DO - 10.1124/jpet.114.216911 SP - jpet.114.216911 AU - Xiangru Li AU - Manami Iida AU - Minoru Tada AU - Akihiro Watari AU - Yumi Kawahigashi AU - Yuka Kimura AU - Taku Yamashita AU - Akiko Ishii-Watabe AU - Tadayuki Uno AU - Masayoshi Fukasawa AU - Hiroki Kuniyasu AU - Kiyohito Yagi AU - Masuo Kondoh Y1 - 2014/01/01 UR - http://jpet.aspetjournals.org/content/early/2014/08/12/jpet.114.216911.abstract N2 - Most malignant tumors are derived from epithelium, and claudin (CLDN)-3 and -4 are frequently overexpressed in such tumors. Although antibodies have potential in cancer diagnostics and therapy, development of antibodies against CLDNs has been difficult because the extracellular domains of CLDNs are too small and there is high homology among human, rat, and mouse sequences. Here, we created a monoclonal antibody that recognizes human CLDN-3 and -4 by immunizing rats with a plasmid vector encoding human CLDN-4. A hybridoma clone that produced a rat monoclonal antibody recognizing both CLDN-3 and -4 (clone 5A5) was obtained from a hybridoma screen by using CLDN-3- and -4-expressing cells; 5A5 did not bind to CLDN-1, -2, -5, -6, -7 or -9-expressing cells. Fluorescence-conjugated 5A5 injected into xenograft mice bearing human cancer MKN74 or LoVo cells could visualize the tumor cells. The human-rat chimeric IgG1 monoclonal antibody (xi5A5) activated FcγRIIIa in the presence of CLDN-3- or -4-expressing cells, indicating that xi5A5 may exert antibody-dependent cellular cytotoxicity. Administration of xi5A5 attenuated tumor growth in xenograft mice bearing MKN74 or LoVo cells. These results suggest that 5A5 shows promise in the development of a diagnostic and therapeutic antibody for cancers. ER -