Talacotuzumab (JNJ 56022473) is an IgG1 fully humanized CD123 neutralizing monoclonal antibody containing a modified Fc structure. Talacotuzumab has a high affinity for CD123, CD32b/c, CD16-158F and CD16-158V, with KD of 0.43 nM, 188 nM, 46 nM and 16.8 nM, respectively. Talacotuzumab inhibits IL-3 signaling in target cells by inhibiting IL-3 binding to CD123. Talacotuzumab induces mutations in the Fc region to increase affinity for CD16 (FCγriiia), thereby enhancing antibody-dependent cell-mediated cytotoxicity (ADCC). Talacotuzumab inhibits leukemia cell growth in xenografted mouse models of acute myeloid leukemia (AML).