Talacotuzumab (JNJ 56022473; CSL 362) is an IgG1-type fully humanized, CD123-neutralizing monoclonal antibody containing a modified Fc structure. Talacotuzumab has KDs of 0.43 nM, 188 nM, 46 nM, 16.8 nM for CD123, CD32b/c, CD16-158F, CD16-158V, respectively. Talacotuzumab inhibits IL-3 binding to CD123, antagonizing IL-3 signaling in target cells. Talacotuzumab has mutated the Fc region to increase affinity for CD16 (FcγRIIIa), thereby enhancing antibody-dependent cell-mediated cytotoxicity (ADCC). Talacotuzumab is highly effective in vivo reducing leukemic cell growth in acute myeloid leukemia (AML) xenograft mouse models.