Clinical Application of Anti-CCR4 Monoclonal Antibody

Mogamulizumab (KW-0761) is a humanized anti-CCR4 monoclonal antibody with a defucosylated Fc region (Potelligent® Technology), which markedly enhances antibody-dependent cellular cytotoxicity by increasing its binding affinity to the Fcγ receptor expressed on effector cells. It is an effective agent for patients with CCR4-positive adult T-cell leukemia and peripheral T-cell lymphoma, for which no standard therapy exists, and it has an acceptable toxicity profile. In addition, because CCR4 is expressed on CD45RA<sup>-</sup>FOXP3<sup>high</sup>CD4<sup>+</sup> effector regulatory T (Treg) cells, it is an even more attractive target, because Treg cells involved in the tumor escape from host immunity in the tumor microenvironment. Based on this concept, we conducted a clinical study of mogamulizumab for the treatment of CCR4-negative advanced or recurrent solid cancer, with the aim of depleting effector Treg cells and thus boosting anti-cancer immune responses. In this study, mogamulizumab infusion at doses ranging from 0.1 to 1.0 mg/kg was safe and well tolerated. Four of 10 patients showed stable disease during treatment and showed long-ter