CCR4 and neoplasm: Using chemokines to block the recruitment of cells such as neutrophils and monocytes, which contribute to tumour growth, could also have an impact on the recruitment of such cells in inflammation or affect immune surveillance, and enhancing antitumour effector T-cell functions or blocking immunosuppressive T-reg functions could have unwanted autoimmune consequences, as seen with the adverse side effects of mogamulizumab treatment; for a more detailed discussion of CCR4-targeted treatments, please consult the article by O. Yoshie in this Special Issue.