CXCR4 and T-cell leukemia: The promising effects of these approaches are supported by the recent approval of a monoclonal antibody targeting CCR4 (mogamulizumab) for the treatment of adult T-cell leukemia [22] and by the results obtained with plerixafor (AMD3100), a blocking compound targeting CXCR4, able to enhance the sensitivity of tumor cells to cytotoxic agents by disrupting their interaction with the tumor microenvironment [23].