CCR4 and plasma cell myeloma: Secondly, the small molecule CXCR4 antagonist AMD3100 (Plerixafor), which is used as a stem cell mobilizer in patients with non-Hodgkin lymphoma and multiple myeloma [174] and finally mogamulizumab, a humanized antibody against CCR4, which is indicated for the treatment of relapsed or refractory CCR4+ adult T‐cell leukemia/lymphoma [175].