CXCR4 and plasma cell myeloma: Three chemokine antagonists have been approved: Maraviroc (a CCR5 antagonist) for anti-HIV treatment (Xu et al., 2014), Plerixafor (a CXCR4 antagonist) for the treatment of multiple myeloma or non-Hodgkin’s lymphoma (Uy et al., 2008), and Mogamulizumab (a CCR4 antagonist) for the treatment of mycosis fungoides or Sézary syndrome (Sato et al., 2018).