Samalizumab (ALXN 6000) is a humanized anti-CD200 monoclonal antibody that specifically targets the CD200 immunoregulatory cell surface protein, a member of the immunoglobulin superfamily which functions to dampen excessive immune responses and maintain self-tolerance, thereby establishing Samalizumab as an effective immune checkpoint inhibitor currently under investigation for the treatment of myeloma and B-cell chronic lymphocytic leukemia (CLL).