Ulocuplumab (MDX-1338) is a fully human anti-CXCR4 antibody that binds to the ECL2 sequence of CXCR4 with antagonistic activity to the receptor; it also showed promising antitumor activity and pro-apoptotic potential in the treatment as monotherapy of chronic lymphocytic leukemia cells in vitro characterized by high expression of CXCR4 [99]. Here, CXCR4 is linked to B-cell chronic lymphocytic leukemia.