Blocking (non-activating) monoclonal antibodies (mAbs) that target CCR7 or its ligands have demonstrated high antitumor efficacy in preclinical models of hematologic malignancies, such as B-cell acute lymphoblastic leukemia [29], chronic lymphocytic leukemia [[30], [31], [32]], mantle cell lymphoma [33], T-cell acute lymphoblastic leukemia [29,34], and T-cell prolymphocytic leukemia [26]. The gene discussed is CCR7; the disease is T-cell prolymphocytic leukemia.