Infusion of donor peripheral blood mononuclear cells to treat relapse after transplantation for chronic myelogenous leukemia

Until recently, the only curative therapy for patients with chronic myelogenous leukemia (CML) who relapse after allogeneic bone marrow transplantation (BMT) has been second allogeneic BMT. Recently, donor mononuclear cells have been given to patients with relapsed CML to induce a potent graft-versus-leukemia reaction and re-establish complete remissions in the majority of patients without the need for a second transplant. The extraordinary success of donor mononuclear cell infusions shows that it is possible to manipulate and harness the graft-versus-leukemia (GVL) reaction for clinical benefit. The identity of the effector cells and target antigens is unclear, but intensive investigation is beginning to define the complex cytokine and cellular interactions that mediate GVL reactivity. Current clinical trials are investigating strategies that will retain and enhance the GVL effects while limiting toxicity from this therapy. Ultimately, the ability to harness the GVL potential of allogeneic donor cells without excessive toxicity from graft-versus-host disease will be a central challenge in BMT and cellular immunotherapy.