The dose escalation of chemo-radiotherapy that is achievable with stem cell transplantation is often insufficient to eradicate malignancy, and an associated immune-mediated graft-versus-malignancy effect may be equally important for many diseases. The most directly compelling evidence for its presence has been provided by the efficacy of donor lymphocyte infusions (DLI) in generating anti-tumor responses, particularly for relapsed chronic-phase CML. Response rates and durability appear lower with myeloma and AML/MDS, and minimal with ALL. There is relatively little data on indolent lymphoid malignancies. Issues that remain to be resolved include the precise nature of the effector cells and their target antigens, the best strategies for separating graft-versus-malignancy from graft-versus-host disease (GVHD) and their effect on the durability of responses, and the role of adjuvant chemotherapy/cytokines. Similar issues surround routine combination with nonmyeloablative transplantation protocols and preliminary data suggests that GVHD may continue to provide a major obstacle.
Allogeneic transplant; donor lymphocyte infusion; graft-versus-host; graft-versus-tumor; adoptive immunotherapy
