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Introduction: Allogeneic hematopoietic stem cell transplantation (SCT) is the treatment of choice for many malignant hematological disorders. Following recent improvements in non-relapse-related mortality rates, relapse has become the commonest cause of treatment failure. Infusion of donor lymphocytes can potentially enhance immune-mediated antitumor activity and offers a salvage option for some patients. This paper reviews the current literature on the efficacy of this therapeutic strategy., Areas Covered: The biology of adoptive cellular therapy with allogeneic immune cells to treat relapse across a spectrum of diseases in both the full intensity and reduced intensity hematopoietic SCT settings is explored. The review discusses the current limitations of the approach and reviews several new experimental strategies which aim to segregate the desired graft-versus-tumor effect from the deleterious effects of more widespread graft-versus-host reactivity., Expert Opinion: Durable responses to DLI have been noted in chronic myeloid leukemia and responses have also been described in acute leukemia, multiple myeloma and chronic lymphoproliferative disorders. The new challenge in transplantation is to optimize DLI therapy in order to further improve patient outcomes.

Allogeneic hematopoietic stem cell transplantation represents a curative treatment approach for a large range of hematologic malignancies. Traditionally, high-dose radiochemotherapy as preparative regimen has been thought to be necessary for successful allogeneic stem cell transplantation. However, high-dose conditioning often results in considerable medullary and extramedullary toxicity, contributing to high rates of treatment-related mortality. This limits the use of this procedure to patients below 60 years of age without significant comorbidities. Since the peak incidence of most hematological malignancies is beyond the 5th decade of life, the majority of patients are not eligible for high-dose treatment. During the last 15 years, several dose-reduced or even non-myeloablative conditioning regimens have been developed, offering a curative treatment option for these patients. This review summarizes the history of reduced-intensity conditioning (RIC) transplantations, depicts the differences among regimens, highlights significant patient factors, and describes the impact on selected hematological malignancies., (Copyright © 2011 S. Karger AG, Basel.)

Allogeneic hematopoietic cell transplantation (HCT) was originally developed as a form of rescue from high-dose chemoradiotherapy, which is given both to eradicate malignancy and provide sufficient immunosuppression for allogeneic engraftment. The first attempts of allogeneic HCT in humans met with little success. However, a better understanding of the complexities of the human leukocyte antigen (HLA) system has allowed selecting compatible sibling donors, and the development of postgrafting immunosuppressive regimens has helped prevent serious graft-versus-host disease, thereby changing the role of allogeneic HCT from a desperate therapeutic maneuver to a curative treatment modality for many patients with malignant hematological diseases. In addition, the establishment of large registries of HLA-typed volunteers has permitted finding suitable unrelated donors for many patients without family donors. Further advances in the immunogenetics of HLA, especially typing by molecular techniques, have improved results after unrelated HCT, which have begun resembling those obtained with HLA-identical sibling grafts, at least in young patients. Important advances have also been made in the prevention and treatment of infectious complications and in other areas of supportive care. Since the late seventies, it has been recognized that allogeneic immunocompetent cells transplanted with the stem cells, or arising from them, mediated therapeutic anti-tumor effects independent of the action of the high-dose therapy, termed graft-versus-tumor (GVT) effects. This has prompted the recent development of non-myeloablative conditioning regimens for allogeneic HCT that have opened the way to include elderly patients and those with comorbid conditions. Remaining challenges include further advances in the prevention and treatment of both severe graft-versus-host disease and infections. Also, progress in adoptive transfer of T cells with relative tumor specificity and disease-targeted therapy with agents such as Imatinib, Rituximab or radiolabeled monoclonal antibodies would make allogeneic HCT even more effective.

After fifty years of investigations into the use of pluripotent haematopoietic stem-cell transplantation for cancer therapy, this procedure has progressed from one that was thought to be plagued with insurmountable complications to a standard treatment for many haematological malignancies. How have these hurdles been overcome, and how can the therapy be expanded to include patients who are too old or medically infirm to tolerate conventional transplant approaches?