Non-myeloablative allogeneic transplantation -- state-of-the-art

Work by several groups of investigators has brought about changes in the way hematopoietic cell allografts are being done to treat patients with hematologic diseases. Less intensive conditioning regimens have been introduced, and in the case of patients with hematologic malignancies, the burden of eradicating malignant cells has shifted from high-dose chemoradiation treatment toward using the hematopoietic cell donor's T lymphocytes for that purpose by invoking allogeneic graft-versus-tumor effects. While the majority of the transplant regimens used in these efforts are still fairly intense and toxic, a radical departure from conventional transplantation focuses on the almost exclusive use of immunosuppressive agents with little toxicity to establish the allografts. The success of the procedure for patients with hematologic malignancies rests on replacing the host's hematopoietic cells by the allograft. For non-malignant diseases, the procedure can be used to establish a stable state of mixed donor/host hematopoietic chimerism, which, in itself, may be sufficient to cure disease manifestations.