Update in Hematology

Nonmyeloablative Hematopoietic Stem-Cell Transplantation

Every year, thousands of patients—typically patients with acute leukemia, chronic leukemia, non-Hodgkin lymphoma, and multiple myeloma—receive a blood or bone marrow transplant to support high-dose chemotherapy. The procedure can be difficult and risky, and the mortality rate after stem-cell transplantation is approximately 12% in the first 100 days. Mortality is linked to a variety of causes, primarily toxicity (graft-versus-host disease, pneumonia, infection, and organ failure). Approximately 30% of deaths occur because the transplant did not eliminate the primary disease.

The cells used for transplantation come either from the individual patient (autologous) or from a donor (allogeneic). Autologous transplantations are the least risky. Cell transplants from HLA-matched related or unrelated donors carry the added complication of graft-versus-host disease, which leads to greater transplant-related morbidity and mortality. Increasingly, both autologous and allogeneic transplantations use peripheral blood cells, in which the concentration of stem cells has been enhanced with granulocyte colony-stimulating factor, instead of bone marrow. The blood stem cells seem to be more beneficial to the patient and easier on the donor, and the blood can be harvested by apheresis rather than surgery. The choice of autologous versus allogeneic transplantation is influenced by many factors, including the availability of a suitable HLA-matched donor, features of individual diseases, and patient age and remission status.

Patients younger than 50 years of age receive most bone marrow transplants because they tolerate the high treatment toxicity better. However, most of the patients who have diseases that would benefit …