Advances in Conditioning Regimens for Older Adults Undergoing Allogeneic Stem Cell Transplantation to Treat Hematologic Malignancies

Allogeneic stem cell transplantation (SCT) is a potentially curative treatment for patients with hematological malignancies. These diseases, however, have their peak incidence in the sixth to eighth decades of life. Historically, elderly patients have been considered unsuitable candidates for SCT because of high treatment-related mortality (TRM). Over the past 15 years, the use of reduced-intensity conditioning (RIC) regimens before SCT has allowed patients in the sixth and seventh decades of life to be routinely transplanted. Despite major differences among transplant centers in the intensity and composition of the conditioning regimen and immunosuppression, choice of graft source, postgraft immunomodulation, and supportive care, there has been a dramatic decrease in TRM, allowing safer delivery of SCT. Major obstacles to SCT in elderly patients include donor availability, graft-versus-host disease, delayed immune recovery, multiple comorbidities, and chemo refractoriness. Here we review the current results of SCT in elderly patients, focusing on the role of RIC, and using myeloid diseases as the model for discussion.