Update on non-myeloablative stem cell transplantation for hematologic malignancies.

Allogeneic stem cell transplantation is an established treatment modality for a variety of hematologic malignancies. Unfortunately it carries a high risk of complications and toxicities related to the intensive preparative regimen which is traditionally used for pre-transplant myeloablation and the graft versus host disease, which may be life threatening. Thus allogeneic stem cell transplantation has been used only for younger patients with a good performance status, excluding many other potential candidates due to advanced age or comorbid conditions. Non ablative or reduced intensity preparative regimens for allogeneic stem cell transplantation (NST) have been proposed as a strategy that would allow exploiting the graft versus tumor effect of allogeneic transplantation without the toxicity of myeloablative therapy. After more than five years of cumulative clinical experience, it is now well established that NST is a feasible treatment option for patients with suboptimal performance status and is mostly effective in slow proliferating malignancies, which gives time for a graft versus malignancy effect to take place. Additionally achievement of stable donor cell engraftment with NSTs provides a platform for adoptive immune cell treatments and may allow to extend indications of stem cell transplantation in the future.