Differences between the different conditioning regimens for allogeneic stem cell transplantation

The aim of this article is to compare the differences in efficacy and toxicity between the various conditioning regimens for allogeneic stem cell transplantation.

Several studies, all retrospective, that compare the impact of various different conditioning regimens amongst each other are presented. Reduced intensity conditioning apparently lowered transplant-related mortality in patients with minimal residual disease who were at high risk for treatment-related mortality. In contrast, patients with active disease could only be salvaged when a myeloablative conditioning regimen was used. By consequence, it was concluded that patients without contraindications for a myeloablative conditioning regimen should not receive reduced regimens outside a prospective randomized trial.

Despite high expectations, non-myeloablative conditioning regimens and regimens that have been reduced in intensity did not prove to be superior in survival when the outcomes were compared with those obtained with conventional myeloablative conditioning. Randomized prospective studies are needed to explore the appropriate niche for the various different regimens.