Allogeneic stem cell transplantation after reduced-intensity conditioning in lymphoid malignancies

Allogeneic stem cell transplantation (allo-SCT) is an effective therapeutic option for a wide range of hematological malignancies. The toxicity of the conditioning regimen and graft-versus-host disease (GVHD) occurring after the infusion of the graft remain the most important factors leading to high morbidity and mortality. Reduced-intensity conditioning regimens have recently been developed in an effort to reduce the toxicity associated with conventional allo-SCT while preserving the curative potential of the graft-versus-tumor (GVT) effect. Most patients with lymphoproliferative disorders are not ideal candidates for allo-SCT due to higher age at diagnosis, which together with the advanced stage of disease at the time of transplantation can lead to a high transplant-related mortality (TRM). Preliminary experience indicates that reduced-intensity allo-SCT is feasible in such patients. The immediate TRM is low in comparison with conventional procedures and overall results seem promising, thus indicating the existence of a GVT effect. Nevertheless, all series are still low in numbers and follow-up is too short to draw definitive conclusions. Acute and chronic GVHD remain a significant problem with incidences comparable to the conventional setting in some series. Thus, therapeutic strategies must be sought to decrease GVHD without abrogating the GVT effect.