Immune-modulating drugs and hypomethylating agents to prevent or treat relapse after allogeneic stem cell transplantation

Allogeneic stem cell transplantation is a curative treatment option for many hematological diseases, and the numbers of transplantations are steadily increasing worldwide. Major progress has been made in lowering treatment-related mortality by reducing intensity of the conditioning regimen and by improving supportive care (eg, for infectious complications). Accordingly, relapse after allogeneic stem cell transplantation has become the major cause for treatment failure. Major efforts to prevent or treat relapse are focused on cellular- (T cell, natural killer cell), cytokine-, or antibody-based strategies to enhance the graft-versus-tumor effect or circumvent immunoescape. In the more recent years, new classes of agents have shown activity in several hematological malignancies, and besides their immediate antitumor activity, most of them also possess immune-modulatory qualities that may be useful alone or in combination with adoptive immunotherapy after allogeneic stem cell transplantation to enhance graft-versus-tumor effects. Here, we summarize the current knowledge and potential use of 2 of these compounds in preventing or treating relapse after allogeneic stem cell transplantation, namely immune-modulating drugs and hypomethylating agents.