title: Approaches to relapse after allogeneic stem cell transplantation.
abstract: OBJECTIVE
  Relapse has become the leading cause of death following allogeneic hematopoietic stem cell transplantation (HSCT). Despite improved understanding of the biology that underlies the graft-versus-leukemia/tumor effect the relapse rate did not decrease over the past 20 years. In general, prognosis is poor for patients who relapsed to an allograft since effective treatment options are limited. Here, we review the available and upcoming treatment approaches for relapse.
  
  
  RESULTS
  Treatment of relapse after allogeneic HSCT has been rarely investigated systematically and results differ substantially from diseases. Withdrawal of immunosuppressive medication, donor lymphocyte infusions with or without chemotherapy and/or second allogeneic HSCT are the most used options. New specific cellular approaches such as disease-specific T-cells, alloreactive natural killer cells or vaccination strategies are under investigation. Novel agents such as tyrosine-kinase inhibitors, hypomethylating agents, monoclonal antibodies, immunomodulating drugs, or proteasome-inhibitors either alone or in combination with adoptive immunotherapy are upcoming promising options, but valid data are lacking so far.
  
  
  CONCLUSIONS
  With some exceptions (chronic myeloid leukemia), treatment options for patients who relapse are limited. The results are poor and the majority of patients ultimately die of their disease. More effort and research is needed to prevent and treat relapse after allogeneic HSCT.
authors.affiliation: Clinic for Stem Cell Transplantation, University Hospital Hamburg-Eppendorf, Hamburg, Germany. nkroeger@uke.uni-hamburg.de
authors.forename: Nicolaus
authors.initials: N
authors.lastname: Kröger
mesh_terms: D019337:Hematologic Neoplasms / Q000601:surgery*; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods*; D006801:Humans; D012008:Recurrence