Acute and chronic graft-versus-host disease (GVHD) are potentially lethal complications after stem cell transplantation (SCT). Steroids are the appropriate firstline treatment for both. However, if patients do not adequately benefit from steroid therapy, mortality is high and standardized treatment algorithms are lacking. This is mainly because of limited data from prospective, randomized clinical trials. In addition, most of the available treatment options only induce clinical benefits in a limited proportion of patients. Thus, there is an urgent clinical need to develop more potent immunosuppressive treatment strategies for patients suffering from acute or chronic steroidrefractory GVHD while maintaining the graft versus tumor effect to avoid a potential rise in relapse-related mortality. The increasing knowledge about host-as well as donor-derived variables favoring GVHD development and the increasing armamentarium of immune-modulatory agents entering preclinical and clinical research will probably allow more effective treatment of GVHD in the future. This review describes novel developments in the treatment of steroid-refractory GVHD, with a special focus on the rationale behind promising pharmacologic compounds or up-coming cellular therapies. (Blood. 2012;119(1):16-25)
IntroductionIn 1957, E. D. Thomas and colleagues first described the infusion of bone marrow cells into patients after prior radio-or chemotherapy in their seminal New England Journal of Medicine paper. 1 This work initiated 5 decades of basic and clinical research in the field of stem cell transplantation (SCT) and nowadays SCT is the treatment of choice for many malignant and benign hematopoietic diseases. It was known before 1957 from preclinical animals studies that tranplantation of splenocytes from noncongenic donor strains, while facilitating hematopoietic recovery, induced a severe illness, characterized by progressive weight loss, hunched posture, and diarrhea. 2 In the following years it has become clear that this was not primarily because of the conditioning therapy, but that it was an immune-mediated syndrome, which is now referred to as graft versus host disease (GVHD). GVHD nowadays remains not only a major cause of non-relapse mortality, but also induces substantial morbidity, which can severely affect quality of life. GVHD is a very complex immunologic disorder characterized by a plethora of clinical presentations. 3 Importantly, the predominant use of peripheral blood stem cells (PBSC) rather than bone marrow (BM) and the increasing proportion of reduced intensity conditioning (RIC) regimens has made multifacetted chronic GVHD (cGVHD) more and more clinically relevant. 4,5 The incidence of GVHD thus depends on several variables, including the donor type (related versus unrelated, matched versus mismatched or haploidentical), the type of conditioning (total boby irradiation [TBI] versus nonTBI), the donor's sex (female or male, versus all other sex combinations) and the stem cell source (PBSC versus BM). 6 Despite the inc...