New immunosuppressants in BMT/GVHD

Mycophenolate mofetil and cyclosporine for graft-versus-host disease prophylaxis following reduced intensity conditioning allogeneic stem cell transplantation

The use of reduced intensity conditioning (RIC) regimens for allogeneic stem cell transplantation (allo-SCT) can result in a significant decrease in early procedure-related toxicity in patients not eligible for standard myeloablative regimens. However, acute graft-versus-host disease (aGVHD) remains a matter of concern after RIC allo-SCT, and its incidence might be expected to be higher in elderly and high-risk patients. This report investigated mycophenolate mofetil (MMF) and cyclosporin A (CsA) combination (n=14) in comparison to CsA alone (n=20) for GVHD prophylaxis in cancer patients aged over 50 years (27 haematological malignancies and seven solid tumours) receiving an HLA-identical sibling antithymocyte-globulin (ATG)-based RIC allo-SCT. Baseline demographic characteristics and risk factors for aGVHD were comparable between both groups. Although MMF administration was not associated with any significant toxicity, the cumulative incidence of any form of GVHD was comparable between both groups (cumulative incidence of grade II-IV aGVHD, 50% (95% CI, 28-72%) for CsA alone, as compared to 64% (95% CI, 39-89%) to CsA and MMF, P=NS), suggesting that adjunction of MMF to CsA is feasible, but does not translate towards a significant reduction of aGVHD, at least in the context ATG-based RIC allo-SCT.

Tumor necrosis factor-alpha blockade for the treatment of acute GVHD

Despite posttransplantation immunosuppressive therapy, acute graft-versus-host disease (GVHD) remains a major cause of sickness and death. Tumor necrosis factor-alpha (TNF-alpha) is implicated in the pathophysiology of GVHD at several steps in the process. Infliximab is a genetically constructed immunoglobulin G1 (IgG1) murine-human chimeric monoclonal antibody that binds the soluble subunit and the membrane-bound precursor of TNF-alpha, blocking its interaction with receptors and causing lysis of cells that produce TNF-alpha. In this study we retrospectively evaluated 134 patients who had steroid-refractory acute GVHD. Of these, 21 who received infliximab as a single agent were analyzed. The overall response rate was 67% (n = 14), and 13 patients (62%) experienced complete response (CR). Five patients (24%) did not respond, and 2 (10%) had progressive GVHD. None had a toxic reaction to infliximab. Ten patients (48%) had 18 fungal infections, including Aspergillus species in 7 and Candida species in 10. Seventeen patients (81%) had bacterial infections, including 32 gram-positive and 8 gram-negative infections. Viral infections, primarily cytomegalovirus reactivation, occurred in 14 patients (67%). The Kaplan-Meier estimate of overall survival was 38%. In conclusion, infliximab was well tolerated and active for the treatment of steroid-resistant acute GVHD, particularly with gastrointestinal tract involvement. Survival after steroid-resistant acute GVHD continues to be problematic. The possibility of excessive fungal and other infections must be explored further.

Pathogenesis and treatment of graft-versus-host disease after bone marrow transplant

Stem cell transplantation is being used to treat a number of hematologic malignancies as well as hematologic and immune deficiency states. The ages of patients being offered this therapy and the donor marrow sources have been expanded. One persistent problem has been graft-versus-host disease (GVHD). This article reviews the basic biology of GVHD, clinical manifestations of acute and chronic GVHD, prophylaxis and treatment of acute GVHD, and treatment of chronic GVHD.

Extracorporeal photopheresis in chronic graft-versus-host disease

Despite significant advances in stem cell manipulation and post-transplant immunosuppression, chronic graft-versus-host disease (cGVHD) remains a cause of major long-term morbidity in survivors of allogeneic stem cell transplantation. Extracorporeal photopheresis (ECP) is a novel therapeutic intervention which has demonstrated efficacy in patients with refractory acute and chronic GVHD. Clinical responses have been reported in skin and visceral GVHD. While the long-term immunomodulatory effects of ECP in cGVHD are unknown, recent studies of patients undergoing a 6- to 12-month course of ECP treatment demonstrated an attenuation of Th1-mediated cytokine secretion by activated T-helper cells, a shift in the DC1/DC2 ratio favoring plasmacytoid rather than monocytoid dendritic cell profiles, and a decrease in antigen responsiveness by dendritic cells. The implications of these immunomodulatory effects of ECP on pathogenesis and clinical outcome remains a fertile area for future research.