Low-dose anti-thymocyte globulin reduce severe acute and chronic graft-versus-host disease after allogeneic stem cell transplantation

Graft-Versus-Host Disease Prophylaxis Using Low-Dose Antithymocyte Globulin in Peripheral Blood Stem Cell Transplantation-A Matched-Pair Analysis

Antithymocyte globulin (ATG) decreases chronic graft-versus-host disease (cGVHD) in peripheral blood stem cell transplantation (PBSCT); however, the optimal ATG dose has not been elucidated. We conducted a matched-pair analysis to evaluate whether low-dose ATG could inhibit cGVHD in HLA-matched PBSCT after myeloablative conditioning. A total of 70 patients who were enrolled in the JSCT-ATG15 study, a multicenter phase II clinical trial of 2 mg/kg of ATG (thymoglobulin) given on days -2 and -1, were compared with 210 patients not receiving ATG, who were matched for age, sex, disease, and calcineurin inhibitor selected from the database in Japan. The primary endpoint, cumulative incidence of extensive cGVHD at 2 years was significantly less in the ATG group than that in the non-ATG group (8.7% [95% CI, 3.5%-16.8%] versus 26.2% [95% CI, 20.3%-32.5%], P = .002). ATG significantly reduced the incidence of overall cGVHD and inhibited multiple organ involvement. The ATG group had favorable outcome compared to the non-ATG group in GVHD-free, and relapse-free survival at 2 years. In conclusion, low-dose ATG effectively inhibits chronic GVHD in PBSCT.

Low-dose antithymocyte globulin inhibits chronic graft-versus-host disease in peripheral blood stem cell transplantation from unrelated donors

Antithymocyte globulin (ATG) has been shown to reduce chronic graft-versus-host disease (GVHD) particularly in allogeneic peripheral blood stem cell transplantation (PBSCT) from unrelated donors; however, anti-GVHD effects of lower doses of ATG remains to be elucidated. We conducted a nationwide retrospective study to compare the outcomes of unrelated PBSCT with or without rabbit ATG (thymoglobulin) in 287 patients. A median ATG dose was 2.0 mg/kg. The primary endpoint, the cumulative incidence of moderate-severe chronic GVHD at 2 years was 22.1% in the ATG group, which was significantly less than that in the non-ATG group (36.3%, P = 0.025). The ATG group had a higher incidence of immunosuppressant discontinuation, GVHD-free, relapse-free survival, and moderate-severe chronic GVHD-free, relapse-free survival at 2 years compared to the non-ATG group. The incidences of grade III-IV aGVHD and moderate-severe chronic GVHD were significantly higher in patients with high absolute lymphocyte count (ALC) before the administration of ATG, whereas relapse rate was significantly higher in patients with low ALC before ATG. In conclusion, low-dose ATG effectively suppresses chronic GVHD in unrelated PBSCT, and ALC before ATG may be a potential predictor for GVHD and relapse.

High lymphocyte counts before antithymocyte globulin administration predict acute graft-versus-host disease

Antithymocyte globulin (ATG) reduces severe acute and chronic graft-versus-host disease (GVHD) in allogeneic peripheral blood stem cell transplantation (PBSCT). However, risk factors for severe acute GVHD in PBSCT using ATG remain to be determined. We conducted a single-center, retrospective study to analyze the association of acute GVHD requiring systemic corticosteroid (SC-aGVHD) with absolute lymphocyte counts (ALC) before the administration of ATG or conditioning in 53 patients with HLA-matched PBSCT using low-dose thymoglobulin (2 mg/kg) after myeloablative conditioning. The cumulative incidence of SC-aGVHD was 17.0% and ALC before ATG were significantly higher in patients with SC-aGVHD compared to that in patients without it (median, 0.15 × 10⁹/L vs 0.06 × 10⁹/L, P = 0.047). The cumulative incidence of SC-aGVHD was significantly higher in patients with high ALC before ATG (≥ 0.15 × 10⁹/L) than in those with low ALC (38.5% vs 10.0%, P = 0.016). Non-relapse mortality (NRM) was also significantly higher in the high ALC before ATG group than the low ALC before ATG group (2-year NRM: 23.9% vs 6.0%, P = 0.048), leading to worse survival (2-year overall survival: 69.2% vs 83.5%, P = 0.039). Our study suggested that high ALC before ATG is a risk factor for SC-aGVHD.

Low-dose anti-thymocyte globulin for GVHD prophylaxis in HLA-matched allogeneic peripheral blood stem cell transplantation

Allogeneic peripheral blood stem cell transplantation (PBSCT) is associated with an increased risk of severe acute and chronic graft-versus-host disease (GVHD) compared to bone marrow transplantation. Anti-thymocyte globulin (ATG) can reduce severe acute and chronic GVHD in PBSCT; however, an optimal dose of ATG remains undefined. We conducted a multicenter phase II study to investigate safety and efficacy of low-dose ATG (a total of 2 mg/kg Thymoglobulin) in patients undergoing HLA-matched PBSCT after myeloablative conditioning. The primary endpoint was grades III-IV GVHD at 100 days. Seventy-seven patients were enrolled and 72 patients with a median age of 46.5 years were eligible for analysis. The primary endpoint, cumulative incidence of grades III-IV acute GVHD at 100 days was 1.4% (95% CI, 0.1-6.7%), which was greatly less than our pre-defined statistical threshold value (18.0%). The incidence of chronic GVHD at 1 year was also low (all-grade; 15.3%, moderate to severe; 5.6%). Non-relapse mortality, relapse, overall survival, disease-free survival, and GVHD-free, relapse-free survival at 1 year were 4.2%, 20.8%, 84.7%, 75.0%, and 69.4%, respectively. Low dose thymoglobulin is promising to reduce severe acute and chronic GVHD in HLA-matched PBSCT following myeloablative conditioning.

Role of thymoglobulin in matched sibling allogeneic hematopoietic stem cell transplantation with busulfan and fludarabine conditioning in myeloid malignanicies

In vivo T-cell depletion using anti-thymocyte globulin (ATG) is widely used in allogeneic hematopoietic stem cell transplantation (HSCT) for prophylaxis of GvHD. We investigated the influence of thymoglobulin dose (an ATG) on GvHD following matched sibling donor (MSD) HSCT with a busulfan and fludarabine preparative regimen. Medical records of 180 patients who received MSD HSCT with a conditioning regimen of busulfan, fludarabine, and ATG (BuFluATG) were reviewed retrospectively. The median age was 53 years (range 18-68). Initial diagnoses were acute myeloid leukemia (73.3%) and myelodysplastic syndrome (26.7%). Forty-four and 68 patients (24.4 and 37.7%) experienced acute and chronic GvHD of any grade, respectively. High-dose (⩾4.5 mg/kg) ATG was independently associated with decreased risk of acute GvHD (hazard ratio=0.36, 95% confidence interval (CI): 0.15-0.84, P=0.019) compared to low-dose ATG (<4.5 mg/kg). Although ATG dose was associated with the risk of acute GvHD, it was not associated with the risk of chronic GvHD in our study. A higher dose (⩾4.5 mg/kg) of ATG decreases the risk of acute GvHD but had no significant impact on disease-free survival in MSD HSCT patients conditioned with BuFluATG. The optimal dose of ATG should be further investigated in a large prospective study context.

In-vivo or ex-vivo T cell depletion or both to prevent graft-versus-host disease after hematopoietic stem cell transplantation

INTRODUCTION

Hematopoietic stem cell transplantation (HSCT) represents a widely accepted therapeutic strategy for the treatment of hematologic disorders which are otherwise considered incurable. Alloreactive T cells infused with the stem cell inoculum may generate graft-versus-host disease (GVHD) representing one the most relevant obstacles to the successful outcome of patients receiving allogeneic HSCT. Areas covered: In this review, the authors provide an overview of the most recent approaches of T-cell depletion (TCD) including ex-vivo αβ+ TCD and in-vivo TCD with anti-thymocyte globulin (ATG). Expert opinion: Ex vivo depletion of donor T-cells prevents both acute and chronic GVHD without the need for any additional posttransplant immunological prophylaxis either in haploidentical HSCT and HLA matched transplants. Three prospective trials evaluating the efficacy of ATG in matched unrelated donor transplant recipients demonstrated that ATG reduces the incidence of both acute and chronic GVHD without a significant increase of relapse rate, and similar results have been reported in the setting of blood stem cell grafts from matched sibling donors.