Antithymocyte Globulin Group Research Articles

Clinical Outcomes of Matched Unrelated Allogeneic Stem Cell Transplant Patients: Low Dose ATG Vs. No ATG

Introduction - Allogenic hematopoietic cell transplantation (HCT) remains potential curative treatment for hematologic malignancies. Anti-thymocyte globulin (ATG) is an immunoglobulin directed to human T lymphocytes, and may decrease the risk of chronic graft versus host disease (cGVHD). Use of ATG has been associated with higher incidence of disease relapse and infection.While the optimal dosing of ATG has not been well established, higher doses (≥ 7.5 mg/kg) have a stronger association with infection and disease relapse. Our institution utilizes low dose rabbit ATG at 2.5 mg/kg for in-vivo T-cell depletion. In this retrospective study we evaluated outcomes in patients receiving low dose ATG to those not undergoing in-vivo T-cell depletion with the hypothesis that low dose ATG protects against cGVHD without impacting infectious complications or relapse.Patients and Methods - We evaluated all patients with 8/8 HLA Matched unrelated Donors (MUD) undergoing HCT between 2007 and 2016. Patients were divided in to two cohorts, those receiving low dose ATG to those that did not. Both cohorts received standard GVHD prophylaxis with calcineurin inhibition plus methotrexate or mycophenolate. The primary outcome was overall survival (OS). Secondary outcomes included relapse free survival (RFS), EBV reactivation, CMV reactivation, CMV disease, invasive fungal infection, incidence of acute GVHD (aGVHD) grades III-IV, and moderate to severe cGVHD. A subset analysis was performed to assess relapse free survival (RFS) in patients with myeloid malignancies.Descriptive statistics were utilized for baseline characteristics; and a series of univariate and multivariant Cox proportional hazard regression models were conducted for outcomes of interest. A Kaplan-Meier (K-M) survival curve was used to depict probability of survival by ATG cohort.Results - We identified 209 patients, with 129 (62%) in ATG group and 80 (38%) in non-ATG group. At baseline, there were no differences in the age at transplant, sex, ABO incompatibility, or performance status. The ATG cohort had fewer low disease risk index (DRI) patients and more patients with intermediate or high DRI (2.4%, 64.6%, 28.3% vs 18.4%, 51.3%, 23.7% respectively), and Fisher's Exact test showed that this difference between ATG groups was statistically significant, p = <0.001. The ATG cohort also had significantly different rates of myeloablative (MA) conditioning regimens from the non-ATG cohort with fewer receiving MA (31% vs 53% p < 0.01).No statistically significant differences in OS were observed between the two ATG cohorts at up to 5 years post-transplant (p=0.35; Fig. 1). The primary predictor of OS was DRI very high vs low [HR 6.0 (2-18) p < 0.01]. The ATG exposed cohort had significantly lower risk of cGVHD [HR 0.17 (0.08-0.37) p = <0.001]. There was no difference in risk of death from relapse, incidence of EBV or CMV reactivation, CMV disease, invasive fungal infection, or grade III-IV acute GVHD. Low dose ATG was not associated with inferior RFS, including in subset analysis of patients with myeloid malignancies [HR 0.85 (0.5-1.4) p = 0.549].Conclusions - Our study shows no significant difference in survival or death from relapse for patients who receive ATG. Importantly, patients receiving ATG had a lower rate of cGVHD with no increased rates of infectious complications. Low dose ATG did not appear to increase the risk of relapse, even when considering only myeloid malignancies. These findings suggest that low dose ATG can improve cGVHD with no impact on survival, relapse, or infectious complications. Additional prospective trials using low dose ATG compared to no ATG are warranted. DisclosuresPalmer:Novartis: Research Funding.

Replacement of Polyclonal Anti-Thymocyte Globulin By Targeted Immunomodulation Is Associated with Improved Outcome of Alfa\\Beta T Cell-Depleted Hematopoietic Stem Cells Transplantation in Children with Acute Leukemia

IntroductionRelapse, graft-versus-host disease (GvHD) and associated non-relapse mortality are the main obstacles to successful hematopoietic stem cell transplantation in children with leukemia. αβ T cell depletion was developed to prevent GvHD and improve immune reconstitution in recipients of mismatched grafts. Most current protocols use rabbit anti-thymocyte globulin (ATG) as an essential component of preparative regimen to secure engraftment and GVHD control. In order to avoid damaging effects of circulating ATG on graft NK and gd T cells, we have replaced ATG with pharmacologic blockade of IL-6 and CD80/CD28 co-stimulation axis in our ongoing study.Patients and methodsMajor transplantation outcomes were compared between participants of the current prospective trial (ATG-) and a retrospective control group (ATG+). A total of 165 children with acute leukemia (67 AML, 98 ALL, 68 female, 97 male, median age 8,7 y) underwent allo HSCT between 01.11.2013 and 01.03.2018. Of them 134 - from haploidentical donor and 31 from unrelated donor. All pts were in complete remission (CR1=80, CR2=67, CR>2=18).Ninety-two pts received treosulfan-based conditioning, 73 - TBI-based (all ALL). Either melphalan (n=46) or thiophosphamide (n=98) or etoposide (n=21) were added as a second agent. Fludarabine was used in all pts.Two types of GVHD prophylaxis were used: type 1 (ATG+), (n=98): thymoglobulin 5mg/kg, rituximab 200mg/m2 with either bortezomib on days +2, +5 (n=72) or tacro (n=9) or without any additional agents (n=17); Type 2 (ATG-) (n=67): tocilizumab at 8 mg/kg on day -1, bortezomib on day +2, +5 with abatacept at 10 mg/kg on day -1, +7, +14, +28 (n=63) or without added agent (n=4).αβ T cell depletion with CliniMACS was used in all cases. The median dose of CD34+ cells was 9x106/kg, αβ T cells - 16 x103/kg.Modified (CD45RA-depleted) donor lymphocyte infusions (DLI) were administered to 113 pts. Twenty-five patients received DLI on day 0 and 88 pts received DLI after engraftment. Median time of follow-up for survivors was 2 years (range, 0,3 - 4,5).ResultsThree patients died before engraftment due to septic event. Primary engraftment was achieved in 161 of 162 evaluable pts (99,3%), the median time to neutrophil and platelet recovery was 16 and 15 days.Among the whole cohort the cumulative incidence of acute graft-versus-host disease (GvHD) grades II - IV and III - IV was 11,5% (95% CI: 7,5-17,6) and 4,8% (95% CI: 2,5-9,5) respectively. The cumulative incidence of cGvHD was 10 % (95% CI: 6,3-15,9). The incidence of aGvHD and cGvHD was not different between ATG (+) and ATG (-).Among the whole cohort 2-year pTRM was 8% (95%CI: 4,8-13,5). pTRM was significantly lower among ATG (-) group - 1,5% (95%CI:0,2-10,4) versus 12,2% (95%CI:7,2-20,8) among ATG (+) group, p = 0,015.The cumulative incidence of relapse at 2 years was 21% (95%CI: 15,5-29), 24% (95%CI: 16-35), among ATG (+) and 19% (95%CI: 11-32), among ATG (-), p = 0,8. Two-year pEFS was 70% (95%CI: 62-77), 2-year pOS - 78% (95%CI: 71-85). Among patients, who received ATG (-) regimen, pEFS was 76% (95%CI: 68-89), as compared to 65% (95%CI: 56-75) among ATG (+), p=0,1 and pOS was 89% (95%CI: 81-97) versus 72% (95%CI: 63-81), p=0,032, respectively.αβ T cell recovery at day +30 was associated with a trend to decreased incidence of relapse, CI of relapse was 32% (95% CI:22 - 47) in those with αβ-T cell count < median vs 18 % (95% CI: 11-32) in those with αβ-cell count >median, p=0,08. EFS among αβ T“ high” was 81% (+/-10) vs 56% (+/-14) among αβ T“low”, p=0,002.DiscussionWe confirm that the depletion of αβ T cells from the unrelated and haploidentical graft in combination with intensive conditioning regimen ensures high engraftment rate and low transplant-related mortality. Our analysis suggests that polyclonal ATG serotherapy is not an essential part of the transplant regimen in αβ T-depleted transplantation. Combined administration of tocilizumab and abatacept after αβ T cell-depleted grafting effectively prevents GVHD, does not compromise engraftment, appears to decrease non-relapse mortality and improve survival. DisclosuresNo relevant conflicts of interest to declare.

Randomized Trial of Two Dosages of Rabbit Antithymocyte Globulin in Patients with Aplastic Anemia

Randomized Trial of Two Dosages of Rabbit Antithymocyte Globulin in Patients with Aplastic Anemia

Incidence of cytomegalovirus in cardiac transplant recipients receiving induction immunosuppression with antithymocyte globulin.

Cytomegalovirus (CMV) is a major cause of morbidity and mortality in cardiac transplant recipients. Use of induction immunosuppression in cardiac transplantation may have an impact on the incidence of CMV, but literature is limited. Single-center, retrospective cohort study comparing the risk of CMV infection and disease in cardiac transplant patients receiving antithymocyte globulin (ATG) induction therapy to those receiving no antibody induction. A total of 75 patients were included in our analysis, 50 who received ATG induction and 25 who did not. CMV infection occurred in 10 (20%) and 5 (20%) patients in the ATG and No ATG groups, respectively (P > 0.99). CMV disease occurred in 10 (20%) and 4 (16%) patients in the ATG and No ATG groups, respectively (P = 0.763). The median time from transplant to CMV infection was 200.0 [142.5, 364.5] days in the ATG group vs 221.0 [192.0, 299.0] days in the No ATG group (P = 0.723). The median time from end of CMV prophylaxis to CMV infection was 94.5 [66.5, 151.0] days in the ATG group vs 53.0 [41.0,149.5] days in the No ATG group (P = 0.202). Freedom from CMV infection was highest in the D+/R+ group and lowest in the D+/R- group. In cardiac transplant recipients, ATG induction was not associated with an increased incidence of CMV infection or disease in the setting of valganciclovir prophylaxis and an initial maintenance immunosuppression regimen of primarily steroids, mycophenolate mofetil, and tacrolimus.

Ex vivo and in vivo T cell-depleted allogeneic stem cell transplantation in patients with acute myeloid leukemia in first complete remission resulted in similar overall survival: on behalf of the ALWP of the EBMT and the MSKCC

BackgroundGraft-versus-host disease (GVHD) is one of the leading causes of non-relapse mortality and morbidity after allogeneic hematopoietic stem cell transplantation (allo-HCT).MethodsWe evaluated the outcomes of two well-established strategies used for GVHD prevention: in vivo T cell depletion using antithymocyte globulin (ATG) and ex vivo T cell depletion using a CD34-selected (CD34+) graft. A total of 525 adult patients (363 ATG, 162 CD34+) with intermediate or high-risk cytogenetics acute myeloid leukemia (AML) in first complete remission (CR1) were included. Patients underwent myeloablative allo-HCT using matched related or unrelated donors.ResultsTwo-year overall survival estimate was 69.9% (95% CI, 58.5–69.4) in the ATG group and 67.6% (95% CI, 60.3–74.9) in the CD34+ group (p = 0.31). The cumulative incidence of grade II–IV acute GVHD and chronic GVHD was higher in the ATG cohort [HR 2.0 (95% CI 1.1–3.7), p = 0.02; HR 15.1 (95% CI 5.3–42.2), p < 0.0001]. Parameters associated with a lower GVHD-free relapse-free survival (GRFS) were ATG [HR 1.6 (95% CI 1.1–2.2), p = 0.006], adverse cytogenetic [HR 1.7 (95% CI 1.3–2.2), p = 0.0004], and the use of an unrelated donor [HR 1.4 (95% CI 1.0–1.9), p = 0.02]. There were no statistical differences between ATG and CD34+ in terms of relapse [HR 1.52 (95% CI 0.96–2.42), p = 0.07], non-relapse mortality [HR 0.96 (95% CI 0.54–1.74), p = 0.90], overall survival [HR 1.43 (95% CI 0.97–2.11), p = 0.07], and leukemia-free survival [HR 1.25 (95% CI 0.88–1.78), p = 0.21]. Significantly, more deaths related to infection occurred in the CD34+ group (16/52 vs. 19/112, p = 0.04).ConclusionsThese data suggest that both ex vivo CD34-selected and in vivo ATG T cell depletion are associated with a rather high OS and should be compared in a prospective randomized trial.

Antithymocyte Globuline Therapy and Bradycardia in Children.

In antithymocyte globulin (ATG) treated patients occasionally bradycardia has been noticed. Therefore, we retrospectively analyzed the occurrence of bradycardia in ATG-treated children. Using medical records between 2007 and 2012 we identified children undergoing a combined therapy with ATG and glucocorticoids (ATG group, n = 22). The incidence of bradycardia was compared to that registered in children treated with glucocorticoids alone (glucocorticoid alone group, n = 21). Heart rates (HR) were registered before and on days 0-3, 4-7 and 8-14 after the ATG or steroid administration. The rate of bradycardic episodes was higher during ATG therapy than in the steroid alone group, while severe bradycardia occurred only in the ATG group (97 versus 32, p = 0.0037, and 13 versus 0, p = 0.0029, respectively). There was an interaction between the time and treatment group on HR (p = 0.046). Heart rates in ATG and steroid alone groups differed significantly on day 0-3 and day 4-7 (p = 0.046, p = 0.006, respectively). Within the ATG group HR was lower on days 4-7 compared to the days before and the days 8-14 values (p < 0.001, 95%CI: 0.020-0.074). These findings indicate that transient asymptomatic bradycardia is probably more common with ATG therapy than previously reported. HR should be closely monitored during and after ATG therapy.

Impact of in vivo T cell depletion in HLA-identical allogeneic stem cell transplantation for acute myeloid leukemia in first complete remission conditioned with a fludarabine iv-busulfan myeloablative regimen: a report from the EBMT Acute Leukemia Working Party

BackgroundThe impact of the use of anti-thymocyte globulin (ATG) in allogeneic stem cell transplantation performed with HLA-identical sibling donors following fludarabine and 4 days intravenous busulfan myeloablative conditioning regimen has been poorly explored.MethodsWe retrospectively analyzed 566 patients who underwent a first HLA-identical allogeneic stem cell transplantation with this conditioning regimen for acute myeloid leukemia in first complete remission between 2006 and 2013 and compared the outcomes of 145 (25.6%) patients who received ATG (ATG group) to 421 (74.4%) who did not (no-ATG group). The Kaplan-Meier estimator, the cumulative incidence function, and Cox proportional hazards regression models were used where appropriate.ResultsPatients in the ATG group were older, received more frequently peripheral blood stem cell grafts from older donors, and were transplanted more recently. With a median follow-up of 19 months, patients in the ATG group had reduced 2-year cumulative incidence of chronic graft-versus-host disease (GVHD) (31 vs. 52%, p = 0.0002) and of its extensive form (8 vs. 26%, p < 0.0001) but similar relapse incidence (22 vs. 27%, p = 0.23) leading to improved GVHD and relapse-free survival (GRFS) (60 vs. 40%, p = 0.0001). In multivariate analyses, the addition of ATG was independently associated with lower chronic GVHD (HR = 0.46, p = 0.0001), improved leukemia-free survival (HR = 0.67, p = 0.027), overall survival (HR = 0.65, p = 0.027), and GRFS (HR = 0.51, p = 4 × 10−5). Recipient age above 50 years was the only other factor associated with worse survivals.ConclusionsThese results suggest that the use of ATG with fludarabine and 4 days intravenous busulfan followed by HLA-identical sibling donor allogeneic stem cell transplantation for acute myeloid leukemia improves overall transplant outcomes due to reduced incidence of chronic GVHD without increased relapse risk.

Meta-analysis of the actions of antithymocyte globulin in patients undergoing allogeneic hematopoietic cell transplantation.

Graft-versus-host disease (GVHD) is a serious complication associated with allogeneic hematopoietic cell transplantation (allo-HCT). Antithymocyte globulin (ATG) is widely used prior to allo-HCT for GVHD prevention, though evidence of its efficacy remains unclear. We therefore identified nine randomized controlled trials (RCTs), enrolling 1089 patients (554 in the ATG group and 535 in the non-ATG group) to conduct a meta-analysis of the actions of ATG in allo-HCT. A relative risk or risk ratio (RR) and 95% confidence interval (CI) were calculated for each outcome. Rabbit ATG reduced overall acute (a) GVHD (RR 0.77, 95% CI 0.67-0.89, P = 0.0004), grade III-IV aGVHD (RR 0.53, 95% CI 0.32-0.88, P = 0.01), overall chronic (c) GVHD (RR 0.52, 95% CI 0.42-0.64, P < 0.00001) and extensive cGVHD (RR 0.28, 95% CI 0.18-0.43, P < 0.00001), without increased risk of relapse (RR 1.17, 95% CI 0.91-1.49, P = 0.23). By contrast, horse ATG did not reduce overall aGVHD (RR 1.25, 95% CI 0.88-1.79, P = 0.22) or cGVHD (RR 1.67, 95% CI 0.96-2.91, P = 0.07). ATG marginally reduced 100-day transplant related mortality (RR 0.75, 95% CI 0.56-1.00, P = 0.05) without compromising overall survival or increased risk of infections. Further studies are required to evaluate the optimal dosage and formulation of ATG in different conditioning regimens of transplantation with varied sources of graft and donor.

Evaluation of the Impact of Anti-Thymocyte Globulin on Post-Transplant Outcomes in Sickle Cell Anemia Patients Undergoing BMT from HLA-Identical Sibling Donors

Introduction. Anti-thymocyte globulin (ATG) was added to the BuCy conditioning regimen to reduce the risk of rejection in patients undergoing BMT for SCA by the French group. Since then it has been widely used as part of conditioning regimens in SCD patients. However, it remains unknown whether ATG has any effect on survival in these patients. Here we compare outcome of BMT in 17 SCA patients who received Thymoglobulin (rabbit ATG, Genzyme) before transplantation to 33 patients who did not.Methods. Between July 2004 and November 2015, 50 consecutive patients of 1.7-17.1 years of age with SCA received their first BMT from HLA-identical sibling donors. Of these patients, 17 were prepared for transplantation with oral (n=5) or weight-based iv Bu Cy200 ATG 10 (ATG group) and 33 patients with Fludarabine 150 iv Bu Cy200 (non-ATG group). GVHD prophylaxis consisted of CSA/Methylprednisolone/short MTX. The two groups showed similar patient demographics. Sixty five percent of patients in the ATG group versus 6% in the non ATG group (p=0.00002) were on regular chronic blood transfusion.Results. All 50 patients had sustained engraftment. Platelet and neutrophil engraftment kinetics were similar between groups. There was no difference in the incidence of acute or chronic GVHD between the 2 groups. The incidence of grade 2-4 aGVHD in the ATG and non-ATG groups were 35% (95% CI 8-55%) and 33% (95%CI 15-48%), respectively. The incidence of grade 3-4 aGVHD was 0% in the ATG, and 20% (95%CI 4-33%) in the non-ATG group (p=0.07). The incidence of moderate or severe chronic GVHD were 11% (95% CI 0-25%) in the ATG and 22% (95%CI 5-34%) the non-ATG group (p=0.4). At the time of survival analysis, all 17 patients in the ATG group and 27 patients in the non-ATG group were alive, with median follow-up durations of 7.5 years (range, 3.9-12 years) and 3.6 years (range, 0.8-4.5 years), respectively. For all patients the probability of disease-free survival (DFS) was 87% (95% CI 73-94%). DFS was superior in the ATG group (100%) compared with the non-ATG group [79% (95%CI 60-90%)] (P=0.050) (Figure 1). In the non-ATG group 6 patients have died from severe acute or chronic GVHD-related complications.There was no significant difference in the rate of infectious complications between groups, except for a high incidence of BK virus-related hemorrhagic cystitis in the ATG group (Table 1). The incidence of CMV reactivation was high in both groups but none of the patients developed CMV disease. Two patients in the ATG and one in the non-ATG group showed EBV reactivation with low viral load and none of them developed lymphoproliferative disorder. Neurotoxicity related to cyclosporine was similar in both groups (17% vs 15%). At present all patients in the ATG group and 2 patients in the non-ATG group are off immunosuppressive medication.Conclusions. From this single center study, we report excellent DFS in SCA patients who received ATG as part of the conditioning regimen. This is the first reported study comparing outcomes after ATG-based vs non-ATG-based conditioning regimen for SCA. There was a trend, not significant (p=0.07), for less grade 3-4 aGVHD with ATG in the conditioning regimen. This study showed that the addition of fludarabine to the standard BuCy regimen was well tolerated, and successfully prevented graft rejection in SCA patients. Further study, using low dose ATG in the FluBuCy regimen to increase DFS is currently in progress. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Anti-Thymocyte Globulin for Graft-Versus-Host Disease Prophylaxis in Patients with Acute Myeloid Leukemia Undergoing Reduced Intensity Conditioning Allogeneic Stem Cell Transplantation in First Complete Remission: A Survey on Behalf of the EBMT Acute Leukemia Working Party

Introduction: Anti-thymocyte globulin (ATG) prophylaxis was shown to be effective in reducing both acute and chronic graft-versus-host disease (GVHD) following allogeneic stem cell transplantation (allo-SCT). In previously published studies, the addition of ATG to the pre-allo-SCT conditioning regimen resulted in substantial reduction in GVHD incidence, but theoretically ATG could be associated with increased relapse rate, especially if administered at high doses (> 6 mg/kg of ATG Thymoglobulin or >15mg/kg of ATG Fresenius) to patients with high-risk acute myeloid leukemia (AML). To further address this question, we assessed transplantation outcome in adult AML patients who underwent reduced intensity conditioning (RIC) allo-SCT from a matched sibling donor (MSD) while in complete remission (CR1), with or without ATG. We used the registry data of the Acute Leukemia Working Party of the European Society forBlood and Marrow Transplantation (EBMT).Patients and Methods: Inclusion criteria were adult patients with AML (de novo or secondary) who underwent RIC allo-SCT from an MSD in CR1 between the years 2000 and 2014. RIC conditioning was defined as per the EBMT criteria. Only patients presenting with intermediate- or poor-risk cytogenetics or secondary AML were included in the analysis. Patients who received any kind of T cell depletion including Campath were excluded. Patients were considered to receive high-dose ATG if they received > 6mg/kg of ATG-Thymoglobulin or >15mg/kg of ATG-Fresenius. All other patients were considered as a control.Results: Two hundred and five of the 1750 patients, included in the analysis, received high-dose ATG. The median patient age at diagnosis was 56 years and the median donor age was 55 years for both groups. Fifty four percent of the patients were males. The graft properties were similar in the high-dose ATG and control groups, with female-to-male transplants in 48/205 (23.4%) and 378/1545 (24.6%) patients, respectively. Peripheral blood was the source of grafts in 193/205 (94.1%) and 1413/1545 (91.5%) patients, respectively (p=NS). Poor cytogenetics was reported in 28/205 (13.7%) patients who were given high-dose ATG and in 247/1545 (16%) patients from the control group. Secondary AML was more prevalent among patients from the high-dose ATG group compared to the control group [84/205 (41%) vs 425/1545 (27.5%; p=0.0003]. The median follow-up was 44.6 (0-177) months.The 3-year overall survival (OS) and leukemia-free survival (LFS) were almost identical in both groups, amounting to 54.9 and 46.3 months, respectively for patients who received high-dose ATG and to 54 and 49.5 months, respectively for patients in the control group (p=0.978 and 0.376 ). Differences in relapse incidence (RI) (40.9% vs 34.4%; p=0.1) and non-relapse mortality (NRM) (11.7% vs 16%; p=0.152) were insignificant. The composite endpoint of GVHD-free/relapse-free survival (GRFS) was similar in the groups after one and three years of follow-up (42.9 vs 49.7 and 31.1 vs 36 months, respectively; p=0.152 and p=0.124). In multivariate analysis, the use of ATG prophylaxis was not found to be associated with any of the evaluated parameters. In contrast, OS, LFS, RI, NRM and GRFS were all affected by patient age and presence of secondary AML. Poor cytogenetics correlated with inferior OS, LFS, RI and GRFS. Donor CMV positivity was associated with lower OS, LFS and GRFS and a higher rate of NRM.Conclusions: In AML patients presenting with intermediate- or poor-risk cytogenetics who are referred to RIC allo-SCT from an MSD in CR1, the addition of ATG to conditioning regimens does not influence the outcome. The composite GRFS endpoint is mainly affected by AML risk factors (hazard ratio of 1.43 for secondary AML and 1.37 for poor-risk cytogenetics; p=0.0001). The role of ATG prophylaxis in AML patients undergoing RIC allo-SCT should be prospectively evaluated. DisclosuresMaertens:Gilead: Consultancy, Honoraria, Speakers Bureau; Amgen: Consultancy; Astellas: Consultancy, Speakers Bureau; Merck Sharp & Dohme: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pfizer: Consultancy, Honoraria, Research Funding, Speakers Bureau.

The Impact of Antithymocyte Globulin (ATG) Dose in Allogeneic Hematopoietic Stem Cell Transplantation with HLA Mismatched Donors

Background: Antithymocyte globulin (ATG) is usually included in conditioning regimens in hematopoietic stem cell transplantation (HSCT) from HLA mismatched donors to reduce the incidence of graft versus host disease (GVHD) and rejection. In this study, we intended to assess the clinical impact of ATG dose in HSCT from HLA mismatched donors.Patients and Methods: We retrospectively analyzed 268 consecutive patients with acute myeloid leukemia (n=159), acute lymphoblastic leukemia (n=49) or myelodysplastic syndrome (n=60) receiving busulfan based conditioning and HSCT with HLA mismatched sibling, unrelated, or haplo-identical family donors in five centers of Korea between 2005 and 2015.Results: The median age was 44.5 (range, 15-75) years. Fourty-two patients were treated with myeloablative conditioning and 226 patients with reduced intensity conditioning regimen. ATG at a total dose of 0 (n=31), 2.5-7.5 mg/kg (n = 16), 9 mg/kg (n = 164) or 12mg/kg (n=57) was given to patients according to protocol. 140 patients received HSCT in complete remission and 73 patients in relapse or refractory status. The median follow up duration for surviving patients was 33.8 (range, 2.0-100.6) months. The 3-year overall survival (OS) and event free survival (EFS) rate for all patients was 44.7% and 39.2% There was no significant difference of OS according to ATG dose (P=0.153), but ATG dose of 2.5-7.5mg/kg was significantly associated with better EFS than 0, 9 mg/kg, or 12mg/kg of ATG groups (79.1% vs. 45.4%, 38.9%, and 31.7%, respectively, P=0.038) (Table 1). In addition, ATG dose significantly affected on relapse (P=0.046). The relapse incidence in patients receiving 2.5-7.5 mg/kg of ATG was lower compared to those given 0, 9, or 12 mg/kg of ATG (6.7% for 2.5-7.5mg/kg of ATG group vs. 29.5%, 34.0%, and 46.9% for 0, 9, and 12 m/kg of ATG groups, respectively). The incidences of acute GVHD grades II-IV were 32.6%, 25.0%, 29.4% and 24.6% in patients receiving 0. 2.5-7.5, 9, and 12 mg/kg of ATG, respectively. The incidence of extensive chronic GVHD tended to be lower according to the increase of ATG dose (36.8%, 34.5%, 27.4%, and 21.1% for 0. 2.5-7.5, 9, and 12 mg/kg of ATG dose, respectively).In multivariate analysis, ATG dose of 9 mg/kg (P=0.023) and 12 mg/kg (P=0.036) was associated with shorter EFS compared to 2.5-7.5 mg/kg of ATG.Conclusion: 9mg/kg of ATG dose or more in HLA mismatched busulfan based HSCT with HLA mismatch donors increased the risk for relapse and reduced the EFS. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Comparison of Induction Therapy Using Antithymocyte Globulin and Using Basiliximab for Live Donor Kidney Transplant Recipients: A Single Centre Prospective Cohort Study

Objective: Acute rejections (AR) have a negative impact on long-term graft survival and are the major predictor of chronic rejection. Induction therapy is used to reduce AR and prevent delayed graft function (DGF). Antithymocyte globulin (ATG) and basiliximab are mainly used for this purpose. In this prospective, cohort study, we analysed and compared the safety and efficacy of ATG and basiliximab in induction therapy for live donor kidney transplant recipients.Methods: Graft survival, AR-free survival, renal function, DGF and tolerability were compared in patients who underwent live-donor transplantation between January 2014 and August 2014 at Muljibhai Patel Urological Hospital, Nadiad, Gujarat, India.Results and Discussion: A total of 85 live-donor kidney transplant recipients who enrolled were followed up for 12 mo. The incidence of AR was greater in the basiliximab group, as compared with the ATG group (25.6% versus 7.1%, p &lt;0.05). The incidence of antibody treated AR was also greater (18.6% versus 2.4 %, p &lt; 0.05). Patient survival rate and graft survival rate were 95.2% and 92.9% in the ATG group, respectively, compared with 90.4%and 90.7% in the basiliximab group, respectively. The incidence of adverse events was higher in the ATG group compared with the basiliximab group (71.4% versus 48.3%, p&lt;0.05).Conclusion: The incidence of AR and antibody-treated AR was significantly higher in the basiliximab group than in the ATG cohort. However, ATG was associated with significantly higher incidence of adverse events and leucopenia than basiliximab. Both the strategies were achieved similar patient and graft survival.

Humoral, T-cell and B-cell immune responses to seasonal influenza vaccine in solid organ transplant recipients receiving anti-T cell therapies

BackgroundWe analyzed the impact of the anti-T-cell agents basiliximab and antithymocyte globulins (ATG) on antibody and cell-mediated immune responses after influenza vaccination in solid-organ transplant recipients. Methods71 kidney and heart transplant recipients (basiliximab [n=43] and ATG [n=28]) received the trivalent influenza vaccine. Antibody responses were measured at baseline and 6 weeks post-vaccination by hemagglutination inhibition assay; T-cell responses were measured by IFN-γ ELISpot assays and intracellular cytokine staining (ICS); and influenza-specific memory B-cell (MBC) responses were evaluated using ELISpot. ResultsMedian time of vaccination from transplantation was 29 months (IQR 8–73). Post-vaccination seroconversion rates were 26.8% for H1N1, 34.1% for H3N2 and 4.9% for influenza B in the basiliximab group and 35.7% for H1N1, 42.9% for H3N2 and 14.3% for influenza B in the ATG group (p=0.44, p=0.61, and p=0.21, respectively). The number of influenza-specific IFN-γ-producing cells increased significantly after vaccination (from 35 to 67.5 SFC/106 PBMC, p=0.0007), but no differences between treatment groups were observed (p=0.88). Median number of IgG-MBC did not increase after vaccination (H1N1, p=0.94; H3N2 p=0.34; B, p=0.79), irrespective of the type of anti-T-cell therapy. ConclusionsAfter influenza vaccination, a significant increase in antibody and T-cell immune responses but not in MBC responses was observed in transplant recipients. Immune responses were not significantly different between groups that received basiliximab or ATG.

Antithymocyte globulin therapy for patients with recent-onset type 1 diabetes: 2year results of a randomised trial.

Aims/hypothesisType 1 diabetes results from T cell mediated destruction of beta cells. We conducted a trial of antithymocyte globulin (ATG) in new-onset type 1 diabetes (the Study of Thymoglobulin to ARrest T1D [START] trial). Our goal was to evaluate the longer-term safety and efficacy of ATG in preserving islet function at 2 years.MethodsA multicentre, randomised, double-blind, placebo-controlled trial of 6.5 mg/kg ATG (Thymoglobulin) vs placebo in patients with new-onset type 1 diabetes was conducted at seven university medical centres and one Children’s Hospital in the USA. The site-stratified randomisation scheme was computer generated at the data coordinating centre using permuted-blocks of size 3 or 6. Eligible participants were between the ages of 12 and 35, and enrolled within 100 days from diagnosis. Subjects were randomised to 6.5 mg/kg ATG (thymoglobulin) vs placebo in a 2:1 ratio. Participants were blinded, and the study design included two sequential patient-care teams: an unblinded study-drug administration team (for the first 8 weeks), and a blinded diabetes management team (for the remainder of the study). Endpoints assessed at 24 months included meal-stimulated C-peptide AUC, safety and immunological responses.ResultsFifty-eight patients were enrolled; at 2 years, 35 assigned to ATG and 16 to placebo completed the study. The pre-specified endpoints were not met. In post hoc analyses, older patients (age 22–35 years) in the ATG group had significantly greater C-peptide AUCs at 24 months than placebo patients. Using complete preservation of baseline C-peptide at 24 months as threshold, nine of 35 ATG-treated participants (vs 2/16 placebo participants) were classified as responders; nine of 11 responders (67%) were older. All participants reported at least one adverse event (AE), with 1,148 events in the 38 ATG participants vs 415 in the 20 placebo participants; a comparable number of infections were noted in the ATG and placebo groups, with no opportunistic infections nor difficulty clearing infections in either group. Circulating T cell subsets depleted by ATG partially reconstituted, but regulatory, naive and central memory subsets remained significantly depleted at 24 months. Beta cell autoantibodies did not change over the 24 months in the ATG-treated or placebo participants. At 12 months, ATG-treated participants had similar humoral immune responses to tetanus and HepA vaccines as placebo-treated participants, and no increased infections.Conclusions/interpretationA brief course of ATG substantially depleted T cell subsets, including regulatory cells, but did not preserve islet function 24 months later in the majority of patients with new-onset type 1 diabetes. ATG preserved C-peptide secretion in older participants, which may warrant further study.Trial registration:ClinicalTrials.gov NCT00515099Public data repository:START datasets are available in TrialShare www.itntrialshare.org Funding:National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health (NIH). The trial was conducted by the Immune Tolerance Network (ITN).Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-016-3917-4) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

Does anti-thymocyte globulin have a place in busulfan/fludarabine conditioning for matched related donor hematopoietic stem cell transplantation?

Background/Aims:There is controversy about the prophylactic effect of anti-thymocyte globulin (ATG) on graft versus host disease (GVHD) in the setting of matched related-donor hematopoietic stem cell transplantation (HSCT). This study assessed the inf luences of ATG on the incidences of acute and chronic GVHD and other clinical outcomes in matched related-donor HSCT.Methods:Sixty-one patients received allogeneic HSCT from human leukocyte antigen-matched, related donors. Patients received busulfan/fludarabine conditioning regimens and standard GVHD prophylaxis with or without additional ATG.Results:There was no significant difference in the cumulative incidences of overall acute GVHD, grade II to IV acute GVHD at day 100, and chronic GVHD during the follow-up period between the ATG and non-ATG groups. Three-year overall survival rates were very similar, but three year disease-free survival of the non-ATG group was higher than that of the ATG group (56.2% for ATG vs. 63.1% for non-ATG, p = 0.597). Relapse rate at 3 years in the ATG group was slightly higher than that of the non-ATG group (37.5% vs. 20%, p = 0.29). Non-relapse mortality rate at 3 years was lower in the ATG group (6.25% vs. 15.6%, p = 0.668).Conclusions:Although the addition of ATG doesn’t guarantee a reduction in the incidences of acute and chronic GVHD, pre-transplantation ATG may result in lower non-relapse mortality in the context of matched related-donor HSCT with a busulfan/fludarabine conditioning regimen. However, caution is needed when using ATG because of a possibility to increase relapse rate.

Graft-versus-Host Disease Prophylaxis in Unrelated Peripheral Blood Stem Cell Transplantation with Post-Transplantation Cyclophosphamide, Tacrolimus, and Mycophenolate Mofetil

Clinical efficacy of post-transplantation cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis has been demonstrated in haploidentical and HLA-matched bone marrow but not in unrelated peripheral blood stem cell (PBSC) transplantations. Also, no direct comparisons have been published with current standard of care, combination of antithymocyte globulin (ATG), calcineurin inhibitors, and either methotrexate or mycophenolate mofetil (MMF). Eighty-six adult patients (median age 34 years; range, 18 to 59) with acute myeloblastic and lymphoblastic leukemia underwent unrelated PBSC transplantation with PTCy, tacrolimus, and MMF as GVHD prophylaxis in the single-center trial (clinicaltrial.govNCT02294552). The control group comprised 125 consecutive historical control patients who received ATG, tacrolimus, and methotrexate or MMF. Cumulative incidences of grades II to IV acute (19% versus 45%, P = .0003), grades III to IV acute (4% versus 27%, P < .0001), and chronic GVHD (16% versus 65%, P < .0001) were significantly lower in the PTCy compared with the ATG group. PTCy-based prophylaxis was associated with reduced incidence of nonrelapse mortality (16% versus 36%, P = .005; HR, .55; 95% CI, .34 to .89) and improved overall survival (69% versus 40%, P = .0007; HR, .43; 95% CI, .26 to .70), event-free survival (65% versus 38%, P = .0006; HR, .49; 95% CI, .31 to .78), and GVHD relapse-free survival (52% versus 12%, P < .0001). PTCy-based prophylaxis also had a better safety profile compared with ATG with reduced incidence of veno-occlusive disease, cytomegalovirus reactivation, invasive mycosis, and reduced severity of mucositis. In this study we demonstrated that PTCy in combination with tacrolimus and MMF is a safe and effective GVHD prophylaxis for unrelated PBSC transplantation. Although there are several limitations of the historical control approach, this study suggests the superiority of a PTCy-based approach over an ATG-based prophylaxis.

Reduced platelet transfusions and earlier platelet engraftment using alemtuzumab-based conditioning regimen in allogeneic stem cell transplantation.

In patients undergoing allogeneic stem cell transplantation, conditioning regimens containing alemtuzumab instead of anti-thymocyte globulin (ATG) may result in an earlier platelet engraftment and a reduced number of platelet transfusions. We performed a retrospective, single-center, case-control study analyzing time to engraftment and transfusion needs using alemtuzumab in comparison with ATG as part of conditioning protocol. Median values for time to platelet engraftment, number of transfused platelet concentrates and number of transfused red cell concentrates were 12 versus 19.5 days (p < 0.001), 2 versus 14 (p < 0.001) and 6 versus 14.5 (p = 0.003) in the alemtuzumab and ATG group. Time to leukocyte engraftment did not differ with median 15 days in both groups. Patients in the ATG group showed a significant higher decrease in platelet count during conditioning (68 vs. 29 %, p = 0.001), leading to significant lower median platelet counts at the day of stem cell infusion (38 vs. 95.5 Gpt/l, p = 0.008), and higher values for median C-reactive protein after first antibody infusion (69.0 vs. 43.6 mg/l, p = 0.001) compared with alemtuzumab group. Test for significance was done by using Wilcoxon rank-sum test. Subgroup analysis considering the type of ATG used (Thymoglobulin vs. ATG Fresenius) revealed that differences between alemtuzumab and ATG group were more due to effects of ATG Fresenius than Thymoglobulin. The use of alemtuzumab in comparison with ATG as part of the conditioning regimen may be an approach to reduce the number of transfused platelet and red cell concentrates after allogeneic stem cell transplantation.

Prevention of Acute Graft-Versus-Host Reaction after Allogeneic Unrelated Hematopoietic Stem Cell Transplantation: Comparison of Effectiveness of Treatment Regimens Based on Anti-Thymocyte Globulin and Cyclophosphamide

Background &amp; Aims. So far there is no data presented on the effectiveness of prevention of the graft-versus-host reaction (GVH) using post-transplant cyclophosphamide (PTCy) prescribed after unrelated donor allogeneic hematopoietic stem cell transplantation (allo-HSCT). The aim of this study is to evaluate the incidence of acute and chronic GVH, the transplantation-associated mortality rate, the event-free and overall survival rates, as well as the toxicity profile and the incidence of infectious complications in the study group using cyclophosphamide for GVH prevention; the other aim is to carry out a comparative analysis of the obtained results with the historical control group. Methods. 110 adult patients were enrolled in a clinical study to evaluate the effectiveness of GVH prevention, using PTCy (No. NCT02294552). In order to prevent GVH, the study group (PTCy group) received cyclophosphamide, tacrolimus and mycophenolate mofetil (MMF). The historical control group (ATG group) consisted of 160 patients prescribed with a GVH prevention regimen including anti-thymocyte globulin (ATG), calcineurin inhibitors, and methotrexate or MMF. Peripheral blood stem cells were used as a source of the transplant. Results. The cumulative incidence of II-IV degree acute GVH (18.2 % vs. 40.4 %, respectively; p &lt; 0.0001), III-IV degree GVH (4.5 % vs. 22.5 %, respectively; p &lt; 0.0001), and chronic GVH (21.7 % vs. 40.6 %, respectively; p &lt; 0.0001) was significantly lower in the PTCy group than in the ATG group. Prevention of GVH based on PTCy was associated with the reduction in transplant-associated mortality (12.7 % vs. 33.7 %, respectively; p = 0.003), increased overall survival (70.9 % vs. 44.4 %, respectively; p &lt; 0.001), event-free survival (68.2 % vs. 38.1 %, respectively; p &lt; 0.001) and GVH- and relapse-free survival rates (59.1 % vs. 16.3 %, respectively; p = 0.001). Prevention of GVH using PTCy (as compared to ATG) was less toxic, accompanied by a reduction in the incidence veno-occlusive disease (2.7 % vs. 10.9 %, respectively; p = 0.016), severe mucositis (69.5 % vs. 87.6 %, respectively; p &lt; 0.001), and invasive mycosis (7.2 % vs. 29 %, respectively; p &lt; 0.001). Conclusion. A combination of cyclophosphamide with tacrolimus and MMF is an effective regimen for GVH prevention in patients after allo-HSCT from an unrelated donor.

Pretreatment with anti-thymocyte globulin versus no anti-thymocyte globulin in patients with haematological malignancies undergoing haemopoietic cell transplantation from unrelated donors: a randomised, controlled, open-label, phase 3, multicentre trial

Pretreatment with anti-thymocyte globulin (ATG) decreases the occurrence of chronic graft-versus-host disease (CGVHD) after haemopoietic cell transplantation from an unrelated donor, but evidence of patient benefit is absent. We did a study to test whether ATG provides patient benefit, particularly in reducing the need for long-term immunosuppressive treatment after transplantation. We did a phase 3, multicentre, open-label, randomised controlled trial at ten transplant centres in Canada and one in Australia. Eligible patients were aged 16 to 70 years with any haematological malignancy and a Karnofsky score of at least 60 receiving either myeloablative or non-myeloablative (or reduced intensity) conditioning preparative regimens before haemopoietic cell transplantation from an unrelated donor. We allocated patients first by simple randomisation (1:1), then by a minimisation method, to either pretransplantation rabbit ATG plus standard GVHD prophylaxis (ATG group) or standard GVHD prophylaxis alone (no ATG group). We gave a total dose of ATG of 4·5 mg/kg intravenously over 3 days (0·5 mg/kg 2 days before transplantation, 2·0 mg/kg 1 day before, and 2·0 mg/kg 1 day after). The primary endpoint was freedom from all systemic immunosuppressive drugs without resumption up to 12 months after transplantation. Analysis was based on a modified intention-to-treat method. This trial was registered at ISRCTN, number 29899028. Between June 9, 2010, and July 8, 2013, we recruited and assigned 203 eligible patients to treatment (101 to ATG and 102 to no ATG). 37 (37%) of 99 patients who received ATG were free from immunosuppressive treatment at 12 months compared with 16 (16%) of 97 who received no ATG (adjusted odds ratio 4·25 [95% CI 1·87-9·67]; p=0·00060. The occurrence of serious adverse events (Common Terminology Criteria grades 4 or 5) did not differ between the treatment groups (34 [34%] of 99 patients in the ATG group vs 41 [42%] of 97 in the no ATG group). Epstein-Barr virus reactivation was substantially more common in patients who received ATG (20 [one of whom died-the only death due to an adverse event]) versus those who did not receive ATG (two [no deaths]). No deaths were attributable to ATG. ATG should be added to myeloblative and non-myeloblative preparative regimens for haemopoietic cell transplantation when using unrelated donors. The benefits of decreases in steroid use are clinically significant. Epstein-Barr virus reactivation is increased, but is manageable by prospective monitoring and the use of rituximab. Future trials could determine whether the doses of ATG used in this trial are optimum, and could also provide additional evidence of a low relapse rate after non-myeloablative regimens. The Canadian Institutes of Health Research and Sanofi.

Partial T-Cell Depletion By Low-Dose Anti-Thymocyte Globulin to Reduce Severe Acute and Chronic Graft-Versus-Host Disease after Allogeneic Stem Cell Transplantation

Background: T cells from a stem cell source are inevitably contaminated, and over 5.0×104/kg T cells are thought to induce graft-versus-host disease (GVHD) in HLA-mismatched or haplo-identical stem cell transplantations (SCTs) [4]. To suppress GVHD reactions, a procedure for T-cell depletion (TCD) was developed over the past several decades, especially for HLA-mismatched and haplo-identical SCTs, which are at high risk for GVHD. To reduce the incidence of GVHD, a potentially effective agent is anti-thymocyte globulin (ATG), which is generally administered at a dose of ≥ 5-10 mg/kg. Based on data regarding the use of ATG for the treatment of aplastic anemia, we hypothesized that ATG might accommodate engraftment and inhibit GVHD. We attempted to use a lower dose of ATG to decrease non-relapse mortality (NRM) in Japanese patients undergoing an HLA-matched SCT.Patients and method: We treated patients with hematological diseases who underwent an allogeneic SCT after March 2010 without or with 2.5 mg/kg ATG. The inclusion criteria for underlying disease included both hematological malignancies and bone marrow failures. All consecutive patients transplanted from an allogeneic related or unrelated donor were included. Cord blood transplantations were omitted from this analysis. The patients who underwent an SCT before February 2010 (n=20) were examined as the control group without ATG treatment. ATG was administered 1 day prior to the transplantation day at 2.5 mg/kg with 500 mg/body methylpredonisolone as a preconditioning procedure. GVHD prophylaxis, tacrolimus 0.03 mg/kg and short-term MTX (10-7-7 mg/m2) was adapted for both the ATG group and the control group.Results: Thirty-nine (21 male, 18 female) recipients were recruited (median age 49 yrs, range 19-64 yrs). Their underlying diseases were acute myeloid leukemia (n=14), acute lymphoblastic leukemia (n=10), myelodysplastic syndrome (n=5), lymphoma (n=7), and myeloma, aplastic anemia, and other malignancy (n=1 each). Preparation regimens were myeloablative for 17 patients (14 cyclophosphamide [CY]/total body irradiation [TBI], two busulfan [BU]/CY, and another) and non-myeloablative for the other 22 patients (14 fludarabine/melphalan [Flu/Mel] and eight Flu/BU). All but one patient achieved engraftment, and one secondary graft failure was observed. The overall incidences of acute and chronic GVHD were 63.2% and 15.8% for the ATG-treated patients (40.0% and 25.0% for the control cohort), respectively. Acute GVHD (grades II to IV and III to IV) in the recipients who received ATG occurred in 21.1% and 0.0% (control cohort, 10.0% and 5.0%), respectively. The estimated probability of overall survival (OS) 2.5 yrs after transplantation was 77.8% for the ATG group (controls, 57.1%). The relapse rate 2.5 yrs after transplantation was 21.1% and 20.0% in the ATG and control groups, respectively. The NRM rate was decreased after ATG treatment: 25.0% vs. 10.5% (not significant). The causes of mortality with or without ATG were recurrent diseases (n=1 and 2), infection (n=1 and 0), and adverse events caused by transplant-related complication (n=1 and 5), respectively. No deaths due to acute or chronic GVHD occurred.Discussion: Low-dose ATG could suppress the incidence of severe acute GVHD and chronic GVHD without increasing the NRM, although our study design did not have enough power to make a conclusion about the efficacy of low-dose ATG. However, partial T-cell depletion may be effective for HLA-matched SCT recipients. Our results show that ATG at 2.5 mg/kg can be used safely for the Japanese transplant population of HLA-matched donors. Low-dose ATG is a potential treatment to partially disempower T cells from a stem cell source, which are inevitably contaminated. Recent developments in the prophylaxis for GVHD, such as selective cytotoxic T-cell depletion by using a post-transplant CY regimen, are promising strategies to fully suppress T cells as the GVHD enhancer. Previous studies revealed the clinical efficacy of GVHD prophylaxis but did not clarify the significance of its survival benefit. Likewise, our present findings indicated a lack of survival benefit by ATG treatment in this small study. However, the low-dose ATG contributed to a reduction of severe GVHD. Although early mortality after transplantation is decreasing, late-onset comorbidity including chronic GVHD remains a significant problem. DisclosuresNo relevant conflicts of interest to declare.