Low-dose Antithymocyte Globulin Research Articles

Reduced-toxicity conditioning regimen with low dose post-transplantation cyclophosphamide and low-dose anti-thymocyte globulin as graft-versus-host disease prophylaxis for haploidentical stem cell transplantation in older patients.

We retrospectively analyzed outcomes in 55 patients ≥ 55 years of age with hematologic malignancies treated with fludarabine, cytarabine, busulfan, and low-dose cyclophosphamide as the conditioning regimen between January 1, 2019, and November 30, 2023. Neutrophil engraftment was successful in all patients within 28 days, with 54 patients (98.2%) achieving complete donor chimerism. The cumulative incidence of non-relapse mortality was 0% at 30 days, 7.5% at 100 days, and 19% at 1 year. The cumulative incidence of grade II-IV acute graft-versus-host disease (aGVHD) was 25% (95%CI, 15-38%), whereas that of grade III-IV aGVHD was 9.1% (95% CI, 3.3-19%). The cumulative incidence of extensive chronic graft-versus-host disease at 1 year was 3.6% (95%CI, 0.66-11%). The cumulative incidences of relapse, overall survival, and GVHD-free/relapse-free survival at 1 year were 9.0%, 71.6%, and 67.1%, respectively. An RIC conditioning regimen, including a combination of lower PTCy/ATG as GVHD prophylaxis, followed by haplo-SCT, might be a promising option for appropriately selected older patients.

Unrelated umbilical cord blood transplantation with low-dose anti-thymocyte globulin for children with severe aplastic anemia: A case series.

This study aimed to investigate the prognosis of unrelated umbilical cord blood transplantation (UCBT) using low-dose anti-thymocyte globulin (ATG) in children diagnosed with severe aplastic anemia (SAA). This retrospective case series study was conducted involving pediatric SAA patients treated at the Capital Institute of Pediatrics from January 2020 to February 2023. All patients underwent a reduced-intensity conditioning (RIC) regimen alongside low-dose ATG. The study comprised nine patients (five males) with a median age of 5 years (range: 1.7 to 7 years). The median follow-up duration was 799 days (range: 367 to 1481 days), during which all patients survived. The median time interval from diagnosis to transplantation was 3 months (range: 1 to 9 months). The median dosage of ATG administered was 5mg/kg (range: 2.5 to 7.5mg/kg). The median durations for granulocyte and platelet engraftment were 15 days (range: 12 to 23 days) and 26 days (range: 12 to 41 days), respectively. Three patients experienced grade 2-4 acute graft-versus-host disease (aGVHD). Epstein-Barr virus (EBV) reactivation was observed in three patients, while cytomegalovirus (CMV) reactivation occurred in seven patients, with no cases of CMV disease or post-transplant lymphoproliferative disorder (PTLD). One patient experienced recurrence 15 months after transplantation due to influenza A infection. These findings indicate that SAA patients may attain a favorable prognosis following UCBT with a RIC regimen combined with low-dose ATG.

Favorable Outcomes with Low Dose Anti Thymocyte Globulin Based Graft Versus Host Disease Prophylaxis after Mismatched Unrelated Donor Allogenic Hematopoietic Cell Transplantation

Favorable Outcomes with Low Dose Anti Thymocyte Globulin Based Graft Versus Host Disease Prophylaxis after Mismatched Unrelated Donor Allogenic Hematopoietic Cell Transplantation

Low-Dose Antithymocyte Globulin: A Pragmatic Approach to Treating Stage 2 Type 1 Diabetes.

Low-dose antithymocyte globulin (ATG) (2.5 mg/kg) preserves C-peptide and reduces HbA1c in new-onset stage 3 type 1 diabetes, yet efficacy in delaying progression from stage 2 to stage 3 has not been evaluated. Children (n = 6) aged 5-14 years with stage 2 type 1 diabetes received off-label, low-dose ATG. HbA1c, C-peptide, continuous glucose monitoring, insulin requirements, and side effects were followed for 18-48 months. Three subjects (50%) remained diabetes free after 1.5, 3, and 4 years of follow-up, while three developed stage 3 within 1-2 months after therapy. Eighteen months posttreatment, even disease progressors demonstrated near-normal HbA1c (5.1% [32 mmol/mol], 5.6% [38 mmol/mol], and 5.3% [34 mmol/mol]), time in range (93%, 88%, and 98%), low insulin requirements (0.17, 0.18, and 0.34 units/kg/day), and robust C-peptide 90 min after mixed meal (1.3 ng/dL, 2.3 ng/dL, and 1.4 ng/dL). These observations support additional prospective studies evaluating ATG in stage 2 type 1 diabetes.

Low-Dose ATG Has the Same Risk of CMV Reactivation after Allogeneic PBSCT As Ptcy, but Letemovir Is Effective in Preventing CMV Reactivation

[Introduction] Allogeneic peripheral blood stem cell transplantation (allo-PBSCT) is a curative treatment for hematological malignancies but has a risk of a chronic graft-versus-host disease (GVHD) compared to other donor sources. Post-transplant cyclophosphamide (PTCY) has been spread rapidly worldwide from HLA haploidentical-SCT (Haplo-SCT) to HLA matched-SCT. Although PTCY was theoretically thought to preserve non-alloreactive T cells which can contribute to fight infection, recent studies showed that PTCY was associated with the increased incidence of cytomegalovirus (CMV) infection. Letermovir (LTV), a novel anti-CMV agent, was useful for the prevention of CMV reactivation after SCT including Haplo-SCT using PTCY. On the other hand, low-dose antithymocyte globulin (ATG) is an alternative and useful option for GVHD prophylaxis in allo-PBSCT and often used in Japan. However, the risk of post-transplant CMV reactivation and the protective effect of LTV when using low-dose ATG remain to be elucidated. [Methods] We retrospectively analyzed 222 recipients who received allo-PBSCT using PTCY or low-dose ATG at Hokkaido University Hospital from January 2013 to July 2021. Of the 121 patients who underwent PBSCT with PTCY, 69 (all patients underwent Haplo-PBSCT) were without LTV prophylaxis and 52 (34 patients, Haplo-PBSCT) were with LTV. On the other hand, of the 101 patients who underwent PBSCT with low-dose ATG, 66 (12 patients, Haplo-PBSCT) were without LTV and 35 (2 patients, Haplo-PBSCT) were with LTV. LTV was administered on the day 0 at a dosage of 480 mg daily. All patients were monitored for CMV reactivation by using the anti-CMV pp65 monoclonal antibody HRP-C7 assay at least weekly from neutrophil engraftment to discharge and after discharge monthly until day 180 after SCT. CMV reactivation was defined as the start of CMV preemptive therapy, generally initiated when there are 2 or more CMV antigen positive cells per 50000 white blood cells. Moreover, CMV disease was defined by organ dysfunction attributable to CMV. [Results] Baseline characteristics of the patients are summarized in Table 1. Although more patients in ATG group compared to PTCY group received myeloablative conditioning regimen significantly, there was no significant difference between the groups in terms of sex, age, underlying disease, disease risk at SCT, and CMV serostatus. GVHD prophylaxis in PTCY consisted of CY (40-50 mg/kg on day 3 and 4), tacrolimus (from day 5), and mycophenolate mofetil (from day 5), whereas that in ATG consisted of ATG at a total dose of 2-3 mg/kg around day -2, tacrolimus (from day -1) and short-term methotrexate. LTV prophylaxis significantly reduced the cumulative incidence of CMV reactivation at 180 days after SCT in PTCY group (69.6% without LTV vs. 22.4% with LTV, p<0.001) and ATG group (62.6% without LTV vs. 18.9% with LTV, p<0.001; Figure 1.). Importantly, although CMV disease were occurred in 2 patients in PTCY (1 gastritis and 1 retinitis) and 8 focuses in 7 patients (3 pneumoniae, 3 enteritis, 1 retinitis, and 1 glossitis) in ATG without LTV prophylaxis, none of the patients receiving LTV developed CMV disease in both group. Moreover, LTV did not affect overall survival, the cumulative incidence of non-relapse mortality, relapse, acute GVHD, and engraftment of neutrophil and platelet. Interestingly, the cases of early CMV reactivation within 100 days after SCT under LTV prophylaxis was significantly more frequent in ATG than in PTCY (p=0.0345). [Conclusion] CMV reactivation occurred with similar frequency after allo-PBSCT with low-dose ATG as after that with PTCY. LTV was effective for prevention of CMV reactivation in both GVHD prophylaxis methods. CMV breakthrough reactivation may be likely to occur in PBSCT with low-dose ATG compared to that with PTCY even under LTV prophylaxis, and careful CMV monitoring may be required.

Favorable Outcomes with Low Dose Anti Thymocyte Globulin Based Graft Versus Host Disease Prophylaxis after Mismatched Unrelated Donor Allogenic Hematopoietic Cell Transplantation

DISCUSSION INTRODUCTION Anti thymocyte globulin (ATG) based Graft versus Host disease (GVHD) prophylaxis is widely used for unrelated donor allogeneic hematopoietic cell transplantation (HCT) although the optimal dose remains unclear. Recently, registry based and single centre retrospective analyses have suggested superior outcomes with the PTCy based GVHD prophylaxis regimens when compared to ATG based regimens in mismatched unrelated donor (MMUD) allogeneic HCT, however, these studies all used doses of ATG ≥ 5mg/kg. Outcomes following MMUD allogeneic HCT with lower dose ATG based GVHD prophylaxis regimens have not been extensively studied. Thus, we analysed outcomes of HLA 9/10 MMUD allogeneic HCTs using two low dose ATG based regimens as GVHD prophylaxis at our centre. All adult patients undergoing standard of care allogenic hematopoietic cell transplant at The Ottawa Hospital from January 1 st 2015- December 31, 2022 were included. Data regarding demographics, HLA mismatched allele, conditioning regimen, dose of ATG, time to engraftment, and rates of acute and chronic GVHD was collected. The primary outcome evaluated was overall survival (OS) and secondary outcomes were GVHD-free relapse-free survival (GRFS), cumulative incidence of relapse (CIR) and non-relapse mortality (NRM). Survival outcomes were analyzed using Kaplan Meier analysis. Predictors of survival were identified using Cox-proportional hazards regression model. 77 patients (Males 62.3% (n=48); Median age - 50 years) underwent allogeneic HCT from MMUD. Most common indication for transplant was MDS/AML in 66.2% (n=51) followed by ALL in 11.3% (n=9) patients. Most frequently mismatched locus was HLA A in 37.7% (n= 29) followed by HLA B in 14.3% (n=11). Myeloablative conditioning regimen was received by 76.6% (n=59) while reduced intensity regimens were used in 23.4% (n=18) patients. Rabbit ATG was part of the GVHD prophylaxis regimen in all patients with majority (81%; n=63) receiving 2.5mg/kg and remaining 18.2% (n=14) receiving 4.5mg/kg of the drug. Grade II-IV acute GVHD occurred in 24.7% (n=19) while chronic GVHD occurred in 32.5% (n= 25) patients. After a median follow up of 21 months, relapse occurred in 28.6% (n=22) patients. Two year OS (Fig 1), and GRFS of the whole cohort were 60.6% and 45.3% respectively. 2-year incidence of non-relapse mortality (NRM) and cumulative incidence of relapse (CIR) were 16.9% and 18.2% respectively. Dose of ATG (2.5 mg/kg vs 4.5 mg/kg) was not a predictor of outcomes in either univariate and multivariate analyses. Age more than 50 years, primary diagnosis of lymphoma, reduced intensity conditioning and mismatch in loci other than HLA C were significant predictors of poor OS after univariate analysis. Only primary diagnosis of lymphoma (Hazard Ratio (HR) - 7.76; p=0.045) and mismatch in loci other than HLA C (HR - 9.53; p=0.03) were significant predictors of poor OS after multivariate analysis. When compared to published single centre and registry-based studies using ATG doses ≥ 5 mg/kg, GVHD prophylaxis using ATG doses ≤4.5 mg/kg seems to provide improved outcomes in patients undergoing allogeneic HCT from mismatched unrelated donors (Table 1). Our findings suggest that further studies are needed directly comparing lower dose ATG based regimens to PTCy based regimens to determine the ideal GVHD prophylaxis regimen for patients undergoing allogeneic HCT from HLA mismatched unrelated donors.

Combining Low-Dose Post-Transplant Cyclophosphamide(PTCY) with Anti-Thymocyte Globulin(ATG) for Prophylaxis of Graft-Versus-Host Disease in Alternative-Donor Hematopoietic Stem Cell Transplantation for β-Thalassemia Major

Background ： The 5-year overall survival rate (OS) for children with thalassemia major who undergo allogeneic stem cell transplantation is 90% and the event-free survival (EFS) rate is 86%. Due to the limited availability of matched sibling donors, the proportion of transplantations from alternative donors is increasing, particularly from haplo-identical donors. Post-transplant infections and graft-versus-host disease (GVHD) remain the major causes of mortality, especially in those who receive transplantation from alternative donors. Post-transplant cyclophosphamide (PTCY) has shown outstanding results of GVHD prophylaxis in haploidentical matched related donors transplantation with hematological malignancies. However, there is insufficient clinical evidence for its application in pediatric patients who received transplantation from haplo-identical donors with non-malignant hematological disease. Here, we retrospectively analyzed the results of 40 cases that underwent allogeneic stem cell transplantation from haploidentical matched related donors (Haplo-RD) and unrelated donors (UD) to evaluate the safety and efficacy of the novel regimen in GVHD prophylaxis. Method A total of 40 patients with β-thalassemia major received stem cell transplantation, 10 haploid donors (Group Haplo-RD), and 30 unrelated donors (Group UD). Among Group UD, 15 donors were 1 or 2 HLA locus mismatched, remaining 15 were identically matched. The median age of the patients was 5.5 years, ranging from 2 to 12. The Conditioning regimen mainly consisted of fludarabine, busulfan, cyclophosphamide, and thiotepa. GVHD prophylaxis included ATG 1.5mg/kg×3d, cyclophosphamide (CTX) 25mg/kg×2d, cyclosporin A (CsA), and mycophenolate mofetil (MMF). We analyzed the engraftment rate, GVHD incidence, survival rate, and virus reactivation rate for each group. Results Engraftment rate was 100%, with a median time of 11 (10-15) days for neutrophil implantation and 12 (6-31) days for platelet implantation. All patients achieved complete chimerism on day 30 after transplantation. Three cases (7.5%) suffered from Ⅲ-Ⅳ aGVHD, with one being in the Group Haplo-RD group and two in the Group UD. Four cases (10.0%) of cGVHD were recorded. The overall survival (OS) rate and thalassemia-free survival rate were both 92.5%. In Group Haplo-RD, both the OS and thalassemia-free survival rates were 100%. Eight cases reported cytomegaloviremia but no one developed to CMV disease. The total activation rate for CMV was 20%. Nine cases suffered from BK virus urinary tract infection, resulting in a total activation rate of 22.5%. Detailed results are shown in Table 1 and Figure 1. Discussion Due to the high risk of GVHD and infection, stem cell transplantation from haploidentical and unrelated donors cannot be routine therapy for children with thalassemia major. Standard-dose PTCY regimen significantly increases the risk of CMV and BK infection after transplantation and is not suitable for non-malignant disease. The results have been reported that low-dose PTCY/ ATG can reduce the risk of GVHD as compared with standard-dose ATG in haploidentical donor stem cell transplantation. In our study, the novel GVHD prophylaxis regimen, semi-dose PTCY (25mg/kg×2d) combined with low-dose ATG (1.5mg/kg×3d), was used for stem cell transplantation from haploidentical and unrelated mismatched donors. The incidence of III-IV aGVHD was 7.5% and cGVHD was 10.0%, and there was no rejection of the transplant. The activation rate of CMV and BKV was significantly lower than reported in the literature, and the non-relapse mortality (NRM) after transplantation was significantly reduced. There was no statistical difference in the rate of OS, EFS, aGVHD, and cGVHD between Group Haplo-RD and Group UD. The results provide an effective approach for preventing GVHD and infectious diseases in thalassemia patients who underwent allo-HSCT with high-risk GVHD.

The Area Under Tacrolimus Concentrations on Day 14-28 Is the Independent Predictor of the Development of Chronic Gvhd in Patients without Severe Acute Gvhd after Unrelated Allogeneic HSCT

Introduction: In unrelated allogeneic hematopoietic stem cell transplantation (UR-SCT), chronic graft-versus-host disease (GVHD) is a critical complication that affects not only patients' quality of life but also post-transplant outcome. Acute GVHD is a major risk factor for the subsequent development of chronic GVHD. The combination of tacrolimus and short-term methotrexate (TAC+sMTX) has been widely used as a GVHD prophylaxis for UR-SCT in Japan. Previous reports have shown that tacrolimus blood concentrations early after transplantation are associated with the development of acute GVHD, but not with that of chronic GVHD. On the other hand, among UR-SCT recipients who did not develop severe acute GVHD, the relationship between tacrolimus blood concentrations and the development of chronic GVHD remains unclear. Methods: To examine the association between tacrolimus blood concentrations and post-transplant outcomes, the area under the tacrolimus concentration on day 0-14 (AUTC 0-14) and day 14-28 (AUTC 14-28) was calculated simply as the sum of the area of the trapezoid for the corresponding period ( Figure). Tacrolimus was initiated by continuous intravenous administration from day -1 in all patients, and no patients were switched to oral administration prior to day 28. Short-term methotrexate was administered at 10 mg/m 2 on day 1 and 7 mg/m 2 on day 3, day 6, and day 11. Among all 151 adult patients with hematopoietic malignancies who underwent first UR-SCT with GVHD prophylaxis of TAC+sMTX between 2010 and 2022 at the Jikei University Hospital, the following were excluded from the analysis: developing grade III-to-IV acute GVHD, using prednisolone or methyl-prednisolone ≥0.5 mg/kg within day 100, engraftment failure, death before day 100, and relapse before day 100. Results: A total of 68 patients were included in the analysis. Median age was 50.5 (range, 16-68) years. Twenty-seven (40%) patients had acute myeloid leukemia, and 18 (27%) had acute lymphoblastic leukemia. Fifty-five (81%) were in complete remission/chronic phase/early stage. The donor source consisted of 42 (62%) bone marrow transplantation (BMT), 20 (29%) cord blood transplantation (CBT), and 6 (9%) peripheral blood stem cell transplantation (PBSCT). BMT recipients transplanted from 22 (52%) HLA 8/8 matched donor, 19 (45%) HLA 7/8 matched donor, and one (3%) HLA 6/8 matched donor. CBT recipients transplanted from 15 (75%) HLA 4/6 matched donor and 5 (25%) HLA 5/6 matched donor. PBSCT recipients transplanted from 5 (83%) HLA 8/8 matched donor and one (17%) HLA 7/8 matched donor. Fifteen (22%) patients were administered additional low-dose anti-thymocyte globulin (ATG) as GVHD prophylaxis. Fifteen male patients transplanted from female donors (22%). Thirty-nine (57%) patients received myeloablative conditioning regimen. The median time from UR-SCT to neutrophil engraftment was 19 days (range, 11-34). Regarding acute GVHD, 46 patients (68%) developed none, 13 patients (19%) developed grade I, and 9 patients (13%) developed grade II. The median observation period for all 68 patients was 48.2 months (4.0 years). The 4-year cumulative incidence (CI) of chronic GVHD was 51%, of which 24% were moderate-to-severe. The CI of moderate-to-severe chronic GVHD was not associated with age, disease status, donor source, HLA incompatibility, ATG use, female to male, intensity of conditioning regimen, and grade I-to-II acute GVHD development. AUTC 14-28 <200 was the only risk factor (AUTC 14-28<200: 32% vs AUTC 14-28≥200: 11%; p=0.047). Multivariate analysis also showed that AUTC 14-28 <200 was the independent factor for development of moderate-to-severe chronic GVHD ( p=0.04). In all 68 patients, 4-year CI of relapse was 20%, 4-year CI of non-relapse mortality was 10%, 4-year GVHD-free, relapse-free, survival (GRFS) was 50%, and 4-year Overall survival was 80%, all of which did not differ between AUTC 14-28 <200 and AUTC 14-28 ≥200 groups. Conclusion: In UR-SCT, our data showed that AUTC 14-28 <200 may be an independent risk factor for developing moderate-to-severe chronic GVHD, even in patients who did not develop severe acute GVHD.

Low-dose anti-thymocyte globulin in combination with verapamil reverses hyperglycaemia in newly diagnosed diabetic NOD mice

Low-dose anti-thymocyte globulin in combination with verapamil reverses hyperglycaemia in newly diagnosed diabetic NOD mice

Low-dose anti-thymocyte globulin plus low-dose post-transplant cyclophosphamide-based regimen for prevention of graft-versus-host disease after haploidentical peripheral blood stem cell transplants: a large sample, long-term follow-up retrospective study.

The novel low-dose anti-thymocyte (ATG, 5 mg/kg) plus low-dose post-transplant cyclophosphamide (PTCy, 50 mg/kg) (low-dose ATG/PTCy)-based regimen had promising activity for prevention of graft-versus-host disease (GVHD) in haploidentical-peripheral blood stem cell transplantation (haplo-PBSCT), but its impacts on long-term outcomes remain to be defined. We performed a large sample, long-term follow-up retrospective study to evaluate its efficacy for GVHD prophylaxis. The study enrolled 260 patients, including 162 with myeloid malignancies and 98 with lymphoid malignancies. The median follow-up time was 27.0 months. For the entire cohort, the cumulative incidences (CIs) of grade II-IV and III-IV acute GVHD (aGVHD) by 180 days were 13.46% (95% CI, 9.64%-17.92%) and 5.77% (95% CI, 3.37%-9.07%); while total and moderate/severe chronic GVHD (cGVHD) by 2 years were 30.97% (95% CI, 25.43%-36.66%) and 18.08% (95% CI, 13.68%-22.98%), respectively. The 2-year overall survival (OS), relapse-free survival (RFS), GVHD-free, relapse-free survival (GRFS), non-relapse mortality (NRM), and CIs of relapse were 60.7% (95% CI, 54.8%-67.10%), 58.1% (95% CI, 52.2%-64.5%), 50.6% (95% CI, 44.8-57.1%), 23.04% (95% CI, 18.06%-28.40%), and 18.09% (95% CI, 14.33%-23.97%, respectively. The 1-year CIs of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) reactivation were 43.46% (95% CI, 37.39%-49.37%) and 18.08% (95% CI, 13.68%-22.98%), respectively. In multivariate analysis, the disease status at transplantation was associated with inferior survivor outcomes for all patients and myeloid and lymphoid malignancies, while cGVHD had superior outcomes for all patients and myeloid malignancies, but not for lymphoid malignancies. The results demonstrated that the novel regimen could effectively prevent the occurrence of aGVHD in haplo-PBSCT.

Haploidentical Cord Blood Transplantation with 8 mg/kg Antithymocyte Globulin as Graft-versus-Host Disease Prophylaxis Compared to Haploidentical Transplantation with 10 mg/kg Antithymocyte Globulin in the Treatment of Acute Leukemia

Clinical outcomes of the transplantation strategy combined with a haploidentical stem cell graft and an unrelated umbilical cord blood unit (haplo-cord HSCT) with low-dose antithymocyte globulin (ATG) as graft-versus-host disease (GVHD) prophylaxis for the treatment of acute leukemia remains unclear. This study aimed to explore the clinical outcomes of haplo-cord HSCT in acute leukemia patients with the GVHD prevention strategy of 8 mg/kg ATG compared with haploidentical transplantation with 10 mg/kg ATG. A total of 130 patients with acute leukemia who underwent allogeneic HSCT between January 2016 and December 2020 were included in this study, including 70 patients who received haploidentical stem cell grafts and unrelated umbilical cord blood units (haplo-cord HSCT) with 8 mg/kg ATG (haplo-cord-ATG8 group) and haploidentical HSCT with 10 mg/kg ATG (haplo-ATG10 group) in 60 patients. Clinical data were collected and analyzed retrospectively. Patients in the haplo-cord-ATG8 group were significantly older compared with the haplo-ATG10 group (P=.000). Haplo-cord HSCT with reduced ATG to 8 mg/kg results in more rapid neutrophil recovery (P=.036). No between-group differences were observed in platelet recovery or the incidences of Epstein-Barr virus viremia, bloodstream infection, or hemorrhagic cystitis. The rate of grade II-IV acute GVHD by day 100 post-transplantation was higher in the haplo-ATG10 group (27.16% versus 11.48%; P=.033), as was the rate of chronic GVHD at 1 year (14.60% versus 3.36%; P=.048). The rate of cytomegalovirus reaction was higher in the haplo-ATG10 group (48.31% versus 26.30%; P=.022). With a median follow-up of 27.4 months for the haplo-cord-ATG8 group and 27.5 months for the haplo-ATG10 group, overall survival (OS) at 2 years was 79.4% versus 62.8% (P=.005), event-free survival (EFS) was 76.3% versus 55.9% (P=.001), the cumulative incidence of relapse was 10.11% versus 25.97% (P=.164), and nonrelapse mortality (NRM) was 14.33% versus 24.43% (P=.0040). Multivariate analysis identified Center for International Blood and Marrow Transplant Research Disease Risk Index was the sole significant predictor of relapse, NRM, OS, and EFS. Haplo-cord HSCT supported by cord blood with 8 mg/kg ATG as GVHD prophylaxis results in better outcomes compared with haplo-HSCT with 10 mg/kg ATG.

Responders to low-dose ATG induce CD4+ T cell exhaustion in type 1 diabetes.

BACKGROUNDLow-dose anti-thymocyte globulin (ATG) transiently preserves C-peptide and lowers HbA1c in individuals with recent-onset type 1 diabetes (T1D); however, the mechanisms of action and features of the response remain unclear. Here, we characterized the post hoc immunological outcomes of ATG administration and their potential use as biomarkers of metabolic response to therapy (i.e., improved preservation of endogenous insulin production).METHODSWe assessed gene and protein expression, targeted gene methylation, and cytokine concentrations in peripheral blood following treatment with ATG (n = 29), ATG plus granulocyte colony-stimulating factor (ATG/G-CSF, n = 28), or placebo (n = 31).RESULTSTreatment with low-dose ATG preserved regulatory T cells (Tregs), as measured by stable methylation of FOXP3 Treg-specific demethylation region (TSDR) and increased proportions of CD4+FOXP3+ Tregs (P < 0.001) identified by flow cytometry. While treatment effects were consistent across participants, not all maintained C-peptide. Responders exhibited a transient rise in IL-6, IP-10, and TNF-α (P < 0.05 for all) 2 weeks after treatment and a durable CD4+ exhaustion phenotype (increased PD-1+KLRG1+CD57- on CD4+ T cells [P = 0.011] and PD1+CD4+ Temra MFI [P < 0.001] at 12 weeks, following ATG and ATG/G-CSF, respectively). ATG nonresponders displayed higher proportions of senescent T cells (at baseline and after treatment) and increased methylation of EOMES (i.e., less expression of this exhaustion marker).CONCLUSIONAltogether in these exploratory analyses, Th1 inflammation-associated serum and CD4+ exhaustion transcript and cellular phenotyping profiles may be useful for identifying signatures of clinical response to ATG in T1D.TRIAL REGISTRATIONClinicalTrials.gov NCT02215200.FUNDINGThe Leona M. and Harry B. Helmsley Charitable Trust (2019PG-T1D011), the NIH (R01 DK106191 Supplement, K08 DK128628), NIH TrialNet (U01 DK085461), and the NIH NIAID (P01 AI042288).

Reduced post-transplant cyclophosphamide dose with antithymocyte globulin in peripheral blood stem cell haploidentical transplantation.

Post-transplant cyclophosphamide (PT-Cy) is effective for graft-versus-host disease (GVHD) prophylaxis, but it may cause dose-dependent toxicities, particularly in frail patients. Therefore, we compared the outcomes with a reduced PT-Cy total dose (70 mg/kg) to those with the standard PT-Cy dose (100 mg/kg) in haploidentical hematopoietic cell transplantation (HCT) patients aged ≥65 years and those with cardiac comorbidities. All consecutive patients with a hematological malignancy receiving peripheral blood stem cells (PBSCs) after a thiotepa-based conditioning with low-dose antithymocyte globulin were included. Thirty-three patients received PT-Cy at 70 mg/kg and 25 at 100 mg/kg. PT-Cy dose reduction did not increase the risk of GVHD and was associated with faster neutrophil and platelet recovery, and lower cumulative incidences of bacteremia (38% versus 72%, p = 0.004) and cardiac complications (12% versus 44%, p = 0.028). At 2 years, GVHD-free, relapse-free survival (GRFS) was higher with the reduced dose compared to the standard dose (60% versus 33%, p = 0.04). In conclusion, reducing PT-Cy total dose to 70 mg/kg is a safe and valid approach for elderly patients and those with cardiac comorbidities underdoing haploidentical HCT with PBSCs and low-dose antithymocyte globulin. The reduced PT-Cy dose was associated with improved hematological count recovery, lower incidence of toxicities, and higher GRFS.

Evaluating anti-thymocyte globulin induction doses for better allograft and patient survival in Asian kidney transplant recipients

Anti-thymocyte globulin (ATG) is currently the most widely prescribed induction regimen for preventing acute rejection after solid organ transplantation. However, the optimal dose of ATG induction regimen in Asian kidney recipients is unclear. Using the Korean Organ Transplantation Registry, we performed a retrospective cohort study of 4579 adult patients who received renal transplantation in South Korea and divided them into three groups according to the induction regimen: basiliximab group (n = 3655), low-dose ATG group (≤ 4.5 mg/kg; n = 467), and high-dose ATG group (> 4.5 mg/kg; n = 457). We applied the Toolkit for Weighting and Analysis of Nonequivalent Groups (TWANG) package to generate high-quality propensity score weights for intergroup comparisons. During four-year follow-ups, the high-dose ATG group had the highest biopsy-proven acute rejection rate (basiliximab 20.8% vs. low-dose ATG 22.4% vs. high-dose ATG 25.6%; P < 0.001). However, the rates of overall graft failure (4.0% vs. 5.0% vs. 2.6%; P < 0.001) and mortality (1.7% vs. 2.8% vs. 1.0%; P < 0.001) were the lowest in the high-dose ATG group. Our results show that high-dose ATG induction (> 4.5 mg/kg) was superior to basiliximab and low-dose ATG induction in terms of graft and patient survival in Asian patients undergoing kidney transplant.

Effects of Induction Therapy on Graft Functions in Terms of Immunologic Risk

Advances in immunosuppressive therapies and surgical techniques have led to a significant reduction in the incidence of rejection within 1 year after kidney transplantation. Immunologic risk is an important factor affecting graft functions and guiding the clinician in the selection of induction therapy. The aim of this study was to investigate graft functions based on serum creatinine levels, Chronic Kidney Disease Epidemiology Collaboration (CKD- EPI) and proteinuria levels, frequency of leukopenia, cytomegalovirus (CMV) and BK virus polymerase chain reaction (PCR) positivity in patients with low and high immunologic risk. This retrospective study included 80 renal recipients. Recipients were divided into 2 groups: patients at low immunologic risk who received basiliximab only and those with high immunologic risk who received low-dose (1.5 mg/kg for 3 days) antithymocyte globulin and basiliximab. No significant differences were observed between the 2 risk groups in terms of first, third, sixth, and 12th-month creatinine levels, CKD-EPI, proteinuria levels, leukopenia frequency, and CMV and BK virus PCR positivity. One-year graft survivals did not differ significantly between these 2 treatment modalities. The combined use of low-dose antithymocyte globulin and basiliximab in the induction treatment of patients with high immunologic risk seems promising in terms of graft survival, leukopenia frequency, and CMV and BK virus PCR positivity.

298-OR: Safety and Efficacy of Immunomodulatory Therapy Using Antithymocyte Globulin and Pegfilgrastim in Japanese Patients with Type 1 Diabetes—A Pilot Randomized Clinical Trial

While immunomodulatory therapy using low-dose anti-thymocyte globulin (ATG) has been shown to be efficacious in preserving pancreatic beta-cell function in patients with type 1 diabetes (T1D) in the United States, no clinical trials of immunomodulatory therapy for T1D have been reported in Asia. In this study, we first evaluated the safety and efficacy of ATG/pegfilgrastim (PEG) therapy in Japanese patients with T1D. This was a pilot, open-label, randomized clinical trial. Twelve patients, with the age ≥ 20 years, T1D duration &amp;lt; 12 months, and serum CPR ≥ 0.3 ng/ml, were randomized into the ATG/PEG group (A/P; n = 6) and control group (Ctrl; n = 6). The A/P was administered 2.0 mg/kg ATG and six times of 3.5 mg PEG. The primary endpoint was the frequency of adverse events (AEs), which were evaluated per the CTCAE v5.0, and secondary endpoints included the percentages of decline (%Dec) in CPR-area under the curve (AUC) after mixed-meal loading, the SUIT index, and changes in glycemic control during an observation period of 104 weeks. Regarding safety, no grade 4 and 5 AEs were reported in either group. Grade 3 lymphocytopenia, which is considered to be the clinical effect of ATG, was noted in all 6 patients in the A/P. One severe AE, cellulitis, was reported in the Ctrl. The frequencies of infection were not significantly different between the two groups. Regarding efficacy, %Dec in CPR-AUC in 52 weeks was less than the median value in 5 out of 6 patients in the A/P, whereas 1 out of 5 patients in Ctrl (P = 0.03). Additionally, %Dec in the SUIT index in 104 weeks tended to be lower in the A/P than in the Ctrl (P = 0.06). Changes in HbA1c and glycated albumin levels and the amount of insulin administered were not significantly different between the two groups. In conclusion, ATG/PEG therapy was safely administered to Japanese patients with T1D. Larger scale trials and mechanistic analyses are required to confirm the efficacy of this treatment. Disclosure D.Chujo: None. N.Ohmagari: None. H.Ohyanagi: None. M.Shimoda: None. K.Ueki: Advisory Panel; Abbott Japan Co., Ltd., Research Support; Abbott Japan Co., Ltd., Boehringer Ingelheim Japan, Inc., Eli Lilly Japan K.K., Sumitomo Dainippon Pharma Co., Ltd., Novo Nordisk, Sanofi K.K., MSD Life Science Foundation, Takeda Pharmaceutical Co., Ltd., Speaker's Bureau; Boehringer Ingelheim Japan, Inc., Eli Lilly Japan K.K., Astellas Pharma Inc., AstraZeneca, Sumitomo Dainippon Pharma Co., Ltd., Novo Nordisk, Taiho Pharmaceutical Co. Ltd., Kowa Company, Ltd., Mitsubishi Tanabe Pharma Corporation, Ono Pharmaceutical Co., Ltd. H.Kajio: None. K.Tobe: Other Relationship; MSD K.K., Novo Nordisk Pharma Ltd., Takeda Pharmaceutical Company Limited, Daiichi Sankyo, Mitsubishi Tanabe Pharma Corporation, Suntory Global Corporation, Ltd.,, Taiho Pharmaceutical Co. Ltd., Japan Diabetes Foundation, Japan Association for Diabetes Education and Care. A.Enkaku: None. M.Kamigishi: None. A.Takikawa: None. M.Matsushita: None. M.Kobayashi: None. K.Yamamoto: None. T.Sato: None. Y.Yamamoto: None. Funding National Center for Global Health and Medicine (28A1204); Japan IDDM Network

Post-transplantation cyclophosphamide combined with tacrolimus and low-dose post-engraftment anti-thymoglobulin as GVHD prophylaxis for patients undergoing peripheral blood stem cell transplantation from haploidentical family donor: A single center analysis.

Post-transplantation cyclophosphamide (PT-Cy) use is a recent graft-versus-host disease (GVHD) prophylaxis strategy for patients undergoing allogeneic stem cell transplantation (allo-HSCT). PT-Cy combined with two immunosuppressants is now widely used after haplo-identical (haplo) and HLA-matched peripheral blood stem cell (PBSC) transplantations with promising GVHD and relapsefree survival (GRFS) probabilities. Although appealing, these results may benefit from improvement notably outside matched sibling donor transplantation, and should be investigated in various ethnic populations. Therefore, we report our experience of GVHD prophylaxis regimen combining PT-Cy and tacrolimus with addition of post-engraftment low-dose anti-thymocyte globulin (ATG) in allogeneic stem cell transplantation from haplo-identical donors (Haplo). Sixtyseven patients were included in the analysis. All patients received myeloablative or intensified sequential conditioning regimen. The median follow-up was 521 (range, 10~991) days. The cumulative incidences of 100-day grade II-IV acute GVHD was 14.9±4.4%, and no case of grade III-IV acute GVHD was documented. The cumulative incidences of 2-yearchronic GVHD and moderate-to-severe chronic GVHD were 25.4±5.4% and 11.9±4%, respectively. The non-relapse mortality at day+100 and 2year were 7.5±3.2% and 9.0±3.5%, respectively. The cumulative incidence of relapse at 2year was 16±6.4%. The 2-year probability of DFS and OS were 73.8% (95%CI, 61.5~88.4%) and 72.5% (95% CI, 57.1~92.1%), respectively. The 2-year GRFS was estimated as 63.6% (95%CI, 50.6~80%). Our results suggested that a combination of PT-Cy, tacrolimus, and low-dose post-engraftment ATG was a promising GVHD prophylaxis with low incidence of acute GVHD in the haplo-transplantation setting.

Post-Transplantation Cyclophosphamide Combined with Tacrolimus and Low-Dose Post-Engraftment Anti-Thymoglobulin As Gvhd Prophylaxis for Patients Undergoing Peripheral Blood Stem Cell Transplantation from Haplo Donors: A Single Center Analysis

Post-transplantation cyclophosphamide (PT-Cy) use is a recent graft-versus-host disease (GVHD) prophylaxis strategy for patients undergoing allogeneic stem cell transplantation (allo-HSCT). PT-Cy combined with two immunosuppressants is now widely used after haplo-identical (haplo) and HLA-matched peripheral blood stem cell (PBSC) transplantations with promising GVHD and GVHD and relapse-free survival (GRFS) probabilities. Although appealing, these results may benefit from improvement notably outside matched sibling donor transplantation, and should be investigated in various ethnic populations. Therefore, we report our experience of GVHD prophylaxis regimen combining PT-Cy and tacrolimus with addition of post-engraftment low-dose anti-thymocyte globulin (ATG) in allogeneic stem cell transplantation from haplo-identical donors (Haplo). Fifty-three patients were included in the analysis. All patients received myeloablative or intensified sequential conditioning regimen. The median follow-up was 397 (range, 191~762) days. The cumulative incidences of 100-day grade II-IV acute GVHD was 9.4±4.1%, and no case of grade III-IV acute GVHD was documented. The cumulative incidences of 1-year chronic GVHD and moderate-to-severe chronic GVHD were 18.9±5.4% and 7.5±3.7%, respectively. The non-relapse mortality at day+100 and 1 year were 9.4±4.4% and 11.3±4.4%, respectively. The cumulative incidence of relapse at 1 year was 3.8±2.7%. The 1-year probability of DFS and OS were 84.5% (95%CI, 75.2~95.0%) and 88.7% (95% CI, 80.5~97.6%), respectively. The 1-year GRFS was estimated as 75.0% (95%CI, 64.1~87.8%). Our results suggested that a combination of PT-Cy, tacrolimus, and low-dose post-engraftment ATG was a promising GVHD prophylaxis with low incidence of acute GVHD in the haplo-transplantation setting. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Low-Dose Antithymocyte Globulin Plus Low-Dose Post-Transplant Cyclophosphamide for Prevention of Graft-Versus-Host Disease after Haploidentical Peripheral Blood Stem Cell Transplants: A Large Sample, Long-Term Follow-up Retrospective Study

Background: The use of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) to treat hematological diseases is increasing. Two regimens for in vivo T-cell depletion are currently used in haplo-HSCT for prophylaxis of graft-versus-host disease (GVHD), including anti-thymocyte globulin (ATG)-based and posttransplant cyclophosphamide (PTCy)-based regimens. Our previous studies have demonstrated that low-dose ATG plus low-dose PTCy (low-dose ATG/PTCy) combined with cyclosporine (CSA) and mycophenolate mofetil had promising activity for the prevention of GVHD in haploidentical peripheral blood stem cell transplantation (haplo-PBSCT). Now, the efficacy of the low-dose ATG/PTCy regimen for GVHD prevention in haplo-HSCT was evaluated in a large sample with a long-term follow-up. Methods: The patients undergoing haplo-PBSCT between May 2017 and June 2021 in our center were enrolled in the retrospective study. The study included a variety of hematological diseases, such as acute myeloid leukemia (AML, n=113), acute lymphoblastic leukemia (ALL, n=49), mixed phenotype acute leukemia (MPAL, n=4), myelodysplastic syndromes (MDS, n=18), chronic myeloid leukemia (CML, n=10), non-Hodgkin's lymphoma (NHL, 30) and multiple myeloma (MM, n=1). All patients received low-dose ATG/PTCy regimen for prophylaxis of GVHD including ATG 2.5 mg/kg administered on day −2 to −1 and cyclophosphamide (Cy) 50 mg/kg on day +3, cyclosporine A (CsA) and mycophenolate mofetil (MMF) initiating on day +4. The starting infusion dose of CsA was 2 mg/kg, after which the dose was modified to obtain a nadir serum level between 200 and 300 ng/ml, eventually tapering from day +90 to day +180. MMF was administered orally at 15 mg/kg three times daily (maximum dose of 3 g per day) until day +34 and discontinued if no aGvHD. Mycophenolic acid sodium enteric tablets (MPA) correspond to MMF instead. Grafts were from mobilized peripheral blood stem cells. Family members selected as haploidentical donors were defined on the HLA-A, -B, -C, -DRB1, and -DQB1 locus at the high-resolution level of the recipient donor number of human leukocyte antigen (HLA) mismatches >2. Results: Two hundred and twenty-five patients undergoing haplo-PBSCT were enrolled in the study. There were 144 males and 81 females with a median age of 38 years (range, 6 to 69 years). At the time of transplantation, 146 (64.89%, 146/225) patients were in complete response (CR), while 79 (35.11%, 79/225) patients had active disease. One hundred and five patients received myeloablative conditioning (MAC) regimens, while 40 patients received reduced-intensity conditioning (RIC) regimens. All patients received PBSC grafts with the median CD34+ cells of 10.3 (1.64-46.55) × 108/kg, and the median mononuclear cells (MNCs) was 15.35 (3.48-39.74) × 108/kg. Ten patients failed to engraft, including 6 patients with primary graft failure and 4 with secondary graft failure. The median time for neutrophil engraftment was 12 days (range, 9-28 days), while the median time for platelet engraftment was observed in 13 days (range, 9-87 days). The cumulative incidence (CI) of grades I-IV acute GVHD (aGVHD) was 30.7% (24.6-36.9%). The CIs of grades II-IV and III-IV acute GVHD by 100 days post-transplant were 12.4% (95%CI, 8.0-16.8%) and 4.6% (95%CI, 1.8-7.4%), respectively. While chronic GVHD was 31.2% (95%CI, 24.6-37.9%) and moderate/severe chronic GVHD was 16.4% (95%CI, 11.1%-21.7%). A total of 90 patients died. Fifty-nine patients died of non-relapse causes (NRM 59/225, 26.2%). With a median follow-up of 26 months (range, 0-61 months), 50 cases relapsed. The median time of relapse was 15.5 months (range, 1−46 months). The mean OS and DFS were 38.01 months (95%CI, 34.33-41.6%) and 35.45 months (95%CI, 31.75-39.15%). The 2-year disease-free survival (DFS), overall survival (OS), and GVHD-free, relapse-free survival (GRFS) was 54.8% (95%CI, 48.94-62.26%) and 60.9% (95%CI, 54.24-67.56%) and 48.0% (95%CI, 41.14-54.86%), respectively. The 2-year CI of relapse was 26.6% and NRM was 16.6%. All patients were included in immune reconstitution studies and 81 cases were analyzed at each endpoint. On days +120, median CD3+, CD4+, CD8+, CD19+ and CD56/CD16+ counts were 954 (95-4891), 180 (8-743),754 (73-4272), 34 (1-276) and 215 (19-2539)/μl, respectively. Conclusion: The low-dose ATG/PTCy regimen presented a high efficacy for prophylaxis of GVHD in haplo-PBSCT.

Reduced Post-Transplant Cyclophosphamide Dose Associated with Antithymocyte Globulin in Peripheral Blood Stem Cell Haploidentical Transplantation

INTRODUCTION Post-transplant cyclophosphamide (PT-Cy) has become the standard graft-versus-host disease (GVHD) prophylaxis for haploidentical hematopoietic cell transplantation (HCT) and has been increasingly used in allogeneic HCT with HLA-matched donors. However, PT-Cy is associated with significant toxicities and organ damage, especially in elderly patients. While toxicities may be correlated with the total cyclophosphamide dose, few studies have evaluated the safety and efficacy of different PT-Cy doses. We aimed to compare the outcomes with a reduced PT-Cy total dose of 70 mg/kg to those with PT-Cy at 100 mg/kg in elderly patients and patients with cardiac comorbidities undergoing haploidentical HCT. PATIENTS AND METHODS Inclusion criteria included: (1) age ≥ 65 years, or patients of any age with a history of cardiac events, (2) hematological malignancy, (3) haploidentical HCT, (4) peripheral blood stem cells, and (5) thiotepa-based conditioning regimen with antithymocyte globulin (ATG). Since 2015, our center policy has been PT-Cy at 100 mg/kg divided in 2 doses, to all patients. Starting from 2020, 40 patients have received PT-Cy at 35 mg/kg/day on day+3 and day+4 either because of older age or cardiac comorbidities. RESULTS Fifty-eight patients met the inclusion criteria. Median age was 68 years (range, 15-76) and 60% of patients were male. Median HCT-specific comorbidity index (HCT-CI) score was 2 (range, 0-5). Patients were transplanted for acute myeloid leukemia (n=37, 64%), myelodysplastic syndrome (n=11, 19%), lymphoma (n=8, 14%), or myeloproliferative neoplasm (n=2, 3%). Disease risk index was intermediate in 22 (38%) patients and high or very high in 36 (62%). Disease status at transplantation was complete remission in 18 patients (31%). Conditioning regimens were reduced intensity thiotepa-based (thiotepa - busulfan - fludarabine) in 25 (43%) patients or Flamsa-like sequential (thiotepa - etoposide - cyclophosphamide, followed by fludarabine - busulfan) in 33 (57%). GVHD prophylaxis included cyclosporin, mycophenolate mofetil, and ATG in all patients. Thirty-three patients received PT-Cy at 70 mg/kg and 25 at 100 mg/kg. There was no significant difference between the 2 groups (PT-Cy at 70 mg/kg versus 100 mg/kg) in terms of age, gender, HCT-CI score, cardiovascular risk factors, type of hematological disease, disease risk index, disease status, and type of conditioning regimen. The median follow-up was 17 months (interquartile range [IQR], 13-20) and 59 months (IQR, 51-66) in patients receiving PT-Cy at 70 mg/kg and 100 mg/kg, respectively. The cumulative incidences (CIs) of acute grade II-IV and grade III-IV GVHD were 18% and 0% with PT-Cy at 70 mg/kg compared to 17% and 5% with 100 mg/kg, respectively (p=0.94 for grade II-IV and p=0.87 for grade III-IV acute GVHD). The CI of chronic GVHD was 27% and 29% with PT-Cy at 70 mg/kg and 100 mg/kg, respectively (p=0.95). No significant difference was observed for moderate to severe chronic GVHD. Neutrophil recovery was significantly improved with 70 mg/kg compared to 100 mg/kg (median time of 16 versus 19 days, respectively, p=0.006). At days +30, +60, and +90 after HCT, 75%, 88% and 91% patients had a platelet count > 50 x 109/L with 70 mg/kg of PT-Cy, respectively, compared to 36%, 64%, and 64% with 100 mg/kg of PT-Cy, respectively (p=0.011). The CI of post-HCT bacteremia was 38% with PT-Cy at 70 mg/kg and 72% with 100 mg/kg (p=0.004). Other complications commonly associated with PT-Cy were also reduced with 70 mg/kg compared to 100 mg/kg of PT-Cy, such as BK-virus associated hemorrhagic cystitis (12% versus 28%) and left ventricular systolic dysfunction (9% versus 24%). At 2 years, CIs of non-relapse mortality were 18% and 33% (p=0.13), progression free-survival 65% and 46% (p=0.09), overall survival 68% and 52% (p=0.31), and GVHD-free, relapse-free survival 60% and 33% (p=0.04) with 70 mg/kg and 100 mg/kg of PT-Cy, respectively. CONCLUSIONS Reducing PT-Cy dose to 70 mg/kg is a safe and valid approach in elderly patients and patients with cardiac comorbidities underdoing haploidentical HCT with peripheral blood stem cells and low-dose ATG. Compared to 100 mg/kg, neutrophil and platelet recovery were improved, CIs of bacteremia, BK-virus associated hemorrhagic cystitis, and cardiac complications were reduced, the risk of acute and chronic GVHD was not increased, and GVHD-free, relapse-free survival was higher with PT-Cy at 70 mg/kg. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal