Antithymocyte Globulin Conditioning Research Articles

Cyclophosphamide and horse anti-thymocyte globulin versus fludarabine, reduced cyclophosphamide and rabbit anti-thymocyte globulin conditioning regimen for allogeneic hematopoietic stem cell transplantation from matched sibling donors in patients with acquired aplastic anemia

ABSTRACT Background Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment for acquired aplastic anemia (acquired AA) in young patients. The objective of the study was to compare patient outcomes after Cyclophosphamide and horse antithymocyte globulin (Cy-hATG) versus Fludarabine-cyclophosphamide and rabbit ATG (Flu-Cy-rATG) as part of conditioning regimen in allo-HSCT for acquired AA. Research design and methods Descriptive retrospective study conducted on patients with acquired AA who received allo-HSCT from HLA-matched sibling donors between January 2008 and August 2022 after conditioning regimen with Cy-hATG or Flu-Cy-rATG. Results A total of 121 patients were enrolled. Cumulative incidence of graft failure was 11.2% in Cy-hATG and 5.3% Flu-Cy-rATG group. There were no significant differences between the two groups in terms of acute GVHD, chronic GVHD, and transplant related mortality. Flu-Cy-rATG group was associated with significantly higher CMV and EBV reactivation(s) compared to Cy-hATG group (p = 0.008 and 0.035, respectively). After a median follow-up of 58 months, estimated overall survival, event-free survival, and graft rejection-free survival were not statistically different between the two groups. Conclusions In high-risk population, Flu-Cy-rATG is associated with comparable outcomes to Cy-hATG in allo-HSCT from MSD. However, it seems to be associated with significant risk of viral infections.

Utility of pulmonary function test screening for bronchiolitis obliterans syndrome stage 0-p among recipients of allogeneic hematopoietic stem cell transplantation conditioned with antithymocyte globulin

INTRODUCTION Timely diagnosis of bronchiolitis obliterans syndrome (BOS) following allogeneic hematopoietic cell transplantation (allo-HCT) is challenging due to the paucity of symptoms early in the disease course. Pulmonary function tests (PFT) are proposed as a screening tool to identify patients at risk of developing BOS in this population. METHODS We performed a retrospective study including patients who underwent allo-HCT with antithymocyte globulin (ATG) conditioning between May 2010 and August 2020, survived without relapse for at least 3 months, and had a pre-transplant PFT and at least 2 post-transplant PFTs. Patients met BOS-0p if their PFTs demonstrated a sustained >10% drop in FEV1 or >25% drop in FEF25-75. A competing risks regression model was used to estimate the cumulative incidence of BOS and BOS-0p. Test performance characteristics for BOS-0p were calculated using 2x2 tables. RESULTS The cumulative incidence of BOS was 2.1% (CI 0.8-4.6) at 12 months and 5.4% (CI 2.8-9.3) at 60 months post-transplant. Meeting BOS-0p during the first 2 years post-transplantation yielded a sensitivity of 64% (CI 31-89), specificity of 71% (CI 64-77), PPV of 10% (CI 4-20), and NPV of 97% (CI 93-99) for subsequent development of BOS. Meeting BOS-0p was associated with increased mortality (HR 2.27, p = 0.006). CONCLUSION Although patients who meet BOS-0p within 2 years of transplant are more likely to develop BOS, prompt repeat testing is needed to confirm entry into the stage if a patient meets spirometric criteria on a single PFT.

Superior Outcome of Bone Marrow Transplantation Using Fludarabine and Cyclophosphamide with ATG over Fludarabine and Cyclophosphamide without ATG Conditioning Regimen in Severe Aplastic Anemia

ABSTRACT Background: Matched sibling donor (MSD) allogenic hematopoietic stem cell transplantation (allo-HSCT) is the standard of care as the first line therapy for young fit patients with severe aplastic anemia (SAA). There are several conditioning regimens that have been evaluated and used for these patients. Fludarabine (Flu)/cyclophosphamide (Cy)/antithymocyte globulin (ATG) or Cy/ATG led to the best survival. The 5-year probabilities of survival after Flu/Cy/ATG, Cy/ATG, Cy ± Flu, and Busulfan /Cy were 91% (95% CI, 85-96), 91% (95% CI, 89-94), 80% (95% CI, 73-87), and 84% (95% CI, 75-91) (P = .001), (Bejanyan et al. 2019). Objective: To report the outcome of a homogeneous cohort of SAA patients who received a uniform transplantation conditioning regimen protocol (Flu/Cy/ATG) and compare it with the historical protocol (Flu/Cy) from the same transplant center for the same patients population. Methods: This study is a 10-year retrospective analysis of SAA patients who underwent MSD allo-HSCT at King Faisal Specialist Hospital & Research Centre, Riyadh City, Saudi Arabia during the period from 2013 to 2022. The conditioning regimen was consistent of Fludarabine 150 mg/m 2/Cyclophosphamide 200 mg/kg/ Anti-thymocyte globulin (rabbit) 2.5 mg/kg (Flu/Cy/ATG). Graft-versus-host disease (GVHD) prophylaxis was methotrexate (MTX)/tacrolimus (FK) or methotrexate/cyclosporin (CsA). The outcome was compared with the historical published data of 82 patients with SAA received Flu/Cy conditioning regimen for MSD allo-HSCT, (El Fakih et al. 2021). Results: The study included 28 patients with SAA, 46.2% (n=12) patients were females, paroxysmal nocturnal hemoglobinuria (PNH) clone detected in 57.1% (n=16). Total body irradiation (TBI) was added to the conditioning regimen in 25% (n=7) for patients with heavily blood products transfusion pre-HSCT. A total of twenty-six patients (93%) has fully MSD, while 2 (7%) has matched unrelated donors (MUD). Bone marrow (BM) was the stem cell source in 60.7% while 28.6% received peripheral blood (PB) stem cell and 10.7 % received combined (BM/PB). There were twelve patients with donor-recipient sex mismatch. Major ABO mismatch counted for 17.9% (n=5). The median age at transplantation was 25 ±10.2 years. During the observational period, there was no graft failure (GF) and none of the patients died. At 60 days of HSCT; 61 % (n=17) patients achieved full donor whole blood (WB) chimerism, while 11 (39 %) patients had mixed chimerism. At both 180 days and 365 days of HSCT; 69.2% (n=18) patients had full donor chimerism and 30.8% (n=8) of the patients had mixed donor chimerism. Acute GVHD occurs in five cases (17.9%) and none had developed grade III or IV, notably; 80% of GVHD cases (4/5) received PB or BM/PB stem cell source. Chronic GVHD was observed in six cases (21.7%), 66% (4/6) of them had received PB or PB/BM stem cell source. The use of PB was due to either donor related reasons like recipient-donor weight discrepancy or patient's medical condition to achieve early engraftment. Hemorrhagic cystitis occurred in one case (3.6%), none had sinusoidal obstruction syndrome (SOS). CMV viremia without disease occurs in eleven patients (39 %). The median follow-up time for survivors was 34 months, the 2 years overall survival (OS) was 100%, the 2 years event free survival (EFS) defined with GF, or death was 100% compared with the previous result published (El Fakih et al., 2021) which had showen lower OS and EFS of 87.8% and 82.9% respectively with median follow-up of 100 months, Figure1&2. Table-1 and table-2 summarize the comparison of patient's characteristics and outcome of both regimens (Flu/Cy vs Flu/Cy/ATG). Conclusions: The results of the present study showed better outcomes for SAA patients using Flu/Cy/ATG compared with the previous study (El Fakih et al., 2021). Early MSD allo-HSCT for SAA patients using Flu/Cy/ATG conditioning regimen is associated with a favorable outcome of excellent graft function, low rate GVHD and no GF. BM should be the stem cell source in severe aplastic anemia HSCT procedure. Key Words: Severe Aplastic Anemia, Matched Sibling Donor, Conditioning, Bone Marrow Graft, Flu/Cy/ATG.

Outcome of first or second transplantation using unrelated umbilical cord blood without ATG conditioning regimen for pediatric bone marrow failure disorders

BackgroundUnrelated umbilical cord blood transplantation (UCBT) for bone marrow failure (BMF) disorders using conditioning regimens without Anti-Thymocyte Globulin (ATG) has been used as an alternative transplantation for emerging patients without matched-sibling donors. Experience with this transplant modality in children is limited, especially as a secondary treatment for transplant failure patients. ProcedureWe retrospectively reviewed 17 consecutive bone marrow failure patients who underwent unrelated umbilical cord blood transplantation in our center and received conditioning regimens of Total Body Irradiation (TBI) or Busulfan (BU) + Fludarabine (FLU) + Cyclophosphamide (CY). ResultsAmong the 17 BMF patients, 15 patients were treated with first cord blood transplantation and another 2 with secondary cord blood transplantation because of graft failure after first haploidentical stem cell transplantation at days +38 and +82.All patients engrafted with a median donor cell chimerism of 50 % at days +7 (range, 16 %–99.95 %) and finally rose to 100 % at days +30. Median time to neutrophil engraftment was 19 days (range, 12–30) and time to platelet engraftment was 32 days (range, 18–61). Pre-engraftment syndrome (PES) was found in 16 patients (94.11 %, 16/17). Cumulative incidence of grades II to IV acute GVHD was 58.8 % (95 % CI: 32.7–84.9 %), and 17.6 % (95 % CI: 2.6–37.9 %) of patients developed chronic GVHD. The 3-year overall survival (OS) and failure-free survival (FFS) rates were 92.86 ± 6.88 %. ConclusionUCBT is an effective alternative treatment for bone marrow failure pediatric patients. TBI/BU + FLU + CY regimen ensure a high engraftment rate for unrelated umbilical cord blood transplantation, which overcomes the difficulty of graft failure. Secondary salvage use of cord blood transplantation may still be useful for patients who have failed after other transplantation.

Impact of Baseline and Week 2 and Week 4 Posttransplant CMV Cell-Mediated Immunity on Risk of CMV Infections and Mortality in Recipients of Allogeneic Hematopoietic Cell Transplant.

Cytomegalovirus (CMV) infection is a common opportunistic infection after allogeneic hematopoietic cell transplant (alloHCT). We explored whether a change in CMV cell-mediated immunity during the first month after transplant predicts the risk of development of CMV infection and all-cause mortality. This follow-up analysis is based on data from the REACT study, a multicenter prospective observational study of recipients of alloHCT who were CMV-seropositive. Production of interferon γ following ex vivo stimulation with CMV antigens IE1 (immediate early 1) and pp65 (phosphoprotein 65) was assessed by CMV ELISPOT assay at baseline and 2 and 4 weeks after transplant. Clinically significant CMV infection (CS-CMVi) was defined as CMV viremia and/or disease necessitating antiviral therapy. We evaluated the impact of CMV CMI changes on the risk of CS-CMVi and post transplant mortality. The analysis included 226 recipients of alloHCT with CMV cell-mediated immunity data at baseline and 2 and/or 4 weeks after transplant. CS-CMVi occurred in 64 patients (28%). On Cox regression analyses, independent predictors of CS-CMVi included a negative Δ change from baseline to week 2 of pp65 spot counts (hazard ratio, 3.65 [95% CI, 1.65-8.04]; P = .001) to week 4 of IE1 spot counts (hazard ratio, 2.79 [95% CI, 1.46-5.35]; P = .002), anti-thymocyte globulin conditioning regimen, type of transplant, female sex, and corticosteroid use. Kaplan-Meir analysis showed a significant association of a negative IE1 change from baseline to week 4 and increased all-cause mortality after transplant (log rank test = 0.041). A decrease in CMV-specific T-cell responses during the first month after transplant may predict CS-CMVi and is associated with all-cause mortality in recipients of alloHCT.

Intensified conditioning regimen with fludarabine combined with post-transplantation cyclophosphamide for haploidentical allogeneic hematopoietic stem cell transplantation in children with high-risk acute leukemia

ABSTRACTObjective:Post-transplantation cyclophosphamide (PTCy) can reduce the incidence of graft versus host disease (GVHD) and this intervention is often applied on adults with hematologic malignancy. However, the high relapse rate hinders the development of the intervention and data of PTCy used on children with hematologic malignancy remains limited. In order to overcome issue of high relapse rate in PTCy treatment, we used fludarabine (Flu), enhanced dose of cytarabine (Ara-C, 9 g/m2), busulfan (Bu), Cy, anti-thymocyte globulin (ATG) combined with PTCy for an intensified conditioning regimen.Methods:A total of 22 children with acute leukemia received intensified PTCy conditioning regimen (PTCy intensified group). We matched with 18 children who received modified Bu-Cy and ATG conditioning regimen in the same period (ATG group).Results:The two-year cumulative incidences of grade II–IV acute GVHD was significantly lower in PTCy intensified group (13.6 ± 7.7% vs 38.9 ± 11.5%, P = 0.048). Two-year GVHD-free relapse free survival (GRFS) in PTCy seems to be better among the increment group despite not being significant (63.3 ± 10.3% vs 35.4 ± 11.9%, P = 0.092). The positive rate of minimal residual disease after transplantation was significantly lower than that before transplantation (20.0% vs 2.5%, P = 0.029).Conclusion:In conclusion, ATG and PTCy combined with Flu-based increased intensity conditioning regimen is effective for acute leukemia in children. It could reduce GVHD rate significantly and potentially improve GRFS.

Anti-Müllerian hormone and pregnancy after autologous hematopoietic stem cell transplantation for multiple sclerosis.

Autologous hematopoietic stem cell transplantation (AHSCT) has been approved for multiple sclerosis (MS) in many European countries. A large proportion of patients are women of child-bearing age. For them, AHSCT may have negative consequences for reproductive health, since the ovaries are particularly susceptible to alkylating agents. Anti-Müllerian hormone (AMH) reflects the ovarian reserve and has been suggested as a potential biomarker of fertility in women. The aim of this study was to investigate AMH levels in relation to age and reproductive potential in MS patients treated with AHSCT. The study cohort comprised 38 female patients, aged 20-44 years, who underwent AHSCT for MS using a cyclophosphamide (200 mg/kg)/rabbit-anti-thymocyte globulin (6 mg/kg) conditioning regimen between 2013-2020. Clinal follow-up visits were made 3 months after AHSCT and then yearly. AMH was analysed in blood samples. The median age at transplantation was 28 years (interquartile range, IQR 25-33). The median AMH concentration was 23 pmol/l at baseline (IQR 6.0-30), 0.5 pmol/l at 3 months (IQR 0-1.5) and 1.1 pmol/l at 2 years (IQR 0-2.9). A multiple linear regression model was used to determine if age and/or AHSCT influenced AMH values; both significantly did (age, -0.21 per year, p = 0.018; AHSCT -19, p <0.0001). Seven women became pregnant, six spontaneously and one both spontaneously and with IVF. One patient underwent an abortion, all other pregnancies led to live births. Six of the women became pregnant despite low or very low post-AHSCT serum concentrations of AMH, suggesting that low serum AMH concentrations do not necessarily reflect impaired fertility in patients treated with high-dose cyclophosphamide.

The Easix Score Predicts Overall Survival and Late Relapse in Patients Undergoing Reduced Intensity Conditioned Allogeneic Stem Cell Transplantation for Myeloid Disease

Background Allogeneic hematopoietic stem cell transplantation (alloSCT) is an effective treatment for myeloid malignancies, however outcomes post-transplant are variable and predictive scores limited. The Endothelial Activation and Stress Index (EASIX) measured at key timepoints pre- and post-transplant has been shown to predict outcomes in alloSCT, including overall survival, non-relapse mortality and incidence of sinusoidal obstructive syndrome (SOS). It can be readily calculated using standard biomarkers (LDH (U/L) x creatinine (mg/dL)/platelets (x109/L). We sought to examine its predictive role in a homogenous population of patients. Methods We conducted a retrospective national review of 117 patients undergoing reduced-intensity alloSCT for myeloid disease including AML (n=56), MDS (n=35) and MPN (n=26). All included received fludarabine, busulfan and rabbit anti-thymocyte globulin (Flu/Bu/ATG) conditioning from 2015-2020. We calculated the EASIX score on the day prior to conditioning, on day 0, at onset of acute graft versus host disease and 1 year post transplant. Univariate analysis was conducted in the STATA statistical package. Results At the pre-conditioning time-point the mean EASIX was 3.11 (0.3-17.54). Increased scores correlated with and were reliably predictive of reduced overall survival (p=0.034) (fig. 1). Higher scores at this time-point did not predict chronic GVHD or relapse, however an increased rate of acute GVHD was seen in those with lower EASIX (p=0.012). At day 0 the mean EASIX was 15.38 (1.07-179.02), however we could not demonstrate a predictive effect on SOS as no events occurred in this cohort. Nor did we identify a predictive value at this point for GVHD risk or relapse. At onset of acute GVHD (n=67, mean 3.52, 0.44-51.43), the EASIX score was predictive of overall survival (p=0.027) but did not predict risk of chronic GVHD or relapse. At 1 year post-transplant (n=88, mean 2.09, 0.48-13.59) a higher score showed a trend towards decreased overall survival (p=0.1) but was associated with an increased risk of subsequent relapse (p=0.01)(fig. 2). Conclusions The EASIX score is an easily applicable clinical tool using real world biomarkers readily available at serial time-points in transplant recipients. When applied to our homogenously treated cohort it retains its value in predicting overall mortality at the key time points of pre-conditioning and at onset of GVHD. Adoption of this simple score may be of benefit in risk stratifying the transplant process for reduced intensity conditioned allograft recipients, particularly when combined with established prediction tools for non-relapse mortality such as the HCT-CI. In addition to this, we have shown that the EASIX score may be a useful predictive tool for late relapse in those patients who are alive at 1 year post transplant. We suspect that this effect is primarily reflective of those patients with persistent thrombocytopenia and raised LDH, both markers of potential disease activity. Importantly, the use of this score in the reduced intensity population may be particularly relevant due to the increasing age of transplant eligibility and its use as a surrogate of endothelial dysregulation and potential for end organ complications through the transplant process. To assess the underlying T cell mediated and cytokine secretome effects on endothelial dysfunction, an observational study is ongoing at our institution, examining the interplay of immunomodulatory therapy, graft T cell content, early T and NK cell recovery and the cytokine secretion patterns at various time points before, during and after transplant in reduced intensity conditioned patients with myeloid disease. We plan to correlate these data with serial EASIX assessments to identify the determinants of the underlying biological process and identify potential time-points and biological targets for future study.

Addition of ATG to Clofarabine-Based Reduced Intensity Conditioning Regimen with PBSC and Ptcy in Adults with Myeloid Malignancies

INTRODUCTION In allogeneic hematopoietic stem cell transplantation (Allo-HSCT), the Clo-Baltimore (CloB) regimen is a variant of the Baltimore reduced-intensity conditioning (RIC) regimen that uses clofarabine in replacement of fludarabine and high-dose post-transplant cyclophosphamide (PTCY). This regimen provides good survivals for patients (pts) with myeloid malignancies (Chevallier et al., Oncotarget 2018). Yet, graft-versus host disease (GVHD) remains a major cause of morbidity and mortality in Allo-HSCT recipients. The administration of anti-thymocyte globulin (ATG) is a standard method to prevent GVHD in matched Allo-HSCT. Here, we retrospectively investigated whether the addition of ATG to CloB conditioning with PTCY was beneficial in terms of GVHD rates. METHODS This retrospective study included all consecutive Allo-HSCT adult recipients with myeloid malignancies transplanted between March 2014 and February 2022 in our hospital after CloB+/-ATG conditioning regimen. CloB consisted in clofarabine 30 mg/m²/day (d) from d-6 to d-2, cyclophosphamide 14.5 mg/kg/d on d-6 and d-5, and cyclophosphamide 50mg/kg/d on d+4 and d+5 after Allo-HSCT. In CloB+ATG, pts additionally received ATG 2.5mg/kg/d on d-2. GVHD prophylaxis consisted in the administration of cyclosporine A and mycophenolate mofetil to all patients. Graft source was exclusively peripheral blood stem cells. We determined overall (OS), disease-free (DFS) and GVHD relapse-free (GRFS) survivals, as well as non-relapse mortality (NRM) and relapse incidences. RESULTS Sixty-six pts (median age 61 years old, range 32-74) were included, with 36 pts treated with CloB conditioning between 2014 and 2017, and 30 with CloB+ATG between 2019 and 2022. Between the two periods other conditioning regimens were used in our Department. Diagnoses comprised acute myeloblastic leukemia (AML, n=32), myelodysplastic syndromes (MDS, n=18), myeloproliferative neoplasms (MPN, n=5), or MDS/MPN (n=10). The disease risk index (DRI) was low in 7 (11%) pts, intermediate in 43 (66%), and high in 15 (23%). The median HSCT-specific comorbidity index was 3 (range 0-7). Donors were haploidentical in 54 (82%) cases, and matched in 12. In the whole cohort, 18-months(m) OS, DFS and GRFS were 71±6%, 65±6%, and 55±6%, and 18-m NRM and relapse incidences were 14±4% and 21±5% respectively. A higher proportion of high DRI was observed in the CloB group (36 vs 10%, p=0.03). The median follow-up was 68 months (m) in the CloB cohort and 19.5 m in the CloB+ATG cohort. These two groups were otherwise comparable (Table 1). A lower proportion of acute GVHD was observed in the CloB+ATG group (23.3 vs 50%, p=0.05), with no statistical differences in terms of chronic GVHD (p=0.49). Of note, no extensive chronic GVHD was observed in the CloB+ATG group (vs 11% in CloB patients, p=0.17) In multivariate analysis, the addition of ATG to CloB conditioning was associated with a significant increase in 18-m GRFS (70±8% vs 43±8%, HR 0.38 [95%CI 0.17-0.85], p=0.02; Figure1). No differences were observed in terms of OS (HR 0.74, p=0.51), DFS (HR 0.58 p=0.22), NRM (HR 0.84, p=0.79), relapse rate (HR 0.51, p=0.25), median time of neutrophil (>1 109/L) and platelet (> 50 109/L) recovery (respectively 19d [range 12-27] vs 18d [8-32], p=0.69, and 36d [22-471] vs 31d [12-134], p=0.09). The results were similar when considering only patients with a haploidentical donor (n=54), with a benefit in terms of GRFS in the ATG group in multivariate analysis: HR 0.30 (95%CI 0.12-0.73; p=0.008). CONCLUSION Addition of ATG to the Clo-Baltimore RIC regimen with PTCY improved GRFS rates in this cohort without increasing infection-related mortality nor relapse rate in pts with myeloid malignancies and matched or haplo-donors. This strategy should be more widely implemented. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Clinical Analysis of Post-Transplant Lymphoproliferative Disorder after Hematopoietic Stem Cell Transplantation in Severe Aplastic Anemia Patients

To analyze the clinical characteristics of SAA patients with post-transplantation lymphoproliferative disease (PTLD) after allogeneic hematopoietic stem cell transplantation, and to improve diagnosis and treatment of PTLD. The clinical data of 192 patients with SAA patients who underwent HSCT in a single center from September 2010 to September 2017 were analyzed retrospectively. All patients were received antithymocyte globulin（ATG） conditioning regimen and mesenchymal stem cell(MSC) infusion. Among 192 cases, PTLD occurred in 14 cases, the incidence was 7.29％， 9 of them were diagnosed by pathology， and 5 were diagnosed clinically. EBV infection occurred with a median time of 72（35-168） days, Viral load higher than 1×104 copies/ml occured in all PTLD patients. The incidence of probable PTLD in patients ≤12 years old and ＞12 years old was 11.11%, 2.38%, respectively (P<0.01）. Univariate and multivariate analysis that the EBV infection, patients age≤12 years old, HLA-mismatch in URD-HSCT, grade II to IV aGVHD were the independent risk factors for PTLD. All PTLD patients were treated with rituximab(RTX) when EBV-DNA load higher than 1×104 copies/ml, or reducted the use of immunosuppression(RIS), patients with poor therapeutic effect were treated combined with EBV-specific CTLs(EBV-CTL) and chemotherapy. All patients were treated effectively, and the total effective rate was 100％. The median follow-up time was 65(62-115) months, and the overall survival rate was 92.85%. One patients died of cerebral hemorrhage, 7 months after PTLD curred. The incidence of PTLD after HSCT with SAA who used ATG and MSC in conditioning regimen closely relates to EBV infection, age of patients≤12 years, HLA-mismatch in URD-HSCT, grade II to IV GVHD. Rituximab combined with RIS may reduce the incidence of PTLD, combined EBV-CTL and chemotherapy may be the useful and most important treatment for PTLD.

The impact of different doses of antithymocyte globulin conditioning on immune reconstitution upon hematopoietic stem cell transplantation

IntroductionAnti-thymocyte globulin (ATG) is used prior to allogeneic hematopoietic stem cell transplantation (allo-HSCT) for graft-versus-host disease (GVHD) prophylaxis. Two different ATG doses (7.5 or 10 mg/kg) were evaluated in comparison with a group without ATG therapy. MethodsWe retrospectively analyzed 132 patients who were transplanted with HSCT without ATG (non-ATG), or who received 7.5 mg/kg ATG (ATG-7.5) or 10 mg/kg ATG (ATG-10) prior to transplantation. The immune cells (CD3+CD4+ T cells, CD3+CD8+ T cells, CD19+ B cells and CD16+CD56+ NK cells) were examined in peripheral blood every three months post-HSCT for 12 months. ResultsCompared with non-ATG group, combined ATG-7.5/ATG-10 groups had significantly lower CD3+CD4+ T cells and higher CD3+CD8+ T cells at 3, 6, 9, 12 months post-HSCT; thus, displaying a lower CD4/CD8 ratio in the ATG groups compared to non-ATG group. The ratio of CD19+ B cells was statistically lower (at 3rd month, p = .014; at 6th month, p = .025) in combined ATG-7.5/ATG-10 groups at 3 and 6 months post-HSCT, but not at 9 and 12 months after HSCT. The ratios of CD3+CD4+ T cells, CD3+CD8+ T cells, CD19+ B cells and CD16+CD56+ NK cells were similar between the ATG-7.5 and ATG-10 groups at all examined time points. The overall survival (OS), progression-free survival (PFS), relapse and acute GVHD (aGVHD) were comparable among recipients without ATG therapy and with ATG-7.5 or/and ATG-10 therapies. Multivariate analysis revealed that immune cells ratios were not independent factors affecting prognosis. ConclusionThe ATG therapy at higher and lower doses led to a delayed reconstitution of T cells and the inversion of CD4/CD8 ratio for at least one year after HSCT.

Outcomes of adults with lymphoma treated with nonmyeloablative TLI-ATG and radiation boost to high risk or residual disease before allogeneic hematopoietic cell transplant.

We evaluated the impact on survival of antithymocyte globulin conditioning (TLI-ATG) with radiation (RT) boost to high risk or residual disease before allogeneic hematopoietic cell transplant (allo-HCT) for adults with lymphoma (excluding mycosis fungoides and low-grade NHL other than SLL/CLL). Of 251 evaluable patients, 36 received an RT boost within 3 months of allo-HCT at our institution from 2001 to 2016. At the time of TLI-ATG, patients who received boost vs no boost had a lower rate of CR (11% vs 47%, p = 0.0003), higher rates of bulky disease (22% vs 4%, p < 0.0001), extranodal disease (39% vs 5%, p < 0.0001), and positive PET (75% vs 28%, p < 0.00001). In the boost group, the median (range) largest axial lesion diameter was 5.2 cm (1.8-22.3). Median follow-up was 50.2 months (range: 1-196). There was no significant difference in OS, time to recurrence, or time to graft failure with vs without boost. A trend toward higher percent donor CD3+ chimerism was seen with vs without boost (p = 0.0819). The worst boost-related toxicity was grade 2 dermatitis. RT boost may help successfully mitigate the risk of high risk or clinically evident residual disease in adults with lymphoma undergoing allo-HCT.

Dynamics of Epstein-Barr virus on post-transplant lymphoproliferative disorders after antithymocyte globulin-conditioned allogeneic hematopoietic cell transplant.

The use of antithymocyte globulin (ATG) in allogeneic hematopoietic cell transplant (HCT) is associated with an increased risk of Epstein-Barr virus (EBV) reactivation and post-transplant lymphoproliferative disorders (PTLD). The dynamics and outcomes of EBV-DNAemia are not well described in this population. We retrospectively assessed the kinetics of EBV-DNAemia after ATG conditioning of HCT recipients. Receiver operating characteristic (ROC) curves were used to assess EBV-DNAemia to predict EBV-PTLD in this group. A total of 174/405 (43%) consecutive HCT recipients from two centers met inclusion criteria of ATG conditioned, non-B-cell lymphoma patients. Of these with EBV-DNA measured using standardized IU/ml, 78.6% (92/117) developed EBV-DNAemia: 62% spontaneously resolved; 19% cleared after preemptive rituximab, and 13% developed EBV-PTLD. ROC curve analysis using maximum pre-EBV-PTLD EBV-DNAemia, demonstrated an AUC of 0.912 with EBV-DNAemia of 9782IU/ml, associated with 82.6% sensitivity and 94.4% specificity for development of EBV-PTLD. Median time for EBV-DNAemia to increase from initial detection to >1000IU/ml was 7days; to >10000IU/ml, 12days; and to >100000IU/ml, 18days. Median EBV-DNAemia level prior to administration of rituximab was significantly lower in patients with successful preemptive treatment, compared with those who developed EBV-PTLD (3.41log10 IU/ml [3.30-3.67] vs. 4.34log10 IU/ml [3.85-5.13], p=.002; i.e., 2628IU/ml vs. 21965IU/ml, respectively). EBV-DNAemia >10000IU/ml was the strongest predictor of the development of EBV-PTLD, and progression to this level was rapid in ATG-conditioned HCT recipients. This information may guide EBV-PTLD management strategies in these high-risk patients.

Development of immunosuppressive myeloid cells to induce tolerance in solid organ and hematopoietic cell transplant recipients

AbstractReplacement of failed organs followed by safe withdrawal of immunosuppressive drugs has long been the goal of organ transplantation. We studied changes in the balance of T cells and myeloid cells in the blood of HLA-matched and -mismatched patients given living donor kidney transplants followed by total lymphoid irradiation, anti-thymocyte globulin conditioning, and donor hematopoietic cell transplant to induce mixed chimerism and immune tolerance. The clinical trials were based on a conditioning regimen used to establish mixed chimerism and tolerance in mice. In preclinical murine studies, there was a profound depletion of T cells and an increase in immunosuppressive polymorphonuclear (pmn) myeloid-derived suppressor cells (MDSCs) in the spleen and blood following transplant. Selective depletion of pmn MDSCs in mice abrogated mixed chimerism and tolerance. In our clinical trials, patients given an analogous tolerance conditioning regimen developed similar changes, including profound depletion of T cells and a marked increase in MDSCs in blood posttransplant. Posttransplant pmn MDSCs transiently increased expression of lectin-type oxidized LDL receptor-1, a marker of immunosuppression, and production of the T-cell inhibitor arginase-1. These posttransplant pmn MDSCs suppressed the activation, proliferation, and inflammatory cytokine secretion of autologous T-cell receptor microbead-stimulated pretransplant T cells when cocultured in vitro. In conclusion, we elucidated changes in receptors and function of immunosuppressive myeloid cells in patients enrolled in the tolerance protocol that were nearly identical to those of MDSCs required for tolerance in mice. These trials were registered at www.clinicaltrials.gov as #NCT00319657 and #NCT01165762.

Consolidative CD8+ Memory T-Cell Donor Lymphocyte Infusion Augments Donor Chimerism with a Low Risk of Gvhd Following Matched Related Donor Hematopoietic Cell Transplantation

IntroductionMixed chimerism (MC) after allogeneic hematopoietic cell transplantation (HCT) is associated with an increased risk of disease relapse. An unmanipulated donor lymphocyte infusion (DLI) can convert MC to full donor chimerism (FC) but can also precipitate severe acute graft-versus-host disease (GVHD). We recently showed in a phase I trial that a subset of purified CD8+CD44hi memory T cells derived from HLA-matched sibling donors may induce graft-versus-tumor reactions in patients with relapsed hematologic malignancies following allogeneic HCT with objective responses in 25% of patients and a low incidence of GVHD (Muffly et al, 2016 ASH Abstract #4615). Here we report on the preliminary results of a phase II study using CD8+ memory T-cell DLI as consolidative therapy early after transplant for patients with MC to assess the rate of conversion to FC, the risk of GVHD, and the prevention of disease relapse.MethodsPatients: Eligible patients were 18-75 years of age with a high-risk or refractory hematologic malignancy who underwent nonmyeloablative allogeneic HCT from a matched sibling donor using total lymphoid irradiation and antithymocyte globulin conditioning, and who had MC (<95% donor CD3+ cells) at day +30. Patients were without acute GVHD at the time of the CD8+ memory T-cell DLI and were on tacrolimus or cyclosporine monotherapy for GVHD prophylaxis at the time of DLI.CD8+ memory T cells: Phenotypic CD8+ memory T cells were isolated from matched sibling donors following two days of unmobilized apheresis using a tandem immunomagnetic selection strategy including CD45RA depletion followed by CD8+ enrichment on the CliniMACS Plus instrument. Cell purity was determined by flow cytometry analysis. CD8+ memory T cells were infused between day +30 and day +70 at a dose of 5 x 106 cells/kg, which was determined in the prior phase I trial to be the maximum dose that could be collected from two apheresis products.Study Endpoints: Following DLI, patients were assessed for the development of acute and chronic GVHD, conversion from MC to FC (≥95% donor CD3+ chimerism) within three months, and for disease relapse. Secondary outcomes included the incidence of adverse events, invasive infections, non-relapse mortality, overall survival, and disease-free survival.ResultsPatient characteristics and outcomes after DLI are summarized in Table 1. Nine patients received CD8+ memory T-cell DLI at a median of 42 days post-HCT (range 33-62 days). The cell product was highly enriched for CD8+/CD45RA-/CD45RO+ cells, and flow analysis confirmed the selected cells were phenotypically consistent with the CD8+ T effector memory subset with a post enrichment purity of ≥96% (range 96.4-98.8%) in all patients. Median age of the patients was 60 years (range 30-71 years) with a median follow up of 306 days post-HCT (range 131-747 days). Diagnoses included non-Hodgkin lymphoma (n=5), acute myeloid leukemia (n=2), myelodysplastic syndrome (n=1), and Hodgkin lymphoma (n=1). Median donor CD3+ chimerism at day +30 was 88% (range 23-93%).CD8+ memory T-cell DLI was well tolerated with no adverse events. Six of the nine patients (67%) converted from MC to FC within three months post-DLI with a median donor CD3+ chimerism of 97% (range 95-100%). Two patients developed grade II acute GVHD (skin only) that was treated to resolution. One patient developed mild chronic GVHD. No patients developed severe acute GVHD (grade III-IV) or extensive chronic GVHD. No patients developed invasive infections, and non-relapse mortality was 0%. Of the three patients who failed to convert from MC to FC, two had residual disease at the time of transplant, one of whom had early disease relapse at day +88. Four of the six patients who converted to FC were in complete remission (CR) at the last follow up. One of the three patients with persistent MC was in CR at the last follow up. For the entire study cohort, the median disease-free survival is 1.1 years and the median overall survival is not yet reached.ConclusionsConsolidative CD8+ memory T-cell DLI following nonmyeloablative matched related donor HCT is well tolerated, converted six of nine patients (67%) with MC to FC, and was associated with a low rate of GVHD with no cases of severe acute or extensive chronic GVHD in this study. Patients continue to accrue to trial, and further accrual and longer follow up are needed to determine if this strategy will reduce relapse rates for high-risk patients with MC. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Long-term Clinical Outcomes of Hematopoietic Stem Cell Transplantation in Multiple Sclerosis.

To determine whether autologous hematopoietic stem cell transplantation (aHSCT) is able to induce durable disease remission in people with multiple sclerosis (MS), we analyzed the long-term outcomes after transplantation in a large cohort of patients with MS. To be included, a minimum dataset (consisting of age, MS phenotype, Expanded Disability Status Scale [EDSS] score at baseline, information on transplantation technology, and at least 1 follow-up visit after transplantation) was required. Two hundred ten patients were included (relapsing-remitting [RR] MS 122 [58%]). Median baseline EDSS score was 6 (1-9); mean follow-up was 6.2 (±5.0) years. Among patients with RRMS, disability worsening-free survival (95% confidence interval [CI]) was 85.5% (76.9%-94.1%) at 5 years and 71.3% (57.8%-84.8%) at 10 years. In patients with progressive MS, disability worsening-free survival was 71.0% (59.4%-82.6%) and 57.2% (41.8%-72.7%) at 5 and 10 years, respectively. In patients with RRMS, EDSS significantly reduced after aHSCT (p = 0.001; mean EDSS change per year -0.09 [95% CI -0.15% to -0.04%]). In patients with RRMS, the use of the BCNU+Etoposide+Ara-C+Melphalan (BEAM) + anti-thymocyte globulin (ATG) conditioning protocol was independently associated with a reduced risk of no evidence of disease activity 3 failure (hazard ratio 0.27 [95% CI 0.14-0.50], p < 0.001). Three patients died within 100 days from aHSCT (1.4%); no deaths occurred in patients transplanted after 2007. aHSCT prevents disability worsening in the majority of patients and induces durable improvement in disability in patients with RRMS. The BEAM + ATG conditioning protocol is associated with a more pronounced suppression of clinical relapses and MRI inflammatory activity. This study provides Class IV evidence that for people with MS, aHSCT induces durable disease remission in most patients.

Outcome After Cord Blood Transplantation Using Busulfan Pharmacokinetics-Targeted Myeloablative Conditioning for Hurler Syndrome

We report the outcomes of cord blood transplantation (CBT) with a busulfan (Bu) pharmacokinetics-targeted myeloablative conditioning regimen in 97 children with Hurler syndrome (HS) performed between 2004 and 2016. The median age at CBT was 10.8 months (range, 0.23 to 63.2 months). The median duration of follow-up for surviving patients was 4.2 years (range, 1.0 to 12.8 years). Five-year overall survival (OS) and engrafted survival (ES) were 88% and 79%, respectively. OS was 95% in patients who received Bu/fludarabine (Flu)/antithymocyte globulin (ATG) conditioning, 90% in those who received Bu/cyclophosphamide (Cy)/ATG, and 74% in those who received Bu/Cy/alemtuzumab (P = .02). ES was 84% for recipients of Bu/Flu/ATG conditioning, 83% for recipients of Bu/Cy/ATG conditioning, and 65% for recipients of Bu/Cy/alemtuzumab conditioning (P = .34). Receipt of washed CB units (P = .03) and HLA matching ≤6/10 (P = .02) were associated with significantly lower ES. The 1-year cumulative incidence of graft failure was 11% (95% confidence interval, 6% to 21%). Five patients (5%) had grade III-IV acute GVHD, 5 patients had limited chronic GVHD, and 1 patient had extensive GVHD. The incidence of veno-occlusive disease was higher in patients conditioned with Bu/Cy compared with those conditioned with Bu/Flu (19% [n = 10] versus 5% [n = 2]: P = .03). Of the 11 patients with graft failure, 8 (73%) were aplastic, and 3 (27%) had autologous reconstitution. Of 11 patients with graft failure, 9 underwent a second CBT, and 8 (89%) survived. Full donor chimerism was observed in 89% patients after first CBT and in all patients after second CBT. Survival after CBT for HS has improved, but better strategies are still needed to improve graft outcomes.

Single-Agent Cyclosporine for Graft-versus-Host Disease Prophylaxis in Patients with Acquired Aplastic Anemia Receiving Fludarabine-Based Conditioning.

Cyclosporine (CsA) combined with short-course methotrexate is considered standard-of-care graft-versus-host disease (GVHD) prophylaxis for patients with severe aplastic anemia (AA) who undergo transplantation using cyclophosphamide (Cy) plus anti-thymocyte globulin (ATG) conditioning. However, there is no consensus on optimal post-transplant GVHD prophylaxis for patients undergoing matched related donor (MRD) transplantation using fludarabine (Flu)-based conditioning. We conducted a single-center retrospective analysis of patients with acquired AA (n=106) undergoing MRD transplantation from July 2007 through January 2019. All patients received Flu-Cy-ATG conditioning and single-agent CsA as GVHD prophylaxis. Median age of the study cohort was 20 years (range, 3 to 52) and male to female ratio was 3.8:1. Median time from diagnosis to transplant was 11.5 months (range, 2.8 to 62). Graft source was bone marrow harvest in 71 (68%), combined bone marrow and peripheral blood stem cells in 34 (31%), and peripheral blood alone in 1 (1%) patient. Cumulative incidence of neutrophil engraftment at day 28 was 93.4% (95% confidence interval [CI], 87.3% to 97.1%) while that of platelet engraftment at day 100 was 90.5% (95% CI, 84% to 96%). Cumulative incidence of primary graft failure at day 28 was 6.6% (95% CI, 4% to 8%) while secondary graft failure occurred at a median of 190 days (range, 90 to 415) at a cumulative incidence of 3.7% (95% CI, 2% to 5%). Cumulative incidence of grade II to IV acute GVHD at day 100 was 3.8% (95% CI, 1.4% to 9.9%), while a 1-year probability of chronic GVHD was calculated as 7.5% (95% CI, 2.6% to 15%). Median follow-up post-transplant was 61 months (range, 6 to 144). Overall survival was 84.9%, disease-free survival was 80.2%, and GVHD-free relapse-free survival was 76.3%. This study indicates that single-agent cyclosporine is a feasible option for GVHD prophylaxis in MRD hematopoietic stem cell transplantation using Flu-Cy-ATG conditioning and is associated with very low rates of acute and chronic GVHD.

An Unexpected Cause of Gastrointestinal Bleeding after Stem Cell Transplantation

Question: A 57-year-old man developed progressively plum colored per-rectal bleeding over 24 hours with a decrease in hemoglobin from 84 g/L to 43 g/L. His medical history included primary myelofibrosis, for which he had a matched unrelated donor allogenic hematopoietic stem cell transplantation (SCT) with antithymocyte globulin conditioning 6 months before this presentation. After his SCT, he was discharged on ciclosporin and prednisolone for biopsy-proven cutaneous graft-versus-host disease.

The Addition of Ibritumomab Tiuxetan (IT) to the ATG/TLI Preparative Regimen Is Safe and May Enhance Post-Transplant Response and Outcomes for Patients with Relapsed or Refractory B Cell Non-Hodgkin Lymphomas

The Addition of Ibritumomab Tiuxetan (IT) to the ATG/TLI Preparative Regimen Is Safe and May Enhance Post-Transplant Response and Outcomes for Patients with Relapsed or Refractory B Cell Non-Hodgkin Lymphomas