Cause Of Transplant-related Mortality Research Articles

An analysis of the efficacy of graft-versus-host disease prophylaxis with post-transplant cyclophosphamide in children with acute myeloid leukemia following allogeneic hematopoietic stem cell transplantation from HLA-matched and partially-matched unrelated donors

An analysis of the efficacy of graft-versus-host disease prophylaxis with post-transplant cyclophosphamide in children with acute myeloid leukemia following allogeneic hematopoietic stem cell transplantation from HLA-matched and partially-matched unrelated donors

Risk factors and characteristics influencing humoral response to COVID-19 vaccination in patients after allogeneic stem cell transplantation.

Vaccination against severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is approved and recommended for immunocompromised patients such as patients after allogeneic stem cell transplantation (allo-SCT). Since infections represent a relevant cause of transplant related mortality we analyzed the advent of immunization to SARS-CoV-2 vaccination in a bicentric population of allogeneic transplanted patients. We retrospectively analyzed data of allo-SCT recipients in two German transplantation centers for safety and serologic response after two and three SARS-CoV-2 vaccinations. Patients received mRNA vaccines or vector-based vaccines. All patients were monitored for antibodies against SARS-CoV2-spike protein (anti-S-IgG) with an IgG ELISA assay or an EIA Assay after two and three doses of vaccination. A total of 243 allo-SCT patients underwent SARS-CoV-2 vaccination. The median age was 59 years (range 22-81). While 85% of patients received two doses of mRNA vaccines, 10% had vector-based vaccines and 5% received a mixed vaccination. The two vaccine doses were well tolerated with only 3% patients developing a reactivation of graft versus host disease (GvHD). Overall, 72% of patients showed a humoral response after two vaccinations. In the multivariate analysis age at time of allo-SCT (p=0.0065), ongoing immunosuppressive therapy (p= 0.029) and lack of immune reconstitution (CD4-T-cell counts <200/μl, p< 0.001) were associated with no response. Sex, intensity of conditioning and the use of ATG showed no influence on seroconversion. Finally, 44 out of 69 patients that did not respond after the second dose received a booster and 57% (25/44) showed a seroconversion. We showed in our bicentric allo-SCT patient cohort, that a humoral response could be achieve after the regular approved schedule, especially for those patients who underwent immune reconstitution and were free from immunosuppressive drugs. In over 50% of the initial non-responders after 2-dose vaccination, a seroconversion can be achieved by boostering with a third dose.

Impact of Allele-Level HLA-Matching on Outcomes after Double Unrelated Cord Blood Transplantation in Adults with Malignant Diseases

Introduction: In single unrelated cord blood transplantation (sCBT), an increasing number of HLA-mismatches (MM) has been associated with inferior overall survival (OS) attributed to higher transplant-related mortality (TRM). These findings have prompted current guidelines to endorse high resolution HLA typing in the selection of CB (cord blood) units, including double CBT (dCBT). However, a comprehensive appraisal of the effect of allele-level HLA matching following dCBT was likely hindered by the relatively small sample sizes in previous studies. Herein we aimed to analyze the impact of allele-level HLA-matching on outcomes of a large cohort of dCBT recipients to improve CB unit selection and further explore the unique dCBT biology. Methods: We included patients ≥18 years-old receiving a dCBT between 2006-2019 with the availability of HLA typing minimally at HLA-A, -B, -C at the antigen-level and HLA-DRB1 at the allele-level for the recipient and both CB units. A validated high-resolution imputation tool, HaploStats, was used to adjudicate allele-level match status for a subset of cord and recipient pairs (n = 173) having only antigen-level typing at HLA-A, -B or -C. A sensitivity analysis for OS was performed excluding imputed cases, and results were unchanged. HLA matching was classified according to the CB unit with the greatest degree of HLA mismatch with the patient, meaning that only the most mismatched unit was considered and that the interunit matching was not considered. Continuous covariates were dichotomized to find an optimal cutoff value by using the Contal-O'Quigley method, except for cryopreserved CD34 and total nucleated cell (TNC) count, whose cutoffs were based on previous findings reported by our group. Pairwise comparisons of the numbers of allele MM showed that receiving units with ≥4 MM had the highest negative impact on OS. Cox and Fine-Gray regression models were built for the different outcomes using the backward elimination method (p<.05 to stay). Results: 963 patients met the eligibility criteria, of which 392 received at least one CB unit with 0-3 allele MM while 571 with ≥4 allele MM. Of those receiving at least one unit with ≥4 allele MM, 18% had a maximum HLA disparity of 5/6 at lower HLA-typing resolution, 69% of 4/6 and 13% of ≤3/6. Median age at dCBT was 49 years old. Acute leukemia and myelodysplastic syndrome (MDS) accounted for 70% of the cases. There was a larger proportion of patients receiving CB units with fewer allele MM after 2012. Other patient-, disease- and CB unit-related characteristics are summarized in Table 1. The day-42 cumulative incidence of neutrophil recovery was 83% (95%CI 81-85). The number of allele MM had no significant impact on neutrophil recovery (≥ 4 MM vs 0-3 MM, multivariate HR 0.94 [0.80-1.11], P=.46). The cumulative incidence of TRM at 4 years was 36% (95% CI 32-40) for patients receiving CB units with ≥4 MM vs. 23% (95% CI 19-28) for those with 0-3 MM (multivariate HR 1.58 [95%CI 1.18-2.11], P=.002] - Fig. 1A). Infectious complications were the most frequent cause of TRM in the group receiving dCBT with ≥ 4 allele MM (40%). Relapse, grade II-IV/III-IV acute and chronic GVHD were not significantly different between the two groups. Patients receiving CB units with 0-3 allele MM had a 4-year survival of 54% (95%CI 49-59) compared to 43% (95%CI 39-47) for those receiving units with ≥4 allele MM (multivariate HR 1.40 [1.11-1.78], P=.005 - Fig. 1B). The inferior OS associated with higher allele HLA disparity was only partially mitigated by increasing the TNC count in multivariate analysis (0-3 MM + TNC ≤ 3.9x10ˆ7/kg vs.0-3 MM + TNC > 3.9x10ˆ7/kg, HR 1.50 [0.97-2.32], P=.07; ≥4 MM + TNC > 4.9x10ˆ7/kg vs. 0-3 MM + TNC > 3.9x10ˆ7/kg, HR 1.42 [1.06-1.89], P=.02; ≥4 MM + TNC ≤ 4.9x10ˆ7/kg vs. 0-3 MM + TNC > 3.9x10ˆ7/kg, HR 1.66 [1.24-2.22], P=<.001 - Fig. 1C). Discussion: Our results confirm that allele-level HLA typing is a significant factor for OS following dCBT. The inferior OS associated with the increasing number of allele-level MM was driven by higher TRM. Selection of CB units with 0-3 allele-level MM is recommended. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Advanced Machine Learning Techniques to Predict Gvhd Occurrence and Severity with High Accuracy

Introduction Graft versus host disease (GVHD) after allo-HSCT is dependent on conditioning regimen, GVHD prophylaxis, HLA matching, as well as recipient-donor discrepancies in sex, age, and CMV status. GVHD is a leading cause of transplant-related mortality with incidence varying between 30% to 70%. Few machine learning (ML) models have been implemented to accurately quantify a patient's risk for aGVHD development and subsequent severity with mixed results, utilizing various ML methodologies of analyzing clinical data, genetic differences, and biomarkers. Comparing across four different ML algorithms, we demonstrate exceptionally high accuracy for prediction of acute GVHD occurrence, severity (Grade I-II vs III-IV), disease relapse, and survival. Materials and Methods Data on 868 adult patients (age 18-76) that received either MA or RIC for any transplant indication between January 2004 and July 2018 at The Ohio State University James Cancer Center was analyzed. Predictive models were developed utilizing four different machine learning algorithms: logistic regression, k-nearest neighbors (KNN), decision tree with hyperparameter tuning, and multilayer perceptron (MLP) neural networks. Models were trained and tuned using K-fold cross validation, and prediction performance was quantified by the receiving operating characteristic area-under-the-curve (ROC AUC) and accuracy. Features included patient demographics (age, gender, KPS/ECOG, race, disease type, disease status, donor type, graft type, sex match, HLA match, conditioning regimens groups, use of (ATG), use of alemtuzumab, GVHD prophylaxis type, date of engraftment, date of aGVHD diagnosis, organ involvement of aGVHD, steroid treatment, specific steroid therapy, date of chronic GVHD diagnosis, relapse date, date of death, and cause of death was collected. The dataset was preprocessed through the standardization of numerical features and encoding of categorical features. This dataset was separated pre-analysis into cohorts - 70% exploratory and 30% validation. Results All 868 patients were included, verified, and data cleaned. The algorithms predicted with high accuracy - >80% for GVHD occurrence and >90% for Grade I-II and Grade III-IV acute GVHD, relapse, and survival. MLP provided the most accurate predictions when compared to decision tree, KNN and logistic regression algorithms. SHapley Additive exPlanations (SHAP) analysis was used to demonstrate the top 20 features contributing to the overall output. SHAP analysis for acute GVHD occurrence is shown for MLP algorithm with age and HLA match as the most critical features. Conclusions We demonstrate the results of utilizing advanced ML algorithms for highly accurate prediction of acute GVHD occurrence, severity (Grade I-II vs III-IV), disease relapse, and survival. The difference between the models' performances may be due to the disproportionate sizes of cohorts in Grade III-IV acute GVHD as opposed to relapse and survival analyses. The risk factors identified as being most influential in affecting outcomes by our ML algorithms are consistent with those historically reported. While the importance of these features are similar to prior models, the ability of the models used to generate highly accurate results is novel contribution. The improved accuracy of our methods compared to previous reports may be due to several factors. MLP algorithm with one or two layers have ample hidden neurons to find patterns to achieve superior and robust classification for GVHD. Such deep learning models have not been used in prior classification. Decision trees also provide higher accuracy compared to KNN and regression due to the deterministic nature of the model which automates feature selection. Our single center data may also present a more homogeneous population with decreased variability of practice and GVHD prophylaxis approaches. Further studies to validate these algorithms in a more recent cohort are planned. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

P1320: INCIDENCE AND IMPACT OF COMPLICATIONS OF ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION (HSCT) IN PATIENTS OVER 60 YEARS. RETROSPECTIVE EXPERIENCE OF TWO SPANISH CENTERS IN THE 2015-2020 PERIOD

Background: Not fully known if allogeneic HCST complications have a more impact on patients over 60 years and this may limit their access to the procedure. Aims: To describe the incidence of the main complications and to analyze their relationship with age, the transplant modalities, and also their impact on survival and transplant-related mortality (TRM). Methods: Retrospective study of 142 patients over 60 years with hematological neoplasms undergoing allogeneic HSCT. Results: Patient characteristics and survival curves are in Image 1. Graft Versus Host Disease (GVHD) results are presented in the abstract EHA-1952. Post-chemotherapy mucositis was the 2nd complication (60%) after aGVHD and only 5.5% were grade IV. The use of myeloablative conditioning (MAC) (86% vs 57% in reduced intensity (RIC); p-value 0.04) and Methotrexate on the immunosuppression regimen (100%; p-value <0.001) were the two factors with more impact on its appearance. A higher incidence was observed in patients >70 years (82%; p-value 0.19) and it was no impact on survival or TRM. CMV reactivation was the 3rd complication (38%) and it appeared early (median 5 weeks after infusion). Patients with severe aGVRD presented more reactivation (73.5%/p-value 0.005) and also the unrelated transplant with MAC regimen (66.5%) or haploidentical (RIC 63%/MAC 59 %) with a low incidence in related transplant with RIC regimen (19.5%/p-value 0.001). There was also more in seropositive recipients (41%; p-value 0.07), especially if there was a discrepancy recipient +/donor- (46%/p-value 0.3). CMV disease had a lower incidence (7%) and 100% were gut forms. Prior reactivation and aGVHD were the two most important factors related (18% and 100%; p-value <0,001). CMV disease had impact on survival (median OS 6 months vs 40 if no disease; p-value 0.005/HR 0.36 (CI 0.17-0.76)). There were a 20% bacterial sepsis and 11.5% invasive fungal infections (IFI), (90% Aspergillus) and both were early complications (median onset of 2 and 4 months). Once again, severe aGVHD was associated with a higher incidence (60% sepsis; p-value <0.001 and 26.5% IFI; p-value 0.001) and an increase was also observed in patients with graft failure (33,5% sepsis, p-value 0.26 and 22% IFI, p-value 0.04). No differences were observed between the different age groups. Both present an unfavorable impact on survival (median OS of 6 months; p-value<0.001/HR 1.8 (CI 0.63-5.2). Sinusoidal obstruction syndrome (SOS) had an incidence of 7.5%, the median onset was 4 weeks and 72.5% were mild cases. All patients were CMV seropositive and it was more frequent in patients with ALL (16.5%) and in haploidentical transplant recipients (14%). The only case in >70 years was severe (in < 69 years; 90% mild cases; p-value 0.13) and was related to lower survival (median OS of 6 months vs 40 if no SOS; p-value 0.001/HR 0.06 (CI 0.17-0.47) with 100% mortality in patients with severe SOS. Primary graft failure was the least frequent complication (6.5%). Patients with cMPN and those transplanted after to 2 years from diagnosis had a higher incidence (28.5% and 13%; p-value 0.03). No differences were found of older age and other known risk factors. Its impact was very high (mortality of 100% with median OS of 1 month). Although SOS and graft failure were infrequent, they were a very early cause of TRM (80% of deaths before day +100). Image:Summary/Conclusion: Age is not a risk factor for the development of complications, given that an incidence similar to that reported in younger patients and related to known risk factors is observed. However, comparative studies are needed to confirm these results.

Ceramide synthase 6 impacts T-cell allogeneic response and graft-versus-host disease through regulating N-RAS/ERK pathway

Allogeneic hematopoietic cell transplantation (allo-HCT) is an effective immunotherapy for various hematologic malignancies, predominantly through potent graft-versus-leukemia (GVL) effect. However, the mortality after allo-HCT is because of relapse of primary malignancy and followed by graft-vs-host-disease (GVHD) as a major cause of transplant-related mortality. Hence, strategies to limit GVHD while preserving the GVL effect are highly desirable. Ceramide, which serves a central role in sphingolipid metabolism, is generated by ceramide synthases (CerS1-6). In this study, we found that genetic or pharmacologic targeting of CerS6 prevented and reversed chronic GVHD (cGVHD). Furthermore, specific inhibition of CerS6 with ST1072 significantly ameliorated acute GVHD (aGVHD) while preserving the GVL effect, which differed from FTY720 that attenuated aGVHD but impaired GVL activity. At the cellular level, blockade of CerS6 restrained donor T cells from migrating into GVHD target organs and preferentially reduced activation of donor CD4 T cells. At the molecular level, CerS6 was required for optimal TCR signaling, CD3/PKCθ co-localization, and subsequent N-RAS activation and ERK signaling, especially on CD4+ T cells. The current study provides rationale and means for targeting CerS6 to control GVHD and leukemia relapse, which would enhance the efficacy of allo-HCT as an immunotherapy for hematologic malignancies in the clinic.

Therapeutic Drug Monitoring of Conditioning Agents in Pediatric Allogeneic Stem Cell Transplantation; Where do We Stand?

Allogeneic hematopoietic stem cell transplantation (HSCT) is an established curative treatment that has significantly improved clinical outcome of pediatric patients with malignant and non-malignant disorders. This is partly because of the use of safer and more effective combinations of chemo- and serotherapy prior to HSCT. Still, complications due to the toxicity of these conditioning regimens remains a major cause of transplant-related mortality (TRM). One of the most difficult challenges to further improve HSCT outcome is reducing toxicity while maintaining efficacy. The use of personalized dosing of the various components of the conditioning regimen by means of therapeutic drug monitoring (TDM) has been the topic of interest in the last decade. TDM could play an important role, especially in children who tend to show greater pharmacokinetic variability. However, TDM should only be performed when it has clear added value to improve clinical outcome or reduce toxicity. In this review, we provide an overview of the available evidence for the relationship between pharmacokinetic parameters and clinical outcome or toxicities of the most commonly used conditioning agents in pediatric HSCT.

Allogeneic Hematopoietic Stem Cell Transplantation in Severe Aplastic Anemia: A Single Centre Experience in Malaysia.

Hematopoietic stem cell transplantation (HSCT) provides curative therapy in almost 90% of patients with severe aplastic anemia (SAA). Older age, long duration of disease with consequent heavy exposure to transfusion, and active infection at the time of HSCT have a negative influence on the outcomes, causing graft failure (GF) and graft versus host disease (GVHD). To describe the outcomes of all patients with SAA who received hematopoietic stem cell transplantation at a tertiary center in Malaysia. We included a 20 y cohort of patients who underwent transplantation from January 1, 1999 to December 31, 2019. Data were obtained from electronic medical records. Demographics, clinical characteristics, and treatment outcomes were analyzed using descriptive statistics. Overall survival (OS) was analyzed using Kaplan-Meier curves. All analyses were conducted using the Statistical Package for the Social Sciences (SPSS) version 25. Eighty patients were analyzed. The median age at diagnosis was 19 years, and 59% patients were male (n = 47). Malay ethnicity was the highest (52.5%), followed by Chinese (20.0%) and Native Sabah (15.0%). The median duration from diagnosis to transplantation was 13.5 weeks. A majority of patients received Cy-ATG conditioning (n = 51, 63.8%). Forty-one patients (51.2%) used peripheral blood as stem cell source, 36 patients (45.0%) used granulocyte colony stimulating factor (G-CSF) primed marrow graft and 3 patients (3.8%) used both. The mean nucleated mononuclear cell and CD34 cell doses were 4.7 ± 1.7 × 108/kg and 4.6 ± 1.9 × 106/kg, respectively. Median engraftment for WBCs and platelets was 14 and 15 days, respectively. There was no difference in WBC and platelet engraftment in patients who received peripheral blood stem cell transplantation or bone marrow transplant. At a median follow-up of 54 months, 49 patients (61.3%) achieved complete remission and 8 patients (10.0%) achieved partial remission. The estimated 5 y OS was 63% and higher among those who received HSCT within 3 months of diagnosis. Twenty-two patients (27.5%) died within 100 d of transplantation, and a majority of these died due to pre-engraftment death. Our study found that patients who received early allogeneic transplantation for SAA had better outcomes. Pre-engraftment failure was the major cause of transplant-related mortality within 100 d. Further studies are required to identify the factors responsible for delaying transplantation to improve treatment outcomes.

COVID-19 Vaccination after Allogeneic Stem Cell Transplantation: Real Word Data on Safety and Efficacy. a Single Center Experience.

IntroductionDifferent vaccines have been recently approved by FDA and EMA for the prevention of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, demonstrating a protection rate ranging from 60% to almost 95% in phase II/III trials. Immunocompromised patients, including those undergoing allogeneic stem cell transplantation (allo-SCT), were excluded from vaccine trials. While EBMT recommended the vaccination for transplanted patients, data concerning efficacy and safety in this particular setting are scarce. Since infections represent a relevant cause of transplant-related mortality and the treatment and management of SARS-CoV-2 infection in allo-SCT patients proved to be challenging and complex, we prospectively evaluated the safety and the development of protective response against SARS-CoV-2 vaccines in our allogeneic transplanted patients.Materials and MethodsStarting in March 2021, allogeneic stem cell transplanted patients with different hematological diseases underwent COVID-19 vaccination. Taking into account the EBMT recommendations, we considered patients suitable for vaccination when (1) they were at least 3-6 months after allo-SCT, (2) didn't have any graft versus host (GvHD) activity, and (3) received less than 0,5 mg/kg steroids as part of the immunosuppressive treatment. There was no recommendation for a specific type of vaccine, with the only exception for life-attenuated vaccines, which are mostly contraindicated in the post allo-SCT setting. Vaccinated patients were regularly monitored for the potential development of adverse events. The anti-SARS-CoV-2 Spike protein antibodies were measured in blood samples to assess the humoral response. In case of no response with undetectable anti-Spike antibodies 2 week after the second dose of vaccine, we repeated the measurements at regular intervals until week + 6-8 after the completion of vaccination. Patients with no measurable antibodies 8 weeks after completion of the vaccination were considered as no responders.ResultsBetween 03/2021 and 06/2021 a total of 83 patients underwent COVID-19 vaccination (including first and second dose) during the post allo-SCT follow-up. Patients' characteristics are listed in Table 1. Most patients (77%) received BNT162b2, while only a small subgroup (8%) underwent a mixed vaccination after a first dose of ChAdOx1-S. We considered the mixed vaccination mostly to maximize the response. Overall, the two vaccine doses were well tolerated, with only 5% of patients developing a reactivation of GvHD. No relevant grade 3 or 4 organ toxicities were observed. Overall, 66% of patients in our cohort showed a humoral response. The incidence of positive serology was lower in patients who underwent the vaccination within the first 18 months after allo-SCT (29% vs 83% for patients >18 months after allo-SCT, p< 0.001). In multivariate analysis other risk factors that were associated with poor or no response were lack of immune reconstitution (p< 0.001) and ongoing immunosuppressive therapy (p= 0.009). The age of patients at the time of vaccination, sex, intensity of conditioning regimen and the use of ATG did not prove to have an influence for a humoral response during the post-transplant follow up.DiscussionThe achievement of a protective immunity against SARS-CoV-2 represents a crucial event for a frail population, like allogeneic stem cell transplanted patients. So far and to our knowledge little is known about the safety and efficacy of the COVID-19 vaccination in this particular setting. Here, we report one of the first series of patients undergoing COVID-19 vaccination after allo-SCT. We demonstrated that a humoral response can be achieved, especially for those patients who are in the long-term follow-up, underwent immune reconstitution and are free from immunosuppressive drugs. For the other patients, who represent the frailer subgroup, in the absence of a documented immune response after 2 doses of vaccine, the option of a third dose in order to increase the probability of response should be evaluated in prospective clinical trials. [Display omitted] DisclosuresViardot: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; University Hospital of Ulm: Current Employment; Amgen: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees. Döhner: Roche: Consultancy, Honoraria; Agios: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Jazz: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Ulm University Hospital: Current Employment; Abbvie: Consultancy, Honoraria, Research Funding; Oxford Biomedicals: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Astex: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; Helsinn: Consultancy, Honoraria; Pfizer: Research Funding; Berlin-Chemie: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; GEMoaB: Consultancy, Honoraria. Sala: Novartis: Consultancy, Honoraria; Celgene/BMS: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Jazz: Consultancy, Honoraria.

Human Amniotic Mesenchymal Stem Cells Inhibit aGVHD by Regulating Balance of Treg and T Effector Cells.

BackgroundAcute graft versus host disease (aGVHD) remains a leading cause of transplant-related mortality following allogeneic haematopoietic cell transplantation (allo-HCT). Human amniotic mesenchymal stem cells (hAMSCs) are a novel mesenchymal stem cells (MSCs), which have stronger proliferation and immunomodulatory ability compared with bone marrow mesenchymal stem cells (BM-MSCs). Besides, as the amniotic membrane is often treated as medical waste after delivery, hAMSCs can be obtained conveniently and noninvasively. The aim of this study was to explore the therapeutic efficacy and underlying mechanisms of hAMSCs transplantation for the humanized aGVHD mouse model.MethodsWe established a humanized aGVHD mouse model by transplanting human peripheral blood mononuclear cells (PBMCs) into NOD-PrkdcscidIL2rγnull (NPG) mice, human amniotic membrane collected from discarded placenta of healthy pregnant women after delivery and hAMSCs were extracted from amniotic membrane and expanded in vitro. Mice were divided into untreated group (Control), aGVHD group (aGVHD), and hAMSCs treatment group (aGVHD+hAMSCs), the hAMSCs labeled with GFP were administered to aGVHD mice to explore the homing ability of hAMSCs. T effector and regulatory T cells (Tregs) levels and cytokines of each group in target organs were detected by flow cytometry and cytometric bead array (CBA), respectively.ResultsWe successfully established a humanized aGVHD mouse model using NPG mice. The hAMSCs have the ability to inhibit aGVHD in this mouse model through reduced villous blunting and lymphocyte infiltration of the gut while reducing inflammatory edema, tissue destruction and lymphocyte infiltration into the parenchyma of the liver and lung. hAMSCs suppressed CD3+CD4+ T and CD3+CD8+ T cell expression and increased the proportion of Tregs, and besides, hAMSCs can reduce the levels of IL-17A, INF-γ, and TNF in aGVHD target organs.ConclusionThe NPG murine environment was capable of activating human T cells to produce aGVHD pathology to mimic aGVHD as in humans. The hAMSCs controlled aGVHD by decreasing inflammatory cytokine secretion within target organs by modulating the balance of Tregs and T effector cells in humanized mice.

Non-TBI Based Conditioning Regimen in Peripheral Blood Stem Cell Transplantation (PBSCT) for Adult Acute Lymphoblastic Leukemia Patients: A Single Center Experience

Introduction: The outcome of adult acute lymphoblastic leukemia (ALL) patients with chemotherapy only is not promising and overall survival (OS) does not exceed 30%. Allogeneic Hematopoietic Stem Cell transplantation (allo-HSCT) in first or beyond complete remission (≥CR1) has shown a superior OS rate of approximately 50 % over conventional chemotherapy protocols. Total body irradiation plus Cyclophosphamide (TBI/Cy) and oral busulfan plus cyclophosphamide (BU/Cy) are commonly used myeloablative conditioning regimens in ALL. TBI-based conditioning regimen is considered the standard of care.Aim: To compare the outcomes of allo HSCT using TBI/Cy and BU/Cy conditioning regimens in adult standard and high risk ALL patients in ≥CR1.Material and methods: We retrospectively analyzed the outcome of TBI/Cy and BU/Cy myeloablative conditioning regimen (MAC). BU/Cy cohort included 33 patients (9 females & 24 males) with a median age of 28 years (19-42). Myeloablative BU oral dose was 16mg/kg/4 days & Cy dose was 120 mg/kg IV over 4 days. TBI/Cy cohort included 45 patients (14 females & 31 males) with a median age of 24 years (19-46). TBI dose was 12 Gy fractionated for 5 days & Cy dose was 120mg/kg IV over 4 days. Both cohorts underwent allo-PBSCT at Nasser Institute Hospital, Cairo, between 1997-2010 (TBI group) and 2010-2017 (BU group) (Table1). All patients received graft-versus-host disease (GVHD) prophylaxis using cyclosporine-A (3mg/kg/day IV) from day -1 and methotrexate (15 mg/m2 IV) on day + 1 then 10 mg/m2 IV on days +3, +6 and +11. Post-transplant neutrophil and platelet engraftment were defined by three successive days with absolute neutrophilic count >=1x 109/L and platelet count >=20 x 109/L (without transfusion).Results:In the TBI arm, median time to neutrophil and platelet engraftment was 15 days (9-22) and 15 days (7-47), respectively vs. 14 days (10-22) and 12 days (10-21), respectively in the BU arm. 11/45 TBI patients (24.4 %) developed grade ≥2 acute-GVHD vs. 7/33 (21.2%) patients in the BU arm. Extensive cGVHD was reported in 8/45 (17.7 %) TBI arm vs. 6/33 (18%) patients in the BU arm. Limited cGVHD occurred in 5/45 (11.1%) TBI patients vs. 3/33 (9%) in the BU arm. Cumulative survival was 42.2 % and 15 months OS was 36.7% in the TBI arm vs. 63.6 % and 51.3 % in the BU arm (p= 0.02) (Figure 1). The incidence of sepsis and aGVHD as a cause of transplant related mortality (TRM) were significantly higher in the TBI arm vs. BU arm (p<0.001) (Table 2).Conclusions: Preliminary data demonstrates thatoutcome of BU/Cy is comparable to TBI/Cy as MAC regimen for Allo SCT inadult ALL. With limitation of resources, standard and high risk ALL patients may benefit from allo PBSCT using irradiation-free conditioning regimen associated with lower incidence of sepsis and aGVHD as a cause of transplant related mortality. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Treosulfan-based conditioning for hematopoietic stem cell transplantation in patients with Diamond–Blackfan anemia

Busulfan-based conditioning regimens before hematopoietic stem cell transplantation (HSCT) in patients with Diamond–Blackfan anemia (DBA) are the standard therapy for a long time. Unfortunately, the high incidence of toxic complications is the cause of transplant-related mortality (TRM) or low quality of life. Treosulfan-based conditioning is very attractive, however only limited data exists of its administration in DBA patients. In this article, we present the experience of treosulfan usage along with novel approaches to “graft versus host” disease (GVHD) prophylaxis in Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. The study was approved by the Independent Ethics Committee of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. From 2012 to 2020, 9 patients with DBA underwent HSCT. Matched unrelated donors were used in 7 patients, mismatched related in 1, and HLA-identical sibling in 1 patient. All patients received treosulfan-based conditioning. The sources of HSC were bone marrow (n = 3) and peripheral blood after TCRab+/CD19+ graft depletion (n = 6). Eight patients received various regimens of post-transplant prophylaxis, included calcineurin inhibitors alone or in combinations, 1 patient – mycophenolate mofetil. All transplanted patients engrafted. Median follow-up in survivors (n = 8) was 35.6 months. One patient (Karnofsky-index before HSCT 40%) died on day +58 due to multio rgan failure, caused by toxic and infectious complications. Besides, three patients had clinically signifiant toxic complications: oral mucositis grade 3 in 1 patient, treosulfan skin toxicity in 2, and moderate veno-occlusive-disease in 1 patient. Five patients had acute GVHD grade II with complete response to the 1st line therapy. There was no evidence of acute GVHD grade III–IV as well as chronic GVHD. Our data demonstrate, that treosulfan-based conditioning, alongside new cellular engineering approaches is effctive options for HSCT outcomes in patients with DBA.

Associations of the gut microbiome and clinical factors with acute GVHD in allogeneic HSCT recipients

AbstractAcute graft-versus-host disease (aGVHD) is a leading cause of transplantation-related mortality after allogeneic hematopoietic stem cell transplantation (aHSCT). 16S ribosomal RNA (16S rRNA) gene-based studies have reported that lower gut bacterial diversity and the relative abundance of certain bacteria after aHSCT are associated with aGVHD. Using shotgun metagenomic sequencing and a large cohort, we aimed to confirm and extend these observations. Adult aHSCT recipients with stool samples collected from day −30 to day 100 relative to aHSCT were included. One sample was selected per patient per period (pre-aHSCT (day −30 to day 0), early post-aHSCT (day 1 to day 28), and late post-aHSCT (day 29 to day 100)), resulting in 150 aHSCT recipients and 259 samples. Microbial and clinical factors were tested for differences between time periods and an association with subsequent aGVHD. Patients showed a decline in gut bacterial diversity posttransplant, with several patients developing a dominance of Enterococcus. A total of 36 recipients developed aGVHD at a median of 34 days (interquartile range, 26-50 days) post-aHSCT. Lower microbial gene richness (P = .02), a lower abundance of the genus Blautia (P = .05), and a lower abundance of Akkermansia muciniphila (P = .01) early post-aHSCT was observed in those who developed aGVHD. Myeloablative conditioning was associated with aGVHD along with a reduction in gene richness and abundance of Blautia and A muciniphila. These results confirm low diversity and Blautia being associated with aGVHD. Crucially, we add that pretransplant conditioning is associated with changes in gut microbiota. Investigations are warranted to determine the interplay of gut microbiota and conditioning in the development of aGVHD.

How to Make an Immune System and a Foreign Host Quickly Cohabit in Peace? The Challenge of Acute Graft-Versus-Host Disease Prevention After Allogeneic Hematopoietic Cell Transplantation.

Allogeneic hematopoietic cell transplantation (alloHCT) has been used as cellular immunotherapy against hematological cancers for more than six decades. Its therapeutic efficacy relies on the cytoreductive effects of the conditioning regimen but also on potent graft-versus-tumor (GVT) reactions mediated by donor-derived immune cells. However, beneficial GVT effects may be counterbalanced by acute GVHD (aGVHD), a systemic syndrome in which donor immune cells attack healthy tissues of the recipient, resulting in severe inflammatory lesions mainly of the skin, gut, and liver. Despite standard prophylaxis regimens, aGVHD still occurs in approximately 20–50% of alloHCT recipients and remains a leading cause of transplant-related mortality. Over the past two decades, advances in the understanding its pathophysiology have helped to redefine aGVHD reactions and clinical presentations as well as developing novel strategies to optimize its prevention. In this review, we provide a brief overview of current knowledge on aGVHD immunopathology and discuss current approaches and novel strategies being developed and evaluated in clinical trials for aGVHD prevention. Optimal prophylaxis of aGVHD would prevent the development of clinically significant aGVHD, while preserving sufficient immune responsiveness to maintain beneficial GVT effects and immune defenses against pathogens.

CT-409: Determining Causes of Post-Allogeneic HCT Mortality by Day +100: A Single-Center Experience

Background Allogeneic hematopoietic cell transplantation (allo-HCT) remains the only potentially curative treatment modality for acute leukemias and other hematologic malignancies and benign blood disorders. In addition to the risk of disease relapse, allo-HSCT is associated with significant treatment related mortality. The first 100 days following allo-HSCT is a particularly high-risk time period, with the reported overall mortality (OM) at 100 days post-allo-HSCT of up to 20%. Methods We conducted a single-center retrospective analysis of patients who underwent allo-HCT, matched unrelated donors (MUD), matched related donors (MRD), and haploidentical-MRD (H-MRD), at Mayo Clinic in Jacksonville, FL, between 01/01/2009 and 03/01/2020. The primary objective of this analysis was to identify the different causes of overall mortality within the first 100 days after allografting and examine the correlation between pre-defined risk factors for allo-HCT and 100-day mortality. Results Our study population consisted of 355 patients (pts) of whom 62 (17.5%) pts were deceased within the first 100 days post-allo-HCT. The median age of pts alive at day +100 was 56 (20–73) years, and 49.8% were male with a median follow-up of 307 (range 100–3429) days. Among the patients deceased by day +100, the median age was 59 (22–74) years; 66% were male. The three most common primary diagnoses were AML (35.5%), MDS (21%), NHL (11.3%). Of these pts, 53 (85.5%) received peripheral blood stem cells, 8 (12.9%) bone marrow, and 1 (1.6%) cord blood. Moreover, 40 (64.5%) received an allo-HCT from a MUD, 16 (25.8%) from an MRD, and 6 (9.6%) from H-MRD. Relapsed/progression was the cause of death in 19.4%, whereas sepsis (30.6%) and acute GVHD (21%) were the most common causes of non-relapse deaths. Conclusions In our study, transplant-related mortality was the main cause of death during the first 100 days after an allogeneic HCT. The main causes of transplant-related mortality were sepsis and acute GVHD.

Association of Country-Specific Socioeconomic Factors With Survival of Patients Who Experience Severe Classic Acute Graft-vs.-Host Disease After Allogeneic Hematopoietic Cell Transplantation. An Analysis From the Transplant Complications Working Party of the EBMT.

Acute graft-vs.-host disease (aGvHD) is one of the most frequent causes of transplant-related mortality (TRM) after allogeneic hematopoietic cell transplantation (alloHCT). Its treatment is complex and costly. The aim of this study was to retrospectively analyze the impact of country-specific socioeconomic factors on outcome of patients who experience severe aGvHD. Adults with hematological malignancies receiving alloHCT from either HLA-matched siblings (n = 1,328) or unrelated donors (n = 2,824) developing grade 3 or 4 aGvHD were included. In univariate analysis, the probability of TRM at 2 years was increased for countries with lower current Health Care Expenditure (HCE, p = 0.04), lower HCE as % of Gross Domestic Product per capita (p = 0.003) and lower values of the Human Development Index (p = 0.02). In a multivariate model, the risk of TRM was most strongly predicted by current HCE (HR = 0.76, p = 0.006). HCE >median was also associated with reduced risk of the overall mortality (HR 0.73, p = 0.0006) and reduced risk of treatment failure (either relapse or TRM; HR 0.77, p = 0.004). We conclude that country-specific socioeconomic factors, in particular current HCE, are strongly associated with survival of patients who experience severe aGvHD.

Bone Marrow-Derived Mesenchymal Stem Cells Modified with Akt1 Ameliorates Acute Liver GVHD

BackgroundLiver injury associated with acute graft-versus-host disease (aGVHD) is a frequent and severe complication of hematopoietic stem cell transplantation and remains a major cause of transplant-related mortality. Bone marrow-derived mesenchymal stem cells (BM-MSCs) has been proposed as a potential therapeutic approach for aGVHD. However, the therapeutic effects are not always achieved. In this study, we genetically engineered C57BL/6 mouse BM-MSCs with AKT1 gene and tested whether AKT1-MSCs was superior to control MSCs (Null-MSCs) for cell therapy of liver aGVHD.ResultsIn vitro apoptosis analyses showed that, under both routine culture condition and high concentration interferon-γ (IFN-γ) (100ng/mL) stimulation condition, AKT1-MSCs had a survival (anti-apoptotic) advantage compared to Null-MSCs. In vivo imaging showed that AKT1-MSCs had better homing capacity and longer persistence in injured liver compared to Null-MSCs. Most importantly, AKT1-MSCs demonstrated an enhanced immunomodulatory function by releasing more immunosuppressive cytokines, such as IL-10. Adoptive transfer of AKT1-MSCs mitigated the histopathological abnormalities of concanavalin A(ConA)-induced liver injury along with significantly lowered serum levels of ALT and AST. The attenuation of liver injury correlated with the decrease of TNF-α and IFN-γ both in liver tissue and in the serum.ConclusionsIn summary, BM-MSCs genetically modified with AKT1 has a survival advantage and an enhanced immunomodulatory function both in vitro and in vivo and thus demonstrates the therapeutic potential for prevention and amelioration of liver GVHD and other immunity-associated liver injuries.

Low Levels of Plasmacytoid Dendritic Cells at the Time of Engraftment Are a Valuable Severe aGVHD Indicator in Children Undergoing Allogeneic Stem Cell Transplantation

Graft-versus-host-disease (GVHD) remains a leading cause of transplant-related mortality (TRM) in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Patients who do not respond to GVHD therapy are at high risk for death without relapse. Strategies that can predict the development of severe GVHD in transplant patients may improve risk stratification for steroids treatment refractory GVHD and TRM. Dendritic cells (DCs) play nonredundant roles in regulating both immunity and tolerance. Clinical and pre-clinical studies suggest that GVHD causes dysregulated development of functional DCs and impaired reconstitution of donor DCs is associated with increased risk of severe GVHD. We demonstrate that donor plasmacytoid DC (pDC) reconstitution around the engraftment time is a useful predictor for the development of severe GVHD in children after allo-HSCT. We examined reconstitution of donor DCs, including total DCs (lineage-negative (LIN-)HLADR+), pDCs (LIN-HLADR+CD123+CD1c-) and CD1c+DCs (LIN-HLADR+CD123-CD1c+), in peripheral blood of patients undergoing allo-HSCT, using age-matched healthy children as controls. The median time for engraftment was 14 days (range, 13.0~17 days), whereas clinical signs of GVHD occurred approximately 10 days later (median time, 24 days;range, 18~35 days). Thus, measuring the number and frequency of circulating blood DCs early at the engraftment time allowed us to evaluate the subsequent occurrence of GVHD. Transplant patients were followed up for 6 months after allo-HSCT. Of evaluable 45 transplant patients, 27 patients had no GVHD (grade 0) or mild GVHD (grade I), and 18 patients developed severe GVHD (grade II-IV GVHD). Patients who developed grade II-IV GVHD had no significant difference in frequency ( median, 0.2%; range, 0.04~0.35%) and number (median, 1.6 cell/ml; range, 1~3.8 cell/ml) of total DCs than patients with grade 0-I GVHD (median frequency, 0.41%; range, 0.15~0.63%, P&lt;0.05; and median number, 2.6 cell/ml , range, 1~6.7 cell/ml,Figure1A,1B). Both pDCs and CD1c+DCs represent the major DC populations in human peripheral blood. Patients with grade II-IV GVHD showed significantly lower frequency and number of pDCs (median frequency, 3.4%; range, 0.64~14%, median number, 0.06/ml, range, 0.02~0.25 cell/ml) than patients with grade 0-I GVHD median frequency, 29.1%, range, 20.3%~39.2%, P&lt;0.01; mediate number, 0.5 cell/ml, range, 0.2~1.9 cell /ml, P&lt;0.01Figure1A,1B). In contrast, there was no significant difference in frequency and number of CD1c+DC between the two groups. These data suggest that the reconstitution of donor pDCs is linked to the occurrence of severe GVHD. Using Receiver operating characteristic (ROC) curve analysis, we explored thresholds of pDCs as a discriminator for grade II-IV GVHD patients versus grade 0-I GVHD patients. The median pDC level in all tested patients was 0.25 cell/ml (range, 0.1~0.9 cell/ml,Figure1C) at the engraftment time. We chose the threshold of pDC level at 0.3 cell/ml to evaluate the difference in patients with high (above the threshold) versus low (below the threshold) pDC levels. Of these 45 patients, 21 (46.7%) patients had high pDCs and 24 (53.3%) were low pDCs. Patients with low pDCs had a significantly higher probability of developing grade II-IV GVHD (p&lt;0.01). The sensitivity of discriminating severe GVHD versus no/mild GVHD was 75% and the specificity was 94%. In addition, low engraftment pDC patients had higher TRM compared to high pDC patients (12.5% versus 0%) for median follow-up time 300 days (range, 210-465 days) after transplantation. However, there was no significant difference in overall survival rate between high pDC- and low pDC-group. Furthermore, the serum level of REG3α and ST2 at the engraftment time was not associated with the incidence of severe GVHD in these patients. Collectively, our findings identify that quantitation of pDCs at the engraftment time is a valuable prognostic predicator for severe GVHD in patients undergoing allo-HSCT. Given the importance of pDCs in modulating GVH reactions, it will be important to further determine whether impaired reconstitution of donor DCs may contribute to dysregulated immune tolerance against host tissues after allo-HSCT. Disclosures No relevant conflicts of interest to declare.

Impact of Graft Composition on Graft-Versus-Host Disease in Peripheral Blood HLA-Identical Sibling Transplants: Protective Role of CD8 Cell Dose

Introduction and Objective:Acute graft-versus-host disease (aGVHD) is a leading cause of transplant related mortality following allogeneic hematopoietic stem cell transplantation (HSCT). Data on the impact of graft composition, namely CD34 and T-cell subsets, and aGVHD is conflicting. We hypothesized an upper cell dose limit of CD34 would exist predictive of aGVHD without affecting engraftment and sought to explore T-cell subsets and their impact on aGVHD outcomes amongst peripheral blood progenitor cell (PBPC) HLA-identical sibling transplants (Allo-Sib).Methods:In an IRB approved protocol, consecutive Allo-Sib patients underwent HSCT for hematologic malignancy at our center from 1/2004 to 12/2012. Demographic and clinical data were prospectively collected and retrospectively confirmed. Patients received the entire D1 CD34 PBPC collection from their donors and from a second day of collection if necessary to achieve a dose of 4 x 106 CD34/kg cells. aGVHD prophylaxis was uniformly tacrolimus and mini-methotrexate. Tacrolimus was monitored to achieve a trough of 10-15 ng/ml. aGVHD was graded as per the International Bone Marrow Transplant Registry System. Exact binary logistic regression models were used to estimate the odds of aGVHD as a function of patient demographic and clinical data. For the association between cell counts and aGVHD, binary cut scores were determined by finding the point along the receiver operating characteristic curve that maximized sensitivity and specificity. Non-parametric Spearman correlation coefficients were used to estimate the association between CD34, CD3, CD4, and CD8 cell counts.Results:We analyzed 160 consecutive patients. In this mostly male (63%) population, median age was 51 and most patients underwent a myeloablative transplant (93%). Disease risk as per Armand et al 2012 was low 45%, intermediate 13.2%, and high 41.7%. Co-Morbidity Index by Sorror et al (HCT-CI) was 30.5% for 0, 33.8% for 1-2, and 35.8% for > 2. Sixteen patients (10%) developed grade II-IV aGVHD while 9 (6%) developed grade III-IV aGVHD. Median CD34 cell dose infused was 6.27 X 106/kg. Median CD3, CD4, and CD8 cell doses infused were 2.51 X 108/kg, 1.80 X 108/kg, and 0.66 X 108/kg, respectively. In univariate analysis, patients (n=67) receiving > 9.94 x 106 CD34/kg were 12 times more likely to develop grade III-IV aGVHD (odds ratio =12.308; p=0.01)(figure 1). Conversely, patients receiving > 0.50 x 108 CD8/kg were less likely to develop grade II-IV aGVHD (odds ratio = 0.30; p=0.049)(Figure 2), but not Grade III-IV aGVHD. The only other factor associated with aGVHD was a diagnosis of AML, which was protective (p=0.01). CD3 and CD4 cell counts did not correlate with aGVHD in our patient cohort. There was no correlation between engraftment and CD34, CD3, CD4, or CD8 cell dose. Finally, we found no direct correlation between CD34 cells counts and CD3, CD4, or CD8 cell counts.Conclusion:This study represents the largest evaluation examining the correlation between both infused CD34 cells and T-cell composition with aGVHD among patients undergoing strictly matched related donor HSCT. Importantly, the data demonstrates patients receiving > 10 x 106 CD34/kg have increased risk of developing clinically significant aGVHD, a dose that far exceeds adequate engraftment doses and serves now as a cap on CD34 cell dose in our program. Interestingly, our data suggests infusion of > 0.50 x 108 CD8/kg may protect from severe aGVHD whereas prior reports have demonstrated no association between CD8 cells and aGVHD. Further investigation is needed to better characterize the relationship between CD8 cells and aGVHD and better define the correlation between CD8 and CD34 cell doses in the development of aGVHD. DisclosuresNo relevant conflicts of interest to declare.

Chronic graft-versus-host disease: Current management paradigm and future perspectives.

The field of allogeneic hematopoietic cell transplantation (allo-HCT) began in the 1950s, and despite a seven decade history of remarkable clinical advances, graft-versus-host-disease (GVHD) remains the greatest obstacle in its success due to considerable morbidity and mortality. Graft-versus-host disease is the second leading cause of transplantation-related mortality (TRM) after relapse of primary disease. There are two main types of GVHD-acute and chronic-differing in the pathogenesis, time of onset, and clinical presentation. This review provides a comprehensive overview of chronic GVHD pathophysiology and current management paradigms, as well as consideration of promising novel therapies. Chronic GVHD is a serious disease which may be active for years, or even decades, requiring potentially years of immunosuppressive therapies and placing patients at risk for a number of late complications. While the oral cavity has long been recognized to be a prominent target of GVHD, and in particular, chronic GVHD, it must be recognized and appreciated that it is a complex systemic disease with a wide spectrum of clinical manifestations.