Unrelated Allogeneic Transplantation Research Articles

Immune reconstitution dynamics after unrelated allogeneic transplantation with post-transplant cyclophosphamide compared to classical immunosuppression with anti-thymocyte globulin: a prospective cohort study.

Post-transplant cyclophosphamide has contributed to the success of haploidentical hematopoietic stem cell transplantation (HSCT) and is also been used in transplantation from matched donors. However, limited data on the immune reconstitution after this type of immunosuppression is available. We aimed to evaluate immune reconstitution after HSCT from unrelated donors, comparing anti-thymocyte globulin (ATG) and post-transplant cyclophosphamide (PTCy). Consecutive patients undergoing HSCT from unrelated donors and receiving either ATG or PTCy were prospectively included. Immune reconstitution analyses were performed by flow cytometry pre transplant and on days 30, 60, 90, and 180 post-transplant. We included 36 patients, 20 in the ATG group and 16 in the PTCy group. In the early post-transplant period (D+30), the ATG group showed a higher number of total lymphocytes, T, B, and NK cells compared to the PTCy group. However, at D+180, the PTCy group exhibited a higher number of B cells. On D+60 and D+90, the ATG group displayed higher number of NK cells CD56dim compared to the PTCy group, while on D+180, the PTCy group showed higher number of CD56neg, CD16pos, and, NKG2Dpos NK cells. Naive CD4+, transition CD4+, and naive CD8+ T cells on D+60 were identified as risk factors for acute graft-versus-host disease (GVHD) grades II-IV, and a higher count of CD4+ memory cells on D+180 was identified as a risk factor for chronic GVHD. In the context of unrelated allogeneic transplantation, immunosuppression with PTCy was associated with later B, T and NK cells reconstitution compared to ATG.

Immunosuppression Free at One-Year Post Haploidentical Hematopoietic Cell Transplantation (Haplo) with Post-Transplant Cyclophosphamide (PTCY)

Haploidentical related donor transplantation with PTCY has expanded the donor availability and made it feasible for most patients with high risk hematologic malignancies to receive a curative transplantation. Haplo with PTCY carries similar disease control and lower incidences of GVHD compared to matched donors using calcineurin inhibitor based GVHD prophylaxis. Chronic GVHD among transplant patients who are one-year survivors after matched related or unrelated allogeneic transplantation was shown to be associated with higher non relapse mortality and worse overall survival 1 . The impact of clinically significant chronic GVHD requiring immunosuppression (IS) on haplo recipients with PTCY who have survived one-year post-transplant has not been studied and is being assessed in this analysis. A total of 322 consecutive adult patients who received haplo transplant with PTCY at our center were included in this study. Two hundred and forty-nine survived first year post-transplant and were included in the primary analysis for predictors of being immunosuppression (IS) free at one year. Two hundred and twenty-one patients were free of relapse at 1-year post haplo and were included in the analyzing the effect of IS free status on non-relapse mortality (NRM), progression free survival (PFS), Relapse and overall survival (OS). Median follow up for survivors was 63.9 months (18.3-165). Patient, disease, and transplant related characteristics were retrieved from our database where they have been prospectively entered. All patient received standard GVHD prophylaxis of PTCY, Mycophenolate (stop day +35) and Tacrolimus through day 180. A total of 163 patients (65%) were IS free at one-year post haplo. Patients' characteristics were as follows: median age 48 (19,80) years, male sex 56%, Race (white 61%, black 34%), most common diagnosis ( AML/MDS 55%), comorbidity index HCT-CI ≥3 52%, cell source (PBSC 81%), and myeloablative intensity (49%). Both groups IS free and still on IS had similar baseline characteristics except for higher female-male donor (28% vs 15 %, P=0.03) and female donors (48% vs 30%, p=0.008) for patients on IS at 1-year. Logistic regression to identify patients more likely to be on IS at 1-year post Haplo showed that female donor sex to be a significant risk (OR 2.11, CI 1.21-3.69, p=0.009). In a Cox analysis on the effects of IS on transplant outcomes, being on IS at 1-year had no impact on OS (HR 1.44, CI 0.90-2.31, p=0.13) or relapse (HR 0.77, CI 0.37-1.61, p=0.49) but a significantly higher NRM ( HR 4.18, CI 1.80-6.72, p<0.001) and a trend towards worse PFS (HR 1.59, CI .95-2.66, p=0.08). These results indicate that female donors are significant risk factor for requiring IS at one-year post haplo with PTCY. Additionally, clinically significant chronic GVHD requiring IS at one-year post haplo with PTCY has no significant effect on relapse but is associated with higher NRM and a trend towards worse PFS. These results can be used to inform appropriate donor selection to avoid late complications among haplo recipients.

Dynamics of Immune Reconstitution after Unrelated Allogeneic Transplantation with Post-Transplantation Cyclophosphamide Compared to Classical Immunosuppression with ATG

Introduction: Post-transplant cyclophosphamide (PTCY), in hematopoietic stem cell transplantation (HSCT), is responsible for the success of haploidentical stem cell transplantation and is also being used in matched transplants such as unrelated transplants, with promising outcomes in graft versus host disease (GVHD). However, we lack data on immune reconstitution with this type of immunosuppression, especially in unrelated transplantation. Immune reconstitution is directly involved with post-transplant morbidity and mortality, being related to GVHD, relapses and infections, such as cytomegalovirus (CMV). Objectives: To evaluate global and CMV-specific immune reconstitution after unrelated donor HSCT, comparing the use of thymoglobulin (ATG) or PTCY protocol. Methods: We prospectively included patients undergoing first unrelated donor HSCT with ATG, methotrexate and tacrolimus or PTCY (50mg/Kg D+3 and D+4), mycophenolate mofetil (MMF) and tacrolimus with patient and/or donor CMV IgG positive. Immune reconstitution analyzes were performed by flow cytometry and CMV-specific recovery by ELISPot technique on days +30, +60, +90 and +180 post HSCT. Results: Thirty-six patients were included in this study, 20 in the ATG group and 16 in the PTCY group (table 1). Only 2 patients were 9x10 match, and the others were 10x10 match. All patients were submitted to preemptive strategy of CMV treatment, without the use of letermovir. Regarding clinical outcomes, neutrophilic engraftment was earlier with ATG (median of 12 days), compared to PTCY (median of 16 days) (p=0.0001). There was no difference between the groups in terms of length of hospital stay (median 33 days in both groups), CMV reactivation (70% in ATG and 75% PTCY, p=0.98), acute GVHD grades II to IV (p=0.26) or grades III-IV (p=0.56), and chronic GVHD (p=0.45), as well as relapse (p=0.3), non relapse mortality (p=0.77) and overall survival (p=0.4). Regarding immune reconstitution we observed an initial expansion of monocytes and NK lymphocytes in both groups and a higher increase in CD8+ T lymphocytes was evidenced, with an inversion of the CD4/CD8 ratio (CD4 14.9% vs 15.5% p=0.9 and CD8 49.7% vs 54.5%p=0.5 in ATG and PTCY respectively). We identified a CD4+/CD8+ double-positive T cell (DP) population, which was higher in PTCY group compared to ATG on days +30 (3.5% vs 10.2%, p=0.009), +90 (3.1% vs 12% p= 0.01) and +180 (5.2% vs 13%, p=0.007, in ATG and PTCY respectively ). On day +30 there were higher proportion of T cells (19.9% vs 9.6% p=0.004), B cells (0.76% vs 0.2%, p=0.006) and NK cells (19.2% vs 8.6% p=0.006) in ATG group compared to PTCY and monocytes were higher in PTCY (31.7 vs 44.5%, p=0.02). On day +180 the proportion of B cell were higher in PTCY (6.1% vs 16.6% p=0.014) and the NK cells were higher in the ATG (22.4% vs 14.7% p=0.021) (Figure 1), with higher CD56dim population in ATG group (46% vs 33.6% p=0.0079), while in PTCY there were a higher NK population CD56high on day +60 (40.3% vs 61%, p=0.014). We identified a peripheral expansion of a CD56negCD16posNKG2Dpos NK cell population, which was higher in the PTCY group on day +180 (3.7% vs 13.2% p=0.017). Regarding CMV-specific immune response, we found no difference between the groups on days +30 (5 vs 5 spots/10 4 PBMC p=0.41), +60 (10 vs 6 spots/10 4 PBMC p=0.38), +90 (13 vs 4 spots/10 4PBMC p=0.33) or +180 (7 vs 6 spots/10 4 PBMC p=0.57). Conclusions: In the context of unrelated HSCT, we found no difference in CMV-specific immune response with the use of PTCY or ATG protocol. Post-transplant immunosuppression with PTCY compared to ATG protocol is related to lower levels of T cells, NK cells and B cells on day +30 and later neutrophil engraftment, but with a higher proportion of double positive T cells on days +30, +90 and +180 and a higher proportion of B cells on day +180. At 6 months after transplantation, a proportionately lower number of NK cells, but higher proportion of CD56negCd16posNKG2D NK population was observed in the PTCY group.

Is the Youngest Donor Always the Best Choice to Optimize Outcomes for Matched Unrelated Allogeneic Transplant? Improving Precision Using Novel Statistical Methodology

INTRODUCTION Our recently published research has shown younger donors have superior survival for recipients of allogeneic hematopoietic stem cell transplant (HSCT). But, previously, we had not explored the donor age impact on other outcomes, or the impact of smaller age differences (<4 years) when balanced against other factors. We report results using our recently developed machine learning survival methodology, Nonparametric Failure Time Bayesian Additive Regression Trees (NFT BART). Here we study patient-specific optimization of donor selection for overall survival (OS) and event-free survival (EFS including events of death, relapse, graft failure/rejection, or moderate/severe chronic graft vs. host disease, GVHD). METHODS The patient data was provided by the Center for International Blood and Marrow Transplant Research. Each recipient underwent matched unrelated donor HSCT from 2016 to 2019 and was followed for OS and EFS outcomes up to three years. We trained our NFT BART model on 10,016 patients to provide predictions for OS and EFS. The model was validated on 1,802 patients among whom 699 had archived unrelated donor search records available from the National Marrow Donor Program. We examined donor age, sex/parity, CMV status, DPB1 nonpermissive mismatching, and DQB1 matching, while adjusting for relevant patient characteristics. We further restricted donor factors to those with a >1% positive impact on 3-year OS and/or EFS. Using archived search data for each patient, we examined three optimal strategies for donor selection: OS only, EFS only and a 2:1 weighted average between OS and EFS (denoted OS2:EFS1). The OS2:EFS1 effectively prioritizes optimizing OS while still allowing EFS consideration when the difference in OS predictions between two potential donors is minimal. We calculated predicted OS and EFS outcomes for each patient under all three optimal donor strategies. These predicted outcomes were benchmarked against observed practice by subtracting the predicted outcomes from the actual donor used for the transplant. RESULTS Among donor features, only age (for OS and EFS) and sex (for EFS) had clinically important impacts on outcomes. For OS, the youngest donor provided the best result regardless of patient characteristics: see the waterfall plot presented in Figure 1. As shown, the older the donor, the greater the impact of selection by age. Compared to donors 34+, use of an 18 year-old donor is associated with a substantial increase in OS where all of the recipient OS differentials are above 0.01. Compared to donors 22 to 30, the impact of an 18 year-old donor is negligible. For EFS, donor sex was the dominant factor, with males having a median 4% improvement in EFS at 3 years compared to females, while the difference for 42 vs. 18 was <2%. Optimizing for OS led to selection of the youngest donor regardless of sex, while optimizing EFS led to selection of the youngest male donor. Optimizing OS2:EFS1 generally picked the youngest donor except for selections of a male donor that may be older than the female when the age difference is small (median is 1 year older: Q1=0, Q3=2). In said cases, the OS detriment was minimal (median=-0.0005, Q1=-0.0008, Q3=-0.0003) with a substantial improvement in EFS (median=0.038, Q1=0.031, Q3=0.042) gained by switching to the male donor. Individual patient differences (OS2:EFS1 vs. actual donor) in OS vs. EFS are plotted in Figure 2. CONCLUSION Using our novel NFT BART methodology, we showed that donor selection to optimize HSCT outcomes can be improved by considering both OS and EFS. This weighted optimization strategy balances outcomes, prioritizing OS while also allowing for consideration of EFS when OS is likely similar between donors. Additionally, this supports previous research showing that choosing among donors from 18 to 30 with resultant minimal differences in outcomes that are negligible allowing for more flexibility in donor selection.

Algorithm for determining the authenticity of biomedical cell preparations containing mesenchymal stem cells

The use of mesenchymal stem cells (MSCs), which have a pronounced immunomodulatory activity, is a promising direction in the development of biomedical cell preparations (BMCPs). In oncohematology, the use of BMCPs containing MSCs is aimed at supporting hematopoiesis during cotransplantation with hematopoietic stem cells (HSCs) and suppressing immune conflicts during allogeneic unrelated transplantation and severe autoimmune processes. An obligatory stage of registration of BMCPs is confirmation of the identity of the MSC cell line (CL), which includes the establishment of morphological characteristics, evaluation of the expression of specific markers and proteins, and confirmation of the genetic stability of CL during cultivation. Determination of markers of genetic stability is possible using various methods, however, according to the recommendations of the American National Standardization Institute, the standard is the analysis of short tandem repeats (STR analysis). The purpose of the study is to develop an algorithm for determining the authenticity of BMCPs containing MSCs, including STR analysis. Material and methods. Identification of MSC cells in BMCP was performed according to the criteria of the International Society for Cell Therapy. Viable cells were counted in a Goryaev chamber. Immunophenotypic characteristics of MSCs were determined by flow cytometry. The level of production of specific proteins was assessed using enzyme immunoassay. Genetic stability markers were identified by STR analysis. Results and discussion. The methods were tested in triplicate for ten BMCP samples to confirm the reproducibility and reliability of the results. The developed algorithm for determining the authenticity of BMCP has a high accuracy, as it includes the STR analysis technique, which makes it possible to identify 19 polymorphic STR markers located on different alleles. Using the method will allow BMCP manufacturers to go through the procedure of state registration of drugs.

Demand and usage of unrelated donor products for allogeneic haematopoietic cell transplantation during the COVID‐19 pandemic: A Canadian Blood Services Stem Cell Registry analysis

Background and ObjectivesUnderstanding changes in the demand and usage of unrelated allogeneic haematopoietic cell transplantation (HCT) donors during the COVID‐19 pandemic is needed to optimize pandemic preparedness of registry and donor collection services. The aim of this study was to understand the extent to which the pandemic has impacted the demand and usage of unrelated donors and cord blood units (CBUs) at Canadian Blood Services (CBS).Materials and MethodsData regarding stem cell donor interest and product usage for unrelated allogeneic HCT were retrieved from the database at CBS using de‐identified anonymous information.ResultsUnrelated donor searches for Canadian patients remained unchanged by the pandemic, reflecting stable demand. The number of unrelated allogeneic transplants performed within Canada also remained stable, while the number of cord blood transplants increased, chiefly for paediatric patients. Requests for donor verification typing, a first signal of potential interest, increased from domestic centres during the first 6 months of the pandemic and decreased from international centres, before returning to baseline levels. The proportion of transplants for Canadian patients who used stem cell products procured from Canadian donors increased between 3 and 6 months after the start of the pandemic before returning to baseline and appears to be increasing again more than 1 year after the start of the pandemic. Use of CBUs for Canadian paediatric patients increased and remains elevated.ConclusionDemand for unrelated adult HCT donors has remained stable despite the evolving pandemic with a transient and recurring increased interest and usage of domestic adult donors. Use of CBUs for paediatric patients has increased and remains elevated. Registries and donor collection centres should maintain the capacity to expand services for domestic donor collection during pandemics to offset threats to international donor usage.

Venetoclax and hypomethylating agents in older/unfit patients with blastic plasmacytoid dendritic cell neoplasm

Venetoclax and hypomethylating agents in older/unfit patients with blastic plasmacytoid dendritic cell neoplasm

Prospective Phase I/II Study of Eltrombopag for the Treatment of Bone Marrow Failure in Fanconi Anemia

Fanconi anemia (FA) is an inherited disorder associated with loss of function mutations in gene members of the FA-BRCA pathway involved in interstrand cross-link DNA damage repair during cell division. Progressive bone marrow failure (BMF) is a primary cause of morbidity and mortality in patients with FA. Allogeneic hematopoietic stem and progenitor cell (HSPC) transplantation is the only curative treatment for FA-associated BMF. However, donor availability, graft failure, and FA-specific transplant toxicities remain significant hurdles. Attempts at genetic correction of FA are underway but collection of sufficient numbers of autologous HSPCs is challenging in subjects with advanced BMF. Androgens have been successfully used but side effects often prevent prolonged therapy. The orally bioavailable small molecule mimetic of thrombopoietin, eltrombopag (EPAG), was recently shown to stimulate multipotent long-term repopulating HSPCs in patients with acquired BMF, resulting in persistent trilineage hematopoiesis. EPAG promotes DNA repair (Guenther, Exp Hematol 2019) and maintains HSPCs under inflammatory conditions (Alvarado, Blood 2019), indicating potential relevance in FA. In this study, we investigated whether EPAG may offer a novel therapeutic modality for FA-associated BMF.We have enrolled 10 patients (FANCA, n=9 and FANCC, n=1) to date in a prospective phase I/II study of EPAG in Fanconi anemia (NCT03204188). All subjects received EPAG at an oral daily dose adjusted for age and ethnicity. The primary efficacy endpoint was the proportion of subjects with at least 2-fold increase in marrow cellularity or CD34+ HSPC frequency (marrow response), or clinically significant improvement in peripheral blood (PB) counts at 6 months (blood response). The primary safety endpoint was the global toxicity profile assessed at 6 months using CTCAE criteria. Responders were invited to continue on the extension phase of the study for an additional 3 years.Four of 10 patients have reached the 6-month assessment endpoint, and a pre-specified 3-month interim analysis is available on two additional subjects. A marrow response was observed in all 4 subjects at 6 months. Mean marrow cellularity increased by a factor of 4 (Fig. A/B), and CD34+ HSPC frequency improved 2.5-fold at 6 months relative to pre-treatment values (Fig. C/D). Marrow response criteria were also met in the other two subjects at the 3-month interim assessment. Primary PB response was observed in 2 of 4 patients in one (hemoglobin) or two lineages (hemoglobin and platelets) at 6 months of treatment. Responders continue to receive EPAG at 10 or 25 months with sustained improvements in blood counts and transfusion independence. The subject treated for 25 months recently met response criteria in a third lineage (neutrophils) (Fig. E). Both patients who had a marrow but no PB response are clinically well; one subject (FANCA) underwent an unrelated allogeneic HSPC transplantation one year ago, and the other subject (FANCC) recently entered the extension phase of this study. Unilineage PB response criteria were also met in one of two subjects at the 3-month interim assessment.No drug-related serious adverse events have occurred during EPAG treatment. All patients tolerated the maximum dose of EPAG and no interruption or dose reduction was required for adverse events attributable to EPAG. Patients without transfusional iron overload at study entry developed progressive depletion of iron stores attributable to the known potent iron chelating and mobilizing properties of EPAG. At a median of 3 months after initiating EPAG (range, 1 to 6 months), affected patients initiated daily oral iron supplementation with gradual amelioration of iron store levels. To date, there has been no occurrence of marrow fibrosis, solid malignancies or clonal evolution, defined as abnormalities on standard metaphase analysis of bone marrow or overt clinical transformation to MDS/AML.In sum, treatment with EPAG was associated with increased marrow HSPCs in all subjects and PB responses in a subset of patients with Fanconi anemia. The overall safety profile was favorable. Further follow-up and expansion of the ongoing patient cohort will confirm EPAG's potential as a safe and efficient long-term therapeutic modality for FA-associated BMF. Alternatively, EPAG could also be used safely to boost marrow CD34+ cell numbers prior to autologous gene therapy applications. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

The role of HLA matching in unrelated donor hematopoietic stem cell transplantation for sickle cell disease in Europe.

We report the results of an analysis of unrelated allogeneic hematopoietic stem cell transplantations (HSCT) in 71 patients with sickle cell disease (SCD) transplanted in EBMT centers between 2005 and 2017. Median age was 9.3 years; graft type was bone marrow in 79% and peripheral blood in 21%. Recipient-donor HLA match at high resolution typing was 10/10 in 31, 9/10 in 20, and 8/10 in 4 patients; the other patients had intermediate resolution typing. The most frequent conditioning regimens were fludarabine-thiotepa-treosulfan (64%) or busulfan-cyclophosphamide (12%). Cumulative incidence of neutrophil engraftment was 92%; platelet engraftment was 90%. Eleven patients (15%) experienced graft failure. Grade II-IV acute graft-vs.-host disease (GvHD) was 23%; 3-year chronic GvHD was 23%. Three-year overall survival (OS) was 88 ± 4%. GRFS was 62 ± 6%. HLA matching was the most significant risk factor for OS: 3-year OS was 96 ± 4% in 10/10 group vs. 75 ± 10% in 9-8/10 (p = 0.042); GRFS was 69 ± 9% vs. 50 ± 12% (p = 0.114), respectively. In conclusion, unrelated donor HSCT is a valid option for SCD patients who lack an HLA-identical sibling donor, preferably in the context of clinical trials. Using a 10/10 HLA-matched unrelated donor yields better survival indicating that HLA matching is an important donor selection factor in this nonmalignant disease.

Immunophenotyping and Function of Peripheral Blood Mononuclear Cells in Patients Undergoing Unrelated Allogeneic Transplantation with Post-Transplantation Cyclophosphamide in Combination with ATG Anti-Graft Versus Host Disease Prophylaxis

Post-transplant cyclophosphamide (PTCy) effectively prevents alloreactive responses from unmanipulated grafts, but its effect on subsequent immune reconstitution remains largely undetermined. A total of 32 patients (pts) (ages > 18) who underwent allogeneic hematopoietic stem cell transplantation (HCT) mainly for acute leukemia and myelodysplastic syndrome were evaluated. Blood samples were collected at 15, 30, 60, 90, 180 and 270 days post-HCT. Cell phenotype was assessed on peripheral blood mononuclear cells (PBMC) using multiparametric flow cytometry. The proliferative and activation T cell capacity in response to mitogenic stimulation was determined. Pts who received graft versus host disease (GVHD) prophylaxis with PTCy/ATG combination (n=8) were compared with pts who received ATG (Grafalon®, Neovii) alone (n=13), and pts undergoing HCT with no ATG (n=11). Five healthy controls served for the functional assays. First, CD4+ and CD8+ T cell differentiation was evaluated assessing CD62L, CD45RA, and CCR7 expression. A smaller percentage of effector cells was detected in the PTCy/ATG group at days 30, 60 and 90 after HCT, compared to the no-ATG and ATG cohorts. Accordingly, the percentage of central memory and effector memory cells was significantly increased in PTCy/ATG pts at the same time points. Next, immuno-modulatory cell populations were assessed. A transient increase in the percentage of CD4+CD25+CD127- Treg cells was detected in both ATG and PTCy/ATG cohorts in the early post-HCT period, reaching maximal frequency of 21% Treg out of the CD4+ subset (range 14-42%) in the ATG group and 19% (range 12-30%) in the PTCy/ATG group on day 21, suggesting that Treg cells are relatively spared by Cy. However, a distinct expression pattern of checkpoint molecules was revealed in pts receiving PTCy/ATG. The percentage of PD1-positive CD4+ and CD8+ cells was comparable in the no-ATG and ATG cohorts (44% vs 45% and 35% vs 41%, respectively). Yet, PD1 expression was significantly increased on both CD4+ (61%, p<0.05) and CD8+ cells (60%, p<0.02) from pts receiving PTCy/ATG. Similarly, an increased frequency of LAG-3+ CD8+ cells was observed in the PTCy /ATG pts, in comparison to the no-ATG and ATG groups. Concomitantly, HLA-DR expression on CD56+ NK subset was decreased in PTCy/ATG pts versus the ATG and non-ATG groups (47% vs 61% vs 67%, respectively, p<0.05), indicating reduced activation of NK cells. Furthermore, a significant increase in the percentage of CD28-CD127- cells out of CD8+ cells was detected in PTCy/ATG pts compared to the ATG and no-ATG groups on day 60 post-HCT (82% vs 56% vs 38%, respectively, p<0.02). CD57 up-regulation combined with CD28 down-regulation on T cells reflected an exhausted/senescent phenotype; therefore, we further analyzed the frequency of CD28-CD57+ T cells. Significantly elevated expression of CD57 on CD8+CD28- cells was detected in the PTCy/ATG cohort, in comparison to the ATG and no-ATG groups (65% vs 43% vs 21%, respectively, p<0.01). Exhausted/senescent T cells showed functional impairment, which manifested as reduced potential for cytokine production and poor proliferative capacity. Notably, both CD4+ and CD8+ cells from ATG and PTCy/ATG cohorts demonstrated diminished proliferation in response to ex-vivo αCD3/αCD28 stimulation, when compared to the no-ATG cohort and healthy controls (p<0.01). Moreover, significantly reduced production of IFNγ in response to stimulation was detected in PTCy/ATG and ATG pts (p<0.01). PBMC from the no-ATG cohort displayed inducible IFNγ production levels comparable with healthy controls. Finally, PTCy/ATG-treated patients demonstrated altered phenotypic and functional recovery of the CD8+ cells. While CD4+ cells gradually downregulated PD1 expression and up-regulated co-stimulatory molecules CD28 and CD127 on days 180 and 270, notably CD8+ cells retained exhausted/tolerogenic phenotype as late as 270 days post-HCT. Our results demonstrate that the acquisition of senescent/exhausted phenotype by cytotoxic CD8+ cells is a distinctive feature of HCT with ATG conditioning. PTCy further compromises recovery of CD8+ cells and impairs NK activation, resulting in a sustained immunosuppression. Hopefully, these results will not only lead to a better understanding of the tolerance mechanisms behind PTCy/ATG anti GVHD prophylaxis but will also assist in the development of novel clinical treatments. Disclosures No relevant conflicts of interest to declare.

Children admitted to PICU after hematopoietic stem cell transplantation: a predictive model of mortality

Introduction: Hematopoietic stem cell transplantation (HSCT) in children is associated with severe complications that need admission to critical care units. Mortality in this group of patients remains high with reported survival that ranges between 38 and 71%. Goals: To analyze the predictive factors of mortality of pediatric patients who received HSCT and were admitted to the pediatric intensive care unit (PICU) Material and methods: Retrospective review and analysis of a population of children and adolescents who underwent hematopoietic stem cell transplantation from 12/01/2008 to 11/30/2018 and were admitted to the pediatric intensive care unit (PICU) of a university hospital. Results: Of 248 patients subjected to the analysis, 109 patients were admitted. Overall mortality was 29% (n=32). After univariate analysis, the type of transplant (unrelated), baseline disease (malignant vs non-malignant), febrile neutropenia, cytomegalovirus (CMV) infection, multiorgan failure, respiratory failure, graft versus host disease (GVHD), conditioning regimen with myeloablative chemotherapy and pre-transplant malnutrition were associated with higher mortality. After the Multivariate Analysis of Logistic Regression, the variables GVHD (OR 2, 23 95% CI: 1.92 a 2, 98), need of mechanical ventilation ( OR 2.47,95% CI 1.39 a 5.73) unrelated allogeneic transplants (OR 1.58, 95% CI 1.14 a 2.17) and previous malnutrition (OR: 1.78, 95% CI 1,223-3.89) were statistically associated with mortality. Conclusion: In our population two of three children receiving HSCT and admitted to PICU survived. Graft vs. host disease, need of mechanical ventilation, unrelated transplantation and previous malnutrition were predictors of mortality.

Development of Resistant GvHD in a Patient Treated with Nivolumab for Hodgkin‘s Lymphoma Relapse after Allogeneic Unrelated Transplantation

Background Allogeneic hematopoietic stem cell transplantation is one of the therapeutic options for patients with relapsed or refractory classic Hodgkins lymphoma (cHL). In the case of dis-ease relapse after transplant, other treatment options are still limited (for example donor lymphocyte infusion, and chemother-apy with brentuximab, bendamustine, or other agents) with uncertain outcomes in terms of patient tolerance and long-term dis-ease remission. One way to achieve remission is administration of the PD-1 inhibitor nivolumab, a PD-1 checkpoint inhibitor. Nivolumab is also indicated for the treatment of cHL relapses after autologous hematopoietic stem cell transplantation. Since September 2018, nivolumab has been approved by the State Institute for Drug Control in the Czech Republic for treatment of cHL autologous hematopoietic stem cell transplantation relapse; however, treatment with nivolumab is accompanied by an increased risk of develop-ing fatal, acute graft-versus-host dis-ease. Case The article describes the development of resistant acute graft-versus-host disease in a patient who had received allogeneic-unrelated transplantation and nivolumab treatment for Hodgkins lymphoma relapse. Conclusion Our case study, as well as the literature review, demonstrates the excellent efficacy of PD-1 inhibitors, but also cautions against the administration of these agents in patients follow-ing allogeneic hematopoietic stem cell transplantation. Administration of nivolumab to these patients should be done on a strictly individual basis in the context of known risks, and consideration should be given to other treatment options. Key words Hodgkins lymphoma - PD-1 inhibitor - nivolumab - GvHD - transplantation.

Post-Transplant Cyclophosphamide and Sirolimus in Matched Related and Unrelated Allogeneic Transplant with a Treosulfan-Based Conditioning

Abstract Introduction: Post transplant cyclophosphamide (PT-Cy) has recently emerged as a very promising pharmacological strategy to overcome human leukocyte antigen (HLA) barriers in the setting of haploidentical hematopoietic cell transplant (HCT). We recently reported a promising preliminary experience on the use of PT-Cy and sirolimus as graft-versus-host disease (GVHD) prophylaxis in matched allo-HSCT (Greco R et al, Blood 2016). Herein we describe long-term outcomes of matched allogeneic HSCT, using treosulfan-based conditioning, and GVHD prophylaxis with PT-Cy and sirolimus. Methods: In our center, we collected 104 adult patients (pts) receiving matched HSCT for high-risk hematological malignancies, mainly acute myeloid leukemia (n=43). Donor was matched related (MRD) for 45 pts, 10/10 matched unrelated (MUD) for 39 pts and 9/10 MUD for 20 pts. Median age was 48 years (range 19-78). At HSCT, 51% of patients were not in complete remission (CR), 39% were in CR1 and 11% in subsequent CR. Graft source was mainly PBSCs (95%). All pts received a conditioning regimen based on treosulfan and fludarabine; 89% received an intensified conditioning with the addition of melphalan. All pts received PT-Cy (50 mg/kg/day) on days 3 and 4. Sirolimus was given from day 5, and withdrawn 3 months after HSCT. Mycophenolate mofetil (MMF) was added from day 5 to day 30, only in MUD. All patients were treated according to current institutional programs upon written informed consent for transplant procedures. Results: Median follow up was over 16 months (range 3-51). Median CD34+ and CD3+ cell doses were 5.6x10^6/Kg (range, 1.5-10.9) and 2.0x10^8/Kg (range, 0.2-8.0), respectively. All the recipients of allo-HSCT experienced a sustained donor cell engraftment. The cumulative incidence of grades II-IV and III-IV acute GVHD at 100 days was 21% and 9%, respectively. The cumulative incidence of chronic GVHD was 25% at 2 years; we observed severe chronic GVHD only in 4% of pts. The cumulative incidences of relapse and non-relapse mortality (NRM) were 33% and 8% at 2 years, respectively. Two-year overall survival (OS) was 67% and progression free survival (PFS) 59%. The composite end point of GVHD-free/relapse-free survival (GRFS) was 52% at 2 years, in which events include grade 3-4 acute GVHD, systemic therapy-requiring chronic GVHD, relapse, or death. There was a longer OS, 2-year OS was 77% (p = 0.05), and a trend towards higher PFS and GRFS, 63% (p=0.07) and 58% (p=0.06) respectively, for pts with CR status at HSCT. We did not found a significant effect of HLA-matching (9/10 versus 10/10) or donor type (related versus unrelated) on major transplant outcomes (NRM, PFS, GRFS, relapse, acute and chronic GvHD). Conclusion: These outcomes confirmed that matched allogeneic HSCT using treosulfan-based chemotherapy, PT-Cy and sirolimus, is associated with low NRM and acceptable severe GVHD, providing relevant long-term survival in high-risk diseases. A randomized trial comparing this strategy with other kind of in-vivo T-cell depletion (i.e. ATG) is warranted. Disclosures Vago: Moderna TX: Research Funding; GENDX: Research Funding.

Effect of nonpermissive HLA-DPB1 mismatches after unrelated allogeneic transplantation with in vivo T-cell depletion

AbstractWe investigated the impact of donor-recipient HLA-DPB1 matching on outcomes of allogeneic hematopoietic stem cell transplantation with in vivo T-cell depletion using antithymocyte globulin (ATG) for patients with hematological malignancies. All donor-recipient pairs had high-resolution typing for HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQB1, HLA-DPB1, and HLA-DRB3/4/5 and were matched at HLA-A, HLA-B, HLA-C, and HLA-DRB1. HLA-DPB1 mismatches were categorized by immunogenicity of the DPB1 matching using the DPB T-cell epitope tool. Of 1004 donor-recipient pairs, 210 (21%) were DPB1 matched, 443 (44%) had permissive mismatches, 184 (18%) had nonpermissive mismatches, in graft-versus-host (GVH) direction, and 167 (17%) had nonpermissive mismatches in host-versus-graft (HVG) direction. Compared with HLA-DPB1 permissive mismatched pairs, nonpermissive GVH mismatched pairs had the highest risk for grade II to IV acute graft-versus-host disease (aGVHD) (hazard ratio [HR], 1.4; P = .01) whereas matched pairs had the lowest risk (HR, 0.5; P < .001). Grade III to IV aGVHD was only increased with HLA-DPB1 nonpermissive GVH mismatched pairs (HR, 2.3; P = .005). The risk for disease progression was lower with any HLA-DPB1 mismatches, permissive or nonpermissive. However, the favorable prognosis of HLA-DPB1 mismatches on disease progression was observed only in peripheral blood stem cell recipients who were in the intermediate-risk group by the Disease Risk Index (HR, 0.4; P = .001) but no other risk groups. Our results suggest avoidance of nonpermissive GVH HLA-DPB1 mismatches for lowering the risk for grade II to IV and III to IV aGVHD. Permissive or nonpermissive HVG HLA-DPB1 mismatches may be preferred over HLA-DPB1 matches in the intermediate-risk patients to decrease the risk for disease progression.

Differences in the economic valuation and determining factors of informal care over time: the case of blood cancer

ObjectiveTo estimate differences in the economic valuation and sociodemographic and clinical factors associated with informal care between phases of the treatment in the case of blood cancer patients. Methods139 haematological cancer patients who underwent a stem cell transplantation completed a longitudinal questionnaire according to 3 phases of the treatment: short-term (pre-transplant), medium-term (1st year post-transplant) and long-term (2nd-6th year post-transplant). Economic value of informal care was estimated using proxy good and opportunity cost methods. Ordered and binary logistic models were performed to identify factors associated with informal care. Results123 patients reported having received informal care. A progressive reduction of the number of hours of care was observed between phases. Monetary value per patient ranged from 1,288 to 3,409; 1,045 to 2,786; and 336 to 854 €/month in the short, medium and long term, respectively. Patients with acute leukaemia and those who received an unrelated allogeneic transplantation were 22% (short-term) and 33.5% (medium-term) more likely to receive more than 8hours/day of care respect to patients diagnosed with lymphoma and autologous transplantation. In the long term, patients with multiple myeloma were more likely to receive more care. Better health status and higher educational level were associated with fewer daily hours of care. ConclusionsInformal care varies greatly between stages of the treatment depending on the clinical and sociodemographic factors. Significant caring time and societal costs are associated with such care in blood cancer patients.

Age up to 75 Years Does Not Influence the Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in Acute Myeloid Leukemia and Myelodysplastic Syndrome

Introduction: Patients with AML and MDS who are age 60 or above represent a discrete group of patients with a different disease biology compared to younger patients. These patients are often not offered allogeneic hematopoietic stem cell transplant (HSCT) as a curative intent because of concern of increased nonrelapse mortality (NRM) and poor overall survival (OS). Hence, the information on transplant outcomes among this population is very limited. Recently with the use of better supportive care measures and reduced intensity preparative regimens, patients greater than 60 are often recommended to proceed to transplant. This study evaluates our single center experience of allogeneic transplantation in patients with MDS and AML aged 60 and older.Patients and Methods: We retrospectively evaluated 60 years or older consecutive patients with AML and MDS who underwent allogeneic HSCT between January 2005 and December 2014. The primary objectives of our study were to determine NRM, relapse, relapse free survival (RFS) and OS at 1 year following transplant. The secondary objectives were to estimate cumulative incidence of acute (aGVHD) and chronic GVHD (cGVHD) at 1 year, length of stay and readmission rate in the first 100 days following transplant.Results: Between January 2005 and December 2014, 159 patients underwent allogeneic HSCT with the median age of 64 (range, 60-75) years and median follow-up duration for OS of 3.34 (95% CI, 2.51-3.87) years. Increasing number of patients were transplanted in recent years, i.e., 67% patients between 2010-2014 compared to 33% between 2005-2009. One hundred three patients (65%) had AML and 56 patients (35%) had MDS. Forty-nine patients (31%) received full intensity regimen and 110 patients (69%) received reduced intensity regimen. Fifty-two patients (33%) underwent allogeneic related transplant and 107 patients (67%) had allogeneic unrelated transplant. Thymoglobulin based GVHD prophylaxis was given in 77 patients (48%) whereas non-thymoglobulin based GVHD prophylaxis was given in 82 patients (52%). The median day to neutrophil and platelet engraftment was 11 (range, 7-22) days and 16 (range, 0-675) days, respectively. Graft failure occurred in 3 patients. At 1-year follow-up, the cumulative incidence of grade II-IV aGVHD was 39.7% (95% CI, 32.0-47.2%), grade III-IV aGVHD was 20.8% (95% CI, 14.9-27.5%) and cGVHD was 54.1% (95% CI, 46.0-61.5%). The cumulative incidence of chronic extensive GVHD was 39.8% (95% CI, 32.1-47.4%). Blood stream infection, cytomegalovirus reactivation, Epstein-Barr virus reactivation, C. difficile diarrhea occurred in 44%, 35%, 22% and 26% of patients, respectively. At 1-year follow-up, NRM was 25.3% (95% CI, 18.8-32.3%), RFS was 53.3% (95% CI, 46.1-61.7%), relapse rate was 21.4% (95% CI, 15.4-28.1%) and OS was 56.4% (95% CI, 49.2-54.7%). The median day of hospitalization following transplant was 26 (range, 19-112) days and almost half (52%) of patients were readmitted in the first 100 days following transplant. Leukemia recurrence was the most common cause of death. Multivariable analysis demonstrated high disease risk index to be the independent predictor of poor RFS, OS and higher relapse rate (p<0.03), whereas non-thymoglobulin based GVHD prophylaxis, higher comorbidity index (≥3) and MDS were found to be associated with higher NRM (p<0.03). Most importantly, age did not shown to have any effect on relapse rate, OS, RFS, or NRM.Conclusion: Our results indicate that allogeneic HSCT is well tolerated and had acceptable NRM, and OS among this group. Hence, older age alone should not be considered a contraindication to HSCT. [Display omitted] [Display omitted] [Display omitted] DisclosuresDeol:Jazz Pharmaceuticals: Consultancy.

Transplant-Associated Thrombotic Microangiopathy: Prevalence, Prognostic Factors and Treatment Outcomes in Unrelated Allogeneic Transplant for Hematologic Diseases

Introduction: Transplant-associated thrombotic microangiopathy (TA-TMA) represents a devastating and life-threatening complication occurring more frequently in allogeneic compared to autologous hematopoietic cell transplantation (HCT). Although it has been a well-recognized syndrome for decades, our understanding in terms of epidemiology and more importantly, treatment options remains unclear. Therefore, we aimed to retrospectively investigate the incidence of TA-TMA in patients undergone HCT from unrelated donors and identify prognostic factors and treatment outcomes.Methods: We enrolled consecutive patients who underwent HCT from unrelated donors from 2003 to 2015. TA-TMA diagnosis was based on EBMT (European Bone Marrow Transplantation) criteria: increased (>4%) schistocytes in peripheral blood, thrombocytopenia, increased lactade dehydrogenase, decreased Hb. Anti-thymocyte globulin (ATG, rabbit) was used as standardised part of the conditioning in almost all patients (total dose of 5-7.5mg/kg). Prophylaxis for graft-versus-host disease (GVHD) consisted of cyclosporine or tacrolimus plus methotrexate in myeloablative and mycophenolate mofetil plus cyclosporine in reduced intensity conditioning transplants. Upon identification of TA-TMA, all possible causative factors were fully investigated. The mainstay of treatment strategy was withdrawal of calcineurin inhibitors, plasma infusion and plasma exchange combined with corticosteroid administration and in refractory cases, humanized anti-CD20 monoclonal antibody (Rituximab).Results: In total, we studied 179 patients, 74 male:105 female, aged 37±14 years, who underwent HCT from matched HLA A/B/C/DRB1 (8/8, n=88) and allele or antigen mismatched (n=91) grafts. Grafts derived from peripheral blood (157), bone marrow (18) and umbilical stem cells (4). Conditioning regimens were myeloablative (139), reduced intensity (28) and toxicity (12). Median follow-up was 11.5 (0.1-147.4) months.TA-TMA was diagnosed in 29 (16.2%) patients, 12 male:17 female, aged 34±12 years, 78 (9-721) days post-HCT for acute leukemia (21), Hodgkin (3) and non-Hodgkin (1), lymphoma, MDS (2), aplastic anemia (1) and MPN (1). Conditioning regimens were myeloablative in 24 (12 based on total body irradiation/TBI) and reduced intensity in 5 patients. Among patients with TA-TMA, 10 (34%) presented severe (grade III-IV) acute GVHD, 15 (52%) extensive chronic GVHD, 12 (41%) bacterial, 2 (7%) fungal and 21 (71%) viral (Cytomegalovirus and/or Epstein-Barr viremia) infectious episodes.In univariate analysis, age, gender, diagnosis, disease phase, previous lines of treatment, conditioning (intensity and TBI-based), ABO and HLA incompatibility, infections, acute and chronic GVHD were studied. The presence of TA-TMA was associated with severe acute and extensive chronic GVHD (p=0.001 and p=0.035 respectively) and TBI-based conditioning (p=0.043). In multivariate analysis, severe acute GVHD was the only independent factor associated with TA-TMA (β=3.4, p=0.038).Regarding treatment outcomes, 8 (28%) patients responded to cyclosporine cessation and plasma infusions. The rest 21 out of 29 patients underwent plasma exchange sessions; 14 (48%) of them responded to plasma exchange treatment. One patient that did not respond to plasma exchange received additional Rituximab treatment and the syndrome resolved. The other 6 (20.6%) patients were refractory and eventually succumbed. Treatment-related mortality was 33.3% (9/29) in TA-TMA patients and was directly associated with refractory microangiopathic syndrome in 6/29.Conclusion: Our results suggest that TA-TMA is not rare in unrelated transplant recipients and can be managed in a portion of patients that respond to cyclosporine cessation and plasma exchange. GVHD was the only independent predictor for the development of TA-TMA and therefore, successful prevention and treatment strategies for GVHD need to be timely employed to prevent complications. More importantly, transplanted patients with refractory microangiopathic syndrome showed increased TRM indicating that conventional treatment is inadequate. Recent data of increased complement activation in TA-TMA pave the way for targeted treatment with complement inhibitors in these patients. DisclosuresNo relevant conflicts of interest to declare.

Unrelated alternative donor transplantation for severe acquired aplastic anemia: a study from the French Society of Bone Marrow Transplantation and Cell Therapies and the EBMT Severe Aplastic Anemia Working Party.

Unrelated allogeneic transplantation for severe aplastic anemia is a treatment option after immunosuppressive treatment failure in the absence of a matched sibling donor. Age, delay between disease diagnosis and transplantation, and HLA matching are the key factors in transplantation decisions, but their combined impact on patient outcomes remains unclear. Using the French Society of Bone Marrow Transplantation and Cell Therapies registry, we analyzed all consecutive patients (n=139) who underwent a first allogeneic transplantation for idiopathic severe aplastic anemia from an unrelated donor between 2000 and 2012. In an adjusted multivariate model, age over 30 years (Hazard Ratio=2.39; P=0.011), time from diagnosis to transplantation over 12 months (Hazard Ratio=2.18; P=0.027) and the use of a 9/10 mismatched unrelated donor (Hazard Ratio=2.14; P=0.036) were independent risk factors that significantly worsened overall survival. Accordingly, we built a predictive score using these three parameters, considering patients at low (zero or one risk factors, n=94) or high (two or three risk factors, n=45) risk. High-risk patients had significantly shorter survival (Hazard Ratio=3.04; P<0.001). The score was then confirmed on an independent cohort from the European Group for Blood and Marrow Transplantation database of 296 patients, with shorter survival in patients with at least 2 risk factors (Hazard Ratio=2.13; P=0.005) In conclusion, a simple score using age, transplantation timing and HLA matching would appear useful to help physicians in the daily care of patients with severe aplastic anemia.

Use of Alefacept for Preconditioning in Multiply Transfused Pediatric Patients with Nonmalignant Diseases

Transfusion-related alloimmunization is a potent barrier to the engraftment of allogeneic hematopoietic stem cells in patients with nonmalignant diseases (NMDs). Memory T cells, which drive alloimmunization, are relatively resistant to commonly used conditioning agents. Alefacept, a recombinant leukocyte function antigen-3/IgG1 fusion protein, targets CD2 and selectively depletes memory versus naive T cells. Three multiply transfused pediatric patients with NMD received a short course of high-dose i.v. alefacept (.25 mg/kg/dose on days −40 and −9 and .5 mg/kg/dose on days −33, −26, −19, and −12) before undergoing unrelated allogeneic transplant in the setting of reduced-intensity pretransplant conditioning and calcineurin inhibitor–based post-transplant graft-versus-host disease (GVHD) prophylaxis. Alefacept infusions were well tolerated in all patients. Peripheral blood flow cytometry was performed at baseline and during and after alefacept treatment. As expected, after the 5 weekly alefacept doses, each patient demonstrated selective loss of CD2hi/CCR7−/CD45RA− effector memory (Tem) and CD2hi/CCR7+/CD45RA− central memory (Tcm) CD4+ and CD8+ T cells with relative preservation of the CD2lo Tem and Tcm subpopulations. In addition, depletion of CD2+ natural killer (NK) cells also occurred. Neutrophil recovery was rapid, and all 3 patients had 100% sorted (CD3/CD33) peripheral blood donor chimerism by day +100. Immune reconstitution (by absolute neutrophil, monocyte, and lymphocyte counts) was comparable with a cohort of historical control patients. All 3 patients developed GVHD but are all now off immune suppression and >2 years post-transplant with stable full-donor engraftment. These results suggest that alefacept at higher dosing can deplete both memory T cells and NK cells and that incorporating CD2-targeted depletion into a reduced-intensity transplant regimen is feasible and safe in heavily transfused patients.

Utility of surveillance blood cultures in patients undergoing hematopoietic stem cell transplantation.

BackgroundSurveillance blood cultures are often obtained in hematopoietic stem cell transplant (HSCT) patients for detection of bloodstream infection. The major aims of this retrospective cohort study were to determine the utility of the practice of obtaining surveillance blood cultures from asymptomatic patients during the first 100 post-transplant days and to determine if obtaining more than one positive blood culture helps in the diagnosis of bloodstream infection.MethodsWe conducted a 17-month retrospective analysis of all blood cultures obtained for patients admitted to the hospital for HSCT from January 2010 to June 2011. Each patient’s clinical course, vital signs, diagnostic testing, treatment, and response to treatment were reviewed. The association between number of positive blood cultures and the final diagnosis was analyzed.ResultsBlood culture results for 205 patients were reviewed. Cultures obtained when symptoms of infection were present (clinical cultures) accounted for 1,033 culture sets, whereas 2,474 culture sets were classified as surveillance cultures (no symptoms of infection were present). The total number of positive blood cultures was 185 sets (5.3% of cultures obtained) and accounted for 84 positive culture episodes. Incidence of infection in autologous, related allogeneic and unrelated allogeneic transplants was 8.3%, 20.0%, and 28.6% respectively. Coagulase-negative staphylococci were the most common organisms isolated. Based on our application of predefined criteria there were 29 infections and 55 episodes of positive blood cultures that were not infections. None of the patients who developed infection were diagnosed by surveillance blood cultures. None of the uninfected patients with positive blood cultures showed any clinical changes after receiving antibiotics. There was a significant difference between the incidence of BSI in the first and second 50-day periods post-HSCT. There was no association between the number of positive blood cultures and the final diagnosis.ConclusionSurveillance blood cultures in patients who have undergone HSCT do not identify bloodstream infections. The number of positive blood cultures was not helpful in determining which patients had infection. Patients are at higher risk of infection in the first 50 days post-transplant period.