HLA-identical Sibling Donor Research Articles

Individual HLA alleles and risk of graft-versus-host disease after haematopoietic stem cell transplantation from HLA-identical siblings

Graft-versus-host disease (GVHD) in its acute (aGVHD) and chronic (cGVHD) form remains one of the most serious complications of allogeneic haematopoietic stem cell transplantation (allo-HSCT). There are several risk factors known to be associated with GVHD development. Some reports suggest that certain human leukocyte antigen (HLA) variants may influence the incidence of GVHD. The aim of our study was to analyse possible association between individual HLA alleles and the occurrence of aGVHD and cGVHD in patients following allo-HSCT from HLA-identical sibling donors. We have retrospectively reviewed medical records of 96 patients who received a transplant in the years 1994–2008. Cumulative incidence of acute GVHD was 31.3% and that of chronic GVHD was 26.0%. Recipients carrying the HLA-A*01, -DRB1*03 and -DQB1*03 alleles showed a statistically significantly lower incidence of aGVHD. Furthermore, the HLA-DQB1*06 allele was associated with a higher incidence of cGVHD. Each of these alleles was confirmed by logistic regression analysis as an independent factor with impact on GVHD development. Our results support findings of authors showing an association between certain HLA variants and GVHD appearance. However, other authors assume that there is no convincing evidence for such an association. Therefore, when taking into account limitations of our study design and the significant inconsistency in the results of the previous reports, a careful approach in judgement is required. To conclude, in our view, the prognostic value of individual HLA variants for GVHD development in a setting of HLA-identical allo-HSCT does not seem to be of great clinical relevance.

Safety and outcome of allogeneic stem cell transplantation in mycosis fungoides and Sezary syndrome: A seven-year tertiary center analysis.

e20038 Background: Allogeneic hematopoietic stem cell transplantation (AHSCT) is a promising strategy for treatment of advanced-stage mycosis fungoides/Sezary syndrome (MF/SS). In this study, we retrospectively analyzed the outcomes of AHSCT for MF/SS and found that MF/SS appears to be susceptible to graft versus leukemia (GVL) effects. Methods: We studied outcomes in a consecutive series of 14 patients with MM/SS who underwent AHSCT between January 2012-November 2019 at our center. Treatment response was evaluated according to the Consensus WHO criteria for MF/SS. Results: The median age of patients 51.5 years (range: 28-68 years). Eight patients had MF and six patients had SS. Nine of those 14 patients had large cell transformation. All patients had advanced disease (stages IIB: n = 1, IIIA: n = 2, IIIB: n = 6, IVA1: n = 2 and IVB = 3). The median interval from disease onset to AHSCT was 3.7 years (range: 10.5 mos-11.3 years). All of the patients received at least three lines of treatments prior to AHSCT. Four patients achieved CR (3 are alive and still in CR) and all the other patients had progressive disease (PD) at the time of AHSCT. Graft source was peripheral blood stem cell in all patients. Six patients underwent transplantation from 9/10 HLA-matched unrelated donors and eight patients from HLA-identical sibling donors. Most of the patients (12/14) received RIC regimen (Flu-Cy-TBI) and ATG-Fresenius also added the protocol in AHSCT from unrelated donors. Five patients had stage 2-4 cutaneous acute GVHD and chronic GVHD developed in four patients (mild: n = 1, moderate: n = 2, severe: n = 1). Six patients who underwent transplantation at PD attained CR after AHSCT however relapse occurred in four patients at a median of four months (range: 3-10 months) after HSCT. At the time of data collection, nine patients have deceased; three were due to early TRM, three were underlying disease, two had aspergillus infection and one had nocardia infection. Two patients were alive with disease being treated by the Brentixumab vedotin, gemcitabine and DLI. With a median follow up period of 8.7 months after AHSCT, the estimated 1-year OS and PFS was 40.4%±5% and 35.4%±3.9%, respectively. Conclusions: AHSCT is an effective treatment option for advanced-stage MF/SS. Further studies are warranted to improve the outcome after AHSCT.

Determinants of survival in myelofibrosis patients undergoing allogeneic hematopoietic cell transplantation

We aimed to evaluate the determinants of survival in myelofibrosis patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) and to describe factors predicting the main post-HCT complications. This retrospective study by the European Society for Blood and Marrow Transplantation included 2916 myelofibrosis patients who underwent first allo-HCT from an HLA-identical sibling or unrelated donor between 2000 and 2016. After a median follow-up of 4.7 years from transplant, projected median survival of the series was 5.3 years. Factors independently associated with increased mortality were age ≥ 60 years and Karnofsky Performance Status <90% at transplant, and occurrence of graft failure, grades III-IV acute graft-vs.-host disease (aGVHD), and disease progression/relapse during follow-up. The opposing effects of chronic graft-vs.-host disease (GVHD) on non-relapse mortality and relapse incidence resulted in a neutral influence on survival. Graft failure increased in unrelated donor recipients and decreased with myeloablative conditioning (MAC) and negative donor/recipient cytomegalovirus serostatus. Risk of grades III-IV aGVHD was higher with unrelated donors and decreased with MAC. Relapse incidence tended to be higher in patients with intermediate-2/high-risk DIPSS categories and to decrease in CALR-mutated patients. Acute and chronic GVHD reduced the subsequent risk of relapse. This information has potential implications for patient counseling and clinical decision-making.

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.

Matched-Pair Analysis of Transplant from Haploidentical, Unmanipulated Bone Marrow Donor versus HLA Identical Sibling for Patients with Hematologic Malignancies.

A matched-pair analysis of transplant-related outcomes was carried out in 116 of 255 consecutive patients who received transplants from an HLA identical sibling (n=58) or haploidentical related donor (n=58). The 2 patient series were matched with 9 variables: period of transplant, patient and donor age, sex, diagnosis, disease phase, conditioning regimen, donor-recipient sex, and cytomegalovirus (CMV) status combinations. As graft-versus-host disease (GVHD) prophylaxis, all patients received the standard cyclosporine and methotrexate association with the addition of anti-thymocyte globulins, mycophenolate mofetil, and basiliximab in haploidentical, unmanipulated bone marrow recipients. Anti-infectious management, transfusion policy, and supportive care were identical for all patients. By comparing the 2 patient series, no statistically significant difference was observed for the cumulative incidence of advanced acute and extensive chronic GVHD, transplant-related mortality, and relapse. With a median follow-up of 3.5 years, the 5-year disease-free survival was 37% ± 6% and 36% ± 6% for HLA identical sibling and haploidentical recipients, respectively. The results of transplant from HLA identical siblings and haploidentical donors are comparable. Regardless of the HLA matching, other factors known to affect the transplant outcomes, such as donor-recipient age, sex, and CMV status combinations, might drive the search for the best donor.

Comparison of Tacrolimus and Cyclosporine Combined With Methotrexate for Graft Versus Host Disease Prophylaxis After Allogeneic Hematopoietic Cell Transplantation.

After patients receive hematopoietic stem cell transplantation (HSCT), both cyclosporine (CsA) and tacrolimus (TAC) in combination with methotrexate (MTX) are recommended as the standard prophylaxis strategy for graft versus host disease (GVHD) by the European Group of Blood and Marrow Transplantation. However, the advantage of TAC combined with MTX lacks conclusive evidence. We searched online databases for studies comparing CsA + MTX and TAC + MTX in patients who received HSCT. The odds ratio (OR) and 95% confidence interval (CI) were applied to compare the pooled data. We found a significant reduction in the grade II to IV acute GVHD (aGVHD) rate (OR, 0.42; CI, 0.28-0.61; P < 0.00001), grade III to IV aGVHD rate (OR, 0.59; CI, 0.38-0.92; P = 0.02), chronic GVHD rate (OR, 0.79; CI, 0.62-1.00; P = 0.05), and nonrelapse mortality rate (OR, 0.62; CI, 0.40-0.95; P = 0.03) and an increase in the overall survival (OS) rate (only in those received from unrelated donor) (OR, 1.30; CI, 1.15-1.48; P < 0.0001) in the TAC + MTX group. Similar outcomes occurred for the relapse rate and disease-free survival rate in both groups. TAC + MTX has a superior effect in the prevention of aGVHD in patients who received HSCT and further prolongs the OS in patients who received from unrelated donor transplants. CsA + MTX prolongs the OS in patients who received HSCT from HLA-identical sibling donors. The leukemic relapse and disease-free survival rate were not different between the 2 regimens. Thus, we conclude that TAC + MTX was superior to CsA + MTX, especially for HSCT patients with nonmalignant disorders. Further studies are still required to evaluate the effect of TAC or CsA combined with other suppressors in the treatment regimen following HSCT.

Decrease in T-Lymphocyte Mitochondrial DNA Copy Number Is Associated with Acute Graft Versus Host Disease

Introduction Mitochondria play an important role in T-lymphocyte activation and initiation of the inflammatory response, two pathways that are important in the pathogenesis of acute graft-versus-host disease (aGvHD). We evaluated whether change in mitochondrial DNA (mtDNA) copy number in CD3+ T-lymphocytes measured at two time-points pre and post aGvHD could be used as a biomarker for aGvHD diagnosis that correlates with clinical and/or biopsy proven aGvHD. Methods 99 patients who underwent an allogeneic hematopoietic cell transplant (allo-HCT) between March 2012 and December 2016, were diagnosed with aGvHD and had samples available before and after aGvHD diagnosis were selected for this analysis. We measured mtDNA copy number in CD3+ T-lymphocytes at two time points using real time quantitative polymerase chain reaction (PCR); once prior to diagnosis of aGvHD (median (Interquartile range): 11 (5 – 22) days prior to aGvHD diagnosis) and once after aGvHD diagnosis (median: 23 (12-34) days after aGvHD diagnosis) in 99 patients. 16% (n=16) of the patients had grade I aGvHD and 84% (n=83) had grade II-IV aGvHD. We used linear mixed models with random subject and batch effects to evaluate the change in mtDNA copy number before to after aGvHD diagnosis within each patient. We also used Fine and Gray regression models to evaluate whether reduction in mtDNA copy number after aGvHD diagnosis was associated with one year non relapse mortality (NRM). Results The median age was 58 (interquartile range 38 to 65). 35% patients underwent a transplant from a HLA-identical sibling donor, 19% matched unrelated donor, 2% mismatched related donor, 14% single and 30% double umbilical cord blood. Conditioning was myeloablative in 36% and reduced intensity in 64%. aGvHD was diagnosed at a median of 42 (range 14-180) days from HCT. 16 (16%) of the patients were diagnosed with grade 1, 38% with grade II, 34% grade III and 11% grade IV aGvHD. Overall, geometric mean mtDNA copy number decreased 14% after aGvHD diagnosis (95% CI: 3% to 26%; p=0.01). MtDNA copy number decreased from pre-aGvHD to post-aGvHD in all grades of aGvHD though a decrease was seen in a larger proportion of patients with grade IV aGvHD (9/11; 82%) vs. patients with grade I aGvHD (8/16; 50%). There were 25 patients who experienced NRM within the first year of transplant. Exploratory analysis showed that mortality was lower among patients in whom mtDNA copy number increased post-aGvHD diagnosis (6/38; 16%) as compared to those in whom mtDNA copy number decreased post-aGvHD diagnosis (19/61; 31%) (p=0.12). Conclusion This study shows that mtDNA copy number was more likely to decrease after diagnosis of aGvHD. Thus, change in mtDNA copy number among CD3+ T lymphocytes may be a useful biomarker to identify individuals with aGvHD. The prognostic significance of reduced mtDNA copy number on NRM needs to be evaluated in larger studies.

Post-Transplant Cyclophosphamide Versus Antithymocyte Globulin in Patients with Acute Myeloid Leukemia Undergoing Allogeneic Stem Cell Transplantation from HLA-Identical Sibling Donors: A Retrospective Analysis from the Acute Leukemia Working Party of the EBMT

Introduction. In patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) from an HLA-identical matched sibling donor (MSD), use of cyclosporine A in association with methotrexate has been the main graft-versus-host disease (GVHD) prophylaxis strategy. Addition of antithymocyte globulin (ATG), especially when using peripheral blood stem cells (PBSC) as source, has also been shown to favor lower rates of chronic GVHD. More recently, use of post-transplant cyclophosphamide (PTCY) in the haploidentical setting resulted in low incidences of both acute and chronic GVHD. Its use has therefore been subsequently reported in other donor settings, including MSD. The aim of our study was to compare GVHD prophylaxis containing either PTCY or ATG in patients diagnosed with acute myeloid leukemia and undergoing allo-HSCT from a MSD. Methods. This was a retrospective study from the EBMT registry. Included were adult patients undergoing their first allo-HSCT during the period 2008-2018 and who were in complete remission at time of allo-HSCT. Results. Globally, 197 and 1,913 patients receiving either PTCY or ATG, respectively, were identified who fulfilled inclusion criteria. Patients in the PTCY group were younger (median age 47 versus 54 years, p&amp;lt;0.01) and had undergone allo-HSCT more recently (median year of allo-HSCT: 2015 versus 2014, p&amp;lt;0.01). Peripheral blood was the more frequently used stem cell source, this being significantly more frequent in the ATG group (95% versus 70%) than in the PTCY group (p&amp;lt;0.01). The conditioning regimen was more frequently myeloablative in the PTCY group (59% versus 48% in the ATG group, p&amp;lt;0.01). Cyclosporine-A alone was the most used systemic immunosuppressive agent associated with either PTCY (22%) or ATG (28%), while 34% and 29% of patients in the ATG group and 7% and 12% in the PTCY group also received either methotrexate or mycophenolate mofetil along with cyclosporine A. No statistical differences were observed for incidence of grade II-IV acute GVHD at 100 days after allo-HSCT, this being 19% versus 17% in the PTCY and ATG groups, respectively (p=0.81). On the other hand, a significantly higher incidence of chronic GVHD at 2 years was observed with the use of PTCY (37% versus 30%, p&amp;lt;0.02) and for extensive chronic GVHD (16% versus 12%, p&amp;lt;0.01) as compared to ATG. There was no impact of conditioning intensity on GVHD incidence. No statistical differences were observed on univariate analysis for all other transplant outcomes, with a leukemia-free survival (LFS) of 55% versus 58%(p=0.75), overall survival (OS) of 64% versus 65% (p=0.61), GVHD-free, relapse-free survival (GRFS) of 44% versus 49% (p=0.19), relapse incidence (RI) of 36% versus 32% (p=0.56) and non-relapse mortality (NRM) of 8% versus 10% (p=0.78). Of note, the cumulative incidences of death due to GVHD were 4.4% and 4% in the PTCY and ATG groups, respectively (p=0.53). Also, there were no differences between the 2 groups for death due to infections: 6% in the PTCY group and 6.3% in the ATG group, respectively (p=0.49). On multivariate analysis, these results were confirmed, with a higher risk of chronic GVHD of any grade (HR=1.41, 95%CI 1.03-1.92; p&amp;lt;0.01) and extensive chronic GVHD (HR=1.68, 95%CI, 1.07-2.62; p&amp;lt;0.01) with PTCY, and no differences with respect to the other outcomes. We also observed that, regardless of the use of PTCY or ATG, use of PBSC was associated with lower RI (HR=0.64, 95% CI 0.46-0.89; p&amp;lt;0.01), higher LFS (HR=0.71, 95% CI 0.53-0.95; p&amp;lt;0.03), and OS (HR=0.72, 95% CI 0.52-0.99; p&amp;lt;0.05). On the other hand, we found no statistical differences in terms of both acute GVHD (HR=0.73, 95%CI, 0.48-1.12; p=0.15) and chronic GVHD (HR=0.83, 95% CI 0.56-1.21; p=0.33) according to stem cell source. These results were also confirmed in a matched-pair analysis. Conclusion. In conclusion, our results highlight that in the HLA-identical sibling setting, the use of ATG provides similar outcomes to those seen with PTCY except for chronic GVHD for which a protective effect of ATG is confirmed as previously reported by different other studies. Disclosures Blaise: Sanofi: Honoraria; Molmed: Consultancy, Honoraria; Pierre Fabre medicaments: Honoraria; Jazz Pharmaceuticals: Honoraria. Chevallier:Incyte: Consultancy, Honoraria; Jazz Pharmaceuticals: Honoraria; Daiichi Sankyo: Honoraria. Socie:Alexion: Consultancy. Mohty:Jazz Pharmaceuticals: Honoraria, Research Funding.

Identification of New Polymorphisms in Genes of the Immune System Associated with Acute Graft Versus Host Disease after Identical HLA-Allogeneic Stem-Cell Transplantation

INTRODUCTION Allogeneic haematopoietic stem cell transplant (allo-HSCT) could be the only curative therapy for patients with hematological malignancies due to graft effect against tumor. However, approximately 40% of patients develop post-transplantation complications such as acute graft-versus-host disease (aGVHD). Cytokines and their receptors are involved in regulatory and inflammatory processes that occur during GVHD. Therefore, the analysis of polymorphisms (SNPs) that affect the expression or activity of these genes could be used as biomarkers to predict the development of these complication. The aim of this study was to select new polymorphisms in cytokine genes (interleukins, chemokines and their receptors) to build models to predict the development of aGVHD after allo-HSCT from an HLA-identical sibling donor. METHODS We retrospectively selected 88 patients with hematological malignancies who received an allo-HSCT from an HLA-identical sibling donor from 2000 to 2015. A total of 176 pre-transplant recipient (R) and donor (D) peripheral blood samples were collected. The genotyping was performed using an enrichment-capture gene panels (include 132 genes (73 interleukins, 59 chemokines) in a HiSeq platform (Illumina, USA). The bioinformatic analysis was carried out with the GeneSystemssoftware (Sistemas Genómicos, Spain). Variants located in coding region, splicing sites, and UTR, 5'upstream and 3'downstream zones (+ 200pb) were analyzed. We selected polymorphisms corresponding to non-synonymous variants, represented in at least 5% of our cohort, with readings ≥30X in the canonical isoformwith an allele frequency ≥ 0.4. Fisher test was used to compare the differences among groups. Multiple logistic regression models were performed using combination of interleukins and chemokines polymorphisms selected previously that could be applied to clinical practice to predict aGVHD. The models with the highest AUC value, sensitivity and specificity value and the lowest number of genetic variants used were selected.Statistical Package for the Social Sciences (SPSS, Chicago, USA) was used for statistical test. RESULTS The cumulative incidence rates for aGVHD of grades II-IV and III-IV at 100 days after transplantation were 48.93% and 18.08%, respectively. The clinical variables (age, gender, pathology, stem cell source and previous transplantation) were not correlated with II-IV or III-IV aGVHD. However, patients who received ablative conditioning regimen presented a lower incidence of III-IV aGVHD (p= 0.041). Using filters defined previously, we detected 481 polymorphisms (350 coincident, 68 specific R and 63 for D) in the interleukins group. On the other hand, we detected 339 polymorphisms (267 coincident, 29 specific R and 43 for D) in the group of chemokines. Finally, 17 polymorphisms were selected in the interleukin group and 10 in the chemokine group for its correlation with the aGVHD (p &lt;0.05). Specifically, 14 SNPs were correlated with II-IV aGVHD (Table 1) and 12 SNPs with III-IV aGVHD (Table 2). Most polymorphisms found are located in regulatory regions, which until have been little studied, but these regions are involved in the expression genes, therefore could be affecting the function of these genes. We developed multiple logistic regression models for II-IV and III-IV aGVHD in interleukins and chemokines genes (Table 3). The identification of these 15 polymorphisms could help us to prevent the developing II-IV and III-IV aGVHD. CONCLUSIONS We have identified new genetic polymorphisms correlate with the risk of developing aGVHD after allo-HSCT from an HLA-identical sibling donor. Based on these data, we have developed a genetic score that encompasses polymorphisms of greater relevance. In this way, patients at greatest risk for developing this type of post-transplantation complication who could benefit from personalized management through immunosuppression and other drugs. Disclosures No relevant conflicts of interest to declare.

Clinical Outcomes after Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Transfusion-Dependent β-Thalassemia Treated at the Bambino Gesù Children's Hospital, Rome, Italy

β-thalassemia is one of the most common monogenic blood disorders worldwide, and is highly prevalent in Mediterranean countries. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been the only curative treatment for transfusion-dependent β-thalassemia (TDT; the most severe disease form) for many years, but it is limited by donor availability and has a significant risk of morbidity and mortality. We conducted a chart review of patients with β-thalassemia who underwent allo-HSCT (N=80) at the Bambino Gesù Children's Hospital, Rome, Italy, between March 2011 and August 2018. Median (range) age at allo-HSCT was 5.5 (0.3-20.0) years [&amp;lt;12 years: n=70 (87.5%), ≥12-18 years: n=7 (8.8%), ≥18 years: n=3 (3.8%)] and all patients but one had TDT [n=79 (98.8%)]. Prior to allo-HSCT, patients received a median (range) of 17.4 (4-52) transfusions per year (n=64) and had a median (range) serum ferritin concentration of 1217 (135-9123) ng/mL and a median (interquartile range) hemoglobin level of 10.3 (9.3-11.4) g/dL. All patients had received regular iron chelation therapy prior to transplantation. In total, 18 (22.5%), 28 (35.0%), and 34 (42.5%) patients received allo-HSCT from human leukocyte antigen (HLA)-identical sibling donors, HLA-haploidentical donors, and unrelated donors (fully matched donor: n=28, donor with a single HLA disparity: n=6), respectively. Of these donors, 42 (52.5%) were carriers for thalassemia-associated mutations. In total, 53 (66.3%) donors and 35 (43.8%) recipients were cytomegalovirus-positive. Bone marrow was the stem cell source in 51 cases (63.8%), while 28 patients received an alphabeta T-cell depleted peripheral blood haploidentical HSCT (35.0%); the remaining child (1.3%) received both bone marrow and cord blood from the same related donor. All patients continued to receive transfusions immediately after allo-HSCT; however, only 7 (8.8%) received a transfusion in the 3 to 12-month post-transplantation period (2 due to underlying disease; 5 due to other reasons including GI bleeding). Median (range) time to reach transfusion-free status was 3.8 (1.1-47.8) weeks. Median (interquartile range) hemoglobin levels at 6 and 12 months after allo-HSCT were 10.9 (10.2-11.9) and 11.9 (10.6-13.0) g/dL, respectively. The cumulative incidences of primary and secondary graft failure were 10.0% and 12.5% at 24 months (HLA-identical donor: 0% and 11.1%, haploidentical donor: 17.9% and 3.6%, unrelated donor: 8.8% and 20.6%). Eleven out of 14 patients experiencing graft failure were successfully rescued with a second allograft, while 2 patients were not retransplanted due to parental decision and 1 patient died after the engraftment of the second allograft. Eight patients developed grade II-IV acute graft-versus-host disease (GVHD) and one patient developed moderate chronic GVHD. Cumulative incidence rates of grades II-IV and III-IV acute GVHD were 12.7% and 8.0% at 24 months (HLA-identical donor: 0% and 0%, haploidentical donor: 7.3% and 0%, unrelated donor: 23.8% and 18.8%). Three patients (3.8%) died of transplant-related causes (1 case each of hemophagocytic lymphohistiocytosis, sepsis, and multi-organ failure [the patient receiving the second allograft]) with a median (range) time from transplantation to death of 8.7 (3.7-11.0) months. Of these patients, all had been transplanted from an unrelated donor and 2 had reached sustained full-donor chimerism. The probability of overall and event-free (event defined as either death or primary/secondary graft failure) survival was 96.2% and 81.2% at 24 months (HLA-identical sibling donor: 100% and 88.9%, haploidentical donor: 100% and 78.6%, unrelated donor: 91.2% and 79.4%). The probability of thalassemia-free survival (event defined as either death or primary/secondary graft failure not rescued by a second allograft) was 93.7% at 24 months (HLA-identical sibling donor: 100%, haploidentical donor: 92.9%, unrelated donor: 91.2%). In this large single-center cohort of children with predominantly TDT, allo-HSCT led to beneficial outcomes for most patients, resulting in the discontinuation of transfusions with 93.7% of patients being thalassemia-free. Nevertheless, HSCT is still associated with GVHD, graft failure, and mortality, and only 22.5% of patients had an HLA-identical sibling donor, illustrating a key limitation of allo-HSCT. Emerging research is addressing such barriers to treatment. Disclosures Merli: Novartis: Honoraria; Sobi: Consultancy; Amgen: Honoraria; Bellicum: Consultancy. Algeri:Miltenyi: Honoraria; Atara Biotherapeutics: Consultancy, Honoraria; Bluebird bio: Consultancy, Honoraria. Gruppioni:Bluebird bio: Employment, Equity Ownership. Kommera:Bluebird bio: Employment, Equity Ownership. Maa:Bluebird bio: Employment, Equity Ownership. Locatelli:Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria.

Comparison of Different Upfront Transplant Strategies in Multiple Myeloma - a Large Registry Study from Chronic Malignancies Working Party of EBMT

Comparison of Different Upfront Transplant Strategies in Multiple Myeloma - a Large Registry Study from Chronic Malignancies Working Party of EBMT

Mapping the Road of Gvhd and GVT: A Longitudinal Study of Immune-Transcriptome Signatures As Novel Approach to Solve Post-Allogeneic Hematopoietic Cell Transplantation Dilemmas

Introduction Allogeneic Hematopoietic Cell Transplantation (allo HCT) is currently the only curative therapy for high-risk hematologic malignancies due to the immune response of the donor cells against the malignant cells (graft versus tumor effect; GVT), but with the cost of Graft Versus Host Disease (GVHD). Despite extensive research, very few predictors of GVHD and GVT have been identified to date. Additionally, clinical GVHD diagnosis can be challenging due to chemotherapy-related or infection-related organ toxicity manifestations, which further complicate prediction and treatment stratification algorithms. In order to study the mechanisms of GVHD and GVT and to identify potential GVHD markers we apply a novel approach, called Transcriptome Fingerprint Assay (TFA), relying on high frequency sampling and blood transcript profiling. The TFA is a multiplex microfluidics q-PCR based assay linked with a computational model for modular functional transcriptome analyses, uniquely tailored to answer complex questions on immune perturbations through frequent profiling of gene expression signatures from &lt; 1 ml of blood (Chaussabel and Baldwin. Nat Rev Immunol 2014, Speake et al. Clin Exp Immunol 2017). This approach has been successfully applied to stratify patients' prognosis in autoimmune and infectious diseases (Banchereau R et al. Cell 2016, Dunning et al. Nat Immunol 2018). In our study we use the TFA to capture longitudinal immune signatures as dynamic "snapshots" of the patient's immune system after HCT. Hypotheses Fluctuations over-time in gene expression of allo HCT patients' immune system reflect the pathologic/disease control programs (GVHD/GVT) and may be used to identify diagnostic and predictive biomarkers. GVHD/GVT control immune programs depend on the "inner" interface between the donor immune-system and the recipient, and are influenced by external variables, as infections or drugs. These variables can affect the immune system-related gene expression and can be measured. Objectives To systematically measure gene expression signatures in immune perturbations post-allo HCT, in order to: Identify GVHD-related immune signatures consistent with clinical diagnosis of GVHD.Predict and stratify therapy-resistant GVHD and severe chronic GVHD, according to immune signatures.Identify links (causative and consequential) between GVHD, GVT, relapse, and other post-transplant immune perturbations (e.g. infections). Methods Enroll 250 allo HCT patients to populate a "GVHD cohort" and a "non-GVHD cohort" of 50 patients each, and 50 donors (healthy controls cohort) . Patients donate micro-quantities of blood (50 to 600 microliters), weekly until day 100 post-transplant and every 2 weeks thereafter until 2 years after transplant. Detailed clinical, laboratory and therapy annotations are captured during the follow-up. Gene expression of 264 immune-related genes for each sample are measured through Fluidigm BioMark high throughput qPCR system, and normalized to the geometric mean Ct of 8 housekeeping genes. Data interpretation is performed through TFA modular analyses and correlated with the clinical annotations. Results Results of three series of patients' samples are shown to exemplify the potential of TFA as a method to study the mechanisms of GVHD and GVT. All three patients underwent myeloablative peripheral blood stem cell transplant from an HLA identical sibling donor. Two patients developed steroid responsive-acute GVHD (patient #1: GVHD stage I was diagnosed on day 38 post HCT, patient #4: GVHD stage III was diagnosed on day 21 post HCT). One patient (Patient #6) did not develop clinical GVHD, but routine skin biopsy on day 80 revealed apoptotic cells consistent with subclinical skin GVHD. Principal Component Analysis (PCA) of the three patients' series is shown in Figure 1, the dynamic transcriptomes according to TFA modules of patients #1 and #6 are shown in Figure 2, and representative TFA modular fingerprints are shown in Figure 3. Conclusion We anticipate that using the TFA approach will help to fill knowledge gaps instrumental to solve clinical dilemmas related to allo HCT complications, and to improve the clinical outcomes of allo HCT patients. Disclosures No relevant conflicts of interest to declare.

Adding Azathioprine and Hydroxyurea Preconditioning to Alemtuzumab/TBI May Improve Donor Chimerism in Matched Sibling Donor Allogeneic Stem Cell Transplantation in Adult Sickle Cell Patients

Introduction Sickle cell disease (SCD) is a severe, inherited hemoglobinopathy, characterized by hemolysis, vaso-occlusive crisis (VOC) and progressive organ damage, resulting in poor quality of life and reduced life expectancy. Improvements in supportive care, use of (exchange) blood transfusions and hydroxyurea have resulted in better survival in SCD children. Nevertheless, SCD related organ damage continues during adult life, resulting in increased morbidity and mortality. Allogeneic stem cell transplantation is currently the only curative treatment option for SCD. In adults, myeloablative conditioning is associated with significant toxicity, primarily due to cumulative organ damage. Matched sibling donor (MSD) transplantation with non-myeloablative conditioning (alemtuzumab + 3 Gy total body irradiation (TBI)) using peripheral blood stem cells has shown promising results in adult SCD patients. In patients treated with this regimen the SCD phenotype resolved with only mild transplantation-related complications, but no reports of graft-versus-host disease (GvHD). However, a large part of these patients did not reach complete donor chimerism and graft failure rates of 8-13% have been reported with this regimen (Hsieh et al. JAMA, 2014; Saraf et al. Biol Blood Marrow Transplant, 2016). Adding azathioprine and hydroxyurea as preconditioning to the alemtuzumab/TBI regimen might improve donor chimerism and reduce risk of graft failure. In this study we prospectively investigate the effects of azathioprine/hydroxyurea preconditioning prior to alemtuzumab/TBI conditioning on donor chimerism and graft failure in patients receiving MSD allogeneic stem cell transplantation for SCD. Methods Adult SCD patients with complications refractory to standard care who had an HLA-identical sibling donor were eligible for this treatment. After 3 months of azathioprine 150mg qd and hydroxyurea 25mg/kg qd, erythrocyte exchange transfusion was performed on day -10, aiming for HbS &amp;lt;30%. Conditioning with alemtuzumab and TBI was started on day -7, as described by Hsieh et al (N Engl J Med, 2009). GvHD prophylaxis consisted of sirolimus. Data regarding SCD phenotype, donor chimerism and transplantation-related complications were collected prospectively. Results Eight patients (6 HbSS, 2 HbS-β+-thalassemia; median age 29 (range 21 - 49) years; 3 males) have been transplanted as of March 2018. All but one patient reached 100 % donor myeloid chimerism at 1 month. Myeloid chimerism remained stable in those who had reached full donor chimerism at one month (Figure 1A). One patient had 69% donor myeloid chimerism at 1 month, which increased gradually to 90 % at 9 months. Median T-cell donor chimerism at 3 months was 37% (range: 23 - 79%; n=6), increasing further during follow-up (Figure 1B). The percentages of donor myeloid and T-cell chimerism are higher than previously reported with alemtuzumab/TBI only (Hsieh et al. JAMA, 2014). All patients had a corrected SCD phenotype with mostly normalized hemoglobin levels at 3 months (from median 9,5 (IQR 7.8 - 10.7) g/dL at baseline to 12.4 (11.6 - 13.5) g/dL at 3 months, increasing further thereafter. Sirolimus tapering was started at 12 months in the first transplanted patient and stopped without affecting donor chimerism. There were no reports of SCD-related complications. One patient developed acute grade III intestinal GvHD, despite appropriate trough levels of sirolimus, though responded well to high dose steroids. Other treatment-related complications were mTOR inhibitor-associated stomatitis (n=5) responding well to local steroids, arthralgia that was moderately severe in 2 patients and progression of preexistent chronic kidney injury in one patient, which partially recovered after switching sirolimus to mycophenolate mofetil. Conclusion Azathioprine/hydroxyurea preconditioning prior to alemtuzumab/TBI conditioning is well tolerated and may result in improved (higher) donor chimerism after non-myeloablatieve MSD transplantation in SCD patients. Importantly, one patient developed acute GvHD. As (acute) GvHD following alemtuzumab/TBI conditioning has not been reported previously, a relation with the preconditioning (azathioprine) cannot be excluded. Longer term results of larger cohorts are needed to determine the place of azathioprine/hydroxyurea preconditioning in non-myeloablative MSD transplantation for SCD. Disclosures Nur: Novartis Pharmaceuticals: Consultancy. Zeerleder:Jazz Pharma: Speakers Bureau; Sanofi/Genzyme: Speakers Bureau; Alexion: Speakers Bureau.

Ruxolitinib Is an Effective Salvage Treatment for Multidrug-Resistant Graft-Versus-Host Disease after Allogeneic Hematopoietic Transplantation

Aim: Graft-versus-host disease (GVHD), particularly the multidrug-resistant (MDR) GVHD, is one of the most important complications for allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. The purpose of our study is to identify the efficacy of ruxolitinib in allo-HSCT recipients with MDR-GVHD. Methods: A total of 44 patients who received ruxolitinib treatment for MDR-GVHD after allo-HSCT between 2017 and 2019 were enrolled in this study (HLA-identical sibling donors: n=10; HLA-haploidentical related donors: n=34). MDR-GVHD was defined as GVHD showing no improvement after at least 3 types of treatments. Patients were treated with ruxolitinib as an add-on immunosuppression therapy at a dose of 5 mg orally twice daily, and it could be increased to 10mg twice daily if hematologic parameters were stable and no treatment-related toxicities were observed after the first 7 days of treatment. This work was supported by the Capital's Funds for Health Improvement and Research (grant number 2018-4-4089). Results: The median number of previous GVHD-therapies was 4 for both MDR-aGVHD and MDR-cGVHD. For MDR-aGVHD (n=16), the median time to response was 10 days (range, 2 to 65), and the overall response rate (ORR) was 62.5% (10/16) in, including 37.5% (6/16) complete response (CR) and 25.0% (4/16) partial response (PR). Patients with 3 organs involvement had a lower ORR compared to that of those with 1-2 organs involvements (88.9% vs 28.6%, P=0.035). The 1-year probability of overall survival after ruxolitinib was 62.1%. The rates of hematologic and infectious toxicities were 75.0% and 50.0% after ruxolitinib treatment. For MDR-cGVHD (n=28), the median time to response was 30 days (range, 6 to 270), and the ORR was 78.6% (22/28), including 28.6% (8/28) CR and 50% (14/28) PR. The 1-year probability of overall survival after ruxolitinib was 90.0%. The rates of hematologic and infectious toxicities were 46.4% and 42.9% after ruxolitinib treatment. Conclusions: Ruxolitinib is an effective and safe salvage treatment for both MDR-aGVHD and MDR-cGVHD in allo-HSCT recipients. Disclosures No relevant conflicts of interest to declare.

An Update of Australasian Trends in Allogeneic Stem Cell Transplantation for Myelofibrosis in the Molecular Era

An Update of Australasian Trends in Allogeneic Stem Cell Transplantation for Myelofibrosis in the Molecular Era

Immunomodulation with Azacytidine and Donor Lymphocyte Infusion Following Sequential Conditioning Allogenic Stem Cell Transplantation Improves Outcome of Unfavorable AML

Background : Patients with acute myeloid leukemia in relapse or refractory to induction therapy have dismal prognosis. Response rates to common salvage regimens are low and allogenic hematopoietic stem cell transplantation is the only curative option. Several studies have demonstrated that salvage chemotherapy with sequential conditioning could reduce leukemia relapse risk with an acceptable toxicity profile for unfavorable acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). [1] Therefore, we decided to assess this procedure in our center at Amiens University Hospital. Methods We conducted a monocentric retrospective study, including 53 patients aged over 18 years undergoing a hematopoietic stem cell transplant (HSCT) with sequential conditioning between January 2012 and December 2018, for relapse/refractory AML or high risk MDS. 44 (83%) patients received sequential conditioning containing clofarabine (SET-RIC) or Amsacrine (FLAMSA) and 9 (17%) thiotepa based (TEC-RIC) with post-transplant cyclophosphamide for mismatched donors. Patients who were GVHD free after immunosuppressors withdrawal received immunomodulation as relapse prevention with azacytidine 37.5mg/m²/day 5 days every 4 weeks for 12 cycles with 3 donor lymphocyte infusions (DLI) alterned between azacytidine cycles. Results The median age was 52 years (range 18-70). Before conditioning, 48 patients had unfavorable AML with ELN intermediate score refractory to at least one course of induction therapy or in relapse, or unfavorable ELN score; 5 patients had high risk MDS with complex karyotype. 32 patients (60,5%) had active disease and 21 (39,5%) were in complete remission (CR) including 12 with positive MRD. 13 (24,5%) patients had HLA-identical sibling donors, 27 (51%) match unrelated donors (MUD), 4 (7,5%) mismatch unrelated donors (MMD) and 9 (17%) haploidentical donors. Majority of patients (90,5%) received peripheral blood stem cell (PBSC) PBSC with median CD34+ count of 7,94.106/kg (1,84-8,44). Acute GvHD prophylaxis with Ciclosporin A, in combination with Mycophenolate mofetil for MUD/MMR/Haplo, was withdrawal with a median time of 90 days. With a median follow-up of 40 months, overall survival (OS) at 1 and 2 years was 68% and 52%. Median OS was 18,7 months (0-72,4 months) and median disease free survival (DFS) was 14,9 months (0-72,4 months). 17 patients (32%) experienced relapse after HSCT with a median time from HSCT to relapse of 6 months (1-35 months). 22 (41,5%) of patients presented with grade I-II acute graft versus host disease (GVHD) and 6 (11,3%) with grade III IV aGVHD . GVHD free relapse free survival (GRFS) at 1 and 2 years was 53% and 34,2%. One-year cumulative incidence of disease related death and non-relapse mortality was 12,6% and 17% respectively. 19 patients received immunomodulation with 5 Azacitidine and DLI if no GVHD occurred within day 120. OS was 79 % in the 19 patients receiving DLI. In univariate analysis immunomodulation post HSCT (Figure 1) was significantly associated with overall survival and leukemia free survival (p=0,0164 and p=0,0359 respectively) but not the disease status before HSCT (p=0,7). Immunomodulation administration with azacytidine and DLI was not significantly associated with cGVHD occurrence (p=0.31). Benefit of immunomodulation OS persisted in multivariate analysis (p=0.0284). Conclusion: Sequential conditioning regimen on refractory AML with secondary immunomodulation with azacytidine and DLI shows very good results with an acceptable toxicity profile in unfavorable AML. We achieve very good OS and DFS whatever disease status before HSCT. GRFS is also encouraging comparing to previously report datas [1]. Reference: [1] Similar outcome of allogeneic stem cell transplantation after myeloablative and sequential conditioning regimen in patients with refractory or relapsed acute myeloid leukemia: A study from the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire. Decroocq et al. Am J Hematol 2018 ;93 :416-423. Figure 1 Disclosures No relevant conflicts of interest to declare.

Elimination of Acute GvHD with Three Doses of Abatacept Prophylaxis Combined with Post-Transplant Cyclophosphamide after Myeloablative Treosulfan-Based Conditioning in the HLA Identical Sibling and Unrelated (10-12/12) Peripheral Blood Stem Cell Donor Setting: Improved Safety and Efficacy Compared to Alemtuzumab Prophylaxis

Background. Acute graft versus host disease (GvHD) remains a major cause of treatment failure post allogeneic stem cell transplantation (HSCT). CD28-CD80/CD86 axis T cell co-stimulation blockade with CTLA4-Ig using abatacept (AB) is an emerging acute GvHD prophylaxis strategy1. After myeloablative conditioning (MAC), together with methotrexate and calcineurin inhibition, four doses of AB commencing day (d)-1 is being investigated in the unrelated HLA 7/8 and 8/8 mismatched/matched donor settings, mostly in children2. It is unknown if AB can be de-escalated in adults to three doses for HLA matched sibling (SIB) or unrelated 10-12/12 donors (MUD), or combined with post-transplant cyclophosphamide (PT-CY) GvHD prophylaxis3, or combined with treosulfan (TREO)-based MAC4, which are other emerging transplant strategies. We investigated the safety and efficacy of this combination, and compared outcomes to a standard anti-CD52 directed IgG1 alemtuzumab (CH) prophylaxis regimen5 in a reduced intensity conditioning (RIC). Methods. We report a single centre consecutive cohort study using peripheral blood stem cells from SIB or HLA 10-12/12 MUDs, for HSCT in adults with blood cancer indications (intuitional registration: 1920-31). One group received AB GvHD prophylaxis while the other group received CH. During 2018-2019, the AB cohort received MAC with IV fludarabine 150 mg/m2, IV TREO 42 mg/m2, and 2 Gy total body irradiation (TBI). GvHD prophylaxis comprised three doses of IV AB 10 mg/kg on d+5, +14, and +28. This was combined with IV PT-CY 50 mg/kg on d+3 and +4, IV tacrolimus 0.03 mg/kg/d infusion from d+5, and IV mycophenolate mofetil 15 mg/kg tds from d+53. The MAC AB cohort was compared to a RIC CH cohort, chosen to be biased against AB. During 2017-2018 the CH cohort received RIC with IV fludarabine 150 mg/m2and IV melphalan 140 mg/m2. GvHD prophylaxis comprised IV CH 10 mg on d-7 to d-3, and IV ciclosporin 1.5 mg/kg bd from d-1. The primary outcome measure was the incidence of acute GvHD6 at d100 and 180 post HSCT. Secondary outcomes measures were the incidence of graft failure, mixed donor chimerism, donor lymphocyte infusion (DLI), CMV reactivation, relapse, overall survival, at d100 and 180. The AB and CH cohorts were indirectly compared. Results. A total of 39 patients were included in this study, with 15 consecutive patients in the AB group (Table). The AB group had a median Karnofsky score of 70% and HCT-CI of 6; significant comorbidity greater than other reports1,2. The major cancer indications were acute leukaemia and myelodysplastic syndrome (MDS). The AB and CH groups were largely balanced. There were no AB related infusion reactions. As expected for MAC, the AB group had a numerically but not clinically significantly slower time to engraftment relative to the RIC CH group. There was no AB group graft failure. Remarkably, the AB group did not experience acute GvHD compared to the CH group by d100 (P=0.03) and d180 (P&lt;0.01). In contrast, by d100, 29% in the CH group experienced acute GvHD after a median of 59 days post HSCT. No AB group patients experienced mixed donor chimerism (P&lt;0.01), nor required a DLI (P&lt;0.01) compared to the CH group, where all had &lt;99% T cell or whole blood values at d100. Consequently, 45% of the CH cohort without acute GvHD were treated with DLI, with all patients experiencing acute GvHD at a median of 39 days post DLI (Table). Other secondary outcomes were similar. The AB group experienced a CMV reactivation rate of 67% in IgG seropositive patients. Unfortunately, 93% of CMV IgG positive patients in the CH group experienced CMV reactivation. No relapses were observed by d180 in the AB group, whereas in the CH group, 8% of patients experienced relapse. Mortality at d180 was 20% in the MAC AB group, and 21% in the RIC CH group. Conclusions. Acute GvHD prophylaxis with only three doses of AB and PT-CY post TREO-based MAC appears to be safe and efficacious in the SIB and MUD settings, in a highly co-morbid adult blood cancer population. This AB approach seems favourable compared to CH despite RIC, where acute GvHD without DLI or post DLI remains significant. A prospective multicentre clinical trial with AB in this setting seems warranted to confirm these remarkable findings of patient benefit. References. 1. Biol Blood Marrow Transplant (BBMT) 2013;19:1638-49. 2. NCT01743131. 3. Lancet Haematol 2019;6:e132-43. 4. Cancer 2017;123:2671‐79. 5. BBMT 2017;23:805-12. 6. BBMT 2016;22:4-10. Table Disclosures No relevant conflicts of interest to declare. OffLabel Disclosure: Abatacept, alemtuzumab, cyclophosphamide all the for the indication of graft versus host disease (GvHD) prophylaxis.

Fludarabine and Cyclophosphamide Based Conditioning Is Associated with Good Outcomes in Patients Undergoing Matched Sibling Donor Transplants for Aplastic Anaemia

Background: Fludarabine based conditioning protocols are increasingly being used for transplant (SCT) in patients with aplastic anaemia (AA) especially in those who have received multiple transfusions. Patients and Methods: Between January 2004 and June 2019, 229 patients with AA and HLA identical sibling donors underwent SCT at CMC Vellore India using Fludarabine [180 mg/m2 over 6 days] and Cyclophosphamide [120 mg/kg over 2 days]. Few patients received low dose ATG [ATGAM 40 mg/kg]. Data on HSCT and outcomes were collected from the institutional database and individual medical records. Results: The median age was 23.9 years (range: 1.5 - 58) including 151 males and 78 females including 78 children (33.4%). Donors were matched sibling (n = 215) or family donors (n = 14). The graft source was Bone marrow in 11 and peripheral blood stem cells in 218. GVHD prophylaxis consisted mainly of cyclosporine and methotrexate mainly with few receiving post-transplant cyclophosphamide. Engraftment occurred in 90% with graft failure in 2.6% and early death in 7.4%. Regimen related toxicity (RRT) was seen in 4.7% and included veno-occlusive disease of liver and hemorrhagic cystitis. Acute GVHD (grade 2-4) occurred in 26.4% while chronic GVHD was seen in 40.3%. The 5 year overall survival (OS) for the entire group is 75.9 + 4.9%. The 5 yr OS was 81.4 + 3.9% for ages 0 - 20, 76.3 + 4.4% for ages 21-40 and 55.3 + 9.3% for ages &gt; 40 years. Age &gt; 40 years (p = 0.000), presence of fever requiring hospital admission within 4 weeks prior to SCT (p = 0.001) and acute GVHD (p = 0.051) were identified as risk factors associated with a poor outcome on a univariate analysis while on a multivariate analysis, older age and fever continued to remain significant. Conclusion: This is the largest series of patients with AA undergoing SCT using a fludarabine based conditioning and is associated with improved survival following sibling donor HSCT for AA. Presence of fever requiring a hospital admission immediately prior to SCT is associated with poor outcomes. Disclosures No relevant conflicts of interest to declare.

Results of Unrelated Donor Hematopoietic Stem Cell Transplantation for Sickle Cell Disease in Europe on Behalf of Paediatric Diseases (PDWP) and Inborn Errors Working Parties (IEWP) of the EBMT

Introduction: Allogeneic hematopoietic stem cell transplantation (HSCT) is, to date, the only curative treatment for sickle cell disease (SCD). Because a human leukocyte antigen (HLA) matched sibling donor is not always available, alternative stem cell sources such as unrelated or haploidentical related donors have been explored. The likelihood of finding a 10/10 (HLA-A, B, C, DRB1 and DQB1) matched donor varies among ethnic groups, with the lowest probability among individuals of African descent. To date, few series of SCD patients transplanted with an unrelated donor (UD) have been reported, but the high rates of rejection and chronic graft versus host disease (cGvHD) have limited its widespread application. Patients and methods: We report the results of a retrospective, registry based, survey on 70 UD HSCT performed in patients (pts) with SCD from UD in 22 European Society for Blood and Marrow Transplantation (EBMT) centers between 2005 and 2017. Data were collected from the EBMT database and missing information was updated by the centers. Median follow up was 38 (range 2-154) months. Most pts were HbSS (n=54; 78%), had positive serology for CMV (80%), and a Karnofsky score &gt;80% (98%). Eighteen pts had a major ABO incompatibility. Recurrent vaso-occlusive crisis (n=58), cerebral vasculopathy (n=23) and acute chest syndrome (n=24) were the main indications for HSCT. Red blood cell (RBC) transfusions pre-HSCT were reported in 97% of pts of whom 53% received more than 20 transfusions; 14% of the transfused pts had RBC alloantibodies. Hydroxyurea pre-HSCT was used in 65% of pts. Median age at HSCT was 9.6 years (range 2-43) with 87% of pts being ≤ 16 years. Stem cell source was bone marrow (BM) in 55 pts (79%) and peripheral blood (PBSC) in 15 (21%). The median number of infused TNC /kg was 3.6 x 108 for BM and 7.1 x 108 for PBSC; the median number of infused CD34/kg was 4.4 x 106 for BM and 8.3 x 106 for PBSC. HLA matching at high resolution typing was 10/10 (HLA-A, B, C, DRB1 and DQB1) in 31, 9/10 in 17 and 8/10 in 4 of the patient-donor pairs; intermediate resolution typing was available for 10 (10/10 or 9/10) and the HLA information was missing for the remaining 8 patient-donor pairs. The most frequent conditioning regimens were fludarabine-thiotepa-treosulfan (64%) and busulfan- cyclophosphamide (12%). GvHD prophylaxis was cyclosporine plus methotrexate in 59%. Anti-thymocyte globulin was used in 90% and alemtuzumab in 9% of pts. Results: The cumulative incidence (CI) of neutrophil engraftment at 60 days was 93% (95% CI 76-100), with median time to engraftment of 18 days; platelet engraftment at 180 days was 90% (95% CI 83-98) with a median time of 20 days. Ten pts had graft failure (5 primary and 5 secondary) of whom 6 had a second transplant and were all alive at last FU (median 9.5 months after second HSCT). The CI of grade II-IV aGVHD at 100 days was 23% (95% CI 15-36), and 8 pts (11%) had grade III-IV. Acute GVHD was more frequent in patients who received PBSC (PBSC 42.9%, BM 18.2%, p=0.062). Three-year CI of cGVHD was 23% (95% CI 15-36), 7 pts (10%) had limited and 9 (13%) extensive cGvHD. Three-year overall survival (OS) was 90±4%; three-year event free survival (EFS) (considering death and graft failure as events) was 76±6%; HLA matching between donor and recipient was the most important factor for OS and EFS. Considering only pts-donor pairs with high resolution HLA typing available (n=52), 3-year OS was 96±4% in 10/10 group compared to 77±11% in 9/10 plus 8/10 group (p 0.065), 3-year EFS was 85±7% vs 62±12% (p 0.040), respectively. No significant differences between the groups were observed in CI of neutrophil engraftment, aGVHD and cGVHD. Conclusion: UD HSCT is a valid option for SCD patients who lack an HLA-identical sibling donor. Nevertheless, efforts are still needed to improve outcomes after UD HSCT. Our results indicate that using a 10/10 HLA matched UD improves both OS and EFS compared to donors with 1 or more mismatches; so, when such a matched unrelated donor is not found, using an haplo relative or an unrelated cord blood as donor source should be evaluated. A prospective trial is in preparation to evaluate the use of haploidentical donors for HSCT in SCD (EudraCT number: 2018-002652-33). Disclosures No relevant conflicts of interest to declare.

Induction, Bridging, or Straight Ahead: The Ongoing Dilemma of Allografting in Advanced Myelodysplastic Syndrome

Induction, Bridging, or Straight Ahead: The Ongoing Dilemma of Allografting in Advanced Myelodysplastic Syndrome