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Subsequent neoplasms (SNs) compromise long-term survivors after hematopoietic cell transplantion. We performed a retrospective analysis of SNs in a cohort of 10358 recipients of umbilical cord blood transplantation (UCBT) reported to Eurocord/EBMT registries from 1988 to 2018. A total of 233 patients developed SNs. Median age at UCBT was 31 years (y) (0.3-69), and 84 were pediatric patients. Indications for UCBT were malignant hematological diseases in 199 patients (85%). Three groups of SNs were observed. Post-transplant lymphoproliferative disorders (PTLD) were reported in 145 patients in a median of 4 months after UCBT. Of these, 9/145 patients died from relapse, 83/145 from PTLD, and 24/145 from transplant-related causes. At last follow-up, 29/145 were alive; 5y-overall survival (OS) after PTLD diagnosis was 21±3%. Acute leukemia / myelodysplasia (AL/MDS) was diagnosed in 23 patients in a median of 28 months after UCBT and included 3 donor-cell AL. Four of 23 patients died from relapse of primary disease, 8/23 from progression of SNs, and 4/23 from TRM. Seven patients were alive at last follow-up; 5y-OS after AL/MDS diagnosis was 36±10%. Solid tumors (ST) were reported in 65 patients in a median of 54 months after UCBT. Most common tumor sites were lung, thyroid, bone and soft tissue. A total of 33/65 patients died (26 due to ST, 6 to relapse of primary disease, 1 cause missing). At last follow-up, 32/65 patients were alive; 5y-OS after the diagnosis of ST was 51±6%. In conclusion, despite their poor outcomes, SNs that occur after UCBT are extremely rare. Identification of associated risk factors and early detection may help to improve OS.

In single unrelated cord blood transplantation (UCBT), an increasing number of HLA allele mismatches (MM) has been associated with inferior overall survival (OS) attributed to higher transplant-related mortali-ty (TRM). Previous studies on the role of allele-level HLA matching following double UCBT (dUCBT) showed conflicting results. Herein we report the impact of allele-level HLA matching on outcomes of a large dUCBT cohort . We included 963 adults with hematologic malignancies, with available allele-level HLA matching at HLA-A, -B, -C and -DRB1, receiving dUCBT between 2006-2019. Assignment of donor-recipient HLA match was performed considering the unit with the highest disparity with the recipient. 392 patients received dUCBT with 0-3 and 571 with ≥4 allele MM. Day-100 and 4-year TRM were 10% and 23%, for recipients of dUCBT with 0-3 MM compared to 16% and 36% for those with ≥4 MM (HR 1.58, p=.002; and HR 1.54, p=.002), respectively. Higher degree of allele MM was also associated with worse neutrophil recovery and lower incidence of relapse; no significant effect on graft-versus-host disease was observed. Patients receiving units with 0-3 MM had a 4-year OS of 54% versus 43% for those with ≥4 MM (HR 1.40, p=.005). The inferior OS associated with higher HLA disparity was only partially mitigated by increased total nucleated cell doses. Our results confirm that allele-level HLA typing is a significant factor for OS following dUCBT and units with ≥4 MM (≤4/8 HLA-matched) should be avoided if possible.

We developed a risk score to predict event-free survival (EFS) after allogeneic hematopoietic cell transplantation for sickle cell disease. The study population (n = 1425) was randomly split into training (n = 1070) and validation (n = 355) cohorts. Risk factors were identified and validated via Cox regression models. Two risk factors of 9 evaluated were predictive for EFS: age at transplantation and donor type. On the basis of the training cohort, patients age 12 years or younger with an HLA-matched sibling donor were at the lowest risk with a 3-year EFS of 92% (score, 0). Patients age 13 years or older with an HLA-matched sibling donor or age 12 years or younger with an HLA-matched unrelated donor were at intermediate risk (3-year EFS, 87%; score, 1). All other groups, including patients of any age with a haploidentical relative or HLA-mismatched unrelated donor and patients age 13 years or older with an HLA-matched unrelated donor were high risk (3-year EFS, 57%; score, 2 or 3). These findings were confirmed in the validation cohort. This simple risk score may guide patients with sickle cell disease and hematologists who are considering allogeneic transplantation as a curative treatment relative to other available contemporary treatments.

Graft failure (GF) is a life-threatening complication after allogeneic hematopoietic stem cell transplantation (HCT). The incidence of GF after HCT using human leukocyte antigen (HLA) matched donors is lower than 5%; however, a higher incidence is observed when considering HLA mismatched donors or alternative donor sources and the use of reduced intensity conditioning (RIC) regimens. In the absence of autologous recovery, a second HCT is necessary to attempt preventing death due to prolonged pancytopenia. Previous studies describing outcomes of second HCT performed after a GF with different types of donor sources report a wide range of overall survival (OS) and transplant related mortality (TRM), however studies including a large number of patients receiving a second transplant with umbilical cord blood (UCB) are scarce. In this retrospective study, using registry data from Eurocord and the European Society for Blood and Marrow Transplantation (EBMT), we report the outcomes of 247 umbilical cord blood transplants (UCBT) performed after GF following a previous HCT. Data were analyzed separately for patients with malignant (n=141) and non-malignant diseases (n=106). UCB was the most frequent stem cell source that resulted in GF (65.0% and 68.9%, for malignant and non-malignant diseases, respectively), and most of the reported GF occurred within 100 days after HCT (92.3% and 85.9%). The most frequent diagnosis in malignant diseases was acute leukemia (64.5%), mainly acute myeloid leukemia (AML). In non-malignant diseases, the diagnoses most often reported were inborn error of metabolism (IEM) (37.7%), followed by bone marrow failure syndrome (BMF) (34.0%) and primary immune deficiency (PID) (21.7%). In malignant and non-malignant diseases, we observed a similar cumulative incidence of neutrophil engraftment of 59.1% (95% CI 51.4- 67.9%) and 60.4% (95% CI 51.7- 70.6%), in a median time of 23 and 24 days, and a 3-year OS of 28.9% (95% CI 21.8- 37.3%) and 49.1% (95% CI 39.5- 58.8%). TRM at 100 days and at 3 years for malignant diseases was 39.9% (95%CI 32.5 - 49.1%), and 57.5% (95%CI 49.4 - 66.8%). In multivariate analyses, none of the characteristics were statistically significantly associated with engraftment or overall survival. Although survival for patients requiring a second transplant is not optimal, UCB remains a valid life-saving option for some patients with GF as it is an immediately available source of stem cells in severely ill patients. The most appropriate stem cell source for salvage transplants remains controversial, as it depends on multiple factors including center choice, donor availability, underlying disease and existing comorbidities. Disclosures Peffault De Latour: Pfizer: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; Amgen: Consultancy, Other, Research Funding; Jazz Pharmaceuticals: Honoraria; Alexion, AstraZeneca Rare Disease: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding.

Four decades ago, Hal Broxmeyer demonstrated that umbilical cord blood (CB) contained hematopoietic stem cells (HSC) and hypothesized that CB could be used as a source of donor HSC for rescue of myeloablated bone marrow. In 1988, Gluckman et al reported the first successful cord blood transplant (CBT) of a child with Fanconi Anemia using matched sibling CB. This patient survives and 35 years later still has durable hematopoiesis from the CB donor graft. In 1991, Rubinstein et al established an unrelated donor (UD) CB bank and in 1993 the first UD CBT was using a unit from this bank. Since that time, >40,000 CBTs have been performed worldwide. We hypothesized that changes in cord blood banking (increased size, diversity, and quality of banked units enabling selection of units with higher cell doses and closer HLA matching) and in transplantation (less use of steroids, availability of newer therapies for prophylaxis and treatment of graft versus host disease [GVHD], improved antifungal and antiviral detection and therapeutics) have improved outcomes of CBT today. To address this hypothesis, we performed a retrospective study combining data from Eurocord and Duke University in a large cohort of children transplanted with a single UD CB unit (CBU) from 1993-2019. Standard transplant outcomes (overall survival [OS], disease free survival [DFS], acute and chronic GVHD, treatment related mortality [TRM], and relapse) and changes in outcomes over 3 time periods (1:2010, n=1802) were studied. Relative contributions of cell dose and HLA matching to transplant outcomes over time were assessed. A total of 4834 patients (4015 from Eurocord and 819 from Duke) were analyzed. The majority of patients, (59%, n=2839) had malignant diagnoses including 1422 with ALL, 887 with AML and 167 with MDS. Of the 1995 with non-malignant diagnoses, 761 had inborn errors of metabolism, 644 had primary immunodeficiency, 325 had a bone marrow failure syndrome and 206 had a histiocytic disorder. Half of the patients had positive serologies for CMV prior to transplant. The median age of the cohort fell from 5.2 to 3.25 years over time. In patients with malignancies, use of total body irradiation decreased over time. The median total nucleated cell (TNC) and CD34+ cell doses administered were 8.07x10e7 and 6.17x10e5 cells/kg and increased over time. HLA matching and transplantation of patients in earlier disease states also increased over time, p In conclusion, we analyzed the largest cohort of pediatric patients undergoing CBT over the past 3 decades. OS, DFS and engraftment have improved over time accompanied by decreases in TRM and acute GVHD. Relapse and chronic GVHD were stable and remain low. These improvements are explained by the increased availability of high quality banked CBUs enabling selection of closer HLA matching and units with higher cell doses. The numbers of CBTs have decreased in the past decade, but these results support the ongoing use of CBT in children lacking matched related or unrelated donors. Figure 1 Figure 1. Disclosures Kurtzberg: Neurogene: Consultancy; CryoCell: Patents & Royalties: Duke licensed IP, and data and regulatory packages for manufacturing and use of cord blood and cord tissue MSCs in the treatment of patients with hypoxic ischemic encephalopathy, cerebral palsy, autism, acute ischemic stroke, COVID-ARDS, and COVID-MIS-C. ; Sinocell: Patents & Royalties: Duke licensed IP, data, and regulatory packages for use of autologous and sibling cord blood to treat children with cerebral palsy.; Celularity: Current holder of stock options in a privately-held company. Troy: SinoCell: Patents & Royalties; CryoCell: Patents & Royalties; Bristol Myers Squibb: Research Funding; Synthetic Biologics: Honoraria; Gamida Cell: Consultancy; The EMMES Corporation: Consultancy; The Community Data Roundtable: Consultancy; AegisCN: Consultancy.

Background: Patients (pts) with sickle cell disease (SCD) show a high phenotype variability that is not fully understood. Because inflammation plays a major role in SCD pathophysiology, we hypothesized that single nucleotide polymorphisms (SNPs) in genes of innate and adaptative inflammatory response modulate the occurrence of SCD complications. Objective: to establish associations between SNPs and clinical complications in pts with SCD. Methods: Case-control retrospective study; 500 pts were included, followed at Senegal (n=56), Brazil (n=230) and France (n=214). We analyzed the effect of 20 SNPs in 6 clinical complications: acute chest syndrome (ACS), stroke, leg ulcers, cholelithiasis, osteonecrosis and retinopathy. Using TaqMan 5'-nuclease assay, we genotyped SNPs in genes encoding Toll-like receptor (TLR) 1 (rs4833095), 2 (rs4308099, rs4308100, rs4696480), 6 (rs5743810), 10 (rs11466653, rs11096957), natural killer (NK) group 2 member D (NKG2D) receptor (rs1982536, rs2617160, rs2617169, rs2617170, rs2617171, rs1049174, rs2246809, rs2255336), human leukocyte antigen (HLA)-G (rs9380142), HLA-E (rs2517523), major histocompatibility complex class I polypeptide-related sequence A (MICA, rs1051792) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) (rs5742909, rs231775). All SNPs had a call rate >90% and minimum allele frequency >1%. We performed analyses of correspondence for indicating associations between SNPs and number of clinical complications. Logistic regressions were used to identify associations between SNPs and each complication, using geographical origin, SCD genotype, rate of transfusions and gender for modeling adjustment; the significance was adjusted for multiple testing using false discovery rate. Comparisons of genotype frequencies with the population of African descent from 1000 genomes database were done by chi-square. Results: Pts were originally from Brazil (n=228), Sub-Saharan Africa (n=200), French West Indies (n=53), North Africa (n=7) and 12 unknown. SCD genotype (available n=498) was SS (n=402), SC (n=46), SB (n=42), SD or SE (n=4). 280 pts were female; median age was 32 years (range 0-69); 184 pts received at least 20 transfusions. 71 pts presented stroke, 200 had at least 1 episode of ACS, 69 had leg ulcers, 271 had cholelithiasis, 150 had retinopathy and 90 osteonecrosis. 97 pts did not present complications, 135 had 1 type of clinical complication, 134 had 2, 94 had 3, 34 had 4 and 6 had 5. 21 pts underwent hematopoietic stem cell transplantation. 11 pts died during follow-up, mostly from ACS and hemorrhagic stroke. Indication of association with number of complications: TLR2 rs4696480 TA, TLR2rs3804099 CC and HLA-Grs9380142 AA were associated with occurrence of 0-1 clinical complications, MICA rs1051792 AA/AG with up to 2 complications and NKG2D rs2617169 AA with 5 complications. Association between genotypes/haplotypes and each complication: no association was found between SNPs and stroke, ACS, leg ulcers and osteonecrosis. Rs9380142 was the only SNP significantly associated with cholelithiasis in the logistic regression additive model. The G allele increased the risk of cholelithiasis (AG x AA, OR 1.57, 95%CI 1.16-2.15; GGxAA, OR 2.47, 95%CI 1.34-4.64; P=0.02). For retinopathy, in the logistic regression additive model, the presence of the A allele decreased the risk of retinopathy for rs2246809 in pts of same origin (AAxGG: OR 0.22, 95%CI 0.09-0.50; AGxGG: OR 0.47, 95%CI 0.31-0.71; P=0.004), rs2617160 (ATxTT: OR 0.67, 95%CI 0.48-0.92; AAxTT: OR 0.45, 95%CI 0.23-0.84; P=0.04) and rs2617169 in pts of same SCD genotype (AAxTT: OR 0.33,95%CI 0.13-0.82; ATxTT: OR 0.58, 95%CI 0.36-0.91, P=0.049). No haplotype was associated with complications. The genotype distribution of SNPs rs4696480, rs3804099, rs1051792 and rs2617169 differed significantly from the population of African descent from the 1000 genomes database. Discussion: We have previously shown that TLR2 rs4696480 TA decreases occurrence of bacterial infections in SCD; in this study, TA is also associated with less complications. Also, HLA-G rs9380142 AA had less complications and cholelithiasis, and 3 SNPs in NKG2D modulated occurrence of retinopathy. TLR and NKG2D may be activated by heat shock proteins, released in ischemia-reperfusion injury that occurs in SCD. Our findings help to better understand the role of inflammation in phenotype heterogeneity in SCD. Disclosures No relevant conflicts of interest to declare.

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 >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.

Background: Hematopoietic stem cell transplantation (HSCT), the only available curative therapy for sickle cell disease (SCD), remains hampered by the lack of histocompatible stem cell donors. Most patients will not have a suitable human leukocyte antigen(HLA) matched sibling donor. In addition, SCD affects ethnic groups that are underrepresented in stem cell donor registries worldwide. Objective: to assess the probability of having a potential allelic HLA matched unrelated donor(MUD) for HLA-A,B and DRB1 loci (6/6) in international donor registries for patients with SCD. Methods: 185 patients with SCD were included, 116 from Brazil, of whom 23 underwent HSCT, and 69 patients who underwent HSCT in centers reporting to the European Society for Blood and Marrow Transplantation (EBMT). All patients had HLA typing available at intermediate or high resolution. For intermediate resolution, using the National Marrow Donor Program (NMDP) code, we assigned alleles based on allele frequencies.We performed HLA haplotype estimation using the HaploStats website, which describes HLA haplotype frequency from the NMDP registry for the following ethnic groups: Caucasian, African-American, Asian, Hispanic and Native American. Because Hispanic is not a primary ethnicity, we did not consider this group in our analyses. Based on haplotype frequency of each ethnic group, we defined the most likely ethnicity for each estimated haplotype; those with frequency >1:1000 in all ethnic groups were named common. Unrelated donor search was done using the World Marrow Donor Association (WMDA) algorithm, which is based on haplotype matching. A potential allelic donor was defined as a full match high resolution 6/6 donor. Because it is described that testing at least 5 potential allelic donors simultaneously increases the chances of having a real donor, we assessed the probability of finding at least 1 and at least 5 potential allelic donors. Patients who received HSCT from MUD were excluded from donor searches (n=10).Comparisons of probabilities of having potential allelic donors between Brazilian and EBMT cohorts were performed by chi-square. Results: In the Brazilian cohort, from 181 HLA haplotypes, 45% were classified as African-American, 18% common, 12% Caucasian, 9% Amerindian and 16% could not be classified. In the EBMT cohort, from 116 HLA haplotypes, 70% were classified as African-American, 8% common, 6% Caucasian, 3% Amerindian and 13% were not classified. Although Brazilians showed greater genetic admixture, chances of finding at least one potential allelic MUD were 47% in both groups (p-value not significant) and chances of having at least 5 potential allelic MUD were 24% for Brazilians and 15% for EBMT (p-value not significant). Overall, most potential allelic MUD were found in the NMDP registry, followed by the Brazilian registry (REDOME) and by the German registry (ZKMD); for the Brazilian cohort, most potential allelic MUD were found in REDOME. Discussion: Migration from Africa to Brazil started at the colonial period, and interethnic admixture have been occurring since then, explaining the higher diversity observed in the Brazilian cohort. Despite differences in ethnic composition, chances of having at least one potential allelic MUD are identical, probably because carrying at least one African or Amerindian haplotype decreases the chances of a full HLA matching. Although we demonstrated higher probabilities of finding a potential allelic MUD in SCD than previous studies, the chances are still low, therefore further strategies are required to increase donor representativeness for SCD. In this setting, alternative sources, such as haploidentical HSCT and cord blood, should be considered. Also, our study might help to predict the probabilities of finding a MUD for patients with SCD. This is important because given that HSCT in SCD has better results if performed at earlier age, knowing which patients are less likely to find a MUD might influence therapy management. Disclosures No relevant conflicts of interest to declare.

Hematopoietic stem cell transplant (HSCT) from an HLA identical sibling is a well-established curative therapy for sickle cell disease (SCD). HSCT from an unrelated donor is a treatment option, but the likelihood of finding a donor varies according to ethnicity and results are still limited. HLA haploidentical relatives can be alternatively used but, to date, only small series of patients have been described. We report outcomes of patients (pts) transplanted with related haploidentical (Haplo) or unrelated (UD) donors grafts and reported to EBMT/EUROCORD databases. Sixty four pts transplanted in 22 EBMT centers between 1991 and 2017 were retrospectively analyzed. Pts were described according to the donor type: haploidentical (n=40) and unrelated (n=24) [adult UD n=19; cord blood (CB) n=5]. The objective of the study was to describe alternative donor transplants for SCD in Europe without performing comparison analyses due to the size and heterogeneity of the groups. Primary endpoint was 3-year overall survival (OS). Median follow-up (FU) was 28 months (range: 1.6-156) [29.5 months (range: 2.1 - 133.5) for Haplo and 24.6 (range: 1.6 - 156) for UD]. Median age at HSCT was 14.2 years (range: 3-31.7) in Haplo and 11.8 (range: 2.1-42.8) in UD, with a predominance of children ( In both groups, vaso-occlusive crisis and cerebral vasculopathy were the most frequent SCD complications and the main indications for HSCT. Other complications were acute chest syndrome (44%), liver disease (31%) and infection (23%). In Haplo, median year of transplant was 2014 (range: 1991-2017) and in UD 2011 (range: 2004-2015). In Haplo, two major protocols were used: (1) post -transplant cyclophosphamide (PTCY) with G-CSF primed bone marrow (BM) and a fludarabine+ cyclophosphamide+thiotepa+2Gy TBI conditioning regimen [16 pts and 2 centers performing most (n=13) of the transplants]; (2) a protocol (performed in 2 centers) consisting in the use of G-CSF mobilized peripheral blood stem cells (PBSC) with ex-vivo B and T cell depletion (BT depleted) (15 pts) and a fludarabine+thiotepa+ treosulfan conditioning regimen (14/15 pts). Haplo donors were most frequently the parents [mother (50%), father (29%), brother (14%) and cousin (7%)]. ATG was used in 95% of transplants and the most frequent combination for graft versus host disease (GvHD) prophylaxis was mycophenolate mofetil (MMF)+sirolimus in PTCY and MMF+ cyclosporine A (CSA) in BT depleted. In UD, graft source distribution was 14 BM, 5 PBSC and 5 CB. Conditioning regimens were mainly myeloablative (83%) with fludarabine+thiotepa+ treosulfan in 54% of HSCT. ATG was used in 87% and campath in 9% of transplants; GvHD prophylaxis was CSA and methotrexate in 50%. Neutrophil engraftment at 60 days was 95±4% in Haplo and 84±8% in adult UD, after a median engraftment time of 18 and 22 days, respectively. In Haplo, 7 pts experienced graft failure (3 primary and 4 late), of those 3 had a second allogeneic transplant and were alive at last FU, at 16, 16 and 63 months respectively; 1 patient died after rescue with autologous transplant and 3 were alive after autologous reconstitution. In adult UD, 3 pts had a primary and 1 a late graft failure, none of them had a second transplant and were all alive at last FU, at 2, 13, 28, 118 months respectively. Grade II-IV acute GvHD at 100 days was 25±7% in Haplo and 21±9% in adult UD; acute GvHD grade III-IV was observed in 3 pts in Haplo (none in BT depleted) and 2 pts in adult UD. Chronic GvHD was observed in 10 pts in Haplo (5 extensive, 3 of these in PTCY) and 3 pts in adult UD (2 extensive). OS at 3 years was 88±4%; being 89±5% in Haplo (88±8% for PTCY, 92±8% for BT depleted) and 94±5% in adult UD. 3-year event free survival was 58±7%; in detail, 60±9% in Haplo (56±12% for PTCY, 68±13% for BT depleted) and 60±12% in adult UD. Overall, 8 pts died (5 Haplo and 3 UD) due to infections or GVHD. Among the 5 pts receiving CB transplant 3 are alive (1 of which after graft failure and a second allogeneic transplant). Conclusion: This preliminary analysis shows that, despite an acceptable OS, rejection and chronic GvHD are still of concern; therefore alternative donor transplants for SCD should be performed in experienced centers with prospective clinical trials. Disclosures Pondarré: Blue Bird Bio: Honoraria; Novartis: Honoraria; Addmedica: Membership on an entity's Board of Directors or advisory committees. Zecca:Chimerix: Honoraria. Locatelli:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy. Bader:Medac: Patents & Royalties, Research Funding; Riemser: Research Funding; Neovii: Research Funding; Cellgene: Consultancy; Novartis: Consultancy, Speakers Bureau. Bernaudin:AddMedica: Honoraria; Pierre fabre: Research Funding; BlueBirdBio: Consultancy; Cordons de Vie: Research Funding.

Background: Sickle cell disease (SCD) patients (pts) are at increased risk of infection. This susceptibility is partially explained by the loss of spleen function, but other factors such as inflammatory status might also play a role. Despite adequate immunization and antimicrobial prophylaxis, bacterial infection remains a major cause of morbidity and mortality in SCD pts. Toll-like receptors (TLR), transmembrane proteins that recognize a wide range of pathogen molecular patterns, are key receptors in innate immune response. The association among TLR and infections in SCD has scarcely been explored. Objective: To analyze if functional polymorphisms in TLR genes can modulate the susceptibility to bacterial infections in SCD pts. Methods: Case-control retrospective study; 430 SCD pts followed in university hospitals in Brazil (n=196), France (n=180, mainly from Subsaharan Africa and French West Indies) and Senegal (n=54) were included. Sites of bacterial infection were lower respiratory system, abdominal, upper urinary system, bone/joints, central nervous system, blood stream, or any site for tuberculosis. For pts who underwent hematopoietic stem cell transplant (HSCT), only bacterial infections before HSCT were considered. All pts were tested for 7 single nucleotide polymorphisms (SNP) in TLR-1(rs4833095), TLR-2 (rs4696480, rs3804099, rs3804100), TLR-6 (rs5743810) and TLR-10 (rs11466653, rs11096957) using TaqMan 5'-nuclease assay. Univariate analysis was performed with chi-square or Mann-Whitney for categorical and continuous variables respectively. Associations were measured by odds ratio (OR). For SNP associations, significant P-value corrected by Bonferroni (cP) was 0.007; for genetic models, cP was 0.01. Results: Median age of cohort was 30 years (range: 2-70) and 87% were ≥18 years; 57% of pts were female. SCD genotype was SS in 81%, SC in 11%, SB in 7% and other in 1%. Fifty-eight percent received hydroxyurea and 79% received red blood cell transfusions; seven pts underwent HSCT. Eleven pts died during follow-up, mostly from acute chest syndrome and hemorrhagic stroke. All pts had access to immunization against encapsulated bacteria and to penicillin prophylaxis. One hundred ninety-five pts (45%) did not present any bacterial infection, whereas 235 (55%) pts presented at least one episode of bacterial infection, of which 20% had ≥ 3 episodes. Bacterial infections were mainly respiratory (51%), bone/joints (23%) and urinary (20%). In 106 cases, etiological agents were identified; most common agents were Escherichia coli, Streptococcuspneumoniae, Mycobacterium tuberculosis and Salmonella spp. In univariate analysis, there was no association among occurrence of infections and gender, origin and age distribution. Gene analysis: all tested SNPs had a typing rate >90% and minimum allele frequency >1%. The TLR-2 SNP rs4696480 (n=425) showed significant association with infection (p Discussion: In SCD pts, TLR-2 rs4696480 TA genotype might be protective against bacterial infections, whereas TT genotype might increase risk of such infections. Previous reports demonstrated higher secretion of inflammatory factors in cells from AA individuals, lower occurrence and severity of immune diseases in T carriers. TA genotype might stand between deleterious effects of over inflammatory response (AA genotype) and under response (TT genotype) to infectious agents. Disclosures No relevant conflicts of interest to declare.

Introduction: Hematopoietic stem cell transplantation (HSCT) is, to date, the only curative therapy for sickle cell disease (SCD). However, HSCT is offered to relatively few patients with SCD for a number of reasons including lack of a suitable HLA-matched donor, lack of consensus on indications for HSCT, the potential for trading one chronic condition (i.e., SCD) for another, such as chronic graft-versus-host disease (GVHD), and the mortality associated with the procedure. To-date, most HSCTs for SCD have utilized matched siblings as donors and are performed in children and adolescents. We report outcomes after HLA-matched sibling HSCT of patients reported to the Eurocord-Monacord/European Group for Blood and Marrow Transplantation (EBMT) and Center for International Blood and Marrow Transplant Research (CIBMTR). Material and methods: One thousandpatients with SCD received HLA identical sibling HSCT between 1991 and 2013; n=439 from CIBMTR and n=561 from EBMT centers. HSCTs were performed in 90 centers in 23 countries. Results: Median age at HSCT was 9 years (range 1-54y); 85% of patients were aged The cumulative incidence (CI) of neutrophil engraftment at day+60 was 98% (96.6% for CB, 98.3% for BM and 95.2% for PB) with a median time to recovery of 19 days, while that for platelet engraftment was 98 % (96±2% for CB, 99±1% for BM and 98±9% for PBSC) with a median time to recovery of 25 days. Twenty-six patients experienced primary and 47 patients secondary graft failure; 67 patients died mainly due to GVH or infection. The 3-year probabilities of overall (OS) and event-free survival (EFS, alive with engraftment) were 94% (95% CI 92-95) and 90% (95% CI 68-82), respectively. According to stem cell source, 3-year OS was 99% after CB, 94% after BM and 80% after PBS (p Conclusion: This large registry based international study shows that HLA identical sibling transplant is successful more than 90% of the patients with severe SCD with limited transplant related complications (rejection, GVHD). Strategies aimed at lowering graft failure and GVHD are desirable to further optimize the observed 3-year event-free survival. Importantly, these data should increase awareness to early referral to HSCT of patients with severe SCD. Disclosures Walters: ViaCord and AllCells, Inc: Other: Medical director. Bertrand:ERYTECH Pharma: Consultancy. Peters:Medac: Research Funding; Fresenius: Research Funding; Amgen: Research Funding; Jazz: Research Funding; Novartis: Research Funding; Pfizer: Research Funding; Sanovi: Research Funding; Pierre-Fabre: Research Funding.

Introduction The only curative therapy for thalassemia remains the replacement of the defective erythropoiesis by allogeneic hematopoietic stem cell transplantation (HSCT). Although largely successful, HSCT can have serious adverse effects such as; veno-occlusive disease (VOD), graft failure and graft versus host disease (GVHD) associated mainly with the conditioning regimen. Most commonly used conditioning regimens in children comprise the alkylating agent busulfan (BU). Interindividual differences in Bu pharmacokinetics (PK) have been observed and may be an important cause of resistance to treatment and toxicity. It has been hypothesized that some of this variability in treatment might be predicted by genetic variants of enzymes involved in the metabolism of BU. Identifying pharmacogenetic determinants of BU may allow for prospective identification of patients with suboptimal drug responses allowing for complementation of traditional treatment protocols by genotype-based BU dose adjustment. Since BU is mainly metabolized by glutathione S-transferase (GST), we studied the relationship between functional variants within GSTA1, GSTM1 and first dose pharmacokinetics (PK) and outcomes of intravenous (IV) busulfan (Bu). Methods The study was performed on 44 thalassemia (thalassemia major = 35 and thalassemia intermediate = 9) pediatric patients (median age = 8, Female = 47.7%) of Middle Eastern origin, who underwent allogeneic HSCT with IV BU as part of a myeloablative-conditioning regimen. According to the standard, 5 different IV Bu doses were given based on weight: 1.0mg/kg for 34 kg. Bu was administered as a 2-hour IV infusion every 6 hours for a total of 16 doses from day -9 to day -6. Bu levels following the first Bu dose were measured using an established analytical method and the PK parameters were estimated using non-compartmental analysis. Bu dose levels were adjusted at dose 4 to achieve Bu Css of 600-900 ng/mL. Genomic DNA collected prior to myeloablation was used for genotyping GSTM1 del by gel electrophoresis and GSTA1promoter variants (-69C>T, -513T>C, -631T>G and -1142) by allele-specific oligonucleotide hybridization. Statistical analysis was performed by using Linear regression to test gene-dosage effect and to assess the effect on genotype on (maximum concentration (Cmax), area under the curve (AUC), Css and Clearance (CL) in a univariate model. The cumulative incidence of aGVHD in relation to GST genotypes was estimated by one-survival curves using Kaplan-Meier analysis and log-rank test. Univariate Cox regression analysis was used to estimate hazard ratio (HR) with 95% confidence interval (CI). Results Neutrophil, platelet recoveries, grade 1-4 acute GVHD, grade 2-4 acute GVHD and VOD incidences were 93.2%, 88.6%, 34.1%, 11.4% and 2% respectively. Overall survival rate was 90.9%, events free survival was 84%, while 13.6% of patients had primary and secondary graft failure. Gene-dosage effect between GSTA1 T-69 and G-1142 alleles (defining haplotypes *B and *B1, respectively) and higher Bu exposure (higher Bu levels, p≤ 0.001 and lower clearance, p=0.001) was seen. An association was also seen with GSTM1, where patients with GSTM1 null genotype had a higher occurrence of GVHD grade 1-4 (p=0.01), see Figure 1. Discussion/Conclusion A strong association between GSTA1*B and BU PK was observed in accordance with the functionality of this variant and our previous analysis in a different patient cohort. We were unable to test whether this variant increases BU related-VOD due to the low VOD cases. GSTA1 and GSTM1 variants could potentially open the possibility to tailor first Bu dose according to patient genetics. Disclosures: No relevant conflicts of interest to declare.

In the developed world, the survival and quality of life of patients with beta thalassemia (Bthal) has dramatically improved with optimization of blood transfusions and iron chelation. By contrast, in countries with limited resources most affected children die before the age of 20 because of the unavailability of safe blood products, expensive iron chelating drugs and inadequate management of co-morbidities. For these patients allogeneic stem cell transplantation (SCT) from matched donors offers a cure with low morbidity and mortality. Between June 2005 and May 2008, 47 consecutive Bthal patients underwent SCT from an HLA identical sibling in our center, among these, 3 patients underwent 2 SCTs. Median age was 8 years (2–15), country of origin: Lebanon (9), Iraq (19), Palestine (3), Syria (16). One pt was classified as Lucarelli class I, 24 as class II and 22 as class III. Most patients had severe iron overload evidenced by irregular iron chelation (83%), median ferritin 2973 (956–14280), median liver iron concentration 22 mg Fe/g (6.9–95.7). Most patients had liver toxicity due to iron overload and hepatitis evidenced by median ALT 71 (12–545), AST 59 (18–371), liver fibrosis Ishak 3 (0–5), HepC pos 16/47 (34%). Patients had inadequate transfusional management evidence by a median pre-transfusion Hb of 8 g/dL and anti HLA antibodies in 81% pts. Class I-II patients were conditioned with a regimen based on iv busulphan (iv Bu, Busilvex®, dosage according to weight, adjusted from the 5th dose to a target AUC 1200 umol/min) and cyclophosphamide (Cy) 200mg/kg (n19) with the addition of thiotepa (TT 10mg/kg) if