ALBERT

Description: 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 (

Description: 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.

Description: 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

Description: 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.

Description: 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.