HLA peptide-binding pocket diversity modulates immunological complications after cord blood transplant in acute leukaemia.

Pocket motifs and their amino acid positions of HLA molecules are known to govern antigen presentation to effector cells. Our objective was to analyse their influence on the risk of graft-versus-host disease (GVHD) and relapse after umbilical cord blood transplant (UCBT). The transplant characteristics of 849 patients with acute leukaemia were obtained from the Eurocord/EBMT database. Higher acute (a) GVHD was associated with homozygosity of UCB HLA-C amino acid positions 77 and 80 (NN/KK) (p = 0.008). Severe aGVHD was associated with HLA-A pocket B YSAVMENVHY motif (p = 0.002) and NN and RR genotypes of the HLA-C amino acid positions 77 and 156 (p = 0.006 and p = 0.002). Such risk was also increased in case of recipient and UCB mismatches in P4 (p < 0.0001) and P9 (p = 0.003) pockets of HLA-DQB1 alleles. For chronic GVHD, the pocket B YYAVMEISNY motif of the HLA-B*15:01 allele and the absence of mismatch between recipient and UCB in the P6 pocket of HLA-DRB1 were associated with a lower risk (p = 0.0007 and p = 0.0004). In relapse, both UCB pocket B YFAVMENVHY belonging to HLA-A*32:01 and recipient pocket B YDSVGENYQY motif of the HLA-C*07:01 allele were associated with higher risk (p = 0.0026 and p = 0.015). We provide clues on HLA-mediated cellular interactions and their role in the development of GVHD and relapse.

Impact of donor NKG2D and MICA gene polymorphism on clinical outcomes of adult and paediatric allogeneic cord blood transplantation for malignant diseases.

OBJECTIVES: NKG2D is an activating receptor expressed by natural killer (NK) and CD8+ T cells and activation intensity varies by NKG2D expression level or nature of its ligand. An NKG2D gene polymorphism determines high (HNK1) or low (LNK1) expression. MICA is the most polymorphic NKG2D ligand and stronger effector cell activation associates with methionine rather than valine at residue 129. We investigated correlation between cord blood (CB) NKG2D and MICA genotypes and haematopoietic stem cell (HSC) transplant outcome. METHODS: We retrospectively studied 267 CB HSC recipients (178 adult and 87 paediatric) who underwent transplant for malignant disease between 2007 and 2018, analysing CB graft DNA for NKG2D and MICA polymorphisms using Sanger sequencing. Multivariate analysis was used to correlate these results with transplant outcomes. RESULTS: In adult patients, LNK1 homozygous CB significantly improved 60-day neutrophil engraftment (hazard ratio (HR) 0.6; 95% confidence interval (CI) 0.4-0.9; p = .003). In paediatrics, HNK1 homozygous CB improved 60-day engraftment (HR 0.4; 95% CI 0.2-0.7; p = .003), as did MICA-129 methionine+ CB grafts (HR 1.7 95% CI 1.1-2.6; p = .02). CONCLUSION: CB NKG2D and MICA genotypes potentially improve CB HSC engraftment. However, results contrast between adult and paediatric recipients and may reflect transplant procedure disparities between cohorts.

Comparative analysis of the variability of the human leukocyte antigen peptide-binding pockets in patients with acute leukaemia.

The association between acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML) and the human leukocyte antigens (HLA) has rarely been studied in terms of diversity of peptide-binding pockets. The objective of this study was to analyse whether motifs of HLA class I and class II peptide-binding pockets and/or their amino acid positions were differentially associated with ALL and AML. We included 849 patients from the Eurocord/European Blood and Marrow Transplant registry. The HLA peptide-binding pockets whose amino acid variability was analysed were B and F for HLA class I, P4, P6, and P9 for HLA-DRB1, and P4 and P9 for HLA-DQB1. The motif RFDRAY in P4 of HLA-DRB1*16:01/02/03/05 alleles and the motif YYVSY in P9 of HLA-DQB1*05:02/04/05 alleles, were statistically associated with ALL (corrected p value [pc ] = 0.001 and pc  = 0.035 respectively). The frequency of serine 57 in the P9 of HLA-DQB1 was higher in ALL (odds ratio 2.09, 95% confidence interval: 1.27-3.44; pc  = 0.037). Our analysis suggests that specific motifs in terms of HLA class II pockets and amino acids might be unique to ALL. The associations identified in this study encourage further investigation oF the role of HLA peptide-binding pockets and their amino acids in immune processes underpinning acute leukaemia and ultimately in immunotherapy settings.

Risk score to predict event-free survival after hematopoietic cell transplant for sickle cell disease.

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.

Use of the HLA-B leader to optimize cord blood transplantation

Cord-blood transplantation (CBT) can cure life-threatening blood disorders. The HLA-B leader affects the success of unrelated donor transplantation but its role in CBT is unknown. We tested the hypothesis that the HLA-B leader influences CBT outcomes in unrelated single-unit cord-blood transplants performed by Eurocord/European Blood and Marrow Transplant (EBMT) centers between 1990 and 2018 with data reported to Eurocord. Among 4822 transplants, 2178 had one HLA-B mismatch of which 1013 were HLA-A and HLA-DRB1-matched. The leader (M or T) was determined for each HLA-B allele in patients and units to define the genotype. Among single HLA-B-mismatched transplants, the patient/unit mismatched alleles were defined as leader-matched if they encoded the same leader, or leader-mismatched if they encoded different leaders; the leader encoded by the matched (shared) allele was determined. The risks of GVHD, relapse, non-relapse mortality and overall mortality were estimated for various leaderdefined groups using multivariable regression models. Among the 1013 HLA-A, -DRB1- matched transplants with one HLA-B mismatch, increasing numbers of cord-blood unit M-leader alleles was associated with increased risk of relapse (hazard ratio [HR] for each increase in one M-leader allele 1.30, 95% confidence interval [CI] 1.05 to 1.60, P 0.02). Furthermore, leader mismatching together with an M-leader of the shared HLA-B allele lowered non-relapse mortality (HR 0.44, 95% CI 0.23 to 0.81; P 0.009) relative to leader-matching and a shared T-leader allele. The HLA-B leader may inform relapse and non-relapse mortality risk after CBT. Future patients might benefit from the appropriate selection of units that consider the leader.

Reduced-Intensity versus Myeloablative Conditioning in Cord Blood Transplantation for Acute Myeloid Leukemia (40-60 years) across Highly Mismatched HLA Barriers-On Behalf of Eurocord and the Cellular Therapy & Immunobiology Working Party (CTIWP) of EBMT.

The use of myeloablative conditioning (MAC) in umbilical cord blood transplantation (UCBT) has been associated with high nonrelapse mortality (NRM) in patients aged >40 years, especially those having a high HLA disparity, thus limiting wider applications. We hypothesized that the NRM advantage of reduced-intensity conditioning (RIC) and higher graft-versus-leukemia effect associated with greater HLA disparities would expand its use for patients (aged 40 to 60 years) without compromising efficacy and compared outcomes between RIC and MAC regimens. In total, 288 patients aged 40 to 60 years, with de novo acute myeloid leukemia, receiving UCBT with at least 2 HLA mismatches with RIC (n = 166) or MAC (n = 122) regimens were included. As compared to RIC, the MAC cohort included relatively younger patients, having received more single UCBT, with lower total nucleated cell counts and more in vivo T cell depletion. Median time to neutrophil engraftment, infections (bacterial, viral, and fungal), and grade II to IV acute and chronic graft-versus-host disease were similar in both groups. In the multivariate analysis, overall survival (hazard ratio [HR], 0.98; P = .9), NRM (HR, 0.68; P = .2), and relapse (HR, 1.24; P = .5) were not different between RIC and MAC. Refractory disease was associated with worse survival. Outcomes of UBCT for patients aged 40 to 60 years having ≥2 HLA mismatches are comparable after the RIC or MAC regimen.

HLA-Matched Unrelated Donors for Patients with Sickle Cell Disease: Results of International Donor Searches.

Sickle cell disease (SCD) is the most common inherited hemoglobinopathy. Hematopoietic stem cell transplantation (HCT) is the sole curative therapy for SCD, but few patients will have a matched sibling donor. Patients with SCD are mostly of African origin and thus are less likely to find a matched unrelated donor in international registries. Using HaploStats, we estimated HLA haplotypes for 185 patients with SCD (116 from a Brazilian center and 69 from European Society for Blood and Marrow Transplantation [EBMT] centers) and classified the ethnic origin of haplotypes. Then we assessed the probability of finding an HLA-matched unrelated adult donor (MUD), considering loci A, B, and DRB1 (6/6), in international registries. Most haplotypes were African, but Brazilians showed a greater ethnic admixture than EBMT patients. Nevertheless, the chance of finding at least one 6/6 potential allelic donor was 47% for both groups. Most potential allelic donors were from the US National Marrow Donor Program registry and from the Brazilian REDOME donor registry. Although the probability of finding a donor is higher than previously reported, strategies are needed to improve ethnic diversity in registries. Moreover, predicting the likelihood of having an MUD might influence SCD management.

Unrelated cord blood transplantation in patients with idiopathic refractory severe aplastic anemia: a nationwide phase 2 study.

Outcomes remain poor for refractory severe aplastic anemia (SAA) patients. Alternative donor transplantation may be considered, but results from previous studies are not encouraging. We conducted a prospective nationwide phase 2 study to assess unrelated cord blood (CB) transplantation (CBT) efficacy and safety in refractory SAA patients (Aplastic Anemia and Cord Blood Transplantation protocol). To demonstrate a significant difference in 1-year survival from 20% (null hypothesis) to 50% (alternative hypothesis), we needed to include 25 transplanted patients and therefore included 26 (median age, 16 years). Eligibility criteria required 1 or 2 unrelated CB units, containing separately or together >4 × 107 frozen nucleated cells (NCs) per kilogram of recipient body weight. Conditioning regimen comprised fludarabine (FLU), cyclophosphamide (CY), antithymocyte globulin (ATG), and 2-Gy total body irradiation (TBI). With a median follow-up of 38.8 months, engraftment occurred in 23 patients (88%); cumulative incidences of grade II-IV acute and chronic graft-versus-host disease were 45.8% and 36%, respectively. Twenty-three patients were alive at 1 year, with an 88.5% overall survival (OS) rate, differing significantly from the expected 20% (P < .0001; 84% OS at 2 years). CBT with units containing ≥4 × 107 frozen NCs per kilogram is therefore a valuable curative option for young adults with refractory SAA and no available matched unrelated donors. This trial was registered at www.clinicaltrials.gov as #NCT01343953.

Extensive multilineage analysis in patients with mixed chimerism after allogeneic transplantation for sickle cell disease: insight into hematopoiesis and engraftment thresholds for gene therapy.

Although studies of mixed chimerism following hematopoietic stem cell transplantation in patients with sickle cell disease (SCD) may provide insights into the engraftment needed to correct the disease and into immunological reconstitution, an extensive multilineage analysis is lacking. We analyzed chimerism simultaneously in peripheral erythroid and granulomonocytic precursors/progenitors, highly purified B and T lymphocytes, monocytes, granulocytes and red blood cells (RBC). Thirty-four patients with mixed chimerism and ≥12 months of follow-up were included. A selective advantage of donor RBC and their progenitors/precursors led to full chimerism in mature RBC (despite partial engraftment of other lineages), and resulted in the clinical control of the disease. Six patients with donor chimerism <50% had hemolysis (reticulocytosis) and higher HbS than their donor. Four of them had donor chimerism <30%, including a patient with AA donor (hemoglobin >10 g/dL) and three with AS donors (hemoglobin <10 g/dL). However, only one vaso-occlusive crisis occurred with 68.7% HbS. Except in the patients with the lowest chimerism, the donor engraftment was lower for T cells than for the other lineages. In a context of mixed chimerism after hematopoietic stem cell transplantation for SCD, myeloid (rather than T cell) engraftment was the key efficacy criterion. Results show that myeloid chimerism as low as 30% was sufficient to prevent a vaso-occlusive crisis in transplants from an AA donor but not constantly from an AS donor. However, the correction of hemolysis requires higher donor chimerism levels (i.e ≥50%) in both AA and AS recipients. In the future, this group of patients may need a different therapeutic approach.

Long-term event-free survival, chimerism and fertility outcomes in 234 patients with sickle-cell anemia younger than 30 years after myeloablative conditioning and matched-sibling transplantation in France.

Allogeneic stem cell transplantation remains the only curative treatment for sickle cell anemia (SCA), but the place of myeloablative conditioning in the procedure remains to be defined. The aim of the present study was to analyze long-term outcomes, including chimerism, SCA-related events and biological data (hemoglobin, reticulocytes, HbS%), and fertility in a French series of 234 SCA patients under 30 years of age who, from 1988 to 2012, received a matched-sibling-donor stem cell transplantation following standardized myeloablative conditioning [busulfan, cyclophosphamide and rabbit antithymocyte globulin (ATG)]. Since the first report of the series (1988-2004), 151 new consecutive patients with SCA have been similarly transplanted. Considering death, non-engraftment or rejection (donor cells <5%) as events, the 5-year event-free survival was 97.9% (95% confidence interval: 95.5-100%), confirming, since the year 2000, an at least 95% chance of cure. In the overall cohort (n=234, median follow up 7.9 years), event-free survival was not associated with age, but chronic-graft-versus-host disease (cGvHD) was independently associated with recipient's age >15 years (hazard ratio=4.37; P=0.002) and lower (5-15 vs 20 mg/kg) ATG dose (hazard ratio=4.55; P=0.001). At one year, 44% of patients had mixed chimerism (5-95% donor cells), but those prepared with ATG had no graft rejection. No events related to SCA occurred in patients with mixed chimerism, even those with 15-20% donor cells, but hemolytic anemia stigmata were observed with donor cells <50%. Myeloablative transplantation with matched-sibling donor currently has a higher event-free survival (98%) in patients under 30 years of age than that reported for non-myeloablative conditioning (88%). Nevertheless, the risk of cGvHD in older patients and the need to preserve fertility might be indications for a non-myeloablative conditioning.

Impact of detectable measurable residual disease on umbilical cord blood transplantation.

The impact of measurable residual disease (MRD) on cord blood transplantation (CBT) outcomes has remained debated. To address this issue, we assessed the impact of measurable MRD at CBT on outcomes in large cohort of patients with acute leukemia. Inclusion criteria included adult patients with acute myeloid (AML) or acute lymphoblastic leukemia (ALL), CBT as first allo-HCT in first or second complete remission (CR) at transplantation, and known MRD status at the time of CBT. Data from 506 patients were included in the analysis. Among them, 317 patients had AML and 189 had ALL. Positive MRD was reported in 169 (33%) patients while the remaining 337 patients were MRD negative at CBT. At 2 years, relapse incidence was 18% in patients with MRD negativity vs 33% in those with MRD positivity at transplantation (P < .001). Two-year leukemia-free survival (LFS) and overall survival (OS) were 57% and 60%, respectively, in MRD negative patients, vs 38% (P < .001) and 48% (P = .004), respectively, in those with MRD positivity. There was no interaction between the impact of MRD on OS and LFS and diagnosis (ie, ALL vs AML), single or double CBT, and reduced-intensity or myeloablative conditioning. On multivariate analysis, MRD positivity was associated with a higher risk of relapse (HR = 1.8, P = .003), comparable non-relapse mortality (P = .44), worse LFS (HR = 1.4, P = .008) and a trend towards worse OS (HR = 1.3, P = .065). In conclusion, these data suggest that novel strategies that are aiming to achieve MRD negativity at CBT are needed for leukemic patients with positive MRD pre-CBT.

Myeloablative Unrelated Cord Blood Transplantation in Adolescents and Young Adults with Acute Leukemia.

Outcomes for adolescents and young adults (AYAs) with leukemia differ from other age groups and are still under-represented in clinical research. The aim of this study was to analyze outcomes of umbilical cord blood transplant (UCBT) in AYAs with acute leukemia reported to Eurocord/European Society for Blood and Marrow Transplantation. Patients (N = 504) had acute lymphoblastic (59%) or myeloid leukemia (41%), were aged 15 to 25 years, and received UCBT after myeloablative conditioning regimens between 2004 and 2016. The primary endpoint was 3-year overall survival (OS). Median follow-up was 3.9 years. Transplant was single in 58% and double UCBT in 42%. Three-year OS was 45% and leukemia free survival (LFS) was 41%. Cumulative incidence functions (CIFs) of nonrelapse mortality (NRM) and relapse were 31% and 28%, respectively. CIF of acute graft-versus-host disease (GVHD) grades II to IV at day 100 was 28%. Three-year CIF of chronic GVHD was 25%. In adjusted analysis, better disease status at UCBT (hazard ratio [HR], 2.74; P < .001) and more recent UCBT (HR, 1.43; P = .01) were associated with increased OS, and a similar effect of these factors was observed on LFS. Contrastingly, the use of antithymocyte globulin had a negative effect in LFS. The risk of acute GVHD grades II to IV increased with the use of double UCBT (HR, 1.65; P  = .02) and decreased with more recent transplant period (HR, .65; P = .02) and antithymocyte globulin use (HR, .55; P  = .01). Outcomes of AYA UCBT improved in more recent years, becoming comparable with pediatric results. Demonstrating the feasibility of UCBT in AYAs facilitates stem cell source selection and provides the basis for future prospective studies.

HLA-Mismatched Donors in Patients with Myelodysplastic Syndrome: An EBMT Registry Analysis.

Recently, haploidentical transplantation (haplo) using post-transplant cyclophosphamide (PTCy) has been reported to give very encouraging results in patients with hematological malignancies. Patients who have no HLA-matched donor currently have the choice between a mismatched unrelated donor, an unrelated cord blood (CB) donor, and a haploidentical related donor. The aim of our study is to compare the outcome of patients with myelodysplastic syndrome (MDS) who have been transplanted from a haploidentical donor using PTCy, an HLA-mismatched unrelated donor (marrow or peripheral blood stem cells), or an unrelated mismatched CB donor. A total of 833 MDS patients from the European Group for Blood and Marrow Transplantation (EBMT) registry, transplanted between 2011 and 2016, were identified. The potential benefit of haplo was compared with mismatched unrelated and CB donors in an adjusted and weighted model taking into account potential confounders and other prognostic variables. Haplo was at lower risk of acute graft-versus-host disease (GVHD) than mismatched unrelated donor (P = .010) but at similar risk than CB. Progression-free survival was better after haplo (versus mismatched unrelated, P = .056; versus CB, P = .003) and overall survival tended to be superior after haplo (versus mismatched unrelated, P = .082; versus CB, P = .002). Nonrelapse mortality was not significantly different between haplo and mismatched unrelated donors. Relapse risk was not influenced by the type of donor. In conclusion, patients with MDS from the EBMT registry receiving hematopoietic stem cell transplantation from a haplo donor have significantly better outcome than those receiving hematopoietic stem cell transplantation from a CB donor and at least similar or better outcome than with a mismatched unrelated donor. Prospective studies comparing the type of donors will be needed to confirm this assumption.

Worldwide Network for Blood and Marrow Transplantation Recommendations for Establishing a Hematopoietic Cell Transplantation Program, Part I: Minimum Requirements and Beyond.

Hematopoietic cell transplantation (HCT) is a highly complex procedure that requires a dedicated multidisciplinary team to optimize safety. In addition, institutions may have different needs regarding indications based on regional disease prevalence or may have an interest in developing specialized services. Structured recommendations are not commonly available, however. The Transplant Center and Recipient Issues Standing Committee of the Worldwide Network for Blood and Marrow Transplantation (WBMT) organized a structured review of all pertinent elements for establishing a transplantation program. First, we solicited components from committee members and grouped them into domains (infrastructure, staff, cell processing laboratory, blood banking, laboratory, radiology, pharmacy, HLA testing, ancillary services, and quality). Subsequently, reviewers scored each element on a 7-point scale, ranging from an absolute requirement (score of 1) to not required (score of 7). An independent group of 5 experienced transplantation physicians reviewed the rankings. The minimum requirements for establishing any HCT program were identified among elements with mean score of ≤2.0, and specific elements for allogeneic and autologous HCT were identified. Mean scores of >2.0 to 4.0 were classified as preferred recommendation, and mean scores of >4.0 to ≤ 7.0 were considered ideal recommendations for advanced and complex types of transplantation. This structured set of recommendations guides the prioritization of minimum requirements to establish a transplantation program and set the stage for expansion and further development.

Worldwide Network for Blood and Marrow Transplantation Recommendations for Establishing a Hematopoietic Stem Cell Transplantation Program in Countries with Limited Resources, Part II: Clinical, Technical, and Socioeconomic Considerations.

The development of hematopoietic stem cell transplantation (HSCT) programs can face significant challenges in most developing countries because such endeavors must compete with other government health care priorities, including the delivery of basic services. Although this is may be a limiting factor, these countries should prioritize development of the needed expertise to offer state-of-the-art treatments, including transplantation, by providing financial, technological, legal, ethical, and other needed support. This would prove beneficial in providing successful programs customized to the needs of their population and potentially provide long-term cost savings by circumventing the need for their citizens to seek care abroad. The costs of establishing an HSCT program and the costs of the HSCT procedure itself can be substantial barriers in developing countries. In addition, socioeconomic factors intrinsic to specific countries can influence access to HSCT, patient eligibility for HSCT, and timely utilization of HSCT center capabilities. This report describes recommendations from the Worldwide Network for Blood and Marrow Transplantation for establishing HSCT programs, with a specific focus on developing countries, and identifies challenges and opportunities for providing this specialized procedure in resource-constrained settings.

Risk factors affecting outcome of unrelated cord blood transplantation for children with familial haemophagocytic lymphohistiocytosis.

Allogeneic haematopoietic stem cell transplantation is still the only available curative option for Familial Haemophagocytic Lymphohistiocytosis (FHLH). Most studies report outcomes after bone marrow or peripheral blood stem cell transplantation. We analysed the outcomes of 118 children with FHLH undergoing single-unit umbilical cord blood transplantation performed from 1996 to 2014. Myeloablative conditioning regimen was given to 90% of the patients, and was mostly busulfan-based (n = 81, 76%), including anti-thymocyte globulin or alemtuzumab (n = 102, 86%). The cumulative incidence of Day 60 neutrophil engraftment was 85%; and that of non-relapse mortality and acute graft-versus-host disease (GvHD) was 21% and 33% at 100 days, respectively. The 6-year cumulative incidence of chronic GvHD was 17% and the 6-year probability of overall survival was 55%. In multivariate analysis, children receiving a graft with a total nucleated cell dose greater than 9·9 × 107 /kg had a better overall survival (hazard ratio [HR]: 0·49, 95% CI: 0·27-0·88, P = 0·02). Degree of human leucocyte antigen (HLA) matching was associated with improved disease-free survival (5/6 vs. 6/6 HR: 2·11, 95% confidence interval [CI]: 1·01-4·4, P = 0·05 and ≤4/6 vs. 6/6, HR: 2·82, CI: 1·27-6·23, P = 0·01). Umbilical cord blood transplantation with a high cell dose and good HLA match is a suitable alternative option to haematopoietic stem cell transplantation in children with FHLH who lack a HLA-matched donor.

A Toll-like receptor 2 genetic variant modulates occurrence of bacterial infections in patients with sickle cell disease.

Despite adequate immunization and penicillin prophylaxis, bacterial infections remain a leading cause of morbidity and mortality in patients with sickle cell disease (SCD). Besides hyposplenism, inflammatory and genetic factors might modulate their susceptibility to bacterial infections. We performed a candidate gene association of single nucleotide polymorphisms (SNPs) located in Toll-like receptor (TLR) genes, encoding prominent molecules for innate immune responses, with the occurrence of bacterial infections in patients with SCD. A cohort followed in centres in Brazil, France and Senegal (n = 430) was divided in two groups: patients who presented at least one episode of bacterial infection (n = 235) and patients who never had bacterial infections (n = 195). There were no differences in gender or age distribution among the groups. The frequency of the TLR2 rs4696480 TA genotype was significantly lower in the infected group (50% vs. 67%, odds ratio [OR] = 0·50, 95% confidence interval [CI] 0·34-0·75, P < 0·001), and the TT genotype was significantly higher in the infected group (15% vs. 5%, OR = 3·18, 95% CI 1·53-6·61, P < 0·001). Previous reports demonstrated higher secretion of inflammatory factors in cells from AA individuals, lower occurrence and severity of immune diseases in T carriers. The rs4696480 TA genotype might stand between deleterious effects of over inflammatory response (AA genotype) and inefficient responses (TT genotype) to infectious agents in SCD settings.

Impact of CTLA4 genotype and other immune response gene polymorphisms on outcomes after single umbilical cord blood transplantation.

We evaluated the impact of recipient and cord blood unit (CBU) genetic polymorphisms related to immune response on outcomes after unrelated cord blood transplantations (CBTs). Pretransplant DNA samples from 696 CBUs with malignant diseases were genotyped for NLRP1, NLRP2, NLRP3, TIRAP/Mal, IL10, REL, TNFRSF1B, and CTLA4. HLA compatibility was 6 of 6 in 10%, 5 of 6 in 39%, and ≥4 of 6 in 51% of transplants. Myeloablative conditioning was used in 80%, and in vivo T-cell depletion in 81%, of cases. The median number of total nucleated cells infused was 3.4 × 107/kg. In multivariable analysis, patients receiving CBUs with GG-CTLA4 genotype had poorer neutrophil recovery (hazard ratio [HR], 1.33; P = .02), increased nonrelapse mortality (NRM) (HR, 1.50; P < .01), and inferior disease-free survival (HR, 1.41; P = .02). We performed the same analysis in a more homogeneous subset of cohort 1 (cohort 2, n = 305) of patients who received transplants for acute leukemia, all given a myeloablative conditioning regimen, and with available allele HLA typing (HLA-A, -B, -C, and -DRB1). In this more homogeneous but smaller cohort, we were able to demonstrate that GG-CTLA4-CBU was associated with increased NRM (HR, 1.85; P = .01). Use of GG-CTLA4-CBU was associated with higher mortality after CBT, which may be a useful criterion for CBU selection, when multiple CBUs are available.

Sickle cell disease: an international survey of results of HLA-identical sibling hematopoietic stem cell transplantation.

Despite advances in supportive therapy to prevent complications of sickle cell disease (SCD), access to care is not universal. Hematopoietic cell transplantation is, to date, the only curative therapy for SCD, but its application is limited by availability of a suitable HLA-matched donor and lack of awareness of the benefits of transplant. Included in this study are 1000 recipients of HLA-identical sibling transplants performed between 1986 and 2013 and reported to the European Society for Blood and Marrow Transplantation, Eurocord, and the Center for International Blood and Marrow Transplant Research. The primary endpoint was event-free survival, defined as being alive without graft failure; risk factors were studied using a Cox regression models. The median age at transplantation was 9 years, and the median follow-up was longer than 5 years. Most patients received a myeloablative conditioning regimen (n = 873; 87%); the remainder received reduced-intensity conditioning regimens (n = 125; 13%). Bone marrow was the predominant stem cell source (n = 839; 84%); peripheral blood and cord blood progenitors were used in 73 (7%) and 88 (9%) patients, respectively. The 5-year event-free survival and overall survival were 91.4% (95% confidence interval, 89.6%-93.3%) and 92.9% (95% confidence interval, 91.1%-94.6%), respectively. Event-free survival was lower with increasing age at transplantation (hazard ratio [HR], 1.09; P < .001) and higher for transplantations performed after 2006 (HR, 0.95; P = .013). Twenty-three patients experienced graft failure, and 70 patients (7%) died, with the most common cause of death being infection. The excellent outcome of a cohort transplanted over the course of 3 decades confirms the role of HLA-identical sibling transplantation for children and adults with SCD.

Cord Blood Unit Dominance Analysis and Effect of the Winning Unit on Outcomes after Double-Unit Umbilical Cord Blood Transplantation in Adults with Acute Leukemia: A Retrospective Study on Behalf of Eurocord, the Cord Blood Committee of Cellular Therapy, Immunobiology Working Party, and the Acute Leukemia Working Party of the European Group for Blood and Marrow Transplantation.

Usually, after double umbilical cord blood transplantation (DUCBT), only 1 of the transplanted units persists in the long term. The characteristics of the winning cord blood unit (W-CBU) that determine unit dominance and how they influence the outcomes of DUCBT remain unclear. We retrospectively analyzed 347 patients with acute leukemia transplanted with a DUCBT (694 CBU) from 2005 to 2013 who had documented neutrophil engraftment and a W-CBU identified by chimerism analysis, to identify unit characteristics impacting on dominance. Median age at DUCBT was 40 years and median follow-up was 35 months. Among W-CBUs, 41% were ≥5/6 HLA matched to the recipient and 59% were ≤4/6. Multivariate analysis indicated that ≤4/6 HLA-matched W-CBUs led to lower leukemia-free survival (44% versus 56%; hazard ratio [HR], 1.5; P = .032) and overall survival (49% versus 62%; HR, 1.5; P = .028), increased nonrelapse mortality (26% versus 18%; HR, 1.9; P = .027), and acute graft-versus-host disease (46% versus 35%; HR, 1.7; P = .013). We were unable to predict unit dominance, but we demonstrated that outcomes were strongly influenced by the degree of HLA mismatch between W-CBU and recipient. Therefore, selection of both units with the lower number of HLA mismatches with the recipient is indicated.