ALBERT

Beschreibung: Abstract 2372 Three polymorphisms of the innate immune response gene NOD2/CARD15 (SNPs 8, 12 and 13) have been correlated with detrimental outcomes post stem cell transplantation. We have shown that the presence of any of the three SNPs in the combined genotype of the pair (that is in the patient, the donor or in both) was associated with significant increases in disease relapse and mortality in a cohort of Acute Leukemia (AL) Unrelated Donor (UD) Hematopoietic Stem Cell Transplant (HSCT) pairs. Several other published studies have described either a detrimental effect or no effect of SNPs 8, 12 and 13 on HSCT outcome in different cohorts. We hypothesised that, given the differing results from various studies, SNPs 8, 12 and 13 were actually only genetic markers for clinical outcome post HSCT and that the functionally relevant polymorphism(s) may be located elsewhere within the gene and may display Linkage Disequilibrium (LD) with the known SNPs in some populations. An exonic sequencing protocol for the entire NOD2/CARD15 gene was established and used to screen a cohort of AL UD-HSCT pairs. A total of 22 NOD2/CARD15 SNPs were identified with frequencies ranging from 1 – 43%. No significant differences in SNP frequency were noted between recipients and donors. Three of the polymorphisms were novel, although in each case the SNP was present in a single individual. In order to demonstrate the existence of LD between the polymorphisms and thus prove that SNPs 8, 12 and 13 were inherited on a single chromosome in combination with one or more other polymorphisms, haplotype estimation was performed on the cohort. Haplotypes were estimated using an in house program Cactus, which employs a gene counting method and the Expectation Maximisation algorithm. Several models were tested which included different combinations of NOD2/CARD15 SNPs. Of particular interest were the results of a model that included data for five polymorphic loci, SNPs 5, 6, 8, 12 and 13. A total of 20 haplotypes were predicted with this model, 13 of which were observed in the cohort. Three haplotypes (WT (Haplotype (H) 1); SNP 5 and 6 positive (H2); and SNP 5, 6 and 8 positive (H3)) comprised greater than 96% of all haplotypes identified (frequencies 70.8%, 21.1% and 4.6% respectively) and were used to determine the effects on HSCT outcome in a total of 238 AL UD-HSCT pairs. Transplants occurred between 1996 and 2005 at UK HSCT centres. Diagnoses were ALL (45%) and AML (55%). 68% of the cohort were 10/10 HLA matched, 10% were also matched at HLA-DPB1. Myeloablative conditioning regimens were used in 74% of transplants; T-cell depletion was included in 81% of protocols usually with in vivo Alemtuzumab. Bone marrow was used in 73% of transplants, 27% used peripheral blood stem cells. Two forms of post-transplant immunosuppression predominated, Cyclosporine A alone (36%) or with Methotrexate (46%). The probability of OS was 28% at 8 years. The estimated probability of OS at one year was higher in recipients with H1/H1 (WT) and H2/H2 (SNP 5 and 6 positive) haplotypes (55% and 67% respectively) as compared to those with H1/H2 (41%) or H1/H3 (H3, SNPs 5, 6 and 8 positive; 29%) haplotypes (p=0.016). The 8-year probability of Event-Free Survival (EFS) was 28%. Recipient NOD2/CARD15 haplotypes also significantly affected EFS (4 years: H1/H1 46%, H1/H2 33%, H2/H2 60%, H1/H3 29%; p=0.020). The 8-year probability of disease relapse was 41%. Significant differences in the risk of disease relapse were seen with individual donor NOD2/CARD15 haplotype combinations (1 year: H1/H1 25%, H1/H2 32%, H2/H2 60%, H1/H3 50%; p=0.013). There were no significant affects of recipient or donor NOD2/CARD15 haplotype combinations on non-relapse mortality, acute Graft-versus-Host Disease (GvHD) or chronic GvHD. The observed effects on OS and relapse persisted after multivariate analysis (OS: Relative Risk (RR) 1.54, p=0.016; EFS: RR 1.41, p=0.052; Relapse: RR 3.36, p=0.023). We conclude that distinct NOD2/CARD15 haplotypes exist and that they significantly affect UD-HSCT outcome. Significant differences in outcome were seen compared to the analysis of SNPs 8, 12 and 13 alone showing the advantage of combining NOD2/CARD15 haplotypes over individual SNPs. Importantly, the inclusion of additional polymorphic positions meant that 60% of individuals previously thought to be WT actually had at least one SNP. We suggest that the effect of NOD2/CARD15 haplotypes may be considerable and must be confirmed in other studies. Disclosures: No relevant conflicts of interest to declare.

Beschreibung: Abstract 467 Background: While donor-recipient disparity at HLA loci is associated with greater risk for severe acute graft vs. host disease (GVHD) and inferior survival after unrelated donor allogeneic hematopoietic cell transplantation (HCT), the impact of amino acid substitution (AAS) at peptide binding pockets of the HLA molecule is incompletely understood. Methods: Adult and pediatric patients who received myeloablative or reduced intensity/non-myeloablative first unrelated bone marrow or peripheral blood stem cell transplantation for AML, ALL, CML or MDS between 1988 and 2009 were included. Donors and patients were fully high resolution matched for HLA-A, B, C, and DRB1 (8/8) or had single mismatch (7/8) at one HLA class I locus. Among 7/8 donor-recipient pairs, cases were categorized based on the presence or absence of the AAS of interest at positions 9, 77, 99, 116, or 156 of the class I molecule. In multivariable analysis accounting for patient, disease, and transplantation variables, we studied the independent impact of AAS at these residues on risk for grade III-IV acute GVHD, chronic GVHD, treatment-related mortality, primary malignancy relapse, and overall survival. We compared 7/8 donor-recipient pairs with AAS of interest to 7/8 pairs without these AAS in the primary analyses. Additionally, we performed this analysis restricted to each HLA class I locus. Results: Donor-recipient pairs were 8/8 matched (n=5282), 7/8 with AAS of interest (n=1713), or 7/8 without AAS of interest (n=318). In multivariable analysis, AAS at position 116 was associated with increased risk for grade III-IV acute GVHD (HR 1.21, 1.04–1.42, p=0.0165). No other significant association was detected between AAS studied and clinical outcomes. In multivariable analysis restricted to each class I HLA locus, we detected the following: Among 7/8 matched pairs with mismatch at HLA-C, AAS at position 116 was associated with increased risk for severe acute GVHD (HR 1.42, 1.13–1.79, p=0.0031) and inferior OS (HR 1.2, 1.01–1.41, p=0.0343). AAS at position 99 was associated with increased TRM (HR 1.37, 1.11–1.69, p=0.0037). Of 7/8 pairs with mismatch at HLA-B, AAS at position 9 was associated with increased chronic GVHD (HR 2.19, 1.31–3.66, p=0.0029). Specific amino acid substitution pairs with frequency 〉 30 were tested for association with HCT outcomes. None met the significance level of 0.00125, pre-specified for multiple comparisons. Conclusions: These results support the concept that AAS at key peptide-binding residues in the HLA class I molecule are associated with increased risk for severe acute GVHD and lower survival. Disclosures: No relevant conflicts of interest to declare.

Beschreibung: Introduction It has been previously recognised that unrelated haematopoietic stem cell donors from certain ethnic minority groups are less likely to be available when called to give a sample for confirmatory (verification) typing (CT), prior to final donor selection. However, a direct impact of such donor attrition on donor selection has not, to date, been shown for patients of any ethnicity. Methods We analysed the outcome of CT requests for 303 patients managed by the Anthony Nolan Graft Identification and Advisory Service (GIAS), with the aim of assessing the impact of donor attrition on the speed of donor provision and donor suitability at CT and at transplant. Patient ethnicity was categorised as white Northern European (WNE) or non-white Northern European (non-WNE). A donor was categorised as unavailable if they were unable to return a sample for CT within the timeframe required by the transplant centre, for whatever reason. Requests cancelled by the transplant centre within this timeframe were not categorised as donor attrition. Results 235 patients (77.6%) were of white Northern European (WNE) descent, and 68 (22.4%) of non-WNE descent. 43 patients (13.0%) had a high, 141 (42.5%) a medium, 127 (38.3%) a low, and 21 (6.3%) a very low probability of search success (identifying a 10/10 matched donor), based on DRB1 allele and DRB1-DQB1 haplotype frequencies. Donor attrition was more common in those donors requested for CT for non-WNE patients (38.4% vs 24.6%, p

Beschreibung: It is well accepted that patients of ethnic minorities who lack a sibling donor are poorly represented on the international unrelated donor panels. As recently as 2000, only 30% of such patients were able to find an unrelated donor suitable for transplantation. Historically these patients would have either not been transplanted, or would receive transplants from unrelated donors with two or more HLA mismatches. Continued expansion of the international donor inventory, and the advent of cord blood and haploidentical transplantation has improved the prospects for transplantation for such patients and, through the expertise of search staff within donor registries and histocompatibility laboratories, transplant centres are increasingly able to identify early on those patients who are unlikely to find a well-matched unrelated adult donor. Surprisingly, however, few contemporary data have been published to show the impact of these search strategies and alternative stem cell sources on provision of transplant to those of non-white Northern European origin. We consecutively enrolled and prospectively followed up (from search request to last contact or death) 332 patients referred by four UK transplant centres to the Anthony Nolan Graft Identification and Advisory Service (GIAS) for identification of an unrelated adult donor or cord blood unit. Of these, 248 (74.7%) were of white Northern European (WNE) descent, and 84 (25.3%) non-WNE. The underlying disease did not differ significantly between ethnicities. The median number of UK donors listed on the search report was 8 (range 0 to 3395) and 0 (0 to 42) respectively, and on BMDW 127 (0 to 38245) and 5.5 (0 to 380) respectively. 69.3% of WNE and 20.5% of non-WNE patients found a 10/10 HLA-matched donor at confirmatory typing (CT) (p

Beschreibung: Patients who are CMV seropositive prior to allogeneic stem cell transplantation are well known to have a worse outcome compared to those who are CMV negative. Historically a CMV negative donor was prioritised for all transplant recipients, however in recent years practice has changed to actively search for a CMV positive donor for a positive recipient. Thus matching the CMV status of the patient and donor is considered important. We performed a study to analyse the impact of donor factors (HLA, CMV, age, gender and ABO matching) on survival of patients receiving an unrelated donor haematopoietic stem cell transplant. We included 1271 recipients transplanted between 1995-2011. All patients had received a transplant for a malignant disease (acute leukaemia/MDS 63%) at a UK transplant centre. Disease type and risk were categorised by the EBMT risk score and 580, 457 and 199 were characterised as good, intermediate and poor risk respectively. The median follow up of 611 surviving patients is 5.5y (range 0.2-15.4). The median age of the cohort is 40.6y (range 0.9-71.9). 661 and 585 patients had myeloablative and reduced intensity conditioning respectively. PBSC and BM were used in 682 and 580 patients respectively. Alemtuzumab was used in 94% of patients. The median donor age was 34.9 (range 19-60.4) with 80% being male and 20% female. The patient/donor CMV status was as follows: pos/pos (n=238), pos/neg (n=244), neg/neg (647), neg/pos (101). The median overall survival for the whole cohort was 2.11 years (range 1.6-2.6). CMV positive patients had a median survival of 1.7 years compared to 2.5 years in CMV negative patients (p=0.013). Furthermore, a significant effect was observed for CMV matching status between patient and donor, with median survivals of 2.8, 2.2, 1.5 and 1.1 years in the categories of neg/neg, pos/pos, neg/pos and pos/neg (p=0.001). In a multivariate analysis that included HLA matching, patient and donor age, disease risk, era and previous autograft; CMV matching status remained highly significantly associated with death, having a RR of 1.37 (95% CI 1.2-1.6, p=0.0002) for CMV mismatched pairs relative to CMV matched pairs (figure 1). Examination of the relationship between patient /donor CMV status and HLA matching revealed an effect dependant on the degree of HLA matching between patient and donor. There was no significant difference in the outcome of CMV negative patients, whether the donor was CMV matched or mismatched (p=0.061), either in the 10/10 (p=0.61) or 9/10 matched setting (p=0.13). However, in CMV positive patients with a 10/10 matched donor, median survival was 1.8y with a CMV negative donor, compared to 2.4y with a positive donor (p=0.23). In contrast, in the 9/10 matched setting, median survival was 0.7y with a CMV negative donor, compared to 2.2y with a positive donor (p=0.004). Grade 3-4 acute GvHD was significantly more likely to be seen in HLA mismatched compared to matched pairs (14% vs 9%, p=0.004). Likewise, CMV matching status had a borderline impact on the development of aGVHD (CMV matched 9% vs CMV mismatched 13%, p=0.053). In conclusion, our results show that selection of a CMV matched donor results in a superior outcome in this modern unrelated donor transplant cohort, especially when selecting a CMV positive donor for a CMV positive recipient. In the 9/10 HLA matched setting the use of a CMV negative donor is particularly deleterious. This may be related to an increase in GvHD in this setting and the morbidity and mortality associated with recurrent CMV reactivations. An alternative stem cell source, such as cord blood, could be considered in for these patients. Novel strategies to control CMV reactivation in the setting of a CMV negative donor are urgently required. Figure 1: Adjusted survival curves showing the impact of CMV matching on overall survival Figure 1:. Adjusted survival curves showing the impact of CMV matching on overall survival Disclosures No relevant conflicts of interest to declare.

Beschreibung: Background. There is no hierarchical algorithm that weights the characteristics of individual donors against each other in a quantitative manner to facilitate donor selection when multiple potential equally HLA-matched unrelated donors (URD) are available. Donor factors, such as age, sex, CMV status, ABO type, and matching of secondary HLA loci (DQB1, DPB1), have been associated with recipient survival in URD hematopoietic cell transplantation (HCT) although the impact of specific factors has varied among studies. The goal of this study was to develop and validate a donor selection score that prioritizes donor characteristics associated with better survival in 8/8 HLA-matched URD transplantation. Methods. Two large CIBMTR patient datasets were studied: HCT from 1999-2011 (n=5952) and 2012-2014 (n=4510). Patients were adults (〉18), transplanted for acute myelogenous leukemia (AML), acute lymphocytic leukemia (ALL), chronic myelogenous leukemia (CML), or myelodysplastic syndrome (MDS). Each dataset was randomly split for the analysis. Cohort 1 (c1): 2/3 (n=3969) for modeling/score development (training) and 1/3 (n=1983) for testing and similarly for cohort 2 (c2): 2/3 (n=3051) and 1/3 (n=1459). Thus, two independent models were built and tested, adjusting for significant patient characteristics associated with survival. Interactions between donor characteristics, and donor and recipient characteristics were tested. The following donor characteristics were considered for the donor score: HLA-DQB1 matching, HLA-DPB1 matching (using the T-cell epitope matching categorization), age, sex matching, parity, CMV matching, ABO matching and race matching. Results. In the final survival model (training set from 1999-2011, c1) we found significant negative associations with survival for three donor risk factors: non-permissive DPB1 matching (HR 1.13; 95% CI 1.01, 1.26; p-value=0.032), older donor age (as a linear effect, HR 1.07 per decade increase in age; 95% CI 1.02, 1.12, p-value=0.004), and CMV mismatching for CMV+ recipients (HR 1.14; 95% CI 1.02, 1.27; p-value=0.022). For CMV- recipients, a CMV+ donor was not significantly associated with an increase in mortality (HR=1.03; 95% CI 0.89-1.20; p-value=0.68), so this was not included in the score. ABO mismatching (any type: major, minor or bidirectional) was associated with mortality in initial modelling, but the effect was not present in more recent transplants (HR for ABO mismatch among patients transplanted since 2007: 1.04; 95% CI 0.91-1.19; p-value=0.638), so it was not included in the final model and donor score. Based on these results a donor risk score was constructed, however this score was not validated in the testing set (c1), nor were any of the individual component donor factors significantly associated with worse overall survival. In the second cohort (c2), only donor age was significantly associated with worse survival, and it validated in the independent test set from c2. Since donor age was significant in 3 of the 4 cohorts, we quantified the impact of donor age in the validation set of the most recent cohort, c2. We found that choosing a donor 2, 5, 10 or 20 years older was associated with a 1%, 2%, 3% or 7% decrease in 2 year OS, adjusted for patient characteristics. Conclusion. Despite data on over 10,000 URD transplants, we were unable to develop a valid donor selection score. The only donor characteristic associated with better survival was younger age, with 2-year survival being 3% better when a donor is 10 years younger. We did not test other endpoints; it is possible that separate scores could be generated to predict the risk of other outcomes (e.g. graft failure, graft-versus-host disease), however, unless the adverse donor characteristics are identical for these outcomes, centers will still have to prioritize the various donor characteristics to select from a pool of potential donors. This large data set shows that none of the other easily available donor clinical and genetic factors tested were reproducibly associated with survival and hence, flexibility in selecting URD based on these characteristics is justified. These data support a simplified URD selection process and have significant implications for URD registries. Disclosures Porter: Incyte: Honoraria; Genentech/Roche: Employment, Other: Family member employment, stock ownship - family member; Servier: Honoraria, Other: Travel reimbursement; Novartis: Honoraria, Patents & Royalties, Research Funding; Immunovative Therapies: Other: Member DSMB. Lee: Amgen: Other: One-time advisory board member; Bristol-Myers-Squibb: Other: One-time advisory board member; Mallinckrodt: Honoraria; Kadmon: Other: One-time advisory board member.

Beschreibung: Background HLA-haploidentical (haplo) blood or marrow transplantation (BMT) with post-transplantation cyclophosphamide (PTCy) is widely used, but few factors that inform donor selection have been identified. Based on prior observations for HLA-B leader (EW Petersdorf et al. Lancet Haematol 2020), HLA-DRB1 (YL Kasamon et al. BBMT 2010), and HLA-DPB1 (SR Solomon et al. BBMT 2018), we hypothesized that mismatching at individual HLA loci may influence BMT outcomes, but single and additive HLA gene effects have not been evaluated systematically in the context of haploBMT with PTCy. Methods The Center for International Blood and Marrow Transplant Research (CIBMTR) identified 1,434 patients who underwent T-cell-replete haploBMT with PTCy for acute leukemia or myelodysplastic syndrome (MDS) between 2008-2017. Multivariable models assessed transplant outcomes associated with 3 HLA-factors: (1) B-leader dimorphism (MM, MT, TT) matching; (2) HLA-DRB1 mismatching in the graft-versus-host (GVH) direction; and (3) nonpermissive HLA-DPB1 mismatching in the GVH direction using the T-cell epitope-3 model, which classifies HLA-DPB1 mismatches into permissive or non-permissive. All final models contained the HLA factors and adjusted for other significant clinical covariates at p