Prognostic Mutations in Myelodysplastic Syndrome after Stem-Cell Transplantation.

BACKGROUND: Genetic mutations drive the pathogenesis of the myelodysplastic syndrome (MDS) and are closely associated with clinical phenotype. Therefore, genetic mutations may predict clinical outcomes after allogeneic hematopoietic stem-cell transplantation. METHODS: We performed targeted mutational analysis on samples obtained before transplantation from 1514 patients with MDS who were enrolled in the Center for International Blood and Marrow Transplant Research Repository between 2005 and 2014. We evaluated the association of mutations with transplantation outcomes, including overall survival, relapse, and death without relapse. RESULTS: TP53 mutations were present in 19% of the patients and were associated with shorter survival and a shorter time to relapse than was the absence of TP53 mutations, after adjustment for significant clinical variables (P<0.001 for both comparisons). Among patients 40 years of age or older who did not have TP53 mutations, the presence of RAS pathway mutations was associated with shorter survival than was the absence of RAS pathway mutations (P=0.004), owing to a high risk of relapse, and the presence of JAK2 mutations was associated with shorter survival than was the absence of JAK2 mutations (P=0.001), owing to a high risk of death without relapse. The adverse prognostic effect of TP53 mutations was similar in patients who received reduced-intensity conditioning regimens and those who received myeloablative conditioning regimens. By contrast, the adverse effect of RAS pathway mutations on the risk of relapse, as compared with the absence of RAS pathway mutations, was evident only with reduced-intensity conditioning (P<0.001). In young adults, 4% of the patients had compound heterozygous mutations in the Shwachman-Diamond syndrome-associated SBDS gene with concurrent TP53 mutations and a poor prognosis. Mutations in the p53 regulator PPM1D were more common among patients with therapy-related MDS than those with primary MDS (15% vs. 3%, P<0.001). CONCLUSIONS: Genetic profiling revealed that molecular subgroups of patients undergoing allogeneic hematopoietic stem-cell transplantation for MDS may inform prognostic stratification and the selection of conditioning regimen. (Funded by the Edward P. Evans Foundation and others.).

Donor Killer Cell Immunoglobulin-Like Receptor Genotype Does Not Improve Graft-versus-Leukemia Responses in Chronic Lymphocytic Leukemia after Unrelated Donor Transplant: A Center for International Blood and Marrow Transplant Research Analysis.

Allogeneic hematopoietic cell transplantation (alloHCT) remains the sole curative therapy for patients with chronic lymphocytic leukemia (CLL), leading to 40% to 45% long-term survival. The impact of donor killer immunoglobulin-like receptor (KIR) genotype on outcomes of unrelated donor (URD) alloHCT for CLL is unknown. We examined 573 adult URD CLL recipient pairs. KIR genotype (presence/absence) was determined for each donor, and comprehensive modeling of interactions with recipient HLA class I loci (KIR ligands) was used to evaluate their effect on relapse and survival. Recipients had a median age of 56 years, and most were not in remission (65%). Both 8/8 HLA-matched (81%) or 7/8 HLA matched grafts (19%) were studied. Factors associated with improved overall survival (OS) were reduced-intensity conditioning (hazard ratio [HR] of death, .76) and good performance status (HR, .46), whereas alloHCT in nonremission (HR, 1.96) and mismatched donors (HR, 2.01) increased mortality. No models demonstrated a relationship between donor KIR genotype and transplant outcomes. Cox regression models comparing donors with A/A versus B/x KIR haplotypes and those with KIR gene content scores of 0 versus 1 versus ≥2 yielded similar rates of nonrelapse mortality, relapse, acute graft-versus-host disease (GVHD), and chronic GVHD and the same progression-free survival and OS. Relapse risk was not different for grafts from donors with KIR3DL1 transplanted into HLA C1/1 versus C2 recipients. This large analysis failed to demonstrate an association between URD KIR genotype and transplant outcome for patients with CLL, and thus KIR genotyping should not be used as a donor selection criterion in this setting.

KIR Donor Selection: Feasibility in Identifying better Donors.

We previously reported that acute myelogenous leukemia (AML) transplants using killer cell immunoglobulin-type receptor (KIR) B haplotype better or best (≥2 B activating gene loci ± Cen B/B) unrelated donors (URDs) yield less relapse and better survival. In this prospective trial we evaluated 535 AML searches from 14 participating centers with centralized donor KIR genotyping for donor selection. This represented 3% to 48% of all AML searches (median 20%) per center, totaling 3 to 172 patients (median 22) per center. Donor KIR genotype was reported at a median of 14 days after request (≤26 days for 76% of searches). In 535 searches, 2080 donors were requested for KIR genotyping (mean 4.3 per search); and a median of 1.8 (range, 0 to 4.5) per search were KIR typed. Choosing more donors for confirmatory HLA and KIR haplotype identification enriched the likelihood of finding KIR better or best donors. The search process identified a mean of 30% KIR better or best donors; the success ranged from 24% to 38% in the 11 centers enrolling ≥8 patients. More donors requested for KIR genotyping increased the likelihood of identifying KIR better or best haplotype donors. Of the 247 transplants, 9.3% used KIR best, 19% used KIR better, and 48% used KIR neutral donors while 24% used a non-KIR-tested donor. KIR genotyping did not delay transplantation. The time from search to transplant was identical for transplants using a KIR-genotyped versus a non-KIR-genotyped donor. Prospective evaluation can rapidly identify KIR favorable genotype donors, but choosing more donors per search would substantially increase the likelihood of having a KIR best or better donor available for transplantation. Transplant centers and donor registries must both commit extra effort to incorporate new characteristics (beyond HLA, age, and parity) into improved donor selection. Deliberate efforts to present additional genetic factors for donor selection will require novel procedures.

Impact of HLA Alleles on Outcomes of Allogeneic Transplantation for B Cell Non-Hodgkin Lymphomas: A Center for International Blood and Marrow Transplant Research Analysis.

Even in the modern era of targeted therapies, allogeneic hematopoietic stem cell transplantation (allo-HCT) can offer a chance of extended survival in B cell non-Hodgkin lymphoma (B-NHL) patients who relapse after or are deemed ineligible for autologous transplantation. A better understanding of the factors influencing the graft-versus-lymphoma (GVL) response would be useful in identifying B-NHL patients who may benefit from allo-HCT. Based on prior single-center reports, we hypothesized that certain HLA alleles, or haplotypes, may be associated with superior GVL compared with others after allo-HCT. To test this possibility we retrospectively evaluated whether the presence of HLA-A2, HLA-C1C1, HLA-DRB1*01:01, or HLA-DRB1*13 alleles or the presence of HLA-A1+, HLA-A2-, and HLA-B44- haplotypes is associated with outcomes in a cohort of 1314 HLA-8/8 matched sibling or unrelated donor HCT for relapsed/refractory B-NHL. We observed no significant association between any HLA allele or haplotype and overall survival or any of the secondary endpoints. In conclusion, this study represents the largest reported series of allo-HCT outcomes of B-NHL patients based on HLA type. Identification of other variables will be required to delineate the immunologic impact of donor-host interactions on outcomes of allo-HCT for B-NHL.

High HLA-DP Expression and Graft-versus-Host Disease.

BACKGROUND: Transplantation of hematopoietic cells from unrelated donors can cure blood disorders but carries a significant risk of acute graft-versus-host disease (GVHD). The risk is higher when the recipient and donor are HLA-DPB1-mismatched, but the mechanisms leading to GVHD are unknown. The HLA-DPB1 regulatory region variant rs9277534 is associated with HLA-DPB1 expression. We tested the hypothesis that the GVHD risk correlates with the rs9277534 allele linked to the mismatched HLA-DPB1 in the recipient. METHODS: We genotyped rs9277534 in 3505 persons to define rs9277534-DPB1 haplotypes. Among 1441 recipients of transplants from HLA-A,B,C,DRB1,DQB1-matched unrelated donors with only one HLA-DPB1 mismatch, linkage of the rs9277534 A and G alleles to the mismatched HLA-DPB1 was determined. HLA-DPB1 expression was assessed by means of a quantitative polymerase-chain-reaction assay. The risk of acute GVHD among recipients whose mismatched HLA-DPB1 allele was linked to rs9277534G (high expression) was compared with the risk among recipients whose mismatched HLA-DPB1 allele was linked to rs9277534A (low expression). RESULTS: The mean HLA-DPB1 expression was lower with rs9277534A than with rs9277534G. Among recipients of transplants from donors with rs9277534A-linked HLA-DPB1, the risk of acute GVHD was higher for recipients with rs9277534G-linked HLA-DPB1 mismatches than for recipients with rs9277534A-linked HLA-DPB1 mismatches (hazard ratio, 1.54; 95% confidence interval [CI], 1.25 to 1.89; P<0.001), as was the risk of death due to causes other than disease recurrence (hazard ratio, 1.25; 95% CI, 1.00 to 1.57; P=0.05). CONCLUSIONS: The risk of GVHD associated with HLA-DPB1 mismatching was influenced by the HLA-DPB1 rs9277534 expression marker. Among recipients of HLA-DPB1-mismatched transplants from donors with the low-expression allele, recipients with the high-expression allele had a high risk of GVHD. (Funded by the National Institutes of Health and others.).

Donor KIR B Genotype Improves Progression-Free Survival of Non-Hodgkin Lymphoma Patients Receiving Unrelated Donor Transplantation.

Donor killer immunoglobulin-like receptor (KIR) genotypes are associated with relapse protection and survival after allotransplantation for acute myelogenous leukemia. We examined the possibility of a similar effect in a cohort of 614 non-Hodgkin lymphoma (NHL) patients receiving unrelated donor (URD) T cell-replete marrow or peripheral blood grafts. Sixty-four percent (n = 396) of donor-recipient pairs were 10/10 allele HLA matched and 26% were 9/10 allele matched. Seventy percent of donors had KIR B/x genotype; the others had KIR A/A genotype. NHL patients receiving 10/10 HLA-matched URD grafts with KIR B/x donors experienced significantly lower relapse at 5 years (26%; 95% confidence interval [CI], 21% to 32% versus 37%; 95% CI, 27% to 46%; P = .05) compared with KIR A/A donors, resulting in improved 5-year progression-free survival (PFS) (35%; 95% CI, 26% to 44% versus 22%; 95% CI, 11% to 35%; P = .007). In multivariate analysis, use of KIR B/x donors was associated with significantly reduced relapse risk (relative risk [RR], .63, P = .02) and improved PFS (RR, .71, P = .008). The relapse protection afforded by KIR B/x donors was not observed in HLA-mismatched transplantations and was not specific to any particular KIR-B gene. Selecting 10/10 HLA-matched and KIR B/x donors should benefit patients with NHL receiving URD allogeneic transplantation.

CD16xCD33 bispecific killer cell engager (BiKE) activates NK cells against primary MDS and MDSC CD33+ targets.

Myelodysplastic syndromes (MDS) are stem cell disorders that can progress to acute myeloid leukemia. Although hematopoietic cell transplantation can be curative, additional therapies are needed for a disease that disproportionally afflicts the elderly. We tested the ability of a CD16xCD33 BiKE to induce natural killer (NK) cell function in 67 MDS patients. Compared with age-matched normal controls, CD7(+) lymphocytes, NK cells, and CD16 expression were markedly decreased in MDS patients. Despite this, reverse antibody-dependent cell-mediated cytotoxicity assays showed potent degranulation and cytokine production when resting MDS-NK cells were triggered with an agonistic CD16 monoclonal antibody. Blood and marrow MDS-NK cells treated with bispecific killer cell engager (BiKE) significantly enhanced degranulation and tumor necrosis factor-α and interferon-γ production against HL-60 and endogenous CD33(+) MDS targets. MDS patients had a significantly increased proportion of immunosuppressive CD33(+) myeloid-derived suppressor cells (MDSCs) that negatively correlated with MDS lymphocyte populations and CD16 loss on NK cells. Treatment with the CD16xCD33 BiKE successfully reversed MDSC immunosuppression of NK cells and induced MDSC target cell lysis. Lastly, the BiKE induced optimal MDS-NK cell function irrespective of disease stage. Our data suggest that the CD16xCD33 BiKE functions against both CD33(+) MDS and MDSC targets and may be therapeutically beneficial for MDS patients.

HLA-C expression levels define permissible mismatches in hematopoietic cell transplantation.

Life-threatening graft-versus-host disease (GVHD) limits the use of HLA-C-mismatched unrelated donors in transplantation. Clinicians lack criteria for donor selection when HLA-C-mismatched donors are a patient's only option for cure. We examined the role for HLA-C expression levels to identify permissible HLA-C mismatches. The median fluorescence intensity, a proxy of HLA-C expression, was assigned to each HLA-C allotype in 1975 patients and their HLA-C-mismatched unrelated transplant donors. The association of outcome with the level of expression of patients' and donors' HLA-C allotypes was evaluated in multivariable models. Increasing expression level of the patient's mismatched HLA-C allotype was associated with increased risks of grades III to IV acute GVHD, nonrelapse mortality, and mortality. Increasing expression level among HLA-C mismatches with residue 116 or residue 77/80 mismatching was associated with increased nonrelapse mortality. The immunogenicity of HLA-C mismatches in unrelated donor transplantation is influenced by the expression level of the patient's mismatched HLA-C allotype. HLA-C expression levels provide new information on mismatches that should be avoided and extend understanding of HLA-C-mediated immune responses in human disease.

Donor killer cell Ig-like receptor B haplotypes, recipient HLA-C1, and HLA-C mismatch enhance the clinical benefit of unrelated transplantation for acute myelogenous leukemia.

Killer cell Ig-like receptors (KIRs) interact with HLA class I ligands to regulate NK cell development and function. These interactions affect the outcome of unrelated donor hematopoietic cell transplantation (HCT). We have shown previously that donors with KIR B versus KIR A haplotypes improve the clinical outcome for patients with acute myelogenous leukemia by reducing the incidence of leukemic relapse and improving leukemia-free survival (LFS). Both centromeric and telomeric KIR B genes contribute to the effect, but the centromeric genes are dominant. They include the genes encoding inhibitory KIRs that are specific for the C1 and C2 epitopes of HLA-C. We used an expanded cohort of 1532 T cell-replete transplants to examine the interaction between donor KIR B genes and recipient class I HLA KIR ligands. The relapse protection associated with donor KIR B is enhanced in recipients who have one or two C1-bearing HLA-C allotypes, compared with C2 homozygous recipients, with no effect due to donor HLA. The protective interaction between donors with two or more, versus none or one, KIR B motifs and recipient C1 was specific to transplants with class I mismatch at HLA-C (RR of leukemia-free survival, 0.57 [0.40-0.79]; p = 0.001) irrespective of the KIR ligand mismatch status of the transplant. The survival advantage and relapse protection in C1/x recipients compared with C2/C2 recipients was similar irrespective of the particular donor KIR B genes. Understanding the interactions between donor KIR and recipient HLA class I can be used to inform donor selection to improve outcome of unrelated donor hematopoietic cell transplantation for acute myelogenous leukemia.

Mapping MHC haplotype effects in unrelated donor hematopoietic cell transplantation.

Life-threatening risks associated with HLA-mismatched unrelated donor hematopoietic cell transplantation limit its general application for the treatment of blood diseases. The increased risks might be explained by undetected genetic variation within the highly polymorphic major histocompatibility complex (MHC) region. We retrospectively assessed each of 1108 MHC region single nucleotide polymorphisms (SNPs) in 2628 patients and their HLA-mismatched unrelated donors to determine whether SNPs are associated with the risk of mortality, disease-free survival, transplant-related mortality, relapse, and acute and chronic graft-versus-host disease (GVHD). Multivariate analysis adjusted for HLA mismatching and nongenetic variables associated with each clinical end point. Twelve SNPs were identified as transplantation determinants. SNP-associated risks were conferred by either patient or donor SNP genotype or by patient-donor SNP mismatching. Risks after transplantation increased with increasing numbers of unfavorable SNPs. SNPs that influenced acute GVHD were independent of those that affected risk of chronic GVHD and relapse. HLA haplotypes differed with respect to haplotype content of (un)favorable SNPs. Outcome after HLA-mismatched unrelated donor transplantation is influenced by MHC region variation that is undetected with conventional HLA typing. Knowledge of the SNP content of HLA haplotypes provides a means to estimate risks prior to transplantation and to lower complications through judicious selection of donors with favorable MHC genetics.

Cytotoxic T-lymphocyte antigen-4 single nucleotide polymorphisms are not associated with outcomes after unrelated donor transplantation: a center for international blood and marrow transplant research analysis.

Cytotoxic T-lymphocyte antigen-4 (CTLA-4) plays an essential role in T cell homeostasis by restraining immune responses. AG and GG genotypes of donor CTLA-4 SNP rs4553808 in patients after unrelated donor hematopoietic stem cell transplantations (HSCT) have been shown to be an independent predictor of inferior relapse-free survival (RFS) and overall survival (OS) compared with those with the AA genotype, in single-center studies. We tested the hypothesis that SNP rs4553808 is associated with RFS, OS, nonrelapse mortality (NRM) and the cumulative incidence of acute graft-versus-host disease (GVHD) and chronic GVHD in adults with acute myeloid leukemia and advanced myelodysplastic syndrome undergoing a first 8/8 or 7/8 HLA-matched unrelated donor HSCT. Multivariable analysis adjusting for relevant donor and recipient characteristics showed no significant association between SNP rs4553808 and OS, RFS, NRM, and incidence of acute and chronic GVHD. An exploratory analysis of other CTLA-4 SNPs, as well as studying the interaction with antithymocyte globulin, also demonstrated no significant associations. Our results indicate that CTLA-4 SNPs are not associated with HSCT outcomes.

Risk factors for acute GVHD and survival after hematopoietic cell transplantation.

Risk factors for acute GVHD (AGVHD), overall survival, and transplant-related mortality were evaluated in adults receiving allogeneic hematopoietic cell transplants (1999-2005) from HLA-identical sibling donors (SDs; n = 3191) or unrelated donors (URDs; n = 2370) and reported to the Center for International Blood and Marrow Transplant Research, Minneapolis, MN. To understand the impact of transplant regimen on AGVHD risk, 6 treatment categories were evaluated: (1) myeloablative conditioning (MA) with total body irradiation (TBI) + PBSCs, (2) MA + TBI + BM, (3) MA + nonTBI + PBSCs, (4) MA + nonTBI + BM, (5) reduced intensity conditioning (RIC) + PBSCs, and (6) RIC + BM. The cumulative incidences of grades B-D AGVHD were 39% (95% confidence interval [CI], 37%-41%) in the SD cohort and 59% (95% CI, 57%-61%) in the URD cohort. Patients receiving SD transplants with MA + nonTBI + BM and RIC + PBSCs had significantly lower risks of grades B-D AGVHD than patients in other treatment categories. Those receiving URD transplants with MA + TBI + BM, MA + nonTBI + BM, RIC + BM, or RIC + PBSCs had lower risks of grades B-D AGVHD than those in other treatment categories. The 5-year probabilities of survival were 46% (95% CI, 44%-49%) with SD transplants and 33% (95% CI, 31%-35%) with URD transplants. Conditioning intensity, TBI and graft source have a combined effect on risk of AGVHD that must be considered in deciding on a treatment strategy for individual patients.

Donor selection for natural killer cell receptor genes leads to superior survival after unrelated transplantation for acute myelogenous leukemia.

Killer-cell immunoglobulin-like receptor (KIR) genes form a diverse, immunogenetic system. Group A and B KIR haplotypes have distinctive centromeric (Cen) and telomeric (Tel) gene-content motifs. Aiming to develop a donor selection strategy to improve transplant outcome, we compared the contribution of these motifs to the clinical benefit conferred by B haplotype donors. We KIR genotyped donors from 1409 unrelated transplants for acute myelogenous leukemia (AML; n = 1086) and acute lymphoblastic leukemia (ALL; n = 323). Donor KIR genotype influenced transplantation outcome for AML but not ALL. Compared with A haplotype motifs, centromeric and telomeric B motifs both contributed to relapse protection and improved survival, but Cen-B homozygosity had the strongest independent effect. With Cen-B/B homozygous donors the cumulative incidence of relapse was 15.4% compared with 36.5% for Cen-A/A donors (relative risk of relapse 0.34; 95% confidence interval 0.2-0.57; P < .001). Overall, significantly reduced relapse was achieved with donors having 2 or more B gene-content motifs (relative risk 0.64; 95% confidence interval 0.48-0.86; P = .003) for both HLA-matched and mismatched transplants. KIR genotyping of several best HLA-matched potential unrelated donors should substantially increase the frequency of transplants by using grafts with favorable KIR gene content. Adopting this practice could result in superior disease-free survival for patients with AML.

Adverse events among 2408 unrelated donors of peripheral blood stem cells: results of a prospective trial from the National Marrow Donor Program.

Limited data are available describing donor adverse events (AEs) associated with filgrastim mobilized peripheral blood stem cell (PBSC) collections in unrelated volunteers. We report results in 2408 unrelated PBSC donors prospectively evaluated by the National Marrow Donor Program (NMDP) between 1999 and 2004. Female donors had higher rates of AEs, requiring central line placement more often (17% vs 4%, P< .001), experiencing more apheresis-related AEs (20% vs 7%, P< .001), more bone pain (odds ratio [OR]=1.49), and higher rates of grades II-IV and III-IV CALGB AEs (OR=2.22 and 2.32). Obese donors experienced more bone pain (obese vs normal, OR=1.73) and heavy donors had higher rates of CALGB toxicities (>95 kg vs <70 kg, OR=1.49). Six percent of donors experienced grade III-IV CALGB toxicities and 0.6% experienced toxicities that were considered serious and unexpected. Complete recovery is universal, however, and no late AEs attributable to donation have been identified. In conclusion, PBSC collection in unrelated donors is generally safe, but nearly all donors will experience bone pain, 1 in 4 will have significant headache, nausea, or citrate toxicity, and a small percentage will experience serious short-term adverse events. In addition, women and larger donors are at higher risk for donation-related AEs.

Decreased infections in recipients of unrelated donor hematopoietic cell transplantation from donors with an activating KIR genotype.

Infectious complications following allogeneic hematopoietic cell transplantation (HCT) from unrelated donors (URD) result in significant morbidity. We hypothesized that recipients of a URD with an activating natural killer cell immunoglobulin-like receptor (KIR) (B/x) genotype would have decreased infectious complications because of enhanced natural killer (NK) cell function. We compared the infectious complications in 116 recipients of a graft from a donor with an A/A KIR (n = 44) genotype and a B/x KIR (n = 72) genotype. All recipients participated in the prospective National Marrow Donor Program infection project collecting infection data from conditioning until 6 months posttransplant. The cohort with a B/x donor had fewer initial bacterial infections by day 180 (A/A: 86%; 95% confidence interval [CI], 75-95; B/x: 68%; 95% CI, 57-78; P = .02). There was no difference in the incidence of viral or fungal infections. When accounting for multiple infections, fewer bacterial infections were seen in the B/x cohort (A/A: 3.55/patient; B/x: 2.63/patient; P = .09). During the study period, only 19 patients had no infections; of these, 15 had received cells from a B/x KIR donor. The role of donor KIR genotype on infection complications is intriguing and warrants further investigation.

HLA-A disparities illustrate challenges for ranking the impact of HLA mismatches on bone marrow transplant outcomes in the United States.

HLA disparity between hematopoietic stem cell donors and recipients is one of the most important factors influencing transplant outcomes, but there are no well-accepted guidelines to aid in selecting the optimal donor among several HLA mismatched donors. In this report, HLA-A is used as a model to illustrate factors that are barriers to delineating the relationship between specific HLA mismatches and transplant outcomes in the United States. Patients in this investigation received transplants for hematologic malignancies that were facilitated by the National Marrow Donor Program (NMDP) between 1990 and 2002 (n = 4226). High-resolution HLA typing was performed for HLA-A, -B, -C, -DRB1, -DQA1, -DQB1, -DPA1, and -DPB1. HLA-A mismatches were observed in 745 donor-recipient pairs and 62% of these pairs also had disparities at HLA-B, -C, and/or -DRB1. The HLA-A mismatches involved 190 different combinations of HLA-A alleles and 51% of these were observed in only 1 pair. Addition of a single HLA-A disparity when HLA-B, -C, and -DRB1 were matched (n = 282) was associated with increased mortality (odds ratio [OR] = 1.32, confidence interval [CI] 1.07-1.63). When HLA-B, -C, and -DRB1 were matched, the most frequent HLA-A mismatches were HLA-A*0201:0205 (n = 28), HLA-A *0301:0302 (n = 15), HLA-A *0201:0206 (n = 15), HLA-A *0201:6801 (n = 12), HLA-A*0101:1101 (n = 11), and HLA-A*0101:0201 (n = 10). There were no statistically significant relationships between any of these disparities and transplant outcomes (engraftment, acute and chronic graft-versus-host disease [aGVHD, cGVHD] relapse, treatment-related mortality [TRM], or overall survival [OS]) when adjustments for multiple comparisons were considered. Achieving 80% power to detect an effect of any 1 of these 6 HLA-A disparities on survival is estimated to require a total transplant population of 11,000 to more than 1 million U.S. donor-recipient pairs depending upon the HLA disparity. Thus, alternative approaches are required to develop a clinically relevant ranking system for specific HLA disparities in the United States.

The effect of NIMA matching in adult unrelated mismatched hematopoietic stem cell transplantation - a joint study of the Acute Leukemia Working Party of the EBMT and the CIBMTR.

Hematological malignancies can be cured by unrelated donor allogeneic HSCT and outcomes are optimized by high-resolution HLA matching at HLA-A, -B, -C, -DRB1 and -DQB1 (10/10 match). If a 10/10 match is unavailable, 9/10 matches may be suitable. Fetal exposure to non-inherited maternal antigens (NIMA) may impart lifelong NIMA tolerance modulating the immune response, as shown in adult haploidentical transplantation. In cord blood transplantation, NIMA matching lowered rates of aGvHD and TRM; in haploidentical transplantation, sibling donors with non-shared maternal antigens showed less grade II-IV aGvHD. This retrospective analysis examined if 9/10 matched unrelated donor HSCT benefits from NIMA matching. DKMS contacted 1,735 donors and obtained 733 (42%) maternal samples. NIMA-matched and -mismatched cases with a minimum follow-up of 1 year were compared by univariate and multivariate analyses adjusted for co-variates for OS, DFS, relapse, TRM and a/cGvHD. The study population (N = 445) comprised 31 NIMA-matched and 414 NIMA-mismatched cases. No significant differences between NIMA-matched and NIMA-mismatched groups were found for any outcomes with similar OS and TRM rates within both groups. This study provides the proof of principle that NIMA matching is possible in the unrelated donor HSCT setting; larger studies may be able to provide significant results.

Multiple functional variants in the IL1RL1 region are pretransplant markers for risk of GVHD and infection deaths.

Graft-versus-host disease (GVHD) and infections are the 2 main causes of death without relapse after allogeneic hematopoietic cell transplantation (HCT). Elevated soluble serum simulation-2 (sST2), the product of IL1RL1 in plasma/serum post-HCT, is a validated GVHD biomarker. Hundreds of SNPs at 2q12.1 have been shown to be strongly associated with sST2 concentrations in healthy populations. We therefore hypothesized that the donor genetic variants in IL1RL1 correlate with sST2 protein levels associated with patient survival outcomes after HCT. We used DISCOVeRY-BMT (Determining the Influence of Susceptibility Conveying Variants Related to 1-Year Mortality after Blood and Marrow Transplantation), a genomic study of >3000 donor-recipient pairs, to inform our hypothesis. We first measured pre-HCT plasma/serum sST2 levels in a subset of DISCOVeRY-BMT donors (n = 757) and tested the association of donor sST2 levels with donor single nucleotide polymorphisms (SNPs) in the 2q12.1 region. Donor SNPs associated with sST2 levels were then tested for association with recipient death caused by acute GVHD (aGVHD)-, infection-, and transplant-related mortality in cohorts 1 and 2. Meta-analyses of cohorts 1 and 2 were performed using fixed-effects inverse variance weighting, and P values were corrected for multiple comparisons. Donor risk alleles in rs22441131 (P meta = .00026) and rs2310241 (P meta = .00033) increased the cumulative incidence of aGVHD death up to fourfold and were associated with high sST2 levels. Donor risk alleles at rs4851601 (P meta = 9.7 × 10-7), rs13019803 (P meta = 8.9 × 10-6), and rs13015714 (P meta = 5.3 × 10-4) increased cumulative incidence of infection death to almost sevenfold and were associated with low sST2 levels. These functional variants are biomarkers of infection or aGVHD death and could facilitate donor selection, prophylaxis, and a conditioning regimen to reduce post-HCT mortality.

Patient HLA Germline Variation and Transplant Survivorship.

Purpose HLA mismatching increases mortality after unrelated donor hematopoietic cell transplantation. The role of the patient's germline variation on survival is not known. Patients and Methods We previously identified 12 single nucleotide polymorphisms within the HLA region as markers of transplantation determinants and tested these in an independent cohort of 1,555 HLA-mismatched unrelated transplants. Linkage disequilibrium mapping across class II identified candidate susceptibility features. The candidate gene was confirmed in an independent cohort of 3,061 patients. Results Patient rs429916AA/AC was associated with increased transplantation-related mortality compared with rs429916CC (hazard ratio [HR], 1.39; 95% CI, 1.12 to 1.73; P = .003); rs429916A positivity was a proxy for DOA*01:01:05. Mortality increased with one (HR, 1.17; 95% CI, 1.0 to 1.36; P = .05) and two (HR, 2.51; 95% CI, 1.41 to 4.45; P = .002) DOA*01:01:05 alleles. HLA-DOA*01:01:05 was a proxy for HLA-DRB1 alleles encoding FEY ( P < 10E-15) and FDH ( P < 10E-15) amino acid substitutions at residues 26/28/30 that influence HLA-DRß peptide repertoire. FEY- and FDH-positive alleles were positively associated with rs429916A ( P < 10E-15); FDY-positive alleles were negatively associated. Mortality was increased with FEY (HR, 1.66; 95% CI, 1.29 to 2.13; P = .00008) and FDH (HR, 1.40; 95% CI, 1.02 to 1.93; P = .04), whereas FDY was protective (HR, 0.88; 95% CI, 0.78 to 0.98; P = .02). Of the three candidate motifs, FEY was validated as the susceptibility determinant for mortality (HR, 1.29; 95% CI, 1.00 to 1.67; P = .05). Although FEY was found frequently among African and Hispanic Americans, it increased mortality independently of ancestry. Conclusion Patient germline HLA-DRB1 alleles that encode amino acid substitutions that influence the peptide repertoire of HLA-DRß predispose to increased death after transplantation. Patient germline variation informs transplantation outcomes across US populations and may provide a means to reduce risks for high-risk patients through pretransplantation screening and evaluation.