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HLA haplotype mismatches have been associated with an elevated risk of acute graft-versus-host disease (aGVHD) in patients undergoing HLA-matched unrelated donor (URD) hematopoietic cell transplantation (HCT). The gamma block (GB) is located in the central MHC region between beta and delta blocks (encoding HLA-B and -C and HLA-DQ and -DR antigens, respectively) and contains numerous inflammatory and immune regulatory genes, including Bf, C2, and C4 genes. A single-center study showed that mismatches in SNPs c.2918+98G, c.3316C, and c.4385C in the GB block (C4 SNPs) were associated with higher risk of grade III-IV aGVHD. We investigated the association of GB SNP (GBS) mismatches with outcomes after 10/10 and 9/10 URD HCT (n = 714). The primary outcome was acute GVHD. Overall survival, disease-free survival, transplantation-related mortality, relapse, chronic GVHD, and engraftment were also analyzed. DNA samples were GBS genotyped by identifying 338 SNPs across 20 kb using the Illumina NGS platform. The overall 100-day incidence of aGVHD grade II-IV and II-IV were 41% and 17%, respectively. The overall incidence of matching at all GBSs tested and at the C4 SNPs were 23% and 81%, respectively. Neither being matched across all GB SNPs tested (versus mismatched) nor having a higher number of GBS mismatches was associated with transplantation outcomes. There was no association between C4 SNP mismatches and outcomes except for an unexpected significant association between having 2 C4 SNP mismatches and a higher hazard ratio (HR) for relapse (association seen in 15 patients only; HR, 3.38, 95% confidence interval, 1.75 to 6.53; P = .0003). These data do not support the hypothesis that mismatching at GB is associated with outcomes after HCT.

Natural killer (NK) cells are regulated by killer immunoglobulin-like receptor (KIR) interactions with human leukocyte antigen class I ligands. Various models of NK cell alloreactivity have been associated with outcomes after allogeneic hematopoietic cell transplant (alloHCT), but results have varied widely. We hypothesized that somatic mutations in acute myeloid leukemia (AML) in the context of KIR profiles may further refine their association with transplant outcomes. In this single-center, retrospective, observational study, 81 AML patients who underwent matched-related donor alloHCT were included. Post-HCT outcomes were assessed based on mutational status and KIR profiles with the Kaplan–Meier method and log-rank test. On multivariable analysis those with any somatic mutations and C1/C2 heterozygosity had less acute graft-versus-host disease (GvHD) (hazard ratio [HR], 0.32; 95% confidence interval [CI], 0.14-0.75; P = .009), more relapse (HR, 3.02; 95% CI, 1.30-7.01; P = .010), inferior relapse-free survival (RFS; HR, 2.22; 95% CI, 1.17-4.20; P = .014), and overall survival (OS; HR, 2.21; 95% CI, 1.17-4.20; P = .015), whereas those with a missing KIR ligand had superior RFS (HR, 0.53; 95% CI, 0.30-0.94; P = .031). The presence of a somatic mutation and donor haplotype A was also associated with less acute GvHD (HR, 0.38; 95% CI, 0.16-0.92; P = .032), more relapse (HR, 2.72; 95% CI, 1.13-6.52; P = .025), inferior RFS (HR, 2.11; 95% CI, 1.07-4.14; P = .030), and OS (HR, 2.20; 95% CI, 1.11-4.38; P = .024). Enhanced NK cell alloreactivity from more KIR activating signals (donor B haplotype) and fewer inhibitory signals (recipient missing KIR ligand or C1 or C2 homozygosity) may help mitigate the adverse prognosis associated with some AML somatic mutations. These results may have implications for improving patient risk stratification prior to transplant and optimizing donor selection.

Objective/Background: Cytomegalovirus (CMV) infection and disease are common infectious complications after allogeneic hematopoietic cell transplantation (alloHCT). Major histocompatibility complex (MHC) class I chain-related gene A (MICA) is a ligand of the natural killer (NKG2D) receptor on immune effector cells that helps mediate NK cell alloreactivity. We hypothesized that MICA polymorphisms may influence CMV infection and disease incidence after alloHCT. Methods: We conducted a retrospective analysis of 423 adults at the Cleveland Clinic with hematologic malignancies treated with a matched related or unrelated donor alloHCT. CMV cases analyzed included a compositive of instances of viral copy replication above detection limits as well as any biopsy-proven tissue invasive disease episodes. Genotypes at the MICA-129 position have been categorized as weak (valine/valine; V/V), intermediate (methionine/valine; M/V), or strong (methionine/methionine; M/M) receptor affinity. Results: In multivariable analysis, V/V donor MICA-129 genotype was associated with CMV infection and disease (hazard ratio [HR] = 1.40; 95% confidence interval [CI], 1.00–1.96; p = .05), but not MICA mismatch (HR = 1.38; 95% CI, 0.83–2.29; p = .22). There was no association of acute or chronic GVHD with MICA donor–recipient mismatch (HR = 1.05; 95% 95% CI, 0.66–1.68; p = .83 and HR = 0.94; 95% CI, 0.51–1.76; p = .85, respectively) or V/V donor MICA-129 genotypes (HR = 1.02; 95% CI, 0.79–1.31; p = .89 and HR = 0.89; 95% CI, 0.65–1.22; p = .47, respectively). Conclusion: These findings suggest that the donor MICA-129 V/V genotype with weak NKG2D receptor binding affinity is associated with an increased risk of CMV infection and disease after alloHCT. Keywords: Allogeneic hematopoietic cell transplantation, Cytomegalovirus, Killer cell immunoglobulin-like receptors, Major histocompatibility complex class I chain-related gene A

We report a case of primary renal allograft dysfunction and early acute cell-mediated rejection after a 12/12 HLA antigen zero-mismatch (0MM) transplant. The recipient was a 40-year-old white man who was highly allosensitized, with a calculated panel reactive antibody score of 100%. In posteroperative day 1 the recipient remained anuric and underwent dialysis because of hyperkalemia. Graft biopsy showed early acute cellular rejection, Banff grade 2B. No evidence of antibody-mediated rejection was observed. To our knowledge, this case is the 1st to report early cell-mediated rejection after 12/12 HLA antigen 0MM kidney transplantation. This case suggests that highly sensitized candidates are at high immunologic risk even in the context of 0MM kidney transplantation.

The clinical relevance of mismatches at the MHC class I–related chain A (MICA) in hematopoietic stem cell transplantation (HSCT) remains unclear. We investigated the association of MICA donor/recipient mismatch and whether there is an interaction between these and HLA-DPB1 mismatch on clinical outcomes after unrelated donor HSCT. Our study included 227 patients who underwent unrelated donor allogeneic HSCT at our institution between 2000 and 2010. Among these, 177 (78%) received HSCT from a 10/10 HLA-matched donor. MICA genotyping was performed using commercially available kits. In univariable analysis, the risk of grade II to IV acute graft-versus-host disease (GVHD) was greater for patients with MICA mismatch (hazard ratio [HR], 1.73; P = .02) than for those with HLA-DPB1 mismatch (HR, 1.62; P = .07). When MICA and HLA-DPB1 were assessed simultaneously, patients mismatched at both loci had the greatest risk (HR, 2.51; P < .01) and those mismatched at only 1 locus had somewhat greater risk (HR, 1.53; P = .12) than patients matched at both loci; this remained significant in multivariable analysis. The 100-day incidence was 66%, 45%, and 31%, respectively (P = .03). Results were similar for grade III and IV acute GVHD, with 100-day incidence 34%, 16%, and 8% (P = .01). These results are clinically pertinent to donor selection strategies and indicate that patients with mismatch at both MICA and HLA-DPB1 are at increased risk for acute GVHD.

Background: Graft-versus-leukemia (GVL) responses after allogeneic hematopoietic cell transplantation (alloHCT) for AML are mediated by alloreactive donor-derived immune effector cells including T lymphocytes and natural killer (NK) cells. The function of NK cells is regulated by inhibitory and activating signals mediated through cell-surface receptors, including KIRs. Various models of NK cell alloreactivity have been associated with post-transplant outcomes, including leukemia relapse. However, these results have varied widely between different investigators employing similar models of NK cell alloreactivity. Assessment of somatic mutations in AML on post-transplant outcomes has not been investigated in the context of KIR profiles. Methods: In this single-institution retrospective cohort study, we investigated KIR haplotypes (haplotype AA vs. Bx [associated with multiple activating KIRs]; Cooley S., et al. Blood. 113:726-732. 2009) in the context of somatic mutations. We included 34 adult patients with AML who underwent alloHCT from a matched related donor from 2006 to 2013. A targeted multi-amplicon deep NGS panel of 79 commonly mutated genes in myeloid neoplasia was performed. Post-HCT outcomes were assessed based on mutational status and KIR haplotype with Kaplan-Meier method and log-rank test. Results: Median age at transplant was 54 (range 31-73). Cytogenetic risk groups were 9% favorable, 56% intermediate, and 35% poor based on 2017 ELN classification. HCT-CI scores included 26% low, 32% intermediate, and 41% high. Disease risk group defined by ASTCT included 71% low, 26% intermediate, and 3% high. Disease status at HCT included 74% CR1 and 26% CR2. Frequencies of somatic mutations prior to HCT were: 21% DNMT3A, 18% IDH2, 9% each for STAG2 and NRAS, 6% each for ASXL1, JAK2, PHF6, RUNX1, TET2, and 3% each for CBL, FLT3, NPM1, and U2AF1. Overall, 53% of patients had at least 1 mutation: 24%, 18%, 9%, and 3% of patients had 1, 2, 3, and 4 mutations, respectively. 41% were carriers of KIR haplotype AA, and 59% were haplotype Bx. Relapse (p=0.40), relapse-free (p=0.33), and overall survival (p=0.30) between haplotypes AA and Bx were not statistically different. However, when considering somatic mutations in the context of KIR haplotypes, those with any somatic mutation (n= 18) present had inferior relapse-free (p=0.002) and overall survival (p=0.002; figures A-B) as compared to those with none. Further assessment of outcomes was then considered for those who had the following poor prognostic mutations (n=12): ASXL1, DNMT3A, FLT3, NRAS, RUNX1, and TET2. KIR haplotype AA with one or more of these mutations was associated with inferior relapse-free (p=0.05) and overall survival (p=0.008). At median follow-up of 83 (range 66-137) months, 38% were alive. Non-relapse mortality rates were 21% (9-36) at 1 year and 29% (15-39) at 3 years. The most common causes of death for all patients were relapse (48%) followed by infection (33%). Conclusion: In presence of somatic mutations, carrying KIR haplotypes Bx was associated with better survival in AML post-alloHCT. The presence of multiple activating KIRs may also help mitigate the worse prognosis associated with some of the more deleterious somatic mutations in AML. These observations may have implications for improving patient risk stratification prior to transplant and optimizing donor selection. Future investigation with larger cohorts interrogating KIR haplotypes in the context of pre-transplant AML somatic mutations on post-transplant outcomes may further elucidate which patients may benefit most from transplant. Disclosures Nazha: Tolero, Karyopharma: Honoraria; Abbvie: Consultancy; Daiichi Sankyo: Consultancy; Novartis: Speakers Bureau; Jazz Pharmacutical: Research Funding; Incyte: Speakers Bureau; MEI: Other: Data monitoring Committee. Mukherjee:Bristol-Myers Squibb: Speakers Bureau; Projects in Knowledge: Honoraria; Celgene Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Partnership for Health Analytic Research, LLC (PHAR, LLC): Consultancy; McGraw Hill Hematology Oncology Board Review: Other: Editor; Pfizer: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees. Advani:Pfizer: Honoraria, Research Funding; Macrogenics: Research Funding; Glycomimetics: Consultancy, Research Funding; Kite Pharmaceuticals: Consultancy; Amgen: Research Funding; Abbvie: Research Funding. Gerds:Sierra Oncology: Research Funding; Incyte: Consultancy, Research Funding; CTI Biopharma: Consultancy, Research Funding; Imago Biosciences: Research Funding; Celgene Corporation: Consultancy, Research Funding; Roche: Research Funding; Pfizer: Consultancy. Sekeres:Celgene: Membership on an entity's Board of Directors or advisory committees; Syros: Membership on an entity's Board of Directors or advisory committees; Millenium: Membership on an entity's Board of Directors or advisory committees. Majhail:Mallinckrodt: Honoraria; Atara Bio: Consultancy; Anthem, Inc.: Consultancy; Nkarta: Consultancy; Incyte: Consultancy. Maciejewski:Novartis: Consultancy; Alexion: Consultancy.

Background MHC class I chain-related gene A (MICA) is a polymorphic ligand of the natural killer (NKG2D) receptor on immune effector cells. The activating NKG2D receptor controls immune responses by regulating NK cells, NKT cells and γδ-T cells. Dimorphisms at sequence position 129 of the MICA gene confers varying levels of binding affinity to NKG2D receptor. MICA previously has been associated with post-allogeneic hematopoietic cell transplantation (alloHCT) outcomes including graft-versus-host-disease (GvHD), infection, and relapse. However, it is unclear how MICA interacts with cytogenetic and somatic mutations in regards to these outcomes in acute myeloid leukemia (AML). Methods We conducted a single center, retrospective analysis of adult AML patients in first or second complete remission (CR1, CR2), who underwent T-cell replete matched related or unrelated donor alloHCT. Analysis was limited to those who had MICA data available for donors and recipients. In addition to cytogenetic risk group stratification by European LeukemiaNet criteria (Döhner H, et al, Blood 2016), a subset of patients had a 36-gene somatic mutation panel assessed prior to alloHCT by next-generation sequencing. Dimorphisms at the MICA-129 position have previously been categorized as weaker (valine/valine: V/V), heterozygous (methionine/valine: M/V), or stronger (methionine/methionine: M/M) receptor binding affinity. Fine and Gray or Cox regression was used to identify the association of MICA and outcomes with results as hazard ratios (HR) and 95% confidence intervals (CI). Results From 2000 - 2017, 131 AML patients were identified meeting inclusion criteria. Median age at transplant was 54 years (18-74), with 98% Caucasian. Disease status at transplant included 78% CR1 and 22% CR2. Cytogenetic risk stratification showed 13% of patients as favorable, 56% as intermediate, and 31% as adverse-risk. The five most common somatic mutations were FLT3 (15%), NPM1 (14%), DNMT3A (11%), TET2 (7%), and NRAS (6%). 60% of patients had a related donor. A myeloablative transplant was performed in 84% of patients and 53% had a bone marrow graft source. The most common conditioning regimen used was busulfan/cyclophosphamide (52%). 12% of patients were MICA mismatched with their donor. The distribution of donor MICA-129 polymorphisms were 41% V/V, 53% M/V, and 6% M/M. In univariable analysis, donor-recipient MICA mismatch tended to be associated with a lower risk of infection (HR 0.49, CI 0.23-1.02, P=0.06) and grade 2-4 acute GvHD (HR 0.25, CI 0.06-1.04, P=0.06) but was not associated with other post-transplant outcomes. In multivariable analysis, donor MICA-129 V/V was associated with a higher risk of non-relapse mortality (NRM) (HR 2.02, CI 1.01-4.05, P=0.047) (Figure 1) along with increasing patient age at transplant (HR 1.46, CI 1.10-1.93, p=0.008) and the presence of a TET2 mutation (HR 6.00, CI 1.77-20.3, P=0.004). There were no differences between the V/V and the M/V+M/M cohorts regarding somatic mutational status, cytogenetics and other pre-transplant characteristics and post-transplant outcomes. With a median follow-up of 65 months for both cohorts, 45% vs. 49% of patients remain alive, respectively. The most common causes of death between the V/V and the M/V+M/M cohorts was relapse (38% vs. 62%) and infection (31% vs. 8%), respectively. Conclusion While previous studies have demonstrated associations of somatic mutations and cytogenetics with survival outcomes after alloHCT for AML, we observed mutations in TET2 and the V/V donor MICA-129 polymorphism to be independently prognostic for NRM. Mechanistic studies may be considered to assess for possible interactions of TET2 mutations with NK cell alloreactivity. The weaker binding affinity to the NKG2D receptor by the V/V phenotype may diminish immune responses against pathogens that subsequently contribute to higher NRM. These observations may have implications for enhancing patient risk stratification prior to transplant and optimizing donor selection. Future investigation with larger cohorts interrogating pre-transplant AML somatic mutations with MICA polymorphisms on post-transplant outcomes may further elucidate which subsets of patients may benefit most from transplant. Disclosures Nazha: MEI: Consultancy. Mukherjee:Pfizer: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Projects in Knowledge: Honoraria; BioPharm Communications: Consultancy; Bristol Myers Squib: Honoraria, Speakers Bureau; Takeda Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; LEK Consulting: Consultancy, Honoraria; Aplastic Anemia & MDS International Foundation in Joint Partnership with Cleveland Clinic Taussig Cancer Institute: Honoraria. Advani:Amgen: Research Funding; Pfizer: Honoraria, Research Funding; Glycomimetics: Consultancy; Novartis: Consultancy. Carraway:Novartis: Speakers Bureau; Balaxa: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz: Speakers Bureau; FibroGen: Consultancy; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Speakers Bureau. Gerds:Apexx Oncology: Consultancy; Celgene: Consultancy; Incyte: Consultancy; CTI Biopharma: Consultancy. Sekeres:Celgene: Membership on an entity's Board of Directors or advisory committees; Opsona: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Opsona: Membership on an entity's Board of Directors or advisory committees. Maciejewski:Apellis Pharmaceuticals: Consultancy; Ra Pharmaceuticals, Inc: Consultancy; Alexion Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Ra Pharmaceuticals, Inc: Consultancy; Alexion Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Apellis Pharmaceuticals: Consultancy. Majhail:Incyte: Honoraria; Anthem, Inc.: Consultancy; Atara: Honoraria.

Background While allogeneic hematopoietic cell transplantation (alloHCT) can be curative for patients with acute myeloid leukemia (AML), relapse remains a significant challenge. Previous work has suggested that disease status at time of transplant and cytogenetics are important predictors of relapse. However, it is unclear if common somatic mutations or dimorphisms of MHC class I chain-related gene A (MICA), a ligand of the natural killer (NKG2D) receptor on immune effector cells that helps mediate NK cell alloreactivity, also contribute. Moreover, the mechanisms of early relapse are an area of ongoing investigation. We assessed risk factors for relapse within 6 and 12 months after alloHCT. Methods We conducted a single center, retrospective analysis of adults with AML who underwent a first alloHCT. Analysis was restricted to patients with T-cell replete HLA-8/8 matched related or unrelated donor. In addition to cytogenetic risk group stratification by European LeukemiaNet criteria (Döhner H, et al, Blood 2016), a subset of patients had a 36-gene somatic mutation panel assessed prior to alloHCT by next-generation sequencing. Dimorphisms at the MICA-129 position have previously been categorized as weaker (valine/valine: V/V), heterozygous (methionine/valine: M/V), or stronger (methionine/methionine: M/M) receptor binding affinity. Risk factors for early relapse were assessed with Fine and Gray competing risk regression with results as hazard ratios (HR) and 95% confidence intervals (CI). Results From 2000 - 2017, 319 adult AML patients were identified meeting inclusion criteria. Median age at transplant was 51 years (range, 18-74), with 95% Caucasian. The distribution of low, intermediate, and high HCT-CI scores was 28%, 28%, and 44%, respectively. 75% of patients were transplanted ≤12 months from diagnosis. Disease status at transplant included 48% in first complete remission (CR1), 19% in second CR (CR2), 33% in third CR or relapsed/refractory or untreated (collectively, In univariable analysis, non-Caucasian race, disease status Conclusion Relapse after alloHCT for AML remains a challenge. In our study, the strongest risk factors for early relapse after alloHCT remains absence of CR1 disease status at transplant and adverse-risk cytogenetics. We observed no prognostic effect of somatic mutations nor MICA dimorphisms prior to transplant on 6 or 12-month relapse post-transplant. Further interrogation of pre-transplant or post-transplant persistence of somatic mutations in a larger series may better risk stratify subjects who may benefit from more intensive or innovative approaches to prevent post-transplant relapse. Disclosures Nazha: MEI: Consultancy. Advani:Amgen: Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Consultancy; Glycomimetics: Consultancy. Carraway:Novartis: Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees; Balaxa: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; FibroGen: Consultancy; Jazz: Speakers Bureau; Agios: Consultancy, Speakers Bureau. Gerds:Celgene: Consultancy; Apexx Oncology: Consultancy; Incyte: Consultancy; CTI Biopharma: Consultancy. Sekeres:Celgene: Membership on an entity's Board of Directors or advisory committees; Opsona: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Opsona: Membership on an entity's Board of Directors or advisory committees. Maciejewski:Apellis Pharmaceuticals: Consultancy; Alexion Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Apellis Pharmaceuticals: Consultancy; Ra Pharmaceuticals, Inc: Consultancy; Ra Pharmaceuticals, Inc: Consultancy; Alexion Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Majhail:Atara: Honoraria; Incyte: Honoraria; Anthem, Inc.: Consultancy.

Killer immunoglobulin-like receptors (KIRs) expressed on natural killer and natural killer T cells are involved in activation of these cells and can influence antiviral immunity in the liver. This study investigated the association between KIR genetic diversity and sustained virologic response (SVR) to Peginterferon and Ribavirin (Peg/RBV) therapy in liver transplant (LT) recipients with hepatitis C virus (HCV) recurrence. We tested KIR genotypes in 44 HCV-infected LT recipients treated with Peg/RBV for 48 weeks. Patients were categorized as having KIR genotypes A/A or B/x and analyzed for association with SVR. Fifteen of 44 (34%) patients had SVR. Only 2 of 18 (11%) who lacked KIR2DS2/KIR2DL2 achieved SVR compared to 13 of 26 (50%) who carried these two genes (odds ratio: 8.0, 95% confidence interval: 1.5-42.0, P = 0.008). The association between lack of KIR2DS2/KIR2DL2 and SVR remained significant after exclusion of 10 patients with non-genotype 1 HCV. No correlation was found with other activating or inhibitory KIR genes. Absence of KIR2DS2 and/or KIR2DL2 is associated with failure of Peg/RBV therapy in patients with recurrent HCV after LT. These findings support the role of natural killer and natural killer T cells in HCV clearance after LT and might be generalizable to treatment of HCV infection outside the setting of LT.

Angiotensin II receptor sub-type 1 (AGTR1) plays an important role in the regulation of the cellular immune process. We hypothesized that recurrent acute rejection is associated with increased gene expression of AGTR1 in human heart transplantation.We identified a group of 14 heart transplant recipients who had recurrent acute cellular rejection (RAR), defined as three consecutive episodes of acute rejection (Gradeor =3A). These patients were matched to a control group (n = 15). mRNA gene expression of AGTR1 was measured in heart biopsy specimens of controls at 1 week post-transplant. AGTR1 mRNA was determined serially in the RAR group at baseline, each rejection episode, and after resolution of rejection. Angiotensin-converting enzyme (ACE) polymorphism was also evaluated.Both the control and RAR groups had similar mRNA AGTR1 expression at baseline. Compared with baseline, the RAR group had significantly increased mRNA expression of AGTR1 at the first episode of rejection (9-fold, p0.001), which increased further at the second episode (12-fold, p0.001) and peaked at the third episode (35-fold, p0.001). After resolution of rejection, AGTR1 expression was decreased significantly (p0.001), but remained elevated above baseline (6-fold, p0.001). No difference in ACE polymorphism was noted between the two groups. Compared with controls, the RAR patients had an increased incidence of hypertension, diabetes mellitus, chronic renal insufficiency and transplant vasculopathy during a mean follow-up period of 51.5 +/- 12 months.This is the first report to describe increased mRNA expression of AGTR1 in response to recurrent cellular rejection. Up-regulation of AGTR1 responds to treatment of rejection but not to complete recovery, a phenomenon that may potentially explain the link between rejection and subsequent clinical outcome.

Background Cytomegalovirus (CMV) is a common infectious complication after allogeneic hematopoietic cell transplantation (alloHCT). Efforts to enhance immune reconstitution post-transplant have been pursued to help facilitate clearance of such infections. Assessment of natural killer (NK) cell allo-reactivity with investigation of killer cell immunoglobulin-like receptors has been reported to be associated with protection from CMV infection after alloHCT (Davis ZB et al, BBMT 2015). In addition, the activating NKG2D receptor controls immune responses by regulating NK cells, NKT cells and γδ-T cells. MHC class I chain-related gene A (MICA) is a polymorphic ligand of the NKG2D receptor on these immune effector cells. Given the potential benefit of NK cell allo-reactivity for protection from CMV infection after alloHCT we hypothesized that MICA polymorphisms may influence CMV infection rates after such transplants. Methods We conducted a single center, retrospective analysis of allogeneic HCTs for adults with hematologic malignancies in which MICA data were available for donors and recipients. Analysis was restricted to patients with T-cell replete HLA-8/8 matched related or unrelated donor. Fine and Gray regression was used to identify risk factors for CMV infection. The first episode of graft-versus-host-disease (GVHD) was analyzed relative to CMV as a time-dependent covariate. An analysis was performed examining dimorphisms at the MICA-129 position, which previously has been categorized as weaker (valine/valine: V/V), heterozygous (methionine/valine: M/V), or stronger (methionine/methionine: M/M) receptor binding affinity. Results From 2000-2016, 423 alloHCT patients were identified who had MICA data. Diagnoses included 197 AML, 82 MDS, 34 ALL, 34 NHL, 22 CML, 12 CMML, 9 CLL, 9 myelofibrosis, 9 plasma cell myeloma, 9 other leukemias, and 6 Hodgkin lymphoma. High, intermediate, and low co-morbidity index was seen in 42%, 33%, and 25% of patients, respectively. Median age at transplant was 52 years (range, 18-76), with 95% Caucasian. A myeloablative transplant was performed in 80% of patients and 52% had a bone marrow graft source. CMV infection occurred in 141 (33%) of patients at a median time of 46 days post-transplant (range, 0-609 days) with 29 (21%) occurring within 30 days, 108 (77%) within 100 days and 33 (23%) after day 100. Thirty-three (8%) patients were MICA mismatched with their donor. Donor MICA-129 dimorphisms included 203 (48%) V/V, 190 (45%) M/V and 30 (7%) M/M. Baseline donor(d)/recipient(r) CMV serostatus for V/V vs. M/V + M/M cohorts were 25% vs. 28% for d+/r+, 11% vs 9% for d+/r-, 39% vs. 37% for d-/r+, and 25% vs. 26% for d-/r- (P=0.75). In univariate analysis, MICA mismatch was associated with a higher risk of CMV (HR 1.64, CI 1.00-2.69, P=0.049), and V/V donor MICA-129 dimorphism with a marginally higher risk of CMV (HR 1.32, CI 0.85-1.83, P=0.10). In multivariable analysis, MICA mismatch was not associated with CMV infection (HR 1.38, CI 0.83-2.29, P=0.22) while V/V donor MICA-129 dimorphism was associated (HR 1.40, CI 1.00-1.96, P=0.05) (Figure 1). Other significant variables in multivariable analysis were year of transplant (HR 0.95, CI 0.92-0.99 P=0.01), non-Caucasian race (HR 2.15, CI 1.18-3.91, P=0.01), high-risk disease (HR 1.62, CI 1.13-2.32 P=0.008), baseline CMV serostatus (HR 7.51, CI 3.76-15.0, P Conclusion We conclude that the donor MICA-129 V/V dimorphism with weak NKG2D receptor binding affinity is associated with increased risk of CMV infection after alloHCT. The presence of at least one M residue encoding allele may confer enhanced NK cell anti-viral reactivity. These observations potentially may have implications in optimizing donor selection. Further investigation of MICA may also help better predict which patients are at higher risk of CMV infection in order to consider intervening sooner with CMV specific therapy or more rapid tapering of immunosuppression. Figure 1 Figure 1. Disclosures Gerds: CTI BioPharma: Consultancy; Incyte: Consultancy. Majhail: Sanofi: Honoraria; Anthem, Inc.: Consultancy.

In this case we describe a Hematopoietic cell transplantation (HCT) African American recipient whose typing included a novel allele initially assigned incorrectly after utilizing 3 traditional Methods Sanger sequence based typing (SBT, Conexio), rSSOP (One Lambda) and SSP (Invitrogen). The correct typing was assigned by Next Generation Sequencing (NGS, MiSeq platform, Omixon reagents and analysis software) and supported by a family study. Initial HLA-C typing in duplicate was assigned as C∗06:44, 08:XX based on rSSOP (positive bead 9 with recognition site highlighted in Fig. 1A) and SBT result of 06:44, 08:05 (0 nucleotide mismatches) or 06:02:01:01, 08:02:01:01 (1 nucleotide mismatch, Fig. 1B). High resolution HLA-C SSP testing assigned 06:44, 08:XX (excluded the 08:05). Two siblings of the patient were HLA typed but neither of them shared any HLA haplotypes with the patient. The typing was reported as 06:44, 08:XX. There was no consistent high resolution assignment by all 3 methods. NGS provided phased information with an unambiguous typing of C∗06:02:01:01, 08:02:01:01v (80 and 93 reads mapping to these alleles respectively, 0 reads mapping to 06:44, Fig. 1C). Subsequent HLA typing of the father ruled out 06:44 and confirmed the NGS results. This novel C∗08:02:01:01v has a non-synonymous substitution at the 3rd nucleotide of codon 66 (AAG > AAC) in exon2 (Fig. 1A) which translates to one amino acid (AA) difference Lys > Asn. This AA resides in the α -1 helix of the HLA molecule, is accessible to antibody recognition and is a T-cell receptor (TCR) and peptide binding site. This novel allele also has intronic substitution at position 1578 (G > A) of intron 3. Currently, IMGT database has no intron 3 or exon 4 sequence information for 06:44 and 08:05 which would be helpful in determining whether the allele stemmed from recombination or point mutation. This case demonstrates that NGS is a powerful tool applicable to HLA-typing in HCT with the capability to resolve typing ambiguity and identify potential clinically relevant novel alleles. Download : Download full-size image

Background and Aims Early post-transplant hepatic fibrosis is associated with poor outcomes and may be influenced by donor/recipient genetic factors. The rs368234815 IFNL4 polymorphism is related to the previously described IL28B polymorphism, which predicts etiology-independent hepatic fibrosis. The aim of this study was to identify the impact of donor and/or recipient IFNL4 genotype on early fibrosis among patients transplanted for hepatitis C (HCV). Methods Clinical data were collected for 302 consecutive patients transplanted for HCV. 116 patients who had available liver biopsies and donor/recipient DNA were included. 28% of these patients with stage 2 fibrosis or greater were compared to patients without significant post-transplant fibrosis with respect to clinical features as well as donor/recipient IFNL4 genotype. Results The IFNL4 TT/TT genotype was found in 26.0% of recipients and 38.6% of donors. Patients who developed early post-transplant fibrosis had a 3.45 adjusted odds of having donor IFNL4 TT/TT genotype (p = 0.012). Donor IFNL4 TT/TT genotype also predicted decreased overall survival compared to non-TT/TT genotypes (p = 0.016). Conclusions Donor IFNL4 TT/TT genotype, a favorable predictor of spontaneous HCV clearance pre-transplant, is associated with increased early post-transplant fibrosis and decreased survival.

Achievement of complete donor chimerism (CDC) after allogeneic nonmyeloablative hematopoietic stem cell transplantation (NMHSCT) is important for preventing graft rejection and for generating a graft-vs-malignancy effect. The alloreactivity of NK cells and some T-cell subsets is mediated through the interaction of their killer immunoglobulin-like receptors (KIRs) with target cell HLA/KIR ligands. The influence of KIR matching on the achievement of T-cell CDC after NMHSCT has not been previously described. We analyzed 31 patients undergoing T-cell replete related donor NMHSCT following fludarabine and 200 cGy TBI. Recipient inhibitory KIR genotype and donor HLA/KIR ligand matches were used to generate an inhibitory KIR score from 1 to 4 based upon the potential number of recipient inhibitory KIRs that could be engaged with donor HLA/KIR ligands. Patients with a score of 1 were less likely to achieve T-cell CDC (P=0.016) and more likely to develop graft rejection (P=0.011) than those with scores greater than 1. Thus, patients with lower inhibitory KIR scores may have more active anti-donor immune effector cells that may reduce donor chimerism. Conversely, patients with greater inhibitory KIR scores may have less active NK cell and T-cell populations, which may make them more likely to achieve CDC.

Although outcomes after allogeneic hematopoietic cell transplantation (alloHCT) for AML have improved, this has mainly been attributed to a reduction in transplant-related mortality rather than reduced leukemia relapse. NK cell alloreactivity is regulated by inhibitory and activating signals mediated through cell-surface receptors including the killer immunoglobulin-like receptors (KIRs). Group A and B KIR haplotypes have distinct centromeric (Cen) and telomeric (Tel) gene-content motifs and donor Cen group B KIR haplotypes have been reported to be associated with decreased relapse and improved survival in AML patients undergoing unrelated donor alloHCT. We hypothesized that donor KIR genotype may also be predictive of outcomes after matched related donor (MRD) alloHCT. We evaluated 93 AML patients in CR1/CR2 who underwent T-cell replete alloHCT using HLA- matched related donors at our institution from 1/2000-3/2013. Sixty-six had myeloablative conditioning (MAC) that that was busulfan/cyclophosphamide-based and 27 had reduced-intensity conditioning (RIC) with fludarabine/total body irradiation or busulfan/fludarabine. Donors were KIR genotyped to assign haplotypes A/A vs. B/X and the distinctive Cen and Tel gene-content motifs of group A and B KIR haplotypes according to the presence or absence of one or more B haplotype-defining KIR genes. KIR B–content score for each KIR genotype was defined as the number of Cen and Tel gene-content motifs containing B haplotype–defining genes (range, 0-4). As compared to those with haplotypes B/X (n=40; B content scores of 1-4) those with haplotype A/A (n=25; B content score of 0) undergoing MAC had significantly lower 100-day, 6-, 12- and 24-month non-relapse mortality (NRM) (8% vs. 0%, 13% vs. 0%, 15% vs. 0%, 25% vs. 0%, respectively, Figure 1) which was confirmed on multivariable analysis (HR 9.19, p=0.03). There were no differences between these groups regarding patient and transplant-related characteristics, or for acute or chronic GVHD, relapse, or survival. The causes of death in the group with haplotypes B/X were most commonly attributed to infection and then GVHD. However, within the group with B/X haplotypes, the B motif content score (1-4) was not associated with significant differences in NRM (HR 0.79, p=0.56). No difference in outcomes was observed for those undergoing RIC. The number of donor activating KIR genes (2SD1, 2DS2, 2DS3, 2DS4, 2DS5, and 3DS1) was then assessed. As compared to those with 3-6 activating KIR genes (n=20) those with 0-2 (n=41) undergoing MAC had significantly lower 100-day, 6-, 12- and 24-month non-relapse mortality (NRM) (15% vs. 0%, 15% vs. 5%, 15% vs. 5%, 29% vs. 8%, respectively, Figure 2) which was confirmed on multivariable analysis (HR 4.07, p=0.01). There were no differences in other post-transplant outcomes when comparing these groups or when considering those undergoing RIC. An increase of 1 donor activating KIR also was highly associated with NRM (HR 1.37, p=0.008). Overall, these results suggest that in the MRD MAC alloHCT setting donor KIR genotype may be predictive of increased NRM risk, particularly for those with B/X haplotypes and greater numbers donor activating KIRs. No comparable effects were observed in the RIC setting. Future strategies to further enhance immune reconstitution post-transplant may be appropriate to pursue for these higher risk patients. These results may have potential implications to improve donor selection for those AML patients with multiple HLA-matched related donors and need to be validated in larger cohorts. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.

CMV remains the most common viral infection after AHSCT. NK and T cells provide protection against CMV reactivation. The interaction of inhibitory killer immunoglobulin-like receptors (KIRs) with target cell HLA class I molecules regulates NK cells and some T cell populations. Donor activating KIR genotype has been suggested to influence CMV reactivation after myeloablative AHSCT (Cook et al, Blood2006;107:1230–1232). However, the effect of donor activating or inhibitory KIR genotype on CMV reactivation after T-cell replete RIC AHSCT has not been reported. We analyzed 64 consecutive patients (pts) who underwent T-cell replete matched sibling donor RIC AHSCT at our institution from 1/16/00-4/24/07 with fludarabine and low-dose total body irradiation (200 cGy: 36 pts; 400 cGy: 28 pts). All pts received cyclosporine and mycophenolate mofetil for GVHD prophylaxis. CMV monitoring was performed by polymerase chain reaction testing. 49 (77%) pts were CMV seropositive or had a CMV seropositive donor; 25/49 (51%) had CMV reactivation post-AHSCT. 15 (23%) pts were CMV seronegative along with their donors and 1 (7%) of them had CMV reactivation. Donor activating KIR genotypes (KIR2DS1, KIR2DS2, KIR2DS3, KIR2DS4, KIR2DS5, KIR3DS1) and inhibitory genotypes (KIR2DL1, KIR2DL2, KIR2DL3, KIR3DL1, KIR3DL2) were determined by PCR-SSOP and/or PCR-SSP. Patient HLA KIR ligands including HLA-Cw groups C1 or C2, HLA-Bw4 and HLA-A3/11 (reviewed in Farag et al Blood2002; 100:1935–1947) and donor inhibitory KIR genotypes were analyzed. Missing patient KIR ligand was observed in 15 (23%) of the C1 group, 27 (42%) of the C2 group, 25 (39%) of the HLA-Bw4+ pts and 43 (67%) of the HLA-A3/11+ pts. There were no differences observed for CMV reactivation between any of these groups when comparing those with or without missing ligands. However, when the number of donor activating KIRs were considered a difference in CMV reactivation patterns was appreciated. Pts whose donor KIR genotype contained 5 or 6 activating KIR genes (N=16) had less CMV reactivation compared to those with only 1 to 4 activating KIR genes (N=48) (19% vs. 48%). This finding remained significant on multivariable analysis (p=0.038). No specific activating KIR was found to be associated with CMV reactivation. There were no differences between the groups (5–6 vs. 1–4 activating KIR genes) with regards to patient/donor CMV seropositivity, age, diagnoses, gender, race, number of prior chemotherapy regimens, prior radiation, time from diagnosis to RIC AHSCT, TBI dose, donor to patient gender, CD34+ and CD3+ cell doses. We conclude that donor activating KIR genotype influences CMV reactivation after matched sibling donor T-cell replete RIC AHSCT. These results may guide the selection of donors as well as identify patients who may benefit from closer CMV monitoring and additional strategies to prevent CMV reactivation post transplant. Figure Figure

Background: Anti B cell antibodies have been proposed as a treatment for post-transplant lymphoproliferative disorders (PTLD). Experience in children is limited. Methods and Results: We report experience (n=40) with use of the chimeric mouse/human antiCD20 monoclonal antibody (rituximab) in pediatric PTLD patients with refractory disease (no response to reduced immunosuppression, progressive or relapsed disease, or concomitant allograft rejection). Initial experience was through a voluntary registry (n=26), and most recent experience is from an onging prospective, non-randomized clinical trial (n=14). Use of chemotherapy or other experimental therapies were an exclusion criteria for both studies. All PTLD were of B cell origin and expressed CD20 and all but 2 (both in registry cohort) were EBV positive. The first cohort (registry) comprised 26 solid organ recipients from 12 centers (heart 11, kidney 6, lung 4, other 5) with mean age of 12.5 years, 29 months (range 2–132) from transplant. Histology revealed these lesions: polymorphic 17, monomorphic 7 (including 1 Burkitts-like), Hodgkins-like 1, unspecified 1. 21/26 received 375mg/m2 x 4 doses. There were no SAE’s. 18 pts (69%) showed CR, and 4 (16%) showed PR. The 4 non-responders comprised the 2 EBV negative cases, the Burkitts-like disease and the earliest onset case (fulminant disease at 2 months post-transplant). At latest follow-up (mean 41 months), 73% survive with one graft loss (kidney). In the prospective clinical trial, 14 patients (to date) with refractory disease were enrolled. The protocol comprises 4 doses of 375mg/m2 (weeks 1–4) with no further treatment for patients with CR or for those with no response. Patients with PR receive 4 further doses (weeks 5–8). The 14 patients were from 5 centers (lung 5, kidney 5, heart 4) with mean age of 6.5 years, 41 months (range 4–120) from transplant. Histology revealed the following: polymorphic 10, monomorphic 3, Hodgkin-like 1. There were no SAE’s. Two are still recieving therapy. Of the other 12, 9 (75%) acheived CR and 10 pts (83%) are alive with one graft loss (kidney) at mean follow-up of 1.5 years. The two deaths were due to fungal pneumonia and complications of elective surgery in a patient in CR (both lung recipients). Conclusions: These results suggest that rituximab may have an important role to play in management of refractory PTLD in solid organ recipients (CR rate approx. 70–75% with low incidence of graft loss). This group of patients traditionally has high mortality and has been treated with chemotherapy. Rituximab should be considered as first line treatment for refractory polymorphic PTLD in children after solid organ transplantation. Role in monomorphic disease requires further investigation. Use of rituximab as first line therapy is under investigation.