ALBERT

Description: Key Points Unidirectional graft-versus-host vector 7/8 HLA mismatches have the same level of risk as bidirectional 7/8 mismatches. For HLA homozygous recipients, a mismatch at the homozygous locus is preferred over a mismatch at the heterozygous loci.

Description: 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.

Description: Key Points High-resolution matching for HLA-A, -B, -C, and -DRB1 is required for optimal survival in myeloablative-unrelated donor transplantation. HLA-DPB1 nonpermissive mismatches should be avoided in otherwise matched transplants to minimize overall mortality.

Description: Disease relapse is a significant cause of treatment failure after allogeneic hematopoietic stem cell transplantation (HCT). In the setting of reduced-intensity conditioning (RIC), a graft-versus-leukemia (GVL) effect is critical for successful outcomes in patients with advanced myeloid malignancies. A GVL effect has been attributed in part to donor-derived alloreactive natural killer (NK) cells, which are regulated by interaction of KIRs with their HLA-class I ligands. Several models of NK reactivity (missing KIR ligand, centromeric haplotype-B content, non-tolerized KIR2DS1) have been associated with improved outcomes following HLA-matched, HLA-mismatched, related, and unrelated donor HCT, particularly for AML patients given myeloablative conditioning. The effect of KIR-HLA combinations on outcomes after RIC HCT, however, is not known. We retrospectively analyzed donor-recipient KIR/HLA genotypes from 929 URD HCTs facilitated by the National Marrow Donor Program for patients with AML (n=624) or MDS (n=305) treated with RIC between 1990 and 2007. 664 donor-recipient pairs were 10/10 HLA-matched and 265 were 9/10 HLA-matched. 332 (37%) patients received ATG and 73 (8%) received alemtuzumab. P-values less than 0.01 were considered significant. We hypothesized that donor-recipient KIR-HLA interactions may be associated with improved post-transplant outcomes following RIC HCT for AML and MDS. Patients lacking the HLA-Bw4 ligand for donor inhibitory KIR3DL1 experienced lower relapse following HCT at 1 year (27 vs 36%, p=0.002) and 5 years (31 vs 42%, p=0.003) compared to patients with the Bw4 ligand (Figure). The lower risk for relapse was confirmed in multivariate analysis (HR 0.71, p=0.005). However, there was no significant association of Bw4 ligand with disease-free survival (HR 0.84, p=0.05) and overall survival (HR=0.97, p=0.70). Risk for acute GVHD was higher among patients lacking KIR ligands after adjusting for other clinical factors. In particular, patients lacking HLA-C2 for donor KIR2DL1 experienced higher grade 2-4 (HR 1.3, p=0.005) and 3-4 acute GVHD (HR 1.5, p=0.002), and patients lacking multiple KIR ligands experienced higher grade 3-4 acute GVHD (HR 1.5, p=0.007). The analysis was then restricted to AML patients, the patient population with greatest reported KIR-HLA effects. Patients whose donors were KIR2DS1+ and HLA-C2C2 (n=33) had higher transplant-related mortality (TRM) (HR, 2.4, p=0.002) compared to all other patients. There was no significant effect of KIR2DS1 with HLA on relapse. In a multivariate analysis, lack of HLA-C2 in AML patients was associated with higher grade 2-4 (HR 1.4, p=0.002) and 3-4 acute GVHD (HR 1.5, p=0.01), and risk for grade 3-4 acute GVHD was higher in patients lacking multiple KIR ligands (HR 1.6, p=0.005). There were no significant associations between donor homozygosity for the centromeric B-haplotype (cenBB) or overall B-haplotype KIR content and RIC HCT outcomes. Overall, these results suggest that in the RIC HCT setting, lack of Bw4 ligand for KIR3DL1 is associated with a lower risk of relapse for AML/MDS. This observation corroborates previous findings in myeloablative HCT transplants. Furthermore, tolerance of donor KIR2DS1 by HLA-C2C2 was associated with worse outcome, as manifested by higher TRM, in AML patients. In contrast, it appears that in RIC HCT homozygosity for the centromeric B-haplotype does not have a significant role in leukemia relapse. The associations of KIR ligands with acute GVHD were not previously observed suggesting that NK cell alloreactivity depends on multiple variables, including RIC. Further elucidation of the biology of NK cell alloreactivity in the RIC setting may provide guidance for future approaches to help optimize conditions for generating GVL reactions without GVHD and less TRM in this transplant population.FigureFigure. Disclosures: No relevant conflicts of interest to declare.

Description: Key Points Mismatches in alleles C*03:03/C*03:04 were most frequent (68.7%) among the transplants with a single allele level mismatch in HLA-C. The 7/8 C*03:03/C*03:04 mismatch group was not significantly different from the 8/8 HLA matched transplants in any transplant outcome.

Description: Key Points Amino acid substitution at peptide-binding residues of the HLA class I molecule is associated with graft-versus-host disease and mortality. Avoidance of donor-recipient combinations that result in amino acid substitution at peptide-binding residues may improve transplant outcomes.

Description: The reactivity of NK cells and some T cell populations is regulated by KIR interactions with HLA class I molecules. Such interactions have been suggested to influence outcomes after myeloablative allogeneic HSCT. However, in NMHSCT the effect of KIR interactions on outcomes including the development of CDC has not been well described. We analyzed 51 pts who received related donor NMHSCT at our institution from 1/10/00–10/25/05. All pts received fludarabine 30 mg/m2/d x 3 days followed by total body irradiation 200 cGy (n=35) or 400 cGy (n=16) for conditioning. The median age was 54 (range, 21–64). Short tandem repeat analysis for T cell (CD3+) chimerism was performed on peripheral blood and CDC was defined as achievement of 〉95% DNA of donor origin in the CD3+ T cells. 37 (73%) of patients achieved CDC at a median time of 3.3 mos (range, 0.4–11.2). KIR genotypes were determined for recipients by PCR-rSSOP analysis. Donor HLA KIR ligands were categorized as: HLA-Cw groups C1 (+ or −); C2 (+ or −); HLA-Bw4 (+ or −); and HLA-A3 or -A11 (+ or −) [as reviewed by Farag et al. Blood2002; 100:1935–47]. Recipient KIR genotype and donor HLA KIR ligands were used to generate an inhibitory KIR score for pts from 1 to 4 corresponding to the potential number of inhibitory KIRs engaged. 7 pts had a score of 1, 27 had a score of 2, 14 had a score of 3 and 3 had a score of 4. Figure Figure The Kaplan-Meier method was used to estimate the achievement of CDC by inhibitory KIR score (figure, p=0.09). Pts with a score of 1 were less likely to achieve CDC compared to those with a score of 2 (p=0.02), while those with a score of 2 tended to be less likely to develop CDC than those with a score of 4 (p=0.07). There were no differences in CD34+ or CD3+ cell doses between any of the groups. When combined with the inhibitory KIR score data the presence of single or multiple activating KIR’s was not found to influence the development of CDC. Thus, pts with lower inhibitory KIR scores may have more active anti-donor effector cells (NK cells and T cell subsets) that may reduce donor cell chimerism. Conversely, those with higher inhibitory KIR scores may have less active populations and be more likely to achieve CDC. Given the genotypic potential to inhibit all NK cells KIR expression may be variable among different clones, and may affect the development of CDC. Further investigation of KIR expression at the cellular level rather than by genotyping alone should be pursued.

Description: Abstract 1094 Poster Board I-116 T cell large granular lymphocyte leukemia (T-LGL) is a rare lymphoproliferative disorder marked by clonal expansion of cytotoxic T lymphocytes (CTL). T-LGL may be a result of clonal outgrowth from initially polyclonal CTL responses seen in the context of viral infections, autoimmune conditions, or tumor surveillance. Similar to classic autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis or aplastic anemia, immunogenetic predisposition to T-LGL is suggested by association with certain immunogenetic polymorphisms including human leukocyte antigen (HLA) and killer immunoglobulin receptor (KIR). In addition to KIR-ligand/KIR interactions, the quality of CTL may be determined by the binding between the major histocompatibility complex class I chain-related gene A (MICA) and its ligand NKG2A. Over fifty five MICA alleles have been documented to date. A number of autoimmune and oncologic conditions such as systemic lupus erythematosus, rheumatoid arthritis, psoriasis, Crohn's disease, cervical cancer, or oral squamous cell carcinoma were all reported to be associated with MICA polymorphism. We hypothesized that specific MICA polymorphisms may be associated with exaggerated CTL responses in T-LGL and may therefore impact clinical features of the disease such as immune cytopenias. We have collected a large well annotated cohort of patients with T-LGL (n=86). HLA, MICA, and KIR alleles were resolved by established molecular techniques. Diagnosis of T-LGL was established by flow cytometry, T cell receptor γ chain rearrangement, Vβ typing, and assessment of peripheral blood smear. Categorical and survival methods of data analysis were used to examine the association between MICA, HLA, and KIR polymorphisms with type and degree of cytopenias, LGL T cell count, response to therapy, splenomegaly, and overall survival. Caucasians accounted for 96.5% of the study cohort (median age, 64 years; 55% males). Neutropenia, anemia, and thrombocytopenia were found in 63.4%, 50%, and 23.5% of the patients, respectively. Bicytopenia and pancytopenia were found in 26% and 13% of subjects, respectively. Median LGL T cell count was 1800 cells/μL (range, 280-20,580 cells/μL). Splenomegaly was found in 47% of patients. Compared to healthy controls (2N=308), our cohort was overrepresented by MICA*A5.1 (population frequency, 0.59 in T-LGL vs. 0.37 in controls, p

Description: The effect of killer cell immunoglobulin-like receptor (KIR) ligand incompatibility on outcomes after unrelated cord blood transplantation (UCBT) has been controversial. Eurocord found that KIR ligand mismatching was associated with decreased relapse incidence (RI) and improved overall (OS) and leukemia-free survival (LFS) for patients with acute lymphoblastic leukemia (ALL) and for those with acute myeloid leukemia (AML). Recently, the Japanese registry found no association between KIR ligand matching and LFS or OS in 643 UCBT recipients with acute leukemia. However, both studies have analysed the KIR ligand matching effect using low resolution typing of HLA-A,-B,-C and HLA-DRB1 high resolution. With the aim to clarify the KIR effect on outcomes (mainly RI and OS) in a larger series of single-UCBT recipients in the era of HLA-allele typing, we have analysed 1098 patients with AML and ALL reported to Eurocord and CIBMTR. All patients received single UCBT and myeloablative conditioning regimen. HLA matching was defined using high resolution typing or imputation for HLA-A,-B,-C and DRB1. Patients and donors were categorized by their KIR-ligand expression for HLA C group 1 or 2 and Bw4 as KIR ligand matched or mismatched. Patients included in the earlier Eurocord analysis were excluded. Univariate and multivariate models were built to analyse the effect of KIR ligand matching on outcomes. Results: None of the 8/8 HLA-matched transplants were KIR ligand mismatched, therefore they were excluded. Since HLA-match and KIR ligand mismatch were confounded, we conducted 2 separate analyses: a) 6-7/8 HLA-matched (n=501) and b) 3-5/8 HLA-matched transplants (n=586). In the group of 6-7/8 HLA matched, 291 recipients (58%) were KIR ligand-matched and 210 (42%) were mismatched. There were no statistically significant differences, between these two groups for gender, age, CMV serostatus, type and remission disease status, cell dose, conditioning regimen, in vivo T-cell depletion, transplant period and follow-up (around 40 months). In the group of 3-5/8 HLA matched, 176 recipients (30%) were KIR ligand-matched and 410 (70%) were mismatched. In this HLA group (i.e 3-5/8), KIR ligand-matched patients were younger (

Description: 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.