Gragert, Loren A.

Abstract Background: HLA associations for the risk of developing MM have been described in various non-Caucasian ethnic groups but have not revealed consistent results. Racial and genetic differences in cytokine polymorphisms linked to extended haplotypes; association of autoimmune disorders with HLA types; the proximity of the HLA Class I and II genes to TNF and other Class III genes responsible for complement and cytokines suggest that HLA polymorphisms may be associated with the risk of developing MM. Aim: We compared HLA-A,-B and -DRB1 2-digit allele and haplotype frequencies in patients with MM to the normal population in order to define HLA specificities associated with the risk of developing MM. Methods: A cohort of 1803 US Caucasian patients with MM were identified based on availability of HLA-A, B, DRB1 DNA-based typing or serologic typing converted to 2-digit alleles. These patients had either received a matched sibling allogeneic transplant for MM reported to the CIBMTR (N=174) or had HLA typing performed for an unrelated donor search conducted through the US National Marrow Donor Program (NMDP) (N=1629). HLA-A, B and DRB1 allele frequencies among patients were compared to A-B-DRB1 frequencies in HLA typed healthy US Caucasian controls (N= 433838) from the NMDP database. The most frequent alleles among patients and controls as well as HLA haplotype frequencies generated using the EM (expectation-maximization) algorithm were compared using Chi-Square analysis with Bonferroni correction for the number of comparisons. Results: Patients with MM had a median age of 49 (range 3–78) years and M/F ratio of 1.86 (1172/631). The controls had a median age of 44 (range 18–60) years and M/F ratio of 0.735 (183785/250053). Comparison of HLA-A, -B and –DRB1 single-locus allele frequencies between the myeloma patients and controls (those in the top 10 in either group) revealed similarity except for HLA-B*07 and B*44. B*44 was observed less frequently among the patients (a protective effect) frequency (f): 0.126 vs 0.145 (p= 0.005, Odds Ratio (OR): 0.848). On the contrary, HLA-B*07 was more common (a predisposing effect) among patients (OR: 1.135, p=0.047). Among the top 20 two locus (HLA-A-B and HLA-B-DRB1) haplotype frequencies in either group, B*44-DRB1*13 and B*07-DRB1*13 were significant: OR: 0.506 and 1.714 (p=0.003 and 0.007) respectively. A-B-DRB1 haplotype comparisons showed significance for: A*02-B*44-DRB1*04 (OR: 0.686, p=0.021), A*02-B*44-DRB1*13 (OR: 0.445, p=0.065) and A*02-B*07-DRB1*04 (OR: 1.968, p=0.029) confirming the single and B-DRB1 combination comparison results. Significantly different HLA-A, -B and -DRB1 single-locus allele or haplotype frequencies between patients and controls are shown in table 1. Conclusion: This is the largest epidemiologic study of HLA allele frequencies and the first study on HLA haplotype frequencies in MM. We observed a protective effect on the risk of developing MM with B*44 and a predisposing effect with B*07. Similar predisposing and protective haplotype associations were observed with A*02-B*07-DRB1*04 and A*02-B*44-DRB1*04 respectively. A revised analysis using a gender-matched control group is in progress. Further study including major histocompatibility region SNP mapping and candidate gene testing will help elucidate the genetic basis underlying this observation. Table 1. Allele/Haplotype Frequency Controls Frequency MM Odds Ratio (OR) P value (corrected) OR = odds of observing the allele/haplotype in patients compared to controls A*02-B*44-DRB1*13 0.00620 0.00277 0.445 0.065 B*44-DRB1*13 0.01359 0.00686 0.507 0.003 A*02-B*44-DRB1*04 0.02605 0.01813 0.686 0.021 B*44 0.14552 0.12618 0.848 0.005 B*07 0.13313 0.14836 1.134 0.047 B*07-DRB1*13 0.00814 0.01397 1.714 0.007 A*02-B*07-DRB1*04 0.00367 0.00721 1.968 0.029

Abstract Background: Persons of African ancestry (AA) have a 2-3-fold higher risk of multiple myeloma (MM) than persons of European ancestry (EA). Like other B-cell malignancies, genome-wide association scans (GWAS) have identified MM risk variants in the HLA region in persons of EA. We conducted a case-control analysis with data from the National Marrow Donor Program (NMDP)1comprising MM patients typed for bone marrow transplant to donor controls matched by race-ethnicity, and found associations between specific HLA alleles/haplotypes and MM risk that varied by race and ethnicity. To confirm our results and identify additional novel signals, we have now investigated associations between HLA alleles and haplotypes and MM risk in the African American Multiple Myeloma Study (AAMMS) Cohort. Methods: The source of subjects was the AAMMS, in which AA MM patients were identified from 10 cancer centers and 4 Surveillance, Epidemiology and End-Results (SEER) Program cancer registries in order to identify genetic risk factors for MM among AAs. A GWAS was conducted using the Illumina Human Core BeadChip array on DNA samples from 1,305 AA MM patients in the AAMMS comparing results to those from 7,078 AA controls with GWAS data generated from the Illumina 1MDuo2. The major histocompatibility complex (MHC) region single nucleotide polymorphisms (SNPs) were imputed to classical HLA variants using HIBAG. Unconditional logistic regression was used to estimate HLA associations, adjusting for sex, age and the first 2 principal components. P-values were adjusted for false discovery rate (FDR) for each locus group. Results: We did not identify any single HLA alleles associated with MM risk among AAs. However, several B*07:02-containing haplotypes were associated with MM risk (odds ratios [OR] ranging from 2.38 to 2.64 and FDR P-values ranging from 1.43 x 10-6 to 3.57 x 10-8). We found associations between MM risk and genotypes containing DRB3*02:02, including DRB3*02:02~DRB1*11:01+ DRB3*02:02~DRB1*11:01 (OR=1.93, PFDR= 9.36 x 10-5) similar to those observed in the NMDP study1. Novel findings included associations between MM risk and HLA Class I haplotypes B*53:01+ B*57:01 (OR=1.94, PFDR= 0.003) and C04:01~B*53:01+C*06:02~B*57:01 (OR=1.96, PFDR= 0.0050). Results from an ongoing meta-analysis between the two data sets (one based on an imputed GWAS and one based on NMDP HLA typing) will be presented. Conclusions: This study is the second to examine HLA alleles and risk of MM among AA's and is by far the largest. We confirmed a previously observed association between an HLA Class II DRB3 variant and MM risk and confirmed an association with B*07 haplotypes previously observed among EAs1. We also identified novel associations between other HLA Class I haplotypes and MM risk in AA's. Because HLA is highly polymorphic, many HLA alleles are rare variants for which genetic associations are difficult to detect without very large sample sizes. Further investigation with large sample sizes will be necessary to refine these associations in order to better identify the underlying causal alleles and determine the functional significance of these HLA associations. 1Beksac M, Gragert L, Fingerson S, et al.: HLA polymorphism and risk of multiple myeloma.Leukemia. 2016 Jul 27. doi: 10.1038/leu.2016.199. 2Rand KA, Song C, Hwang AE, et al. Genetic susceptibility markers of multiple myeloma in African-Americans. Abstract # 2030, 56th Annual American Society of Hematology Meeting, San Francisco, California, 2014. Disclosures Ailawadhi: Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy. Nooka:Spectrum, Novartis, Onyx pharmaceuticals: Consultancy. Zonder:Pharmacyclics: Other: DSMC membership; Prothena: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria. Lonial:BMS: Consultancy; Novartis: Consultancy; Millenium: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Merck: Consultancy; Celgene: Consultancy; BMS: Consultancy; Novartis: Consultancy; Onyx: Consultancy; Janssen: Consultancy; Onyx: Consultancy.