Caporaso, Neil E.

Abstract Introduction: With over 80, 000 new cases of non-Hodgkin's lymphoma (NHL) diagnosed annually, modifiable risk factors remain unclear. Circadian disruption, linked to cancers like breast and prostate, affects immune cells (e.g., natural killer cells and T-helper cells) by altering their trafficking and proliferation. Some studies (PMID: 30566672, 27611440) suggest long sleep may increase overall NHL risk, including a Mendelian randomization (MR) study (PMID: 32895918). However, no research has examined the causal relationship between sleep traits, including long sleep, and NHL risk, by subtypes. We hypothesize that sleep traits are causally associated with NHL subtypes in European populations, testing this using MR with data from the International Lymphoma Epidemiology Consortium (InterLymph). Methods: We conducted two-sample MR using genome-wide association studies (GWAS) summary data for sleep traits and NHL subtypes. Only independent, genome-wide significant (p < 5×10-8) Single Nucleotide Polymorphisms (SNPs) were selected as valid instruments, sourced from the UK Biobank. Sleep traits included chronotype (153 SNPs), insomnia (48 SNPs), sleep duration (78 SNPs), excessive daytime sleepiness (37 SNPs), short sleep (27 SNPs), and long sleep (8 SNPs). NHL subtype data were from InterLymph: follicular lymphoma (6, 508 cases / 64, 183 controls), mantle cell lymphoma (1, 169 cases / 61, 603 controls), Waldenstrom macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL: 1, 697 cases / 59, 333 controls), and chronic lymphocytic leukemia (8, 522 cases / 67, 653 controls). The primary analysis used inverse-variance weighted (IVW) random-effects, with MR-Egger for pleiotropy adjustment. Results: Using the IVW method, we did not identify any statistically significant causal association between sleep traits and the risk of NHL subtypes, but did yield several intriguing trends. Long sleep (sleep duration >= 9 h per night) showed a marginally increased NHL risk [Odds ratio (OR) range: 1.51 - 247.9] across each subtype. Short sleep (sleep duration < 7 h per night) showed a similar trend [OR range: 1.25 - 1.81], except for WM/LPL, where we noticed a negative trend. The confidence limit for long sleep was imprecise due to the small number of variants. We did not notice any significant directional horizontal pleiotropy or weak instrument bias. Conclusions: We found no conclusive evidence of a relationship between sleep traits and four NHL subtypes. However, we see suggestive trends of long and short sleep associated with higher risk of some NHL subtypes. These findings align with the previous studies, which showed long sleep was associated with higher risk of NHL overall. Future directions include expanding our analysis to additional NHL subtypes, generating polygenic risk scores, and conducting stratified analyses. Citation Format: Pankhil Shah, Brittany Crawford, Anwar Merchant, Brenda Birmann, Angelica Macauda, Michelle A. Hildebrandt, Aaron Norman, Neil E. Caporaso, Meredith Yeager, Michael Dean, Immaculata De Vivo, Lynn Goldin, Nicola J. Camp, Rosalie Griffin, Delphine Casabonne, Federico Canzian, Pelin Unal, Elad Ziv, Catherine R. Marinac, Alexandra Nieters, Stephen J. Chanock, Mitchell J. Machiela, Michael Conry, Charlie Zhong, Hanla A. Park, Simon Cheah, Jonathan N. Hofmann, Elizabeth E. Brown, Celine Vachon, Susan Slager, Sonja Berndt, Sophia S. Wang, Vijai Joseph, James McKay, Henrik Hjalgrim, Lara Sucheston-Campbell, Karl Smith-Byrne, Alyssa Clay-Gilmour. Association between sleep traits and risk of non-Hodgkin's lymphoma subtypes: a mendelian randomization study in the International Lymphoma Epidemiology (InterLymph) Consortium [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7415.

Abstract Chronic lymphocytic lymphoma (CLL) has one of the highest familial risks among cancers. Monoclonal B-cell lymphocytosis (MBL), the precursor to CLL, has a higher prevalence (13%-18%) in families with 2 or more members with CLL compared with the general population (5%-12%). Although, the rate of progression to CLL for high-count MBLs (clonal B-cell count ≥500/µL) is ∼1% to 5%/y, no low-count MBLs have been reported to progress to date. We report the incidence and natural history of MBL in relatives from CLL families. In 310 CLL families, we screened 1045 relatives for MBL using highly sensitive flow cytometry and prospectively followed 449 of them. MBL incidence was directly age- and sex-adjusted to the 2010 US population. CLL cumulative incidence was estimated using Kaplan-Meier survival curves. At baseline, the prevalence of MBL was 22% (235/1045 relatives). After a median follow-up of 8.1 years among 449 relatives, 12 individuals progressed to CLL with a 5-year cumulative incidence of 1.8%. When considering just the 139 relatives with low-count MBL, the 5-year cumulative incidence increased to 5.7%. Finally, 264 had no MBL at baseline, of whom 60 individuals subsequently developed MBL (2 high-count and 58 low-count MBLs) with an age- and sex-adjusted incidence of 3.5% after a median of 6 years of follow-up. In a screening cohort of relatives from CLL families, we reported progression from normal-count to low-count MBL to high-count MBL to CLL, demonstrating that low-count MBL precedes progression to CLL. We estimated a 1.1% annual rate of progression from low-count MBL, which is in excess of that in the general population.

Abstract Clonal hematopoiesis of indeterminate potential (CHIP) is defined as somatic mutations in clonal blood cells of individuals without any other hematological abnormalities and have been identified using whole exome sequencing (WES) from pre-specified genes. CHIP is reportedly associated with aging, reduced overall survival, cardiovascular disease, and hematologic disease, mainly myeloid cancers. Additionally, whole genome sequencing and WES studies in CLL cases have identified putative CLL driver genes with recurrent somatic variants or copy number alterations. Here, we investigate the associations of CHIP and mutations in CLL somatic driver genes with risk of CLL and MBL, a precursor to CLL. Using WES, 571 individuals from 132 CLL families were sequenced from two different sites, Mayo Clinic (92 families) and National Cancer Institute (NCI, 40 families), including 251 CLLs, 74 MBLs, and 246 unaffected relatives. DNA was extracted from buccal cells (Mayo Clinic) and peripheral blood (NCI). Allele counts from gVCF files were extracted for specific genes and analyzed. Variants were annotated using the Variant Effect Predictor in Ensembl, genome build GRCh37 (http://useast.ensembl.org/index.html). Highly-sensitive flow cytometry of the blood was used to screen for MBL. CHIP was defined as in Genovese et al., 2014 as the presence of any of the following: A) disruptive mutations in ASXL1, TET2, or PPM1D; B) missense mutation p.617F in JAK2; C) disruptive or missense mutations in DNMT3Alocalized to exons 7 to 23D) any mutations reported at least 7 times in hematological malignancies in the Catalogue of Somatic Mutations in Cancer (COSMIC); and (E) No variant allelic fraction (VAF) threshold. CLL driver genes included disruptive or missense mutations in ATM, BIRC3, MYD88, NOTCH1, SF3B1, TP53, EGR2, POT1, NFKBIE, XPO1, or FBXW7with VAF greater than 0.1. Mutations from COSMIC and CLL driver genes were excluded if the minor allele frequency in 1000 Genomes was greater than 0.5%. Data was analyzed using logistic regression adjusting for age, sex, and site. Odds ratios (OR) and 95% confidence intervals (CI) were estimated. Median age for CLL, MBL, and unaffected was 63, 61.5, and 54, respectively. The unaffected relatives were significantly younger than both the CLL and MBL groups (p<0.0001), with no difference between CLL and MBL (p=0.46). A total of 70 (12%) individuals from 54 different families had CHIP. CHIP was characterized in the majority of samples as mutations in DNMT3A, ASXL1, and TET2with 43, 9 and 8 individuals, respectively. As expected, CHIP was associated with age (p<0.001) but not sex (p=0.87). CHIP was present in 42 (17%) CLLs, 9 (12%) MBLs, and 19 (8%) unaffected relatives. There was a significant association between the presence of CHIP and CLL risk compared to unaffected relatives (OR= 2.19, 95% CI: 1.20 - 4.13, p=0.013) but not with MBL risk (OR=1.34, 95% CI: 0.54 - 3.11, p=0.51). Using the CLL driver genes, we found mutations in 119 (47%) CLL, 20 (27%) MBL, and 70 (29%) unaffected relatives. Mutations in CLL driver genes were associated with CLL risk compared to unaffected relatives (OR = 2.51, 95% CI: 1.64 - 3.87, p<0.0001), but there was no evidence for increased MBL risk (OR = 1.00). These results held when we subset the analysis to the Mayo only data where the DNA was extracted from buccal cells. This study further supports the association between mutations in CHIP related genes and risk of hematologic malignancies, in particular CLL. This is the first report of the prevalence of CHIP in MBLs. Although MBL and CHIP represent clonal population of blood cells, our data suggest the clones are different. Mutations in CLL driver genes are also associated with CLL risk but show little to no evidence with increased MBL risk. Interestingly, our unaffected relatives of CLL cases also had a high frequency of CLL driver mutations. Future studies are needed to understand these acquired mutations (both in CHIP- and CLL driver- related genes) in the unaffected to MBL to CLL continuum. Disclosures Parikh: Abbvie: Honoraria, Research Funding; Pharmacyclics: Honoraria, Research Funding; MorphoSys: Research Funding; AstraZeneca: Honoraria, Research Funding; Gilead: Honoraria; Janssen: Research Funding. Ding:Merck: Research Funding. Cerhan:Jannsen: Other: Scientific Advisory Board; Celgene: Research Funding; Nanostring: Research Funding. Shanafelt:Jansen: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; GlaxoSmithKline: Research Funding. Kay:Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Infinity Pharm: Membership on an entity's Board of Directors or advisory committees; Cytomx Therapeutics: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta: Research Funding; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees.

Abstract Abstract 3881 Background: Chronic lymphocytic leukemia (CLL) is largely incurable neoplasm of the blood and has one of the highest familial risks of disease among cancers. Monoclonal B-cell lymphocytosis (MBL) with a CLL immunophenotypic profile (i.e., CLL-like MBL) is a precursor state to CLL. In the general adult population, the prevalence rate of MBL is 5–9% and increases with age. This is in contrast to the 13–18% rate of MBL in first-degree relatives of CLL patients from high-risk families (defined here as families with at least two confirmed living cases of CLL). Few longitudinal studies of MBL incidence exists. One study evaluated MBL status over time in a cohort of individuals with MBL from a rural valley in Northern Italy. Our work herein will be the first to evaluate the status of MBL over time in relatives of CLL patients from high-risk families. Methods: Using a cohort of 41 high-risk CLL families, we evaluated the MBL status and clonal blood B-cell counts in 94 relatives of CLL patients at two time points at least 1 year a part. High sensitivity, multi-color flow cytometry was performed on fresh or previously frozen blood samples in three laboratories: Duke University, the US Food and Drug Administration, and Mayo Clinic. The number of cell events collected for flow cytometry evaluation varied from 1 to 5 x105 cells. To assure concordance across flow cytometry laboratories, 15 samples were evaluated at multiple labs. The concordance of MBL calling was a 100%. We defined three monotypic B-cell subsets as CLL-like MBL (CD5+ CD20dim), atypical MBL (CD5+ CD20+), and non-CLL like MBL (CD5−CD20+). Results: Of the 94 relatives, the median age at consent was 57 years (range 42–93) and 39% were male. At the initial MBL screening, 70 (74%) relatives had normal immunophenotype (NIPT) and 24 (26%) had MBL (1 atypical MBL, 3 non-CLL like MBL, and 20 CLL-like MBL). Seven of the 24 individuals with MBL had monoclonal B-cell counts available at baseline screening; median = 147.4 cells/uL (range 22.7–1663). The 94 relatives underwent repeat evaluation with a median follow up time of 1.8 years (range 1–6). At the second evaluation, we found an increase in the prevalence of MBL, with 11 of the 70 (12%) initially NIPT relatives developing a new MBL clone (10 CLL-like, 1 non-CLL like). These 11 incident MBL cases were from 9 families with 2 families each having 2 relatives changing MBL status. The median number of monoclonal B-cells in these 11 incident MBL cases was 0.58 cells/uL (range 0.38–60.3). The 23 out of the 24 relatives with baseline MBL (20 CLL-like MBL and 3 non-CLL like MBL) had a persistent MBL clone. Only 6 of these 23 individuals had monoclonal B-cell counts available at both time points, and among these 6, the clonal B-cell counts decreased at follow-up screening; median difference −64.1 cells/uL (range −1204.3– 10.5). The second evaluation of the initial atypical MBL relative had too few clonal cells for flow assessment. Conclusion: We found that our CLL-like MBL clones persisted over the period of observation in relatives from high-risk CLL families; this finding is similar to that previously reported using a population-based study conducted in Northern Italy. Notably, 12% of relatives from high-risk CLL families developed incident MBL during just 2 years of follow up. Although these MBL clones are all low count (< 1500 cells/uL), these data provide further evidence that MBL is a marker of inherited predisposition to CLL. It will be important to see how our rate of change of MBL status compares to that of the general population as we continue to follow our cohort of CLL families. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 1241 Poster Board I-263 Background and Significance Monoclonal B lymphocytosis (MBL) is a hematologic syndrome characterized by accumulations of clonal B lymphocytes in the peripheral blood. Most MBL have a CLL-like immunophenotype, though other, less common phenotypes are observed. Although some MBL, particularly those with MBL cell counts >1.9 × 109 / L, progress to CLL, “low count” MBL (<0.2 × 109 MBL / μL) have little potential to progress to MBL and may have different biologic characteristics from MBL with lymphocytosis or Rai Stage 0 CLL. Our hypothesis was that detailed characterization of family-associated MBL may also provide biologic insights into the pathogenesis of CLL. Methods Individuals with MBL were identified by flow cytometry screening of fresh and cyropreserved peripheral blood from unaffected members of CLL kindreds ascertained by Genetic Epidemiology of CLL Consortium (GEC) sites. We defined MBL as populations of CD5+, CD19+, CD20lo, CD23+ B cells that comprised at least 0.02% of the PBMC and did not exceed 5.0 × 109 MBL cells / L. Flow cytometry was used to determine the surface immunophenotype including prognostic parameters of CD38, intracellular ZAP-70, immunoglobulin isotype, CD49d, and the ratio of CD69:71. mRNA and genomic DNA from single MBL cells isolated by flow cytometric sorting were analyzed using PCR to determine immunoglobulin heavy and light chain sequences (IGVH status). MBL cells were sorted in bulk for FISH determination of genetic loci associated with clinical CLL. Results Fifty-four unaffected family members were found to have MBL, of these 48 (89%) showed a typical CLL immunophenotype (CLL-like MBL). We observed significant variability in the size of the MBL clone as a percentage of the CD19+ B cell compartment (mean 30%, median 16%; range 2% - 97%). CD38 positive (defined as CD38 surface expression in ≥ 30% of MBL cells) was observed in 6 of 38 (16%) subjects tested. ZAP-70 positive (defined as intracellular expression in ≥ 20% of MBL cells) was expressed in 5 of 28 (18%) participants. CD49d positive (defined as surface expression in ≥ 45% of MBL cells) was observed in 4 of 17 (24%) subjects. The ratio of surface expression of CD69:CD71, a measure of cellular activation that also correlates with an unmutated IGVH, was ≥2.0 in 3 of 34 (9%) subjects tested. Among 36 subjects tested, 9 (25%) MBL expressed both surface IgD and IgM (defined as surface expression ≥ 40% for both IgM and IgD), 12 (33%) expressed IgD only, 2 (6%) expressed IgM only, and 13 did not express IgD or IgM (36%). Analysis of IGVH status has been completed in 10 individuals. Both immunoglobulin heavy chain variable (IGVH) region mutated (n = 14) and unmutated (n = 5) sequences were observed. Six of 10 individuals had 2 or more unrelated MBL clones (range 2 - 4), including two individuals with both unmutated and mutated clones. Among the 19 MBL clones identified in these 8 subjects, VH3 or VH4 rearrangements were observed in all MBL clones. The most commonly rearranged IGVH genes were 3-07 (3 MBL clones), 3-15 (3), and 4-34 (3). No VH1 family gene rearrangements were observed. MBL cells were bulk sorted for FISH from 14 subjects. Mono or biallelic deletion of 13q14.3 was observed in 9 subjects, 4 were normal, and one showed trisomy 12. Conclusions Our data affirms that CLL-like MBL are commonly observed among the unaffected family members from CLL kindreds. We found that family associated MBL clones (most of which were small clones) express ZAP-70, CD38, and CD49d at an apparently lower frequency than observed in CLL. Unlike in CLL, the surface immunoglobulin isotype showed co-expression of IgM and IgD in only one third of cases. Moreover, small MBL clones are commonly oligoclonal and predominantly express mutated IGVH genes with an IGVH usage that also appears different from CLL. Taken together, these findings suggest that small MBL clones, though phenotypically similar to CLL, have important biologic differences from CLL that may explain the limited potential of these clones to progress to CLL. The clinical outcome of these MBL clones in relation to our baseline prognostic characterization will be of interest. In addition the further investigation of family associated MBL is being conducted and may clarify the genetics and immunobiology of familial CLL. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 1232 Poster Board I-254 B-Chronic Lymphocytic Leukemia (CLL) shows a strong familial risk and also co-aggregates with other indolent lymphomas. Monoclonal B-cell lymphocytosis (MBL) is an asymptomatic hematologic condition characterized by small B-cell clones, most with a surface phenotype similar to that of chronic lymphocytic leukemia (CLL). These clones are detectable at low absolute lymphocyte cell (ALC) numbers in otherwise healthy individuals using sensitive 6 or 8 color flow cytometry analysis and can be a precursor to CLL. In the general population, MBL increases with age with a prevalence of 5% in individuals over age 65. In contrast, the rate of MBL is 13-18% in first degree relatives of CLL patients in high risk families. In the largest study to date, we report the characteristics of MBL among 430 first-degree relatives of CLL patients (with no associated lymphoproliferative diseases [LPD]) in 132 high risk families. Patients and Methods Individuals studied came from “high risk” families (defined as those with two or more confirmed cases of CLL) that are participating in the Genetic Epidemiology of CLL Consortium. Multi-parameter flow cytometry analysis with a detection sensitivity of 0.02% was performed on either fresh or cryopreserved PBMC and MBL was classified according to previously published criteria (Marti et al, Br. J Haematol 130:325, 2005). Both the ALC and the absolute B cell count (B-ALC) were calculated for each individual. Survival analysis was used to compute the probability of developing MBL with age using the life table method. Results The overall rate of MBL was 17% (73/430) among first–degree relatives but the probability for developing MBL by age 90 was 51%. Males had a slightly higher (but non-significant) risk for MBL than females. MBL patients had significantly higher ALC and B-ALC than did those with normal immunophenotype. The mean ALC was 2.5×109/L among MBL patients, and 20% had an ALC greater than 3 ×109/L. The B-ALC count averaged 0.51 ×109/L. Ninety percent of the MBL cases had a CLL-like phenotype (CD20dim, CD5+, CD23+). Conclusions MBL is found at a very high rate in families selected for having 2 or more patients with CLL suggesting that MBL reflects inherited predisposition to CLL. Although most of the MBL cases in these families had low cell counts and thus have a presumed low likelihood of progressing to CLL or other LPD, a higher proportion of them had lymphocytosis compared to those with normal immunophenotype. We hypothesize that if MBL is an early step in the process of development of CLL, then germ line genes are likely to be acting early in carcinogenesis with more “hits” required before CLL develops. By looking for genes associated with MBL or CLL in families or in the population, we could substantially increase our power to identify germ line genes predisposing to CLL. Disclosures Kay: Biogenc-Idec, Celgene, Genentech, genmab: Membership on an entity's Board of Directors or advisory committees; Genentech, Celgene, Hospira, Polyphenon Pharma, Sanofi-Aventis: Research Funding.

Abstract Abstract 2443 Background: There is strong and consistent evidence that a genetic component contributes to the etiology of chronic lymphocytic leukemia (CLL). A recent genome-wide association (GWA) study of CLL identified genetic variants located on chromosomes 2q13, 2q37.1, 6p25, 11q24, 15q23, and 19q13 that increased the risk of CLL within a European population. We replicated 5 of these 6 loci in an independent sample of CLL cases and controls from the United States. We now investigate whether these loci also influences MBL, a reported precursor condition of CLL. In addition, a follow-up analysis of the initial GWA study identified four more CLL-susceptibility loci on 2q37.3, 8q24.21, 15q21.3, and 16q24.1. Herein, we also evaluate the association of these four loci with risk of CLL. Methods: Peripheral blood samples were obtained from three ongoing studies: the Genetic Epidemiology CLL (GEC) Consortium, the Mayo Clinic non-Hodgkin lymphoma (NHL)/ CLL study, and the Mayo Clinic Biobank. We implemented rigorous genotyping quality-control measures, and successfully genotyped a total of 407 CLL patients, 965 controls, and 60 MBLs from these studies. Within each locus, the previously reported single nucleotide variants (SNPs) or variants in high linkage disequilibrium (LD) with the previously reported SNPs were evaluated with risk of MBL or CLL. Tests for association was done using the Cochran-Armitage trend test, and unconditional logistic regression was used to estimate odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for CLL or MBL risk Results: In our evaluation of the six initially reported CLL-susceptibility loci (2q13, 2q37.1, 6p25, 11q24, 15q23, and 19q13) with MBL risk, we found three of the six had suggestive associations (p-value < 0.20) with ORs comparable to and in the same direction as those observed from CLL risk. Our strongest finding was with rs13397985 at locus 2q37.1 (OR= 1.56; 95% CI: 1.05, 2.31; p-trend = 0.041), followed by rs17483466 at locus 2q13 (OR= 1.49; 95% CI: 0.99, 2.24; p-trend = 0.074). As expected given our previously reported findings with CLL risk, the association between rs11083846 on chromosome 19q13 and MBL risk was not significant (p-trend = 0.70). Of the four recently reported CLL-susceptibility loci SNPs located on 2q37.3, 8q24.21, 15q21.3, and 16q24.1, we found all to be associated with CLL risk but one. Specifically, the strongest association was seen for locus 8q24.21 (best tagged SNP rs1021955; OR = 1.37; 95% CI: 1.10, 1.70; p-trend = 0.005), followed by locus 16q24.1 (best tagged SNP rs305065; OR= 0.77; 95% CI: 0.61, 0.97; p-trend = 0.024). However, we found no associations for locus 15q21.3 for the previously reported SNP nor for any SNPs in LD with the previously reported SNP. Conclusions: Our MBL results provide additional robust genetic evidence that MBL is a precursor to CLL and that it shares similar underlying genetic predisposition. Also our results confirm three of the four recently reported CLL-susceptibility loci and further support the role of a genetic basis in the etiology of CLL. More research is needed to elucidate the potential manner in which these genetic loci function in CLL or MBL. Disclosures: No relevant conflicts of interest to declare.

Key Points PRS, based on the known CLL loci, predicts CLL risk with high discrimination. This PRS predicts risk of monoclonal B-cell lymphocytosis, a precursor to CLL and a condition that has clinical impact beyond risk for CLL.

Abstract Waldenström macroglobulinemia (WM) is a unique subset of lymphoplasmacytic lymphoma (LPL) that is defined by the presence of an LPL infiltrate in the bone marrow together with a monoclonal IgM protein in the serum. A somatic activating mutation, MYD88 L265P, occurs in 85+% of WM and in 25%-50% of patients with the precursor condition, IgM monoclonal gammopathy of undetermined significance (MGUS); however, germline MYD88 mutations have not been observed in WM patients, and the genetic basis for WM predisposition remains undefined. To identify novel WM susceptibility loci we conducted a two-stage genome-wide association study (GWAS) in over 450 WM cases and 4300 controls of European ancestry. Discovery (stage 1) included 217 WM cases (40% familial) and 3798 controls genotyped on the Illumina Omni Express or Illumina Omni2.5 platforms following standard quality control procedures. The genotyped data were imputed using the Haplotype Reference Consortium panel as a reference and analyzed using logistic regression. In stage 1, we identified three loci on chromosomes 6, 14 and 3 significantly associated (P&lt;5.0x10-8) with risk of WM. Eleven promising SNPs in these and other suggestive loci (P&lt;5.0x10-7) were selected for replication (stage 2) in 269 WM or LPL cases (4% familial) and 571 controls, and genotyping was conducted using standard methods on Taqman and Sequenom platforms or Sanger sequencing (1 SNP). Preliminary results confirm replication of the chromosome 6 locus. Stratification on familial status will illuminate the contribution of familial disease. These results will provide insight into the underlying genetic basis of WM susceptibility. Citation Format: Mary L. McMaster, Sonja I. Berndt, Shengchao A. Li, Susan Slager, Joseph Vijai, Charles C. Chung, Bin Zhu, Laurie Burdette, Brenda Birmann, Elizabeth E. Brown, James R. Cerhan, Karin Ekstrom-Smedby, Henrik Hjalgrim, Geffen Kleinstern, Brian K. Link, James McKay, Alain Monnereau, Lindsay M. Morton, Alexandra Nieters, Nathaniel Rothman, Christine F. Skibola, Alex Smith, Lauren R. Teras, Claire M. Vajdic, Roel Vermeulen, Belynda Hicks, Lynn R. Goldin, Neil E. Caporaso. A genome-wide association study of Waldenström macroglobulinemia/lymphoplasmacytic lymphoma demonstrates association with chromosome 6 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1318. doi:10.1158/1538-7445.AM2017-1318

Abstract Background: Our genome-wide association study (GWAS) of chronic lymphocytic leukemia (CLL) identified 4 highly correlated intronic variants within the IRF8 gene that were associated with CLL. These results were further supported by a recent meta-analysis of our GWAS with two other GWAS of CLL, supporting the IRF8 gene as a strong candidate for CLL risk. Methods: To refine the genetic association of CLL risk, we conducted Sanger sequencing of IRF8 in 94 CLL cases and 96 controls. We then conducted fine mapping by genotyping 39 variants (of which 10 were identified from sequencing) in 745 CLL cases and 1,521 controls. We also assessed these associations with risk of other non-Hodgkin lymphoma (NHL) subtypes. Results: The strongest association with CLL risk was observed with a common single-nucleotide polymorphism (SNP) located within the 3′ untranslated region (UTR) of IRF8 (rs1044873, log additive OR = 0.7, P = 1.81 × 10−6). This SNP was not associated with the other NHL subtypes (all P &gt; 0.05). Conclusions: We provide evidence that rs1044873 in the IRF8 gene accounts for the initial GWAS signal for CLL risk. This association appears to be unique to CLL with little support for association with other common NHL subtypes. Future work is needed to assess functional role of IRF8 in CLL etiology. Impact: These data provide support that a functional variant within the 3′UTR of IRF8 may be driving the GWAS signal seen on 16q24.1 for CLL risk. Cancer Epidemiol Biomarkers Prev; 22(3); 461–6. ©2013 AACR.