Hassan, Manal M.

Abstract Cholangiocarcinoma (CCA) is a rare and aggressive cancer of the bile ducts, with a poor prognosis and limited treatment options. CCA are classified as intrahepatic and extrahepatic based on anatomical location. CCA are often diagnosed at an advanced stage because there are no effective tools for early detection. Although genome-wide association studies (GWASs) have discovered many genome-wide significant contributing risk loci, the genetic underpinning of cholangiocarcinoma remains poorly understood. To date, there is no cholangiocarcinoma-specific GWAS. We conducted GWAS of cholangiocarcinoma in 9,648 individuals of European ancestry using TOPMed reference panel. The putative associations in or near THSD7A on chromosome 7 (OR=2.61, P=7.13 × 10−8), ZBTB16 on 11 (OR=0.16, P=6.02 × 10−8) for non-PSC-related CCA, PUM3 on 9 (OR=10.74, P=6.12 × 10−8), AGBL1 on 15 (OR=2.08, P=5.67 × 10−8) for PSC-related CCA, and LINC02506 on 4 (OR=0.16, P=8.83 × 10−9) for extrahepatic CCA. We also implemented linkage disequilibrium score regression (LDSR) analysis to quantify the genetic correlation between phenotypes using publicly available GWAS summary statistics. Our study aimed to identify possible clinical and epidemiological traits associated with CCA. We identified numerous biomarkers, medical conditions, environmental and behavioral traits, and physical measurements showing high heritability, which is the proportion of phenotypic variance explained by all SNPs included in the analysis, and pairwise genetic correlation with CCA and other CCA subtypes. Elevations of selected biomarkers such as alkaline phosphatase, cystatin C, HbA1c, monocyte count, and white blood cell count show a positive genetic association with CCA in European-ancestry population. Also, autoimmune-mediated conditions show a strong positive genetic association with CCA, non-PSC related CCA, and intrahepatic CCA. The GWAS of CCA and CCA subtypes revealed potential genetic susceptibility associations and will allow us to compare the genetic architecture underlying CCA and other diseases of the bile ducts such as primary sclerosing cholangitis and liver cancer. LDSR provided an improved understanding of the genetic architecture between CCA and potential comorbid conditions and biomarkers. Mendelian randomization analysis will be needed to elucidate the causal relationship between CCA and traits of interest. Citation Format: Younghun Han, Katherine A. McGlynn, Jinyoung Byun, Matthew A. Cooley, Manal M. Hassan, Christopher I. Amos, Lewis R. Roberts, The International Consortium for the Genetics of Biliary Tract Cancers. Genome-wide association study and LD score regression analysis for cholangiocarcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5228.

Abstract Background: Whether circulating polyunsaturated fatty acid (PUFA) levels are associated with pancreatic cancer risk is uncertain. Mendelian randomization (MR) represents a study design using genetic instruments to better characterize the relationship between exposure and outcome. Methods: We utilized data from genome-wide association studies within the Pancreatic Cancer Cohort Consortium and Pancreatic Cancer Case–Control Consortium, involving approximately 9,269 cases and 12,530 controls of European descent, to evaluate associations between pancreatic cancer risk and genetically predicted plasma n-6 PUFA levels. Conventional MR analyses were performed using individual-level and summary-level data. Results: Using genetic instruments, we did not find evidence of associations between genetically predicted plasma n-6 PUFA levels and pancreatic cancer risk [estimates per one SD increase in each PUFA-specific weighted genetic score using summary statistics: linoleic acid odds ratio (OR) = 1.00, 95% confidence interval (CI) = 0.98–1.02; arachidonic acid OR = 1.00, 95% CI = 0.99–1.01; and dihomo-gamma-linolenic acid OR = 0.95, 95% CI = 0.87–1.02]. The OR estimates remained virtually unchanged after adjustment for covariates, using individual-level data or summary statistics, or stratification by age and sex. Conclusions: Our results suggest that variations of genetically determined plasma n-6 PUFA levels are not associated with pancreatic cancer risk. Impact: These results suggest that modifying n-6 PUFA levels through food sources or supplementation may not influence risk of pancreatic cancer.

Abstract Registry-based epidemiologic studies suggest associations between chronic inflammatory intestinal diseases and pancreatic ductal adenocarcinoma (PDAC). As genetic susceptibility contributes to a large proportion of chronic inflammatory intestinal diseases, we hypothesize that the genomic regions surrounding established genome-wide associated variants for these chronic inflammatory diseases are associated with PDAC. We examined the association between PDAC and genomic regions (±500 kb) surrounding established common susceptibility variants for ulcerative colitis, Crohn's disease, inflammatory bowel disease, celiac disease, chronic pancreatitis, and primary sclerosing cholangitis. We analyzed summary statistics from genome-wide association studies data for 8,384 cases and 11,955 controls of European descent from two large consortium studies using the summary data-based adaptive rank truncated product method to examine the overall association of combined genomic regions for each inflammatory disease group. Combined genomic susceptibility regions for ulcerative colitis, Crohn disease, inflammatory bowel disease, and chronic pancreatitis were associated with PDAC at P values < 0.05 (0.0040, 0.0057, 0.011, and 3.4 × 10−6, respectively). After excluding the 20 PDAC susceptibility regions (±500 kb) previously identified by GWAS, the genomic regions for ulcerative colitis, Crohn disease, and inflammatory bowel disease remained associated with PDAC (P = 0.0029, 0.0057, and 0.0098, respectively). Genomic regions for celiac disease (P = 0.22) and primary sclerosing cholangitis (P = 0.078) were not associated with PDAC. Our results support the hypothesis that genomic regions surrounding variants associated with inflammatory intestinal diseases, particularly, ulcerative colitis, Crohn disease, inflammatory bowel disease, and chronic pancreatitis are associated with PDAC. Significance: The joint effects of common variants in genomic regions containing susceptibility loci for inflammatory bowel disease and chronic pancreatitis are associated with PDAC and may provide insights to understanding pancreatic cancer etiology.

480 Background: Currently, there is a lack of imaging biomarkers of immunotherapy outcome in hepatocellular carcinoma (HCC). The study aim was to determine if HCC enhancement on MRI and stiffness change measured by magnetic resonance elastography (MRE) can predict immunotherapy response. Methods: This was a prospective, Institutional Review Board approved study of 38 patients with HCC treated with immune checkpoint blockade (ICB) therapy. All patients had liver MRI/MRE and HCC biopsy at baseline, and MRI/MRE with biopsy or resection after 6 weeks therapy. HCC stiffness (kPa) was measured on MRE elastograms (liver stiffness maps). HCC enhancement and change in stiffness were compared with treatment response to ICB in 1) non-surgical patients (pembrolizumab), and 2) surgical patients (nivolumab +/- ipilimumab). For non-surgical patients, treatment response was defined as overall survival >1 year. For surgical patients, treatment response was defined as <50% viable tumor at time of resection. Analysis was performed using descriptive statistics and Spearman correlation; p-value <0.05 was considered statistically significant. Results: Twenty-five patients were evaluable. Median age was 67 years (32, 78). Etiology of liver disease was NASH (n=8), HCV (n=8), HBV (n=2) and unknown (n=7). Treatment response occurred in 11/25 (44%) patients. Median HCC size and change in size were 4.7 cm (1.2, 14.0) and –0.32 cm, respectively. Median baseline HCC stiffness and change in stiffness were 5 kPa (2.2, 12.4) and –0.1 kPa (–2.2, 1.5), respectively. Median change in HCC size for responders and non-responders was –1.2 cm (–4.8, 0.4) and 0 cm (–1.5, 1.1), respectively (p = 0.02). Treatment response was associated with absence of portal venous phase capsular enhancement and increase in HCC stiffness, (p<0.001). Conclusions: Capsular enhancement and MRE stiffness change may be useful biomarkers of immune cell activated response to ICB therapy.