Citations

e22024 Background: Disease surveillance in high risk melanoma patients using PET/CT is recommended every 6 months, an algorithm that is extremely expensive and often difficult to access. Biomarkers capable of detecting recurrence and low volume metastasis have application in tools to improve the cost effectiveness of surveillance. Towards this long term goal, our aim was to discover melanoma-specific methylated DNA markers (MDMs). Methods: Candidate MDMs were identified by reduced representation bisulfite sequencing of selected age- and sex-balanced snap frozen metastatic melanoma, benign control skin and white blood cells. Sequences were filtered for highest methylation difference, lowest control methylation background ( < 1%), and highest discrimination by variance inflated logistic regression. Using formalin-fixed tissues, the top 32 MDMs were further evaluated in metastatic melanoma from 35 patients, primary melanoma from 26 patients, and 73 control samples (47 benign precursor lesions or normal skin, and 26 healthy buffy coat samples to assess for background DNA in circulation). Candidate markers were blindly assayed by quantitative methylation specific PCR. After normalization by within sample ACTB level, random forest modeling with cross-validation identified marker combinations with greatest predictive accuracy. Results: On receiver operator characteristics analyses of individual marker candidates, areas under the curve (AUCs) ranged from 0.43 to 0.97. Median AUC was 0.835. At 100% specificity, a cross-validated panel of five MDMs (see Table), yielded a sensitivity of 33/35 cases (94.3%; 95% CI, 86.6-100%) for metastatic melanoma and 22/26 cases (84.6%; 95% CI, 70.7-98.5%) for primary melanoma. Furthermore, none of the 5 markers were detected in normal buffy coat samples. Conclusions: A panel of five novel MDMs assayed on tissue and undetectable in normal buffy coat achieves very high discrimination between melanoma and benign control tissues. This panel can be assessed in blood or other bodily fluids for application in melanoma surveillance. [Table: see text]

Dyn2 and α-actinin 4 interact directly to regulate invasive cell migration and the stabilization of invadopodia. Intriguingly, this is specific for α-actinin 4, and not the highly related protein α-actinin 1. These findings elucidate a novel mechanism of regulating cell migration, with important implications for invasive tumor cells.

Abstract Background: Leukocyte telomere length (LTL) has been associated with risk of multiple cancers, but its association with pancreatic ductal adenocarcinoma (PDAC) is unclear. We therefore investigated the association between peripheral blood LTL and PDAC risk, and examined effect modification by candidate SNPs previously reported to be associated with variation in LTL. Methods: A case–control study of 1,460 PDAC cases and 1,459 frequency-matched controls was performed using biospecimens and data from the Mayo Clinic Biospecimen Resource for Pancreas Research. Quantitative PCR was used to measure LTL and categorized into tertiles based on sex-specific control distribution. Eleven telomere-related SNPs also were genotyped. Logistic regression was used to calculate ORs and 95% confidence intervals (CI). Results: Shorter peripheral blood LTL was associated with a higher risk of PDAC (ORT1vsT3 = 1.26, 95% CI = 1.03–1.54, Ptrend = 0.02; ORcontinuous = 1.14, 95% CI = 1.02–1.28), but the association was restricted to cases with treatment-naïve blood samples (ORT1vsT3 = 1.51, 95% CI = 1.16–1.96, Ptrend = 0.002; ORcontinuous = 1.25, 95% CI = 1.08–1.45) and not cases whose blood samples were collected after initiation of cancer therapy (ORT1vsT3 = 1.10, 95% CI = 0.87–1.39, Ptrend = 0.42; ORcontinuous = 1.08, 95% CI = 0.94–1.23). Three SNPs (TERC-rs10936599, ACYP2-rs11125529, and TERC-rs1317082) were each associated with interindividual variation in LTL among controls, but there was no evidence of effect modification by these SNPs. Conclusions: Treatment-naïve short LTL is associated with a higher risk of PDAC, and the association does not differ by germline variation in the candidate telomere-related SNPs examined. Impact: Peripheral blood LTL might serve as a molecular marker for risk modeling to identify persons at high risk of PDAC.

e14594 Background: PNETs are uncommon malignancies and little is known about risk their factors and association with other cancers. Our aim was to evaluate smoking, alcohol use, personal history of diabetes and a family history of PNET and other cancers as potential risk factors. Methods: PNET cases seen at Mayo Clinic Rochester from 2000 to 2011 were evaluated. Insulinoma and high-grade PNETs were excluded. Primary care patients served as controls and were matched (2:1 ratio) to cases on age, sex and region of residence. Cases and controls completed questionnaires at the time of evaluation. Categorical variables were compared with the chi-square test; continuous variables were compared using a two-sample t test. Results: 355 cases were evaluated, mean age was 56.6 years, 52% were males and 96% were White. Personal smoking history was not associated with PNETs (cases 51%, controls 47%, p=0.24). Ever-alcohol use was less common among cases (54% vs. 67%, p=0.001). 19% of cases reported a history of diabetes compared with 11% of controls (p<0.001). Cases were more likely than controls to report a family member with sarcoma (p=0.02), PNET (p=0.024), gall bladder cancer (p=0.024), ovarian cancer (p=0.04) and stomach cancer (p=0.01). Conclusions: Cases with PNETs were more likely than controls to report a history of diabetes and less likely to report alcohol use. There was no association with smoking. Several types of cancer were more commonly reported in family members of cases than controls.

751 Background: Pancreatic adenosquamous carcinomas (PASC) are rare malignancies, with limited evidence regarding best treatment options. The Mayo Clinic Pancreatic Cancer SPORE Registry was utilized to compare/contrast outcomes for pancreatic cancers with a squamous component to pancreatic ductal adenocarcinoma (PDAC). Methods: Patients were identified from the SPORE Registry (2000-2019), were reviewed and confirmed by expert pathologists. Demographic and clinical information was ascertained from medical records and risk factor questionnaires. A case control study of patients with PASC vs PDAC was constructed. PASC patients were also followed for outcome and treatment records were extracted. Results: Of 2,584 total patients with pancreatic cancers, 45 cases of PASC and 2,438 with PDAC were identified. There were no differences in age (median 69 vs 67 years, p=0.42), sex (male 64.4vs 56.6%, p= 0.29), BMI (27.41 vs 27.78 kg/m2, P=0.50), or ever-smoking (61.0 vs 55.3%, P=0.47), with a borderline association with reported diabetes (17.8 vs 29.9%, p =0.08). Compared to PDAC, PASCs were more likely to involve the body/tail (48.9 vs 33.2%, p= 0.02) and had poorer overall survival, adjusted for age, gender, and stage (median 7.1 m vs 12.8m, HR 1.89, p=0.0004). Of 9 PASC pts treated with neoadjuvant intent, 4 were surgically resected, median survival was 7 months. Eleven pts underwent upfront surgery, with variable adjuvant treatments. Median OS post- surgery was 18m (range 7-51). Of 14 patients presenting with metastatic disease, median survival was 4.5 m (range 1-22). With regard to systemic chemotherapy, for neoadjuvant or metastatic disease median duration of treatment was 3 months (range 0.5-7m) for Gemcitabine + nab-paclitaxel (N=9) and also 3 months (range 2-6m) for FOLFIRINOX (N-13). Conclusions: The diagnosis of PASC carries an even poorer outcome than pancreatic adenocarcinoma. Tumors are more likely to arise in the distal pancreas, and patients may be less likely to report associated diabetes. Limited antitumor activity was noted with multi-agent chemotherapeutic regimens. Prospective trials will be needed to clarify choice of regimen in the future.

706 Background: In recent years, there has been a shift towards neo-adjuvant treatment (NAT) of non-metastatic pancreas cancer in the hopes of improving negative margin rate, lymph node negativity, recurrence and survival. Even patients deemed resectable based on NCCN criteria are receiving NAT but data for these patients remains limited. This current study evaluated the outcomes of patients diagnosed with resectable pancreatic adenocarcinoma. Methods: Patients were retrospectively identified through the Mayo Clinic, Rochester SPORE pancreatic cancer registry as well as search of the electronic medical record via Advanced Cohort Explorer from May 2011 to 2016. Baseline demographics, tumor characteristics, treatments rendered, and outcomes were collected. Variables were analyzed for association with recurrence from time of surgery and survival from time of diagnosis using Kaplan-Meier curves and Cox proportional hazards regression. Results: A total of 520 patients with resectable pancreatic adenocarcinoma were identified. 72 patients received upfront chemotherapy with 44 (61.1%) proceeding to surgical resection. 62 patients received upfront chemotherapy followed by radiation with 33 (53.2%) proceeding to surgical resection. 12 patients received upfront radiation alone with 7 (58.3%) proceeding to surgical resection. 374 patients did not receive any NAT with 293 (78.3%) proceeding to surgical resection. In total, 377 (72.5%) went to resection. Median time to recurrence from surgery was 27.7 months vs. 21.7 months for NAT and upfront resection, respectively (HR 0.87, 95% CI 0.60-1.72, p = 0.48). Median overall survival from diagnosis for those receiving NAT was 40.6 months vs. 24.7 months for those receiving upfront resection (HR 0.62, 95% CI 0.41-0.92, p = 0.02). Conclusions: This study shows an approximate 16 month improvement in overall survival of patients receiving upfront NAT for resectable pancreatic adenocarcinoma. This might be due to a better selection of patients. It also highlights that not all patients with resectable cancer undergo resection. Further studies are warranted to identify why resectable patients are not proceeding to resection and which specific NAT approaches benefit patients the most.

Abstract Background Although 20 pancreatic cancer susceptibility loci have been identified through genome-wide association studies in individuals of European ancestry, much of its heritability remains unexplained and the genes responsible largely unknown. Methods To discover novel pancreatic cancer risk loci and possible causal genes, we performed a pancreatic cancer transcriptome-wide association study in Europeans using three approaches: FUSION, MetaXcan, and Summary-MulTiXcan. We integrated genome-wide association studies summary statistics from 9040 pancreatic cancer cases and 12 496 controls, with gene expression prediction models built using transcriptome data from histologically normal pancreatic tissue samples (NCI Laboratory of Translational Genomics [n = 95] and Genotype-Tissue Expression v7 [n = 174] datasets) and data from 48 different tissues (Genotype-Tissue Expression v7, n = 74–421 samples). Results We identified 25 genes whose genetically predicted expression was statistically significantly associated with pancreatic cancer risk (false discovery rate &lt; .05), including 14 candidate genes at 11 novel loci (1p36.12: CELA3B; 9q31.1: SMC2, SMC2-AS1; 10q23.31: RP11-80H5.9; 12q13.13: SMUG1; 14q32.33: BTBD6; 15q23: HEXA; 15q26.1: RCCD1; 17q12: PNMT, CDK12, PGAP3; 17q22: SUPT4H1; 18q11.22: RP11-888D10.3; and 19p13.11: PGPEP1) and 11 at six known risk loci (5p15.33: TERT, CLPTM1L, ZDHHC11B; 7p14.1: INHBA; 9q34.2: ABO; 13q12.2: PDX1; 13q22.1: KLF5; and 16q23.1: WDR59, CFDP1, BCAR1, TMEM170A). The association for 12 of these genes (CELA3B, SMC2, and PNMT at novel risk loci and TERT, CLPTM1L, INHBA, ABO, PDX1, KLF5, WDR59, CFDP1, and BCAR1 at known loci) remained statistically significant after Bonferroni correction. Conclusions By integrating gene expression and genotype data, we identified novel pancreatic cancer risk loci and candidate functional genes that warrant further investigation.

Abstract Background: Pancreatic cancer is associated with development of cachexia, a wasting syndrome thought to limit survival. Few studies have longitudinally quantified peripheral tissues or identified biomarkers predictive of future tissue wasting. Methods: Adipose and muscle tissue were measured by computed tomography (CT) at diagnosis and 50 to 120 days later in 164 patients with advanced pancreatic cancer. Tissue changes and survival were evaluated by Cox proportional hazards regression. Baseline levels of circulating markers were examined in relation to future tissue wasting. Results: Compared with patients in the bottom quartile of muscle change per 30 days (average gain of 0.8 ± 2.0 cm2), those in the top quartile (average loss of 12.9 ± 4.9 cm2) had a hazard ratio (HR) for death of 2.01 [95% confidence interval (CI), 1.12–3.62]. Patients in the top quartile of muscle attenuation change (average decrease of 4.9 ± 2.4 Hounsfield units) had an HR of 2.19 (95% CI, 1.18–4.04) compared with those in the bottom quartile (average increase of 2.4 ± 1.6 Hounsfield units). Changes in adipose tissue were not associated with survival. Higher plasma branched chain amino acids (BCAA; P = 0.004) and lower monocyte chemoattractant protein-1 (MCP-1; P = 0.005) at diagnosis were associated with greater future muscle loss. Conclusions: In patients with advanced pancreatic cancer, muscle loss and decrease in muscle density in 2 to 4 months after diagnosis were associated with reduced survival. BCAAs and MCP-1 levels at diagnosis were associated with subsequent muscle loss. Impact: BCAAs and MCP-1 levels at diagnosis could identify a high-risk group for future tissue wasting.

Abstract Background: Pancreatic cancer is the fourth-leading cause of cancer death in both men and women in the United States. The currently identified common susceptibility loci account for a small fraction of estimated heritability. We sought to estimate overall heritability of pancreatic cancer and partition the heritability by variant frequencies and functional annotations. Methods: Analysis using the genome-based restricted maximum likelihood method (GREML) was conducted on Pancreatic Cancer Case-Control Consortium (PanC4) genome-wide association study (GWAS) data from 3,568 pancreatic cancer cases and 3,363 controls of European Ancestry. Results: Applying linkage disequilibrium- and minor allele frequency-stratified GREML (GREML-LDMS) method to imputed GWAS data, we estimated the overall heritability of pancreatic cancer to be 21.2% (SE = 4.8%). Across the functional groups (intronic, intergenic, coding, and regulatory variants), intronic variants account for most of the estimated heritability (12.4%). Previously identified GWAS loci explained 4.1% of the total phenotypic variation of pancreatic cancer. Mutations in hereditary pancreatic cancer susceptibility genes are present in 4% to 10% of patients with pancreatic cancer, yet our GREML-LDMS results suggested these regions explain only 0.4% of total phenotypic variance for pancreatic cancer. Conclusions: Although higher than previous studies, our estimated 21.2% overall heritability may still be downwardly biased due to the inherent limitation that the contribution of rare variants in genes with a substantive overall impact on disease are not captured when applying these commonly used methods to imputed GWAS data. Impact: Our work demonstrated the importance of rare and common variants in pancreatic cancer risk.

239 Background: Pancreatic adenocarcinoma is a rapidly fatal cancer with 5-year overall survival <5%. 5-10% of pancreatic cancers occur in patients with family history of disease, and 5-27% of these familial cancers are BRCA associated, with defects in Homologous Recombination Repair (HRR). In breast and ovarian cancer, BRCA mutations may be associated with increased risk for brain metastasis (BM). BM is rare in pancreatic cancer, but it is suggested HRR deficient pancreatic cancer patients may have an increased risk for BM/LC. Methods: We analyzed 3030 prospectively identified patients with pancreatic cancer and HHR mutation germline sequencing data (BRCA1/2, ATM, PALB2) from the Mayo Clinic Pancreatic Cancer SPORE Registry. We used clinical databases (2000-2018) to assess the presence of BM or leptomeningeal carcinomatosis (LC). Unconditional logistic regression analysis, with Odds Ratio (OR) and 95% Confidence Interval (CI), assessed the association between HRR gene germline mutation carrier status and any BM. Results: Of 3030 total pancreatic cancer patients, 8 were diagnosed with clinically evident BM/LC (0.26%), confirming the very low incidence of this metastasis site (Table). Of these, all had BM, and 4 also had LC present. No patients had LC diagnosed without BM present. 175/3030 (5.8%) patients had a germline HHR gene mutation. Of these, 1 patient was a BRCA2 carrier (0.57% of HRR deficient patients). 7 /2763 (0.25%) patients without germline HRR mutations had BM or LC (p = 0.44, OR 2.26; 95% CI: 0.27, 18.49). Conclusions: To our knowledge, this is the largest review of BRCA-associated pancreatic cancer patients with BM or LC. The incidence of BM is rare at 0.27%, with LC at 0.14%. Limitations include likely underdiagnosis given short clinical course and lack of availability of somatic HRR gene status. Our study suggests HRR germline carrier patients may have an increased risk of BM/LC development compared to non-carriers. Given rarity, larger studies should be explored. [Table: see text]