Citations

Abstract Purpose: We aimed to assess the concordance of colorectal cancer–associated methylated DNA markers (MDM) in primary and metastatic colorectal cancer for feasibility in detection of distantly recurrent/metastatic colorectal cancer in plasma. Experimental Design: A panel of previously discovered colorectal cancer–associated MDMs was selected. MDMs from primary and paired metastatic colorectal cancer tissue were assayed with quantitative methylation-specific PCR. Plasma MDMs were measured blindly by target enrichment long-probe quantitative-amplified signal assays. Random forest modeling was used to derive a prediction algorithm of MDMs in archival plasma samples from primary colorectal cancer cases. This algorithm was validated in prospectively collected plasma samples from recurrent colorectal cancer cases. The accuracy of the algorithm was summarized as sensitivity, specificity, and area under the curve (AUC). Results: Of the 14 selected MDMs, the concordance between primary and metastatic tissue was considered moderate or higher for 12 MDMs (86%). At a preset specificity of 95% (91%–98%), a panel of 13 MDMs, in plasma from 97 colorectal cancer cases and 200 controls, detected stage IV colorectal cancer with 100% (80%–100%) sensitivity and all stages of colorectal cancer with an AUC of 0.91 (0.87–0.95), significantly higher than carcinoembryonic antigen [AUC, 0.72 (0.65–0.79)]. This panel, in plasma from 40 cases and 60 healthy controls, detected recurrent/metastatic colorectal cancer with 90% (76%–97%) sensitivity, 90% (79%–96%) specificity, and an AUC of 0.96 (0.92–1.00). The panel was positive in 0.30 (0.19–0.43) of 60 patients with no evidence of disease in post-operative patients with colorectal cancer. Conclusions: Plasma assay of novel colorectal cancer–associated MDMs can reliably detect both primary colorectal cancer and distantly recurrent colorectal cancer with promising accuracy.

Abstract Background: Discovery of methylated DNA markers (MDM) of esophageal squamous cell carcinoma (ESCC) has sparked interest in assessing these markers in tissue. We evaluated MDMs in ESCC from three geographically and ethnically distinct populations, and explored the feasibility of assaying MDMs from DNA obtained by swallowed balloon devices. Methods: MDMs were assayed in ESCC and normal tissues obtained from the populations of United States, Iran, and China, and from exfoliative cytology specimens obtained by balloons in a Chinese population. Areas under the receiver operating curve (AUC) of MDMs discriminating ESCC from normal tissues were calculated. Random forest prediction models were built, trained on U.S. cases and controls, and calibrated to U.S.-only controls (model 1) and three-country controls (model 2). Statistical tests were used to assess the relationship between dysplasia and MDM levels in balloons. Results: Extracted DNA from 333 ESCC and 322 normal tissues was analyzed, in addition to archival DNA from 98 balloons. For ESCC, model 1 validated in Iranian and Chinese tissues with AUCs of 0.90 and 0.87, and model 2 yielded AUCs of 0.99, 0.96, and 0.94 in tissues from the United States, Iran, and China, respectively. In Chinese balloons, MDMs showed a statistically significant trend of increasing levels with increasing grades of dysplasia (P < 0.004). Conclusions: MDMs accurately discriminate ESCC from normal esophagus in tissues obtained from high- and low-incidence countries. Preliminary data suggest that levels of MDMs assayed in DNA from swallowed balloon devices increase with dysplasia grade. Larger studies are needed to validate these results. Impact: MDMs coupled with minimally invasive collection methods have the potential for worldwide application in ESCC screening.

INTRODUCTION: Nonendoscopic Barrett's esophagus (BE) screening may help improve esophageal adenocarcinoma outcomes. We previously demonstrated promising accuracy of methylated DNA markers (MDMs) for the nonendoscopic diagnosis of BE using samples obtained from a capsule sponge-on-string (SOS) device. We aimed to assess the accuracy of these MDMs in an independent cohort using a commercial grade assay. METHODS: BE cases had ≥ 1 cm of circumferential BE with intestinal metaplasia; controls had no endoscopic evidence of BE. The SOS device was withdrawn 8 minutes after swallowing, followed by endoscopy (the criterion standard). Highest performing MDMs from a previous study were blindly assessed on extracted bisulfite-converted DNA by target enrichment long-probe quantitative amplified signal (TELQAS) assays. Optimal MDM combinations were selected and analyzed using random forest modeling with in silico cross-validation. RESULTS: Of 295 patients consented, 268 (91%) swallowed the SOS device; 112 cases and 89 controls met the pre-established inclusion criteria. The median BE length was 6 cm (interquartile range 4–9), and 50% had no dysplasia. The cross-validated sensitivity and specificity of a 5 MDM random forest model were 92% (95% confidence interval 85%–96%) and 94% (95% confidence interval 87%–98%), respectively. Model performance was not affected by age, gender, or smoking history but was influenced by the BE segment length. SOS administration was well tolerated (median [interquartile range] tolerability 2 [0, 4] on 10 scale grading), and 95% preferred SOS over endoscopy. DISCUSSION: Using a minimally invasive molecular approach, MDMs assayed from SOS samples show promise as a safe and accurate nonendoscopic test for BE prediction.

Abstract Background We sought to compare the dysplasia detection rate of high-definition white light endoscopy (HDWLE) with that of chromoendoscopy in patients with long-standing inflammatory bowel disease (IBD). Methods This is a retrospective observational cohort of patients with IBD who underwent surveillance colonoscopy between October 1, 2016 and September 30, 2017. We assessed the association between dysplasia detection and multiple variables. Results A total of 808 unique colonoscopies were performed, of which 150 (18.6%) included chromoendoscopy. Primary sclerosing cholangitis was a comorbid diagnosis in 24.5% of patients. The performing endoscopist was an IBD specialist with 37.1% of patients and had >10 years’ experience with 64.9% of patients. Prior dysplasia had been seen in 245 (30.3%) patients: 102 (68.0%) and 143 (22.0%) among patients who had chromoendoscopy and HDWLE, respectively. Dysplasia in polyps was found in 129 procedures (15.1%). Among patients who had chromoendoscopy and HDWLE, polypoid dysplasia was identified in 50 (33.0%) and 79 (12.0%) patients, respectively, P < 0.01. Dysplasia in random biopsies was found in 39 patients (4.8%): 15 (10%) who had chromoendoscopy and 24 (3.6%) who had HDWLE (P < 0.001). On multivariate analysis, patient and disease characteristics significantly associated with an increased odds for polypoid dysplasia included older age at diagnosis (odds ratio [OR] = 1.3 per 10 years; 95% confidence interval [CI], 1.07-1.60), having an IBD physician endoscopist (OR = 1.6; 95% CI, 1.01-2.67), having an endoscopist with less than 10 years’ experience (OR = 1.8; 95% CI (1.16-2.89), and prior random dysplasia (OR = 4.2; 95% CI (1.93-9.17). Concomitant primary sclerosing cholangitis was significantly associated with random dysplasia (OR = 2.3; 95% CI, 1.02-5.07). After multivariate analysis adjusting for these variables, chromoendoscopy was no more likely to identify dysplasia than was HDWLE. Conclusions Chromoendoscopy and HDWLE had a similar diagnostic yield for dysplasia detection in patients with chronic IBD-colitis after adjusting for multiple known risk factors.

Abstract Background: Emerging colorectal cancer trends demonstrate increased incidence and mortality in younger populations, prompting consideration of average-risk colorectal cancer screening initiation at age 45 versus 50 years. However, screening test performance characteristics in adults 45–49 years have been minimally described. To inform the biologic rationale for multi-target stool DNA (mt-sDNA) screening in younger patients, we analyzed and compared tissue levels of methylation (BMP3, NDRG4) and mutation (KRAS) markers included in the FDA-approved, mt-sDNA assay (Cologuard; Exact Sciences Corporation). Methods: Within 40–44, 45–49, and 50–64 year age groups, archived colorectal tissue specimens were identified for 211 sporadic colorectal cancer cases, 123 advanced precancerous lesions (APLs; adenomas >1 cm, high-grade dysplasia, ≥25% villous morphology, or sessile serrated polyp; 45–49 and 50–64 age groups only), and 204 histologically normal controls. Following DNA extraction, KRAS, BMP3, and NDRG4 were quantified using QuARTS assays, relative to ACTB (reference gene). Results: None of the molecular marker concentrations were significantly associated with age (P > 0.05 for all comparisons), with the exception of NDRG4 concentration in APL samples (higher in older vs. younger cases; P = 0.008). However, NDRG4 levels were also statistically higher in APL case versus normal control samples in both the 45–49 (P < 0.0001) and 50–64 (P < 0.0001) year age groups. Conclusions: Overall, these findings support the potential for earlier onset of average-risk colorectal cancer screening with the mt-sDNA assay. Impact: These novel data address an identified knowledge gap and strengthen the biologic basis for earlier-onset, average-risk screening with the mt-sDNA assay.

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]

6072 Background: Effective screening tests for ovarian cancer (OC) are lacking; most cases present at advanced stage and portend poor prognosis. DNA methylation is an early event in carcinogenesis and can be detected in blood plasma samples from cancer patients. In DNA extracted from tissues, we first discovered, then validated discriminant methylated DNA marker (MDM) candidates for OC and subsequently tested independent plasma from women with and without OC. Methods: For discovery, DNA from 67 frozen tissues (18 high grade serous (HGS), 18 endometrioid, 15 clear cell (CC), 6 mucinous OCs; 10 benign fallopian tube epithelium (FT); and 19 buffy coats from cancer-free women underwent reduced representation bisulfite sequencing (RRBS) to identify MDMs associated with OC. Candidate MDM selection was based on receiver operating characteristic (ROC) discrimination, methylation fold change, and low background methylation among controls. Blinded biological validation was performed using methylated specific PCR on DNA extracted from independent FFPE tissues from OCs (36 HGS, 22 endometrioid, 21 CC, and 14 mucinous) and 29 FT. Top performing MDMs in tissue were tested using long-probe quantitative amplified signal assays in independent pre-treatment plasma samples from women newly-diagnosed with OC and population-sampled healthy women. A random forest modeling analysis was performed to generate predictive probability of disease; results were 500-fold in silico cross-validated. Results: After RRBS discovery and biological validation, 33 MDMs showed marked methylation fold changes (10 to > 1000) across all OC histologies vs FT. The top 11 MDMs ( GPRIN1, CDO1, SRC, SIM2, AGRN, FAIM2, CELF2, DSCR6, GYPC, CAPN2, BCAT1) were tested on plasma from 91 women with OC (76 (84%) HGS) and 91 without OC; the cross-validated 11-MDM panel highly discriminated OC from controls (96% (95%CI 89-99%) specificity; 79% (69-87%) sensitivity, and AUC 0.91 (0.86 - 0.96)). Among HGS, the panel correctly identified 83%, including 5/6 stage I/II, and the majority of other subtypes (Table). Conclusions: Whole methylome sequencing, stringent filtering criteria, and biological validation yielded outstanding candidate MDMs for OC that performed with promisingly high sensitivity and specificity in plasma. Larger plasma-based OC MDM testing studies, with larger numbers of non-HGS histologies are warranted. [Table: see text]

e16705 Background: The prevalence of pancreatic neuroendocrine tumors (PNETs) has increased in the last decade. Despite being clinically asymptomatic PNETs can be biologically aggressive. There is currently no reliable non-invasive diagnostic biomarker for PNETs. In this study we aimed to identify and validate methylated DNA marker (MDM) candidates that differentiate PNET from normal pancreas. Methods: For discovery, reduced representation bisulfite sequencing (RRBS) was performed on DNA extracted from frozen normal pancreas (n = 13) and PNET (n = 51) tissues. Area under the receiver operator characteristic curve (AUC), fold-change, and p-value criteria selected candidates MDMs for blinded validation in independent FFPE tissues from primary PNET (n = 67; solid = 50, cystic = 17), normal pancreas controls (n = 24), and normal buffy coat (n = 36) using methylation specific PCR. MDM distributions in primary PNETs were compared to primary lung (n = 36) and small bowel (n = 36) NETs and metastatic PNET tissue (n = 25). The discrimination accuracy of candidate markers was summarized as the AUC with corresponding 95% confidence intervals (CI). Results: From the RRBS discovery, 31 candidate MDMs were selected for validation. Four MDMs ( SRRM3, HCN2, SPTBN4 and TMC6) achieved individual AUCs ≥0.95 in the validation set (Table). These MDMs were similarly discriminant in metastatic PNET tissue and in primary lung and small bowel NETs. Three out of these 4 MDMs perfectly differentiated PNET tissue from buffy coat with AUC of 1 and may be ideally suited for further development of a blood-based assay. Conclusions: We identified and validated novel MDMs in tissue that discriminate PNETs from controls with normal pancreas and buffy coat with high accuracy. These MDMs also differentiated metastatic PNETs from normal pancreas tissue. Further exploration of these candidate tissue MDMs in plasma can potentially guide diagnosis and management of PNETs. Funding: P30DK084567. [Table: see text]