McGlinch, Maria

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.

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 The SOS device was withdrawn 8 minutes after swallowing, followed by endoscopy (the criterion standard).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.

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]

4088 Background: Methylated DNA markers (MDMs) are broadly informative for early detection of colorectal cancer (CRC) but have not been extensively studied for post-treatment surveillance and disease monitoring. We aimed to assess the feasibility of novel CRC-associated MDMs for detection of distant recurrent CRC (rCRC) in plasma. Methods: A panel of 13 MDMs previously identified to be discriminant for primary CRC was selected. In a cross-sectional analysis of plasma samples, MDMs were assayed blindly (by target enrichment long-probe quantitative amplified signal assay) from 160 age/sex-balanced patients (60 healthy controls, 60 with resected CRC and no evidence of disease (NED), and 40 rCRC after primary tumor resection). Plasma-derived carcinoembryonic antigen (CEA) was measured on all patients. Random forest modeling was used to derive a prediction algorithm of MDMs (with and without CEA) for the endpoint of rCRC relative to healthy controls. The accuracy of the algorithm was summarized as sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) with 95% confidence intervals (CI) in the test set. Results: Median patient age was 55 (interquartile range: 49-64) years. As shown in the Table below, a single MDM with the highest AUC was significantly better than CEA ( p= 0.02). On cross validation, CEA provided no additional improvement to the performance of the panel of 13 MDMs ( p= 0.2). The cross-validated panel of MDMs detected rCRC liver metastases with 96% (79-100%) sensitivity, lung metastases with 78% (40-97%) sensitivity, and peritoneal/nodal metastases with 57% (18-90%) sensitivity. Lesions with Response Evaluation Criteria in Solid Tumors sum > 4 cm were detected with 94% (73-100%) sensitivity and ≤4 cm with 78% (52-94%) sensitivity. Conclusions: Novel MDMs in plasma detect rCRC with promising accuracy. The clinical utility of MDMs for non-invasive post-treatment surveillance and treatment monitoring in CRC warrants further evaluation in longitudinal studies with sufficient follow-up to exclude sub-clinical recurrence in those with NED. [Table: see text]

3599 Background: Existing tools for post-treatment CRC surveillance and monitoring are insensitive and expensive. MDMs are broadly informative for early detection of CRC but have not been extensively studied for disease monitoring. As a first step, we sought to assess the concordance of novel CRC-associated MDMs in pCRC and mCRC. Methods: A panel of 14 MDMs previously identified to be highly discriminant for pCRC was selected on the basis of high median fold-change of MDM levels relative to buffy coat (682 (IQR: 132-19347)). Surgically resected pCRC and paired mCRC were identified from institutional pathology databases. Quantitative methylation-specific PCR was used to assay MDMs. 30 paired samples per metastatic subtype were calculated to be sufficient. MDM levels were compared using two-sample and paired Wilcoxon rank sum tests. Results: 87 patients with paired pCRC and mCRC including 57 synchronous and 30 metachronous metastases were included. 41/87 (47%) had neoadjuvant and 59/87 (68%) had adjuvant chemotherapy. All synchronous metastases were to liver. Metachronous metastases were to liver in 19/30 (63%) and to lung in 11/30 (37%). The levels of 14 selected MDMs were remarkably similar between paired pCRC and mCRC (Table). Individual MDM levels and the average level of all MDMs combined were not significantly different ( p> 0.0018 by Bonferroni correction). Conclusions: MDM levels are highly concordant in pCRC and mCRC. Thus, MDMs discovered from pCRC should be further studied for non-invasive surveillance after surgical resection and monitoring of treatment response in mCRC. [Table: see text]