Abstract B037: Disks large-associated protein 5 (DLGAP5) is a putative prognostic biomarker for intraductal papillary mucinous neoplasm (IPMN) of pancreas

Abstract Pancreatic cancer is one of the deadliest malignant diseases, accounting for nearly 500,000 deaths worldwide each year. One of the pancreatic cancer precursors are mucinous pancreatic cystic lesions (PCL). Although only a minority of these PCLs undergo malignant transformation, the clinical significance is considerable, particularly given the prevalence of up to 45% in individuals over the age of 65. The most prevalent type of neoplastic PCL is intraductal papillary mucinous neoplasm (IPMN) and the management of different IPMN grades varies, with high- grade dysplasia and invasive carcinoma being indicated for surgery. However, the current guidelines for patient stratification are limited and often lead to either overtreatment or undertreatment, both of which are associated with high mortality and morbidity. Therefore, there is a pressing need to identify biomarkers associated with progression of IPMN from low to high grade that can be used for more accurate lesion assessment. Here we identified a novel biomarker highly correlated with IPMN progression – DLGAP5. Both mRNA as well as protein expression of DLGAP5 is positively associated with increased grade of IPMNs as determined by analysis of patient derived tumor samples. Additionally, in vitro experiments confirmed that knock down of DLGAP5 in pancreatic cancer cells leads to reduction of cell proliferation, and conversely, overexpression of DLGAP5 in IPMN precursor cells resulted in increased proliferation. Since one of the functions of DLGAP5 is microtubule stabilization, we hypothesized that the secretome of IPMN precursor cells will be altered by the expression of DLGAP5. Indeed, our mass spectrometry-based analysis of secreted proteins identified several hits (e.g. DKK1) that were correlated with DLGAP5 expression and were previously confirmed to be present in IPMN cyst fluid in patients. Subsequently, we aim to validate the correlation of the putative biomarkers in IPMN cyst fluid and serum with IPMN grade and patients’ clinical outcome in a prospective manner. To sum up, we validated DLGAP5 as an IPMN-progression biomarker and identified several secreted proteins that could serve as DLGAP5-surrogate biomarkers for stratification of the patients with IPMN and subsequent treatment optimalization. Citation Format: Radoslav Janostiak, Peter Mačinga, Lucia Csergeová, Ondřej Fabián, Eva Sticová, Jiří Zahradník, Martin Květoň, Tomáš Hucl. Disks large-associated protein 5 (DLGAP5) is a putative prognostic biomarker for intraductal papillary mucinous neoplasm (IPMN) of pancreas [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr B037.