PROJECT SUMMARY: Pancreatic cancer is a highly aggressive malignancy that is estimated to become the second leading cause of cancer-related deaths by 2026. Pancreatic ductal adenocarcinoma (PDAC) accounts for >90% of all pancreatic cancer cases and has an overall five-year survival rate of ~8%, the lowest among the major cancers. In PDAC, only 15–20% of patients present with localized, resectable, potentially curable tumors at initial diagnosis. However, currently there is an unmet clinical need for the lack of availability of highly robust diagnostic strategies for the early detection of PDAC. MicroRNAs (miRNAs) are small non-coding RNAs that regulate genes implicated in every human cancer, including PDAC, and may thus be ideal biomarkers. Indeed, circulating cell-free miRNAs (cf-miRNAs) have been shown to have diagnostic potential. Furthermore, the recent discovery that cancer cells actively excrete miRNAs in small extracellular vesicles called exosomes (exo-miRNAs) has revolutionized the field, as tumor-derived exosomal cargo enables the identification of cancer- specific molecular markers. During the previous cycle of funding, we performed unbiased and genome-wide sequencing-based miRNA profiling approaches, together with rigorous bioinformatics and machine-learning algorithms, and 1) identified panels of 5 cf-miRNAs and 8 exo-miRNAs that could robustly identify patients with early-stage PDAC; 2) combined the cf- and exo-miRNAs into a “transcriptomic signature” that was superior to individual biomarker panels, including patients with early-stage (stage I/II) disease; 3) showed that combining our transcriptomic signature with CA19-9 further improved diagnostic performance; and 4) most importantly, showed that our transcriptomic signature accurately identified patients with PDAC who were CA19-9-negative. In this competing renewal application, we will build upon our previous success by undertaking 4 specific aims. In Aim 1, we will expand our biorepository via continued prospective enrollment of patients with PDAC and precancerous neoplasms (PNs), including those with pancreatic cystic neoplasms (PCNs) and familial risk, with an additional focus on enrollment of and specimen collection from patients of racial/ethnic minority populations. In Aim 2, we will further validate the transcriptomic signature and establish its performance in prospective cohorts of patients with early-stage PDAC. In Aim 3, we will determine the clinical significance of our transcriptomic signature to detect the presence of high-grade dysplasia and invasive cancer in pre-operative plasma collected from patients clinically diagnosed as PCNs. In Aim 4, we will evaluate the ability of our transcriptomic signature to detect PDAC at its earliest stages in pre-diagnosis plasma specimens and to determine lead time before disease presentation. Our proposed project will be the first to establish a clinically feasible, sensitive, specific, and robust blood-based assay for identifyin...