KRAS mutations allelic frequency dynamics using plasma extracellular vesicles: Association with survival outcomes in localized pancreatic adenocarcinoma.

person Asmita Chopra Department of Surgery, University of Pittsburgh, Pittsburgh, PA info_outline Asmita Chopra, Hongzhang He, Jadranka Milosevic, Nikhil Tirukkovalur, Rudy El Asmar, Ibrahim Nassour, Geoffrey Nunns, Mingxi Chen, Jiaqi Chen, Siyu Jiang, Aatur D. Singhi, Anwaar Saeed, Janie Yue Zhang, Kenneth K. Lee, Amer H. Zureikat, Si-Yang Jiang, Alessandro Paniccia

Authors person Asmita Chopra Department of Surgery, University of Pittsburgh, Pittsburgh, PA info_outline Asmita Chopra, Hongzhang He, Jadranka Milosevic, Nikhil Tirukkovalur, Rudy El Asmar, Ibrahim Nassour, Geoffrey Nunns, Mingxi Chen, Jiaqi Chen, Siyu Jiang, Aatur D. Singhi, Anwaar Saeed, Janie Yue Zhang, Kenneth K. Lee, Amer H. Zureikat, Si-Yang Jiang, Alessandro Paniccia Organizations Department of Surgery, University of Pittsburgh, Pittsburgh, PA, Captis Diagnostics, Inc, Pittsburgh, PA, Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, Department of Pathology, University of Pittsburgh, Pittsburgh, PA, Department of Medical Oncology, University of Pittsburgh, Pittsburgh, PA, Department of Medical oncology, University of Pittsburgh, Pittsburgh, PA Abstract Disclosures Research Funding No funding sources reported Background: Pancreatic ductal adenocarcinoma (PDAC) lacks an effective and consistent biomarker to emulate treatment response and predict survival. Extracellular vesicles (EV) carrying tumor-specific mutations are disease-specific biomarkers that hold promise to address this unmet need. Methods: Informed by tumor profiling, plasma from 44 PDAC patients with confirmed KRAS mutations, treated with neoadjuvant therapy (NAT) and definitive surgery between 2019 and 2021, was analyzed. Samples were collected at diagnosis, day of surgery, and 1-month post-surgery. A lipid nanoprobe technique was used for EV isolation and droplet digital PCR was used for detection of tumor-specific KRAS mutations. Patients were categorized based on the temporal change in KRAS mutation allelic frequencies (MAF) into ND (no detection at any time point), ID (increasing MAF detection), or DD (decreasing MAF detection). Optimal CA19-9 response was defined as >50% reduction from baseline and normalization (<37 U/mL) before surgery. Survival associations were evaluated using Kaplan-Meier analysis and log-rank tests. The median follow-up was 36.1 months. Results: Among the cohort (mean age 66.5±8.2 years, 36% females), 29 (65.9%) patients had ND, 7 (15.9%) had ID and 8 (18.2%) had DD of KRAS MAF. No significant differences were noted in demographic or clinical variables (p > 0.05). Stages III, II, and I PDAC had detectable mutant KRAS in 50%, 30%, and 21% cases, respectively. The ND group exhibited significantly longer restricted mean disease-free survival (rmDFS) [31.2 months (95% CI: 24.1–38.3)] compared to DD [27.8 months (95% CI: 12.4–43.1)] and ID [9.8 months (95% CI: 0.1–19.7)] (p=0.010). The ND group also showed a superior rmOS [40.3 months (95% CI: 34.2–46.4)] outperforming DD [35.7 months (95% CI: 22.1–49.2)] and ID [17.7 months (95% CI: 6.4–28.9] (p = 0.012). Eleven patients (25%) exhibited optimal CA19-9 response. Patients in ND cohort with optimal CA19-9 response (n=6; 20%) had the longest DFS and OS (median DFS and OS not reached), outperforming all other subgroups (p<0.001). Conversely, patients in ID group had the lowest rmDFS (5.1 months 95%CI 2.4-7.8), irrespective of CA19-9 response (p<0.001). Conclusions: Detection and temporal increase of EV-KRAS MAF are significant indicators of reduced DFS and OS in PDAC patients. These findings highlight the potential of dynamic EV-KRAS profiling as a prognostic biomarker and underscore the need for expansive validation studies.