Extra Domain B-Fibronectin Targeted Ultrasound Contrast Agents for Pancreatic Cancer Diagnosis

Abstract

Pancreatic cancer is the sixth leading cause of global cancer related death with a rising incidence projected as ~1M new cases by 2050 [1]. Most patients present with non-resectable pancreatic ductal adenocarcinoma (PDAC), resulting in a global five-year survival rate of 10% [1]. To increase treatment options, more effective early PDAC detection tools are needed. Endoscopic and transabdominal ultrasound (US) are frequently used in PDAC diagnosis. In this work, we aim to improve US-based PDAC diagnostic sensitivity by developing a sub-micron contrast agent targeting extra domain B-fibronectin (EDB-FN), a biomarker overexpressed in PDAC [2]. To address these challenges, we propose the addition of ZD2, an EDB-FN targeted molecule, to increase PDAC signal intensity, thus improving diagnosis. The EDB-FN targeted peptide, ZD2, was successfully incorporated into lipid shell stabilized, C<inf>3</inf>F<inf>8</inf> core nanobubble (NB) contrast agents (ZD2-NB) without significantly altering agent size or echogenicity. The peptide retained its ability to interact with the target (EDB-FN) after incorporation into the contrast agent; significantly increasing the in vitro retention of ZD2-NBs in Capan-1 and BxPC3 cells compared to untargeted NBs. Finally, ZD2-NBs resulted in higher nonlinear contrast (NLC) signal intensity (maximum 123x, mean 12x) compared to untargeted NBs in a murine flank PDAC tumor model. The ZD2-NBs had a slower washout in EDB-FN+ tumors compared to untargeted NBs (maximum 13x, mean 4x). The data demonstrate that ZD2-NBs have higher NLC signal intensity and longer retention in EDB-FN+ tumors, suggesting their utility as an US-based early PDAC detection method.