Abstract 5753: Milk-derived extracellular nanovesicles: A novel delivery strategy for transcriptome targeting therapies in cholangiocarcinoma

Abstract Introduction: Cholangiocarcinoma (CCA) is an aggressive and heterogenous biliary malignancy. Previous therapeutic shortcomings have encouraged the investigation of new strategies, such as targeted therapeutics. YAP/TAZ, transcriptional coactivators of the hippo pathway, have been implicated in the tumorigenesis of CCA along with the Src familiar kinase, LCK. Milk-derived nanovesicles (MNVs) have emerged as a promising biologic delivery apparatus for hepatobiliary malignancy due to their predilection for hepatic uptake. We sought to investigate the utility of aptamer guided MNVs loaded with short interfering RNA (siRNA) targeting YAP, TAZ, and LCK. Methods: MNVs were prepared and loaded with species-specific siRNA prior to decoration with an epithelial cellular adhesion molecule (EpCAM) targeting aptamer. In vitro studies were performed using murine and human CCA cell lines, SB1 and HuCCT-1, respectively. In vivo studies were carried out using C57BL/6 mice following Institutional Animal Care and Use Committee protocols. Results: We previously validated EpCAM as an effective aptamer demonstrated by increased levels of expression in CCA cell lines using immunoblot, RT-PCR and immunofluorescence. Additionally, in vivo experiments demonstrated excellent biodistribution and affinity for tumor-selective uptake. To evaluate knockdown efficacy, CCA cell lines were incubated with EpCAM aptamer guided MNVs individually targeting YAP, TAZ, and LCK which resulted in downregulation of these targets on immunoblot and RT-PCR. MNVs were then loaded with equal concentrations of siRNA targeting YAP, TAZ, and LCK in combination which resulted in similar degrees of gene downregulation compared with single transcriptome targeting MNVs. Due to the role of YAP/TAZ activation in CCA systemic therapy resistance, we investigated the effect of MNVs loaded with either single target or combinatory target siRNA alongside and in combination with gemcitabine and cisplatin (GemCis). Incubation with both combinatory siRNA and GemCis significantly intensified cell death on Pi/Hoechst staining compared with single target knockdown alone. Similar findings were found using separate assays of cell viability, including ATP luminescent quantitation and caspase 3/7 activity. These data suggest MNV transcriptome targeting may induce a state of cell stress which allows for amplification of chemotherapy treatment effect. Conclusion: Aptamer guided, nanovesicle mediated transcriptome targeting is a promising therapeutic strategy in preclinical CCA models that may potentiate chemotherapy response. Our future direction involves further investigating the role of CCA target downregulation and its effect on the tumor immune microenvironment utilizing aptamer guided nanovesicle delivery and inducible knockdown cell lines. Citation Format: Jack W. Sample, Mincheng Yu, Hendrien Kuipers, Danielle M. Carlson, Nathan W. Werneberg, Jennifer L. Tomlinson, Gregory J. Gores, Rory L. Smoot. Milk-derived extracellular nanovesicles: A novel delivery strategy for transcriptome targeting therapies in cholangiocarcinoma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5753.