Abstract 2667: Mucin 5AC inhibition via intratracheal RNAi delivery as an effective alternative strategy for prevention and treatment of Kras mutant lung cancer

Abstract Lung cancer, including lung adenocarcinoma (LUAD), is the leading cause of cancer-related deaths in the United States. KRAS mutations are the most prevalent oncogenic driver alteration in human LUAD. We have previously shown that high expression of Mucin 5 AC (MUC5AC), a main airway secretory mucin, is significantly associated with poor prognosis. Mucins are essential for mucociliary clearance and the maintenance of airway homeostasis, however, their overproduction could negatively affect the lung immune microenvironment and has been shown to promote airway diseases such as chronic obstructive pulmonary disease (COPD) and lung cancer. Previously, we have shown that genetic deletion of MUC5AC in a murine model of K-ras mutant lung adenocarcinoma (KM-LUAD) impedes tumor development and reduces pro-tumor inflammatory and immune phenotypes. These findings indicate that MUC5AC is a potential druggable target against KM-LUAD. In this study, we sought a translational approach and inhibited MUC5AC in our K-rasG12D mutant mouse model of LUAD via RNA interference (RNAi). Six-week-old mice were given RNAi (5mg/kg) or vehicle (saline) via biweekly intratracheal administration for 8 weeks. This approach led to a significant decrease in tumor burden (40%) and a trending increase in total white blood cell counts, predominantly macrophages in the lung tumor microenvironment which was associated with phenotypic changes in macrophages characterized by reduced expression of Fizz1, and M2 pro-tumor macrophage marker. Additionally, RNAi-treated mice had reduced expression of Siglec-E, a mucin receptor and known inhibitor of the TLR4 endocytosis and promoter of NF-ĸB signaling, as well as a significant decrease in IL-6, a product of the NF-ĸB pathway and promoter of STAT3 signaling which we have previously shown to have an essential role in promotion of KM-LUAD. In summary, these findings elucidate a potential mechanism by which MUC5AC protects tumor cells from apoptosis and immune-mediated cytotoxic activity but also highlights how MUC5AC RNAi is an effective indirect preventive and therapeutic strategy in high-risk individuals (smokers with COPD) and patients with early stage KM-LUAD, respectively. Citation Format: Melvin Zarghooni, Maria T. Grimaldo, Avantika Krishna, Michael J. Clowers, Linda Phan, Yasmina H. Rezai, Arnav Gaitonde, Carlos Rodriguez Reyna, Walter Velasco Torrez, Erik Bush, Seyed Javad Moghaddam. Mucin 5AC inhibition via intratracheal RNAi delivery as an effective alternative strategy for prevention and treatment of Kras mutant lung cancer [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(6_Suppl):Abstract nr 2667.