Innate lymphoid Cells Drive Young Onset Lung Cancer Incidences in Females - Since the recognition of tobacco smoking as a major risk factor for non-small cell lung carcinoma (NSCLC), the rate of incidence in males has significantly declined. However, new cases of lung adenocarcinoma (LUAD), a subset of NSCLC, continue to rise among females and non-smoking populations. Recent epidemiological studies, along with our preliminary analysis of the US National Cancer Database, have found that the incidence of LUAD in females has surpassed that in males in age groups younger than 50, suggesting that factors beyond smoking drive the sexual dimorphism in lung tumorigenesis. There is growing appreciation of the immune system in various cancers, including LUAD, with increasing evidence of a pro-tumorigenic role for type 2 inflammation. Our comprehensive whole tumor transcriptomic, scRNA-seq, and immunophenotypic analyses of mouse LUAD tumors have identified multiple immune regulatory pathways, among them type 2 immune cells (innate lymphoid cells 2 [ILC2], TH2, eosinophil, and mast cells) were the top-enriched immune cell types in the TIME of female compared to male mice. ILC2s are the first responders in the host innate immune defense, and recent evidence indicates that ILC2s are the linchpin of type 2 immunity, which orchestrates various downstream immune responses. Studies have linked sex hormone signaling to ILC2 regulation, which may influence female sex disparity in allergic asthma, but how ILC2 function is regulated in LUAD remains unknown. Using metabolomic, transcriptomic, and molecular biology analyses, we discovered that female ILC2s exhibit heightened arginine metabolism and are associated with ILC2 function in females. In vitro, analysis of arginine depletion and specific Arg1 inhibition disrupted metabolic programming and function in female ILC2s. These data underscore the role of arginine metabolism in ILC2 function and provide new clues into the low immunotherapy response and decreased survival in females compared to males. These observations led to our overarching hypothesis that arginine-driven ILC2 proliferation promotes type 2 immune responses and dampens immunotherapy efficacy in females with LUAD. This proposal will elucidate the importance of arginine metabolism in ILC2s and the extent to which arginine metabolism can be targeted to improve ICI response in females. A mechanistic understanding of this process should uncover Arg1 blockade as a novel combination to combat immunotherapy resistance in female LUAD patients. To that end, we will determine the necessity and sufficiency of ILC2 cells in driving sexual disparity in LUAD. We will also establish that arginine metabolism is key to the differential ILC2 responses in females. Finally, we will test a novel combination approach using an Arginase 1 inhibitor and an immune checkpoint blockade. In conclusion, our study is an essential step in understanding the fundamental biology underpinning ILC2 function in females, which can lead to new therapeutic resistance, as well as provide a strong rationale for targeting arginine metabolism to boost immunotherapy. Human biospecimens are not readily available, especially for comprehensive time-course, functional, mechanistic, and therapeutic studies necessary to inform a strong scientific rationale for subsequent studies involving such precious human resources. Validation of cancer-relevant genes also requires in vivo assessment of their activities, as in vitro or ex vivo cell-based systems do not recapitulate the authentic in vivo cancer microenvironment. The mouse is a well-established model for cancer research and will be used in our studies
