Development of Mouse and Humanized Models to Study Sex Disparities in Tumor Progression and Treatment of NSCLC

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Project Summary According to the American Cancer Society, lung cancer is the second most commonly diagnosed cancer in men and women. Outside of the sex-specific cancers, lung cancer and melanoma have the greatest sex disparity, though the exact mechanisms behind these differences are not well understood. In the United States, men have a higher lifetime risk of developing lung cancer and are more likely to develop severe disease than women. Additionally, there are sex disparities in responses to treatment, such as men having better responses to immunotherapies over women. There are multiple factors contributing to this sex disparity including lifestyle choices, sex hormones, and differences in immune response. Our preliminary data shows that two mouse tumors models of lung cancer, CMT-167 and Lewis Lung Carcinoma (LLC), two models of non-small cell lung cancer (NSCLC), grow slower in female than in male mice. This sex difference is dependent on the ovary as tumors in ovariectomized female mice grow equivalent to those in male mice. Innate immune cells (macrophages and NK cells) and more specifically NKG2D receptor activity are required for reduced tumor growth in females. Multi- parameter flow cytometry analysis shows significant sex differences in NSCLC tumor resident innate immune cells. We show that these sex-disparities extend to several chemotherapy and anti-PDL1 immunotherapy treatments. In preliminary in vivo data we show that the sex-disparity in NSCLC tumor growth and the response to chemotherapy requires NK cells. Ex vivo NK cell killing assays show that preincubation of NSCLC cells with female serum, but not male serum or serum from ovariectomized females, stimulates enhanced NK cell activity utilizing the secreted pro-apoptotic factor TRAIL. This ex vivo NK cell assay provides a means to identify bioactive molecules. Based upon this preliminary data, we propose two Aims for our future studies. Aim 1 we will fractionate serum from female mice to identify a biological molecule from female serum required for LLC and CMT-167 sensitization to NK cell killing via TRAIL. The sensitization of LLC and CMT-167 tumor cells in female mice to the effects of TRAIL are proposed to contribute to the observed sex–differences in tumor growth and sensitivity to therapies (both chemotherapy and immunotherapy). For Aim 2, we will determine if the response to standard of care chemotherapies or anti-PD1 immunotherapy using orthotopic CMT-167 and LLC tumor models is dependent on sex. If a sex difference in response is observed, we will characterize the immune responses of male and female mice to lung tumors in the context of these drugs. In summary, this project aims to gain an understanding of the biological mechanisms behind the sex disparities in NSCLC progression and response to treatment, with the hopes of gaining knowledge to inform clinic decisions and treatment of the human disease.