Summary Lung cancer is the number one cancer diagnosis at Wake Forest Baptist Comprehensive Cancer Center (WFBCCC).  Our Office of Cancer Health Equity found that African Americans (AAs) in our region have incidence and mortality rates 15.1% and 15.5% higher, respectively, than the already elevated lung cancer rates among AAs in the U.S. Understanding health disparities in our patients, 14% of whom are AA, and identifying targeted therapeutics that can overcome them are among the top priorities of WFBCCC, consistent with the stated mission of NCI as described in PAR-18-655.  Clinically, immune checkpoint blockade (ICB) drug treatment can benefit 30% of non-small cell lung cancer (NSCLC) patients.  At WFBCCC, AA patients have a relatively better response to ICB compared to Caucasian American (CA) patients, suggesting ICB has the potential to eliminate cancer disparities.  To gain insight into this clinical observation we investigated the infiltrating immune tumor microenvironment (TME) between AAs and CAs using the state-of-the-art single cell RNA sequencing (scRNA-Seq).  Preliminary analysis of 4 CA and 4 AA samples from patients with NSCLC showed marked difference in the immune TME between the two racial groups.  Somatic mutations in tumor cells play important roles in immune regulation and the interactions between tumor cells and TME.  Specific genetic mutations in the tumor may impact the immune landscape, and consequently associate with cancer disparities.  For example, we recently reported a higher TP53 mutation rate and tumor mutation burden in AA cancer patients.  In this project, we propose to validate these preliminary observations with data from a larger cohort of lung cancer patients.  Specific aim 1 will characterize and contrast the TME landscapes of AA and CA patients with NSCLC.  Additional samples from both races will be collected and profiled using the scRNA-Seq technique.  Specific aim 2 will generate the mutation profiles of the patient samples with the objective to associate specific mutational events, or patterns of mutations, with the characterized immune TME (SA1) by patient race.  Our overarching hypothesis is that an immunosuppressive TME in AA patients with NSCLC has been a contributing factor to racial health disparities, but may be overcome by newer ICB-based immunotherapies.  The data and observations from this developmental R21 will be interpreted in the context of the ongoing clinical association studies.  This proposal will also produce a valuable scRNA-Seq dataset for the AA minority NSCLC population and be made available to the cancer research field.  Altogether, the proposed study has the potential to benefit an underserved patient population and provide a basis for generating hypotheses for future R01 proposals on lung cancer health disparities.