Abstract 4832: Copy number amplification of OXPHOS genes drives tumor hypoxia in NSCLC

Abstract Non-small cell lung cancer (NSCLC) is a highly aggressive disease with a dismal prognosis associated with high rates of treatment resistance and disease recurrence. High-dose stereotactic body radiation therapy (SBRT) is the standard of care for locally advanced non-resectable NSCLC. However, as discovered more than six decades ago, tumor hypoxia is a significant barrier to effective radiation therapy. In the last decade, immunotherapy targeting immune checkpoints such as programmed cell death 1 (PD-1) has been introduced as first-line NSCLC treatment, yet long-term disease control occurs in less than 25% of patients. Therefore, understanding the mechanisms of the treatment resistance is essential to address the need for novel synergistic therapies to sensitize refractory NSCLC tumors to anti-cancer treatment. Tumor hypoxia has been associated with treatment resistance for decades, yet its role in the clinical management of NSCLC remains largely unexplored. The basis of tumor hypoxia has traditionally been attributed to the oxygen supply deficit as malformed tumor vasculature fails to meet the high demand of the rapidly proliferating tumor mass. However, our preliminary analysis of NSCLC patient datasets in the Cancer Genome Atlas (TCGA) revealed a significant correlation between high-level expression of nuclear genes encoding mitochondrial subunits essential for oxidative phosphorylation (OXPHOS) and the expression of validated hypoxia-regulated genes (Buffa hypoxia score). The oxygen-consumption expression signature was implemented in software that enables the calculation of numerous tumor microenvironment expression signatures, called tmesig. Furthermore, we have observed a direct positive correlation between the hypoxia expression signatures levels in NSCLC patient samples and the copy number amplification (CNA) of essential OXPHOS genes. Because mitochondrial function consumes up to 90% of available cellular oxygen, its activity may indirectly regulate oxygen availability in the tumor microenvironment by rapidly consuming oxygen upon its delivery to the tumor. Mechanistically, this leads to the hypothesis that OXPHOS gene amplification drives mitochondrial function, which may, in turn, promote tumor hypoxia and treatment resistance in NSCLC. Citation Format: Martin Benej, Katarina Benejova, McKenzie Kreamer, Jinghai Wu, Syed Ashraf, Caroline Wheeler, Rebecca Hoyd, Daniel Spakowicz, Nicholas C. Denko. Copy number amplification of OXPHOS genes drives tumor hypoxia in NSCLC. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4832.