Abstract P4-07-29: Reactive Oxygen Species (ROS) pathway is associated with aggressive cancer biology, elevated immune response, and with worse survival in ER-positive/HER2-negative breast cancer
Authors: Oshi Masanori , Wu Rongrong , Yamada Akimitsu , Yan Li , Ishikawa Takashi , Endo Itaru , Takabe Kazuaki 
Published: March 2022

Abstract
Background: Reactive oxygen species (ROS) in tumor microenvironment are known to promote many aspects of cancer progression. On the other hand, excessive accumulation of ROS can induce cancer cell apoptosis. To our knowledge, clinical relevance of ROS response signaling in breast cancer has never been studied in multiple large patient cohorts. Here, we hypothesized that the high ROS pathway score reflect tumor aggressiveness, thus, it predicts worse survival in breast cancer patients. Methods: A total of 6245 breast cancer patients from three independent cohorts (GSE96058, METABRIC, and TCGA) were analyzed. We defined the ROS pathway score by the degree of enrichment by Gene Set Variant Analysis (GSVA) and median was used to divide high vs low score groups in each cohort. Results: The ROS score was significantly associated with aggressive clinical factors, such as triple-negative breast cancer (TNBC) subtype, Nottingham histological grade, American Joint Committee on Cancer (AJCC) Stage and lymph node metastasis consistently in both GSE96058 and METABRIC (all p &lt; 0.001). High ROS score was significantly associated with worse overall survival (OS) in the GSE96058 (hazard ratio (HR) = 3.59, 95% confidence interval (CI); 2.47-5.20, p &lt; 0.001), as well as OS (HR = 1.55, 95%CI; 1.16-2.07, p = 0.002), disease-free survival (HR = 1.63, 95%CI; 1.10-2.43, p = 0.016), and disease-specific survival (HR = 2.57, 95%CI; 1.75-3.77, p &lt; 0.001) in the METABRIC cohort. Subgroup analysis revealed that a high ROS score was significantly associated with worse OS in ER-positive/HER2-negative breast cancer in both cohorts. High ROS ER-positive/HER2-negative breast cancer was significantly associated with high level of intratumor heterogeneity (p = 0.013), homologous recombination deficient (HRD) (p &lt; 0.001), and mutation-related score (silent and non-silent mutation rate (p = 0.003 and 0.011, respectively), fraction altered (p = 0.038), and single-nucleotide variant (SNV) neoantigens (p = 0.006)) in the TCGA cohort. In agreement, high ROS ER-positive/HER2-negative breast cancer significantly enriched cell proliferation-related gene sets; E2F targets, G2M checkpoint, and MYC targets v1 and v2 consistently in both GSE96058 and METABRIC cohorts (all false discovery rate (FDR) &lt; 0.25). On the other hand, high ROS ER-positive/HER2-negative tumors were associated with elevated infiltration of multiple immune cells, including anti-cancer immune cells (CD8+ T cell, CD4+ memory T cell, M1 macrophage, dendritic cell, gamma-delta T cell), as well as pro-cancer immune cells (regulatory T cell, T helper type2 cell, and M2 macrophage) and with high level of cytolytic activity (CYT) consistently in both cohorts (all p &lt; 0.001). Those tumors also enriched immune-related pathway (Interferon (IFN)-α response, IFN-γ response, allograft rejection, complement, IL6/JAK/STAT3 signaling, and inflammatory response) consistently in both cohorts (all FDR &lt; 0.25). Finally, high ROS ER-positive/HER2-negative breast cancer was significantly associated with high expression of immune checkpoint molecules including PD-1, PD-L1 and PD-L2, CTLA4, IDO1, LAG3, BTLA, HLA-A, and TIGIT, in (all p &lt; 0.005). Conclusion ROS pathway is associated with cancer aggressiveness, elevated immune response, and with worse survival in ER-positive/HER2-negative breast cancer.
Citation Format: Masanori Oshi, Rongrong Wu, Akimitsu Yamada, Li Yan, Takashi Ishikawa, Itaru Endo, Kazuaki Takabe. Reactive Oxygen Species (ROS) pathway is associated with aggressive cancer biology, elevated immune response, and with worse survival in ER-positive/HER2-negative breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-07-29.