Abstract 3278: Neoadjuvant EGFR-TKI therapy reshapes tumor immune microenvironment in resectable EGFR-positive non-small cell lung cancer

Abstract Background: Patients with EGFR-positive non-small cell lung cancer (NSCLC) do not respond as well to immunotherapy as patients without an EGFR mutation. Nevertheless, recent studies indicate that subsequent immunotherapy following EGFR-TKI treatment may be effective in EGFR-positive NSCLC. Given the critical role of the tumor immune microenvironment (TIME) in determining immunotherapy efficacy, understanding the influence of EGFR-TKI on the TIME in NSCLC remains an important yet unresolved area of research. Methods: Single-cell RNA sequencing (scRNA-seq) was performed to investigate the TIME of NSCLC patients. Post-treatment samples were analyzed from three EGFR-positive NSCLC patients treated with neoadjuvant EGFR-TKI (Neo-TKI) and two EGFR-negative NSCLC patients treated with neoadjuvant immunotherapy (Neo-IO). The scRNA-seq datasets of seven EGFR-positive NSCLC patients undergoing surgery only (TN-TKI) from the National Genomics Data Center (CRA001477, CRA001963) and six EGFR-negative NSCLC patients received surgery only (TN-IO) from the Gene Expression Omnibus (GSE131907) were analyzed to assess the TIME in treatment-naïve conditions. Results: A total of ∼173, 000 single cells were sequenced, revealing 6 subpopulations. Compared to TN-TKI samples, Neo-TKI samples showed a higher proportion of T and B cells, whereas the proportion of myeloid cells significantly decreased. Further analysis of T cell composition in Neo-TKI samples revealed a trend towards a higher prevalence of GZMK+CD8+T cells and enrichment of positive regulation of T cell activation pathway. The expression of TLS-associated genes in CD4+ T cells was significantly elevated, along with the upregulation of immune-related pathways, such as B cell activation signaling and IL-17-related signaling, underscoring the immunomodulatory role of EGFR-TKI. Regarding B cell composition, Neo-TKI samples showed a higher proportion of germinal center B cells with an enrichment in positive regulation of B cell signaling pathway compared to TN-TKI samples. Notably, a shift in tumor-associated macrophages from an M2 phenotype to a neutral phenotype was observed in Neo-TKI samples, supporting the notion that EGFR-TKI impacts the immune landscape. Further, we conducted an exploratory analysis comparing the effects of immunotherapy and EGFR-TKI treatment on the TIME. Distinct differences were observed in cellular subpopulation distribution, enriched genes, and activated pathways. Overall, EGFR-TKI therapy appears to have a more pronounced effect on the TIME of patients with NSCLC. Conclusion: EGFR-TKI therapy alleviated the immunosuppressive TIME of EGFR-positive NSCLC, providing valuable insights for optimizing subsequent immunotherapy strategies in EGFR-positive NSCLC. Citation Format: Fang Wu, Dan Fan, Yingzhe Zhang, Wenliang Liu, Fenglei Yu, Wen Hu, Yue Zeng, Yurong Peng, Chunhong Hu, Xianling Liu, Fang Ma, Chao Deng, Zhenhua Qiu, Shijiao Yao, Shuxing Wang, Xiaoqiao Lin, Aoxi Liang, Xinzhu Lin, Qian Guan, Han Yang, Yiyang Li. Neoadjuvant EGFR-TKI therapy reshapes tumor immune microenvironment in resectable EGFR-positive non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3278.