Abstract 4077: Immune suppressive phenotypes and pre-existing bystander T cell repertoire in early-stage lung adenocarcinoma revealed by integrative single-cell profiling

Abstract Lung adenocarcinomas (LUADs) constitute the most frequently diagnosed lung cancer subtype and are typified by poor clinical outcome and inferior response to therapy. Strategies to treat LUAD at its earliest stages heavily rely on improved understanding of its pathogenesis. Accumulating evidence shows that progression of cancers, including LUADs, is tightly linked to a dynamic interplay between cancer cells and the tumor immune microenvironment (TIME), which can block activation of tumor-infiltrating T cells (TILs), thereby hindering an effective anti-tumor immune response. Yet, how the TIME is shaped and the mechanisms mediating immune evasion in early-stage LUAD remain poorly understood. To fill this void, we dissected the phenotypic and clonotypic states as well as interaction networks of TILs by performing deep cellular and molecular profiling of 225,641 T cell transcriptomes and their T cell receptor (TCR) repertoire in 16 early-stage LUADs and matched normal lung (NL) samples using simultaneous single-cell RNA and TCR sequencing (scRNA/TCR-seq). Clustering analysis revealed a highly heterogeneous T cell landscape with distinct cell states identified including naïve, effector, regulatory, helper and exhausted cell subsets, as well as cellular phenotypes indicating stress and interferon response. The landscape of TILs in LUAD tissues was far more heterogeneous when compared to NLs, and the compositions and phenotypes of TILs differed significantly across patients and in association with clinicopathological variables. Relative to NLs, LUADs were specifically enriched with regulatory and stress response subsets, whereas fractions of cytotoxic T cell subsets (e.g., CD4+ CTLs, CD8+ tissue-resident memory/TRMs, and CD8+ natural killer T/NKT cells) were decreased. scTCR-seq analysis revealed significantly increased TCR clonotype diversity and reduced clonality in LUADs compared to NLs. We then tracked phenotype transitions of TILs by integrative analysis of TCR clonotypes and transcriptional states. Intriguingly, expanded TCR clonotypes were mostly TILs with effector phenotypes that were largely shared between LUADs and NLs, suggesting that their clonal expansion may not be tumor-specific. Of note, expanded clones were also enriched with immunosuppressive phenotypes (e.g., regulatory, exhausted CD8, and stress response T cells). In contrast, we found that contracted TCR clonotypes were characterized by memory/effector phenotypes. Together, our results reveal and characterize a diverse TIL landscape in early-stage LUAD encompassing a pre-existing and expanded T cell compartment that is likely tumor-unspecific, as well as switching in T cell phenotypes, and that together comprise viable targets for early immunotherapeutic interception of this malignancy. Citation Format: Guangchun Han, Ansam Sinjab, Dapeng Hao, Lorena Gomez Bolanos, Enyu Dai, Luisa Maren Solis, Edwin Parra, Stephen Swisher, Tina Cascone, Boris Sepesi, Junya Fujimoto, Steven Dubinett, Ignacio Wistuba, Christopher Stevenson, Avrum Spira, Humam Kadara, Linghua Wang. Immune suppressive phenotypes and pre-existing bystander T cell repertoire in early-stage lung adenocarcinoma revealed by integrative single-cell profiling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4077.