Abstract 3919: Targeting tissue-resident macrophage progenitors by anti-IL34 restores anti-tumor immunity and suppresses tumor growth

Abstract

Abstract Macrophages play important roles in tumor microenvironment, where they can promote immune suppression, tumor growth and resistance to checkpoint inhibitor therapy and are the focus of efforts to develop novel cancer therapeutics. Strategies to inhibit macrophage accumulation to suppress tumor growth by blocking their recruitment from circulation have been only partially effective, leading to the identification of roles in tumor progression for tissue resident macrophages that are seeded during embryonic development. We examined the origins of lung tumor associated macrophages using lineage tracing, flow cytometry, and single cell sequencing. By comparing gene expression profiles of resident F4/80hi Lyve1+ Ly6C- macrophages and Ly6C+ F4/80lo CCR2+ recruited macrophages in subcutaneous, lung, central nervous and renal normal and tumor tissues, we identified generic tissue resident macrophage and recruited macrophage transcriptomic signatures, revealing that resident macrophages are characterized by signatures of Myc driven proliferation, fatty acid and cholesterol metabolism and immune suppression, while recruited macrophages are characterized by signature of inflammation and immune stimulation. Resident macrophages were associated with worse outcomes in cancer patients than recruited macrophages. Single cell sequencing and flow cytometry of genetically engineered mouse models of CC10-Cre KrasG12D;p53-/- and SPC-Cre KrasG12D lung cancer revealed that lung tumor progression was characterized by extensive expansion of immune suppressive, Ki67+ resident alveolar macrophages and loss of T cells in the lung. Single cell transcriptomics identified IL-34 expressed exclusively by tumor cells as a possible driver of alveolar macrophage proliferation and IGF1 expressed by tumor associated alveolar macrophages as a possible regulator of tumor cell proliferation. Accordingly, blockade of IL-34 profoundly reduced tissue resident macrophage proliferation, stimulated recruitment of activated T cells, and suppressed growth of KrasG12D driven tumors. Analysis of TCGA data sets revealed that expression of IGF1 or IL34 was associated with reduced survival in lung, kidney, liver, head and neck and ovarian cancer. These studies identify key roles for IL-34 and IGF1 in solid tumor progression and suggest new therapeutic targets for the development of therapeutic strategies to stimulate anti-cancer immunity. Citation Format: Hui Chen, Jaroslav Zak, Mark Paradise, Guangfang Wang, John Teijaro, Mark Onaitis, Judith Varner. Targeting tissue-resident macrophage progenitors by anti-IL34 restores anti-tumor immunity and suppresses tumor growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3919.