Activity of tumor-associated macrophage depletion by CSF1R blockade is highly dependent on the tumor model and timing of treatment.
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ABSTRACT: Tumor-associated macrophages (TAMs) are abundant in solid tumors where they exhibit immunosuppressive and pro-tumorigenic functions. Inhibition of TAM proliferation and survival through CSF1R blockade has been widely explored as a cancer immunotherapy. To further define mechanisms regulating CSF1R-targeted therapies, we systematically evaluated the effect of anti-CSF1R treatment on tumor growth and tumor microenvironment (TME) inflammation across multiple murine models. Despite substantial macrophage depletion, anti-CSF1R had minimal effects on the anti-tumor immune response in mice bearing established tumors. In contrast, anti-CSF1R treatment concurrent with tumor implantation resulted in more robust tumor growth inhibition and evidence of enhanced anti-tumor immunity. Our findings suggest only minor contributions of CSF1R-dependent TAMs to the inflammatory state of the TME in established tumors, that immune landscape heterogeneity across different tumor models can influence anti-CSF1R activity, and that alternative treatment schedules and/or TAM depletion strategies may be needed to maximize the clinical benefit of this approach.
SUBMITTER: O'Brien SA
PROVIDER: S-EPMC8289806 | biostudies-literature |
REPOSITORIES: biostudies-literature
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