Related Experiment Video
Updated: Sep 17, 2025
Studying Interactions between Myeloid Cells and CAR T Cells In Vitro and In Vivo
Published on: July 25, 2025
Exploitable mechanisms of antibody and CAR mediated macrophage cytotoxicity
Tianyi Liu1,2, Meng Zhang1,2, Tatyanah Farsh1,2
1University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, 94158, USA.
Abstract:
Macrophages infiltrate solid tumors and either support survival or induce cancer cell death through phagocytosis or cytotoxicity. To uncover regulators of macrophage cytotoxicity towards cancer cells, we perform two co-culture CRISPR screens using CAR-macrophages targeting different tumor associated antigens. Both identify ATG9A as an important regulator of this cytotoxic activity. In vitro and in vivo, ATG9A depletion in cancer cells sensitizes them to macrophage-mediated killing. Proteomic and lipidomic analyses reveal that ATG9A deficiency impairs the cancer cell response to macrophage-induced plasma membrane damage through defective lysosomal exocytosis, reduced ceramide production, and disrupted caveolar endocytosis. Depleting non-cytotoxic macrophages using CSF1R inhibition while preventing ATG9A-mediated tumor membrane repair enhances the anti-tumor activity of therapeutic antibodies in mice. Thus, macrophage cytotoxicity plays an important role in tumor elimination during antibody or CAR-macrophage treatment, and inhibiting tumor membrane repair via ATG9A, particularly in combination with cytotoxic macrophage enrichment through CSF1R inhibition, improves tumor-targeting macrophage efficacy.
Insights
Autophagy gene ATG9A regulates cancer cell defense against macrophage killing. Inhibiting ATG9A enhances cancer cell sensitivity to macrophage-mediated death, improving anti-tumor immunity when combined with CSF1R inhibitors.
Area of Science:
- Immunology
- Cancer Biology
- Cell Biology
Background:
- Macrophages are key immune cells in tumors, influencing cancer cell survival or death.
- Macrophage-mediated cytotoxicity is crucial for anti-tumor immunity, but its regulators are not fully understood.
Purpose of the Study:
- To identify regulators of macrophage cytotoxicity against cancer cells.
- To explore therapeutic strategies combining macrophage-based therapies with tumor intrinsic mechanisms.
Main Methods:
- Utilized CRISPR screens in co-culture systems with CAR-macrophages.
- Performed in vitro and in vivo experiments with ATG9A-depleted cancer cells.
- Conducted proteomic and lipidomic analyses.
- Investigated combined therapies involving CSF1R inhibition and ATG9A modulation in mouse models.
Main Results:
- Autophagy gene ATG9A was identified as a critical regulator of cancer cell resistance to macrophage killing.
- ATG9A deficiency in cancer cells sensitized them to macrophage-induced death.
- ATG9A deficiency impaired cancer cell membrane repair mechanisms, including lysosomal exocytosis, ceramide production, and caveolar endocytosis.
- Combined inhibition of CSF1R (to enrich cytotoxic macrophages) and ATG9A-mediated tumor membrane repair enhanced anti-tumor antibody efficacy in mice.
Conclusions:
- Macrophage cytotoxicity is vital for tumor elimination in CAR-macrophage and antibody-based therapies.
- Targeting ATG9A to impair tumor membrane repair, especially when combined with strategies that enhance cytotoxic macrophage populations, can significantly improve the efficacy of cancer immunotherapies.
Related Concept Videos
01:27Cytotoxic T Cells-mediated Immune Response
Immunological surveillance is the ability of immune cells to monitor and eliminate infected cells with intracellular pathogens, neoplastically transformed cells, and cells with non-self antigens. Cytotoxic T cells and NK...
01:40Cell-mediated Immune Responses
01:26Antibody Actions
Neutralization
Antibodies can bind to pathogens, preventing them from infecting host cells. This process...
01:31Defense Against Bacterial Pathogens
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...