Resident Kupffer cells and neutrophils drive liver toxicity in cancer immunotherapy

Immunotherapy is revolutionizing cancer treatment but can trigger toxicities that remain poorly understood. Here, by comprehensively analyzing mouse models following anti-CD40 therapy, we found an interdependent induction of the cytokines IFN-g and IL-12, which caused inflammatory pathology in various tumor-free tissues. In the liver, Kupffer cells mediated toxicity by sensing lymphocyte-derived IFN-g and producing IL-12, highlighting the vulnerability of tissue-resident macrophages to promote toxicity when reacting to proinflammatory cues. Conversely, dendritic cells drove tumor control but were dispensable for toxicity. We further show that liver macrophages, IL-12, and IFN-g were not toxic themselves, but prompted a neutrophil response that determined the severity of tissue damage. Similar inflammatory pathways characterized immunotherapy-related adverse events in cancer patients. These findings implicate resident macrophages and neutrophils as mediators and effectors of aberrant inflammation, and suggest distinct cellular mechanisms of toxicity and antitumor immunity. Overall design: Bulk RNAseq of neutrophils either sufficient or deficient for IFNgR1, isolated from the livers of MC38 tumor-bearing mice treated with anti-CD40 agonist immunotherapy. Mice were 50:50 bone marrow chimeras harboring both wild type and Ifngr1-/- immune cells. Each mouse (2-9) yielded samples n.1 (wild type) and n.2 (Ifngr1-/-).