Macrophage-Targeted Therapy Unlocks Antitumoral Cross-talk between IFNγ-Secreting Lymphocytes and IL12-Producing Dendritic Cells.

Macrophages often abound within tumors, express colony-stimulating factor 1 receptor (CSF1R), and are linked to adverse patient survival. Drugs blocking CSF1R signaling have been used to suppress tumor-promoting macrophage responses; however, their mechanisms of action remain incompletely understood. Here, we assessed the lung tumor immune microenvironment in mice treated with BLZ945, a prototypical small-molecule CSF1R inhibitor, using single-cell RNA sequencing and mechanistic validation approaches.

Resident Kupffer cells and neutrophils drive liver toxicity in cancer immunotherapy.

Immunotherapy is revolutionizing cancer treatment but is often restricted by toxicities. What distinguishes adverse events from concomitant antitumor reactions is poorly understood. Here, using anti-CD40 treatment in mice as a model of T1-promoting immunotherapy, we showed that liver macrophages promoted local immune-related adverse events.

Tumor-Promoting Ly-6G SiglecF Cells Are Mature and Long-Lived Neutrophils.

Myeloid cells co-expressing the markers CD11b, Ly-6G, and SiglecF can be found in large numbers in murine lung adenocarcinomas and accelerate cancer growth by fostering tumor cell invasion, angiogenesis, and immunosuppression; however, some of these cells' fundamental features remain unexplored. Here, we show that tumor-infiltrating CD11b Ly-6G SiglecF cells are bona fide mature neutrophils and therefore differ from other myeloid cells, including SiglecF eosinophils, SiglecF macrophages, and CD11b Ly-6G myeloid-derived suppressor cells. We further show that SiglecF neutrophils gradually accumulate in growing tumors, where they can live for several days; this lifespan is in marked contrast to that of their SiglecF counterparts and neutrophils in general, which live for several hours only.