Spatially organized SPP1⁺ macrophage–CD1C⁺ conventional dendritic cell interactions shape an immunosuppressive niche in EGFR-mutant NSCLC

EGFR-mutant non-small cell lung cancer (NSCLC) shows limited benefit from immune checkpoint inhibitors (ICIs), but the spatial immune mechanisms associated with resistance remain unclear. We applied a single-cell-resolution multimodal spatial proteomic–transcriptomic framework integrating imaging mass cytometry (IMC; n = 12) and Xenium-based spatial transcriptomics ( n = 8) to map the tumor microenvironment of EGFR-mutant NSCLC after chemoimmunotherapy. Single-cell RNA sequencing datasets ( n = 11) were incorporated for cell–cell interaction inference and pathway analysis. Spatial profiling showed that non-major pathologic response (non-MPR) tumors were enriched for immunosuppressive cellular neighborhoods containing SPP1⁺ macrophages and CD1C⁺ conventional dendritic cells (cDCs). These CD1C⁺ cDCs exhibited reduced immune activation and antigen-presentation programs. Spatial distance analysis showed closer proximity between SPP1⁺ macrophages and CD1C⁺ cDCs in non-MPR tumors than in MPR tumors. Ligand–receptor analysis identified candidate macrophage-derived signals associated with altered CD1C⁺ cDC states, which was supported by Xenium-based co-localization and reduced pro-inflammatory programs in spatially interacting CD1C⁺ cDCs. Together, these findings suggest that an SPP1⁺ macrophage–CD1C⁺ cDC spatial niche is associated with reduced immunotherapy response and may inform future strategies to restore DC immunogenicity in EGFR-mutant NSCLC.