Spatial multiplex analysis of lung cancer reveals that regulatory T cells attenuate KRAS-G12C inhibitor–induced immune responses

Kirsten rat sarcoma virus (KRAS)–G12C inhibition causes remodeling of the lung tumor immune microenvironment and synergistic responses to anti–PD-1 treatment, but only in T cell infiltrated tumors. To investigate mechanisms that restrain combination immunotherapy sensitivity in immune-excluded tumors, we used imaging mass cytometry to explore cellular distribution in an immune-evasive KRAS mutant lung cancer model. Cellular spatial pattern characterization revealed a community where CD4 + and CD8 + T cells and dendritic cells were gathered, suggesting localized T cell activation. KRAS-G12C inhibition led to increased PD-1 expression, proliferation, and cytotoxicity of CD8 + T cells, and CXCL9 expression by dendritic cells, indicating an effector response. However, suppressive regulatory T cells (T regs ) were also found in frequent contact with effector T cells within this community. Lung adenocarcinoma clinical samples showed similar communities. Depleting T regs led to enhanced tumor control in combination with anti–PD-1 and KRAS-G12C inhibitor. Combining T reg depletion with KRAS inhibition shows therapeutic potential for increasing antitumoral immune responses.