COX-2 inhibition synergizes with radioimmunotherapy by promoting TCF1⁺CD8⁺ T cell infiltration in NSCLC

Upregulation of the COX-2/PGE2 axis impairs the therapeutic efficacy of radioimmunotherapy in mice. (A) CMT-167 cells were inoculated into the right hind leg of the mice, then radiotherapy, anti-PD-1, and radioimmunotherapy were given at the indicated times. (B) The tumor burden of mice was significantly reduced after radioimmunotherapy (n = 4). (C) The tumor weight was significantly reduced after radioimmunotherapy (n = 4). (D) The relationship between the PGE2 level in the tumor microenvironment after radioimmunotherapy (n = 4). (E) The PGE2 level in tumor tissue increased significantly after radioimmunotherapy (n = 4). (F, G) COX-2 overexpression significantly attenuated the efficacy of radioimmunotherapy in mice. (H) CMT-167 cells were inoculated into the right hind leg of the mice, then celecoxib, radioimmunotherapy, and celecoxib combined with radioimmunotherapy were given at the indicated times. (I) The tumor burden of mice was significantly reduced after radioimmunotherapy combined with celecoxib (n = 5). (J) The tumor weight was significantly reduced after radioimmunotherapy combined with celecoxib (n = 5). (K) Changes in the immune microenvironment of tumor-bearing mice after radioimmunotherapy combined with celecoxib (n = 5). (L) The images are representative of low and high intratumoral COX-2 expression. Scale bars: 20 μm. (M) Multiple immunofluorescence (mIF) images representative of T cell infiltration. Fused and single-channel mIF images of tumor tissues. Single staining images of CD8, TOX, TCF-1, and double-staining images of TCF1⁺CD8⁺ and TOX⁺CD8⁺ were included. Scale bars: 50 μm. Orange represents CK+ used to mark tumor cells. CK: orange, CD8: red, TOX: yellow, TCF-1: green. (N) Correlation between intratumoral COX-2 expression and TCF1⁺CD8⁺ cells. (O) TCF1⁺CD8⁺ T cells were associated with better OS under low COX-2 conditions; TCF1⁺CD8⁺ T cells were not significantly associated with OS. ns, P > 0.05; *P < 0.05; **P < 0.01; ***P < 0.001; iRT, radioimmunotherapy.