Fig. 1.

Radiation sensitizes nonimmunogenic tumors to immune checkpoint therapy. (A) Growth kinetics of KP9093.PADRE cells irradiated in vitro with 0, 2, 4, or 9 Gy. Numbers on the growth curves indicate the numbers of tumor clone lines that were rejected (Top). Cells were injected into mice at >95% viability. Representative data are shown as average tumor diameter ± SEM; n ≥ 4 per group. Bar graphs summarize results from multiple biological repeats (Bottom). (B) Bulk tumor lines receiving the indicated dose of radiation were single-cell-cloned by limiting dilution, and multiple clones from each bulk line were inoculated into Rag2^−/− mice (red), syngeneic WT mice (black), or WT mice treated with anti–CTLA-4/anti–PD-1 (blue). Representative data are shown as the tumor diameter of individual clones. Bar graphs show cumulative percent rejection from multiple biological replicates. ns, not significant; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.