Figure 1:

Increasing the proportion of py117 cell that are sensitive to radiation and checkpoint therapy results in increased radiation sensitivity (18). A) Increasing the proportion of Py117 tumor cells out of a total of 1×10⁶ increased RT sensitivity to 12 Gy (arrow). Images of mice depict immunosuppressive Py8119 tumors (red) down to the immune sensitive Py117 tumors (green) and the accompanying growth curves after RT are show below. B) Response curves were modeled using single cell line growth curves revealing that tumors with 50% or greater Py117 cells responded better to RT than predicted. C) Tumors with 5×10⁵ Py8119 cells with an additional 2×10⁵ Py117 cells responded better than tumors with 5×10⁵ Py8119 cells alone, confirming the sensitizing or licensing effect of Py117 cells. D-E) Tumors with the greatest response and smaller size 10 days after 12 Gy exhibited an increased proportion of CD8⁺ T cells and decreased proportion of CD45⁺CD11b⁺F4/80⁺ macrophages. F) Relative PD-L1 expression on tumor cells increased with increasing proportions of Py117 cells, suggesting an immune response form increased interferon. G) The presence of Py117 cells in tumors resulted in greater than expected MHCI antigen presentation on tumor cells compared to tumors with only Py8119 tumor cells alone. * p<0.05, **<0.01, and *** p<0.0001 on analysis of variance with pairwise comparisons.