Figure 1.
Higher radiation doses in combination with intratumoral α-OX40 control the growth of local (primary) tumors, improve survival rates, and produce fewer lung metastases. A-C, Mice (8 per group) were injected s.c. with 0.5 x 106 344SQ anti-PD1-resistant tumor cells into the right hind leg and given intratumoral injections of α-OX40 antibody (100 μg/injection) or rat IgG isotype control (100 μg/injection) on days 7, 11, 15, 19, and 23 after tumor inoculation. On day 7, the right hind legs of the mice were irradiated with one of the following schedules: A, three fractions of 5 Gy each; B, five fractions of 3 Gy each; or C, two fractions of 12 Gy each. 12Gyx2 + α-OX40 was superior to 5Gyx3 + α-OX40 group (two-way ANOVA, P<0.0001); 12Gyx2 was inferior to 12Gyx2 + α-OX40 group (two-way ANOVA, P=0.0453). D, Proportions of anti-PD1-resistant tumor-bearing mice surviving after the indicated treatments. E, lung metastasis counts enumerated at experimental endpoint (day 32) for different treatment groups as shown.