Figure 2

Combination of RNA immunotherapy with radiation allows for the eradication of large established tumors and induction of epitope spreading. (A) C57BL/6 mice (n = 8 per group) were challenged subcutaneously on the right limb with 0.3 × 10⁶ syngenic E.G7-OVA tumor cells. 13 days after tumor challenge (at a median tumor volume of 150 mm³) mice were treated either with OVA mRNA vaccine (32 μg), radiation (6 Gy total, divided into 3 equal fractions on 3 consecutive days) or radioimmunotherapy as indicated (with first vaccination given 6h before first radiation). Untreated mice served as a control. *** - p < 0.001 (B) Median survival time of mice analysed in Figure 2A. (C) C57BL/6 mice (n = 8 per group) were challenged subcutaneously on the right limb with 0.5 × 10⁶ syngenic E.G7-OVA tumor cells. 13 days after tumor challenge (at a median tumor volume of 300 mm³) mice were treated either with local radiation (8 Gy total, divided into 4 equal fractions on 4 consecutive days) or radioimmunotherapy as indicated (64 μg/vaccination, with first vaccination given 6 h before first radiation). Untreated mice served as a control. ** - p < 0.01 (D) All complete responders, which were tumor free after combination therapy (day 106), were re-challenge subcutaneously with 1 × 10⁵ parenteral OVA-negative EL-4 cells. Tumor growth was monitored by measuring the tumor size in 3 dimensions using calipers. All presented data show representative results of at least two independent experiments.