OX40 triggering protects from tumor challenge. 5 × 10⁴ CT26 colon carcinoma cells were injected s.c. into the right flank of BALB/c mice 7 d after the systemic administration of 1 mg anti-OX40 mAb OX86 (A) or anti-CD25 mAb PC61 (B). As mock treatment, rat IgG was injected. Tumor growth was monitored twice per week. The percentages of tumor-free mice are given at the indicated time points. Six mice were included in each experimental group. Results are from one representative out of three independent experiments.