Boosting T-cell response through OX40 engagement can substitute cellular vaccine in mice previously treated with autologous tumor plus IL-12–secreting bystander cells.

On days 1, 5, and 15 after tumor challenge, BALB/c mice were immunized with the indicated irradiated tumor vaccines. On day 30, mice received an additional dose of cellular vaccine (open symbols) or were injected intraperitoneally with 200 μg anti-OX40 mAb (closed symbols). As controls, nonvaccinated tumor-bearing mice were left untreated or received mAb against OX40. Mice were evaluated for tumor-free survival over a 4-month observation period. Eight mice were included in each group.