Mice cured with anti-CD137 mAb develop long-lasting antitumor immunity. (A-B) BALB/c mice treated and cured by anti-CD137 mAb therapy for more than 100 days or naive mice were (re)challenged subcutaneously with 5 × 10⁶ A20 tumors at a different site from original tumor challenge. Mice were then monitored for tumor growth (A, mean ± SEM) and overall survival (B). (C-D) After tumor rechallenge, splenocytes from αCD137-cured mice or control splenocytes from naive mice were harvested, restimulated in vitro with irradiated A20 tumor cells for 24 hours, and assessed for intracellular IFN-γ secretion by flow cytometry. Dot plots from FACS analysis show the proportion of IFN-γ–positive cells among all CD3⁺ T cells (C) and CD8 T cells (D).