Combined treatment of anti-PD-1/CD137 mAb and chemotherapeutic drugs induced complete remission of established tumors. A, The experimental schematic: mice (10 mice/group) were transplanted i.p. with 5 × 106 ID8 cells (B) or s.c. with 5 × 105 4 T1 cells (C and D) on day 1 and were pretreated with a dose of cisplatin (10 mg/kg) or paclitaxel (10 mg/kg) on day 8 and followed by three doses of anti-PD-1/GITR mAb (250 μg/mice) on day 9, 12 and 16. The mice were treated with PBS, cisplatin, paclitaxel or anti-PD-1/GITR mAb alone as controls. B, The overall survival of mice in the ID8 cancer model. C, The tumor growth curve in the 4 T1 breast cancer model. D, The overall survival of mice in the 4 T1 breast cancer model. Data are representative of 2 independent experiments. *P < 0.05, ***P < 0.001, compared to control-treated mice.