Effects of anti-IFNγ mAb on the antitumor activity of treatment with lenvatinib only, anti-PD-1 mAb only, or their combination in the RAG model. Mice bearing RAG tumors were injected intraperitoneally with anti-IFNγ mAb or control IgG1 at 300 μg/animal 2 days before allocation to treatment groups (i.e., day −1) and twice weekly thereafter. On day 1, when TVs were approximately 90 mm3, mice were allocated randomly into treatment groups. Lenvatinib was orally administered at 10 mg/kg once daily, and anti-PD-1 mAb was injected intraperitoneally at 200 μg/mouse twice weekly for 4 weeks. A, TVs of control IgG-treated (left) and anti-IFNγ mAb–treated (right) groups. Data are presented as means ± SEM (n = 8). *, P < 0.05; **, P < 0.01; ****, P < 0.0001 versus control group; ##, P < 0.01; ####, P < 0.0001 versus combination treatment animals (Dunnett multiple comparison test after logarithmic transformation). TVs of mice that were found dead or were euthanized preemptively during the treatment period were imputed by last observation carried forward (control IgG1: 3 mice in control group, 4 mice in anti-PD-1 mAb group; anti-IFNγ mAb: 1 mouse in control group, 1 mouse in anti-PD-1 mAb group). B, Relative body weight of control IgG-treated (left) and anti-IFNγ mAb-treated group (right). Data are presented as means ± SEM. Combo, combination; LEN, lenvatinib.