WT mice were given B16-F10 (B16) melanoma cells or control vehicle and treated with control IgG, FRG, and/or anti–PD-1 antibodies (alone or in combination) and bispecific FRGxPD-1 antibody. Melanoma lung metastasis was evaluated 2 weeks later. (A) Schematic illustration of antibody treatment protocol in the course of B16 melanoma cell challenge and mouse sacrifice. (B) Representative lungs from mice treated with control IgG, FRG, and/or anti–PD-1 antibodies (alone or in combination) and bispecific FRGxPD-1 antibody. The antibodies were given at the noted doses by i.p. injection. (C) The number of pleural melanoma colonies was quantitated in the lungs from the mice in A. Each dot is representative of an individual animal. B is representative of at least 3 similar evaluations. The values in C represent the mean ± SEM of the evaluations represented by the individual dots in the lungs from the experiment representatively illustrated in B. *P < 0.05, ***P < 0.001 (1-way ANOVA with Tukey’s post hoc test).