PD1 blockade increases the therapeutic efficacy of TriVax. WT mice (4/group) were inoculated subcutaneously with B16, and vaccinated with Trp2₁₈₀TriVax (A) or Trp1₄₅₅TriVax (B). Anti-PD-L1 mAb (10F.9G2) was administered intraperitoneally on days 2, 4, 6, and 8 after each TriVax administration at 200 μg/dose. Nonvaccinated mice (No Vax) and Ova₅₅TriVax were included as controls. Arrows, days when TriVax administered; gray bars, time when anti–PD-L1 mAb was administered. Tumor sizes were determined in individual mice by measuring 2 opposing diameters and are presented as tumor areas in square millimeters. Points indicate means for each group of mice; and bars, SD. P values were calculated using 2-way ANOVA test comparing with the TriVax alone with TriVax plus anti–PD-L1 mAb. These experiments were repeated twice with similar results.