CD8A and neoplasm: Quantitative analysis revealed that the percentage of CD3+CD8+ T cells within tumors treated with anti–PD-1 plus TRACER (18.5% ± 10.3% of tissue area in the field of view) was significantly higher than tumors treated with PBS (1.8% ± 1.4%) or anti–PD-1 plus DBCO–anti–4-1BB with free Maz (3.9% ± 2.4%), whereas neither anti–PD-1 plus anti–4-1BB nor anti–PD-1 plus DBCO–anti–4-1BB with free Maz induced tumor infiltration of CD3+CD8+ T cells when compared with the PBS control group (Figure 3F).