CD19 and neoplasm: To assess the anti-tumor efficacy of CD19.BBz and CD19.BBz.PD-L1 CAR T cells, we applied an experimental procedure as shown in Figure 5A. Compared with the CD19.BBz CAR T cell treatment group, the tumor burden in the CD19.BBz.PD-L1 CAR T cell treatment group significantly decreased, the luciferase activity reduced approximately 10-fold on day 7 and 100-fold on day 14 (Figure 5B).