PDCD1 and neoplasm: In the tumor, PD-1 blockade led to more GZMB+ and CXCL13+ CD4+ cells, and fewer Tregs, in post-atezolizumab tumors versus untreated standard-of-care tumors (22% vs. 0%, 40% vs. 21%, 12% vs. 50% in branch C; Figure 3B, left column), supporting intratumoral mobilization of cytotoxic CD4+ effectors.