Despite having largely distinct TCR repertoires, Tfh and Treg cells share region-dependent gene expression programs, including the upregulation of exhaustion-associated genes such as PDCD1, CTLA4, and TIGIT. Notably, the authors identified a key finding: tumor-infiltrating Tfh cells were clonally linked to TCF7+PDCD1+ stem-like progenitor populations residing in tumor-draining lymph nodes, suggesting a lineage relationship and a tissue-specific differentiation trajectory [134]. This evidence concerns the gene PDCD1 and neoplasm.