PDCD1 and neoplasm: The tumor-draining lymph node (TdLN) is important for a robust RT or anti-PD-1/L1 stimulated immune response.20–24 More recent studies have shown that the TdLN acts as a reservoir for stem-like T cells.22,25,26 This population of stem-like T cells in the TdLN serve as developmental precursors for the intra-tumoral population, and they continuously migrate from the TdLN to the tumor under basal conditions.25 Once in the tumor they undergo further differentiation into TE.