Since PD-1 is not clearly expressed on most splenic tumor-specific T cells (Fig. 1) [8, 25, 28], and migration of T cells from periphery into tumors is required for αPD-L1 transient antitumor activity [8], we sought other markers to identify peripheral tumor-specific T cell subsets that mediate immunotherapy response. Here, PDCD1 is linked to neoplasm.