PD-1 defines a distinct, functional, tissue-adapted state in Vδ1+ T cells with implications for cancer immunotherapy.

Checkpoint inhibition (CPI), particularly that targeting the inhibitory coreceptor programmed cell death protein 1 (PD-1), has transformed oncology. Although CPI can derepress cancer (neo)antigen-specific αß T cells that ordinarily show PD-1-dependent exhaustion, it can also be efficacious against cancers evading αß T cell recognition. In such settings, γδ T cells have been implicated, but the functional relevance of PD-1 expression by these cells is unclear. Here we demonstrate that intratumoral TRDV1 transcripts (encoding the TCRδ chain of Vδ1+ γδ T cells) predict anti-PD-1 CPI response in patients with melanoma, particularly those harboring below average neoantigens. Moreover, using a protocol yielding substantial numbers of tissue-derived Vδ1+ cells, we show that PD-1+Vδ1+ cells display a transcriptomic program similar to, but distinct from, the canonical exhaustion program of colocated PD-1+CD8+ αß T cells. In particular, PD-1+Vδ1+ cells retained effector responses to TCR signaling that were inhibitable by PD-1 engagement and derepressed by CPI.