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 αβ T cells that ordinarily show PD-1-dependent exhaustion, it can also be efficacious against cancers evading αβ 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⁺ αβ 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.