Immune checkpoint therapy (ICT) has the power to eradicate cancer, but the mechanisms that determine effective therapy-induced immune responses are not fully understood. Here, using high-dimensional single-cell profiling, we interrogate whether the landscape of T cell states in the peripheral blood predict responses to combinatorial targeting of the OX40 costimulatory and PD-1 inhibitory pathways. Single-cell RNA sequencing and mass cytometry expose systemic and dynamic activation states of therapy-responsive CD4⁺ and CD8⁺ T cells in tumor-bearing mice with expression of distinct natural killer (NK) cell receptors, granzymes, and chemokines/chemokine receptors. Moreover, similar NK cell receptor-expressing CD8⁺ T cells are also detected in the blood of immunotherapy-responsive cancer patients. Targeting the NK cell and chemokine receptors in tumor-bearing mice shows the functional importance of these receptors for therapy-induced anti-tumor immunity. These findings provide a better understanding of ICT and highlight the use and targeting of dynamic biomarkers on T cells to improve cancer immunotherapy.

SummaryFactors that govern the complex formation of memory T cells are not completelyunderstood. A better understanding of thedevelopment of memory Tcell hetero-geneity is however required to enhance vaccination and immunotherapy ap-proaches. Here we examined the impact of pathogen- and tissue-specific cueson memory CD8+T cell heterogeneity using high-dimensional single-cell mass cy-tometry and a tailored bioinformatics pipeline. We identified distinct populationsof pathogen-specific CD8+T cells that uniquely connected to a specific pathogenor associated to multiple types of acute and persistent infections. In addition, thetissue environment shaped the memory CD8+T cell heterogeneity, albeit to alesser extent than infection. The programming of memory CD8+T cell differenti-ation during acute infection is eventually superseded by persistent infection.Thus, the plethora of distinct memory CD8+T cell subsets that arise upon infec-tion is dominantly sculpted by the pathogen-specific cues and further shaped by the tissue environment.