PD-1 antibody-bound progenitor-exhausted CD8+ T cells in lymph nodes boost PD-1-blockade anti-tumor immunity in gastrointestinal cancer.

While progenitor-exhausted T cells (Tpex) expressing TCF1 and PD-1 are crucial for the therapeutic effect of immune checkpoint inhibitors (ICIs) with therapeutic anti-PD-1 antibodies (aPD-1), the dynamics of ICI-bound Tpex are not fully understood. In this study, we investigate ICI-bound T cells in detail using combined sequencing analysis at the single-cell level. By analyzing samples from gastrointestinal cancer patients with or without ICI treatment, we find that Tpex are enriched in proximal lymph nodes (LNs) and proliferate at a high rate after ICI treatment. Importantly, aPD-1 high-bound Tpex in LNs share T-cell receptor clonotypes with intratumoral exhausted CD8+ T cells (Tex), suggesting their migration to tumor sites after ICI treatment. This study thus provides new insights into how ICIs enhance anti-tumor immunity by acting on Tpex in LNs, deepening our understanding of the cellular mechanisms underlying ICI therapy.