show Abstracthide AbstractCD8+ exhausted T (Tex) cells are heterogeneous with distinct transcriptional and epigenetic landscapes. PD-1 inhibitors reinvigorate progenitor Tex cells, which subsequently differentiate into irresponsive terminal Tex cells and impair the longlasting antitumor response of PD-1 blockade therapy. How to maintain durable proliferative capacity of progenitor Tex cells is important but remains largely unknown. Here, we showed that low-dose DNA demethylating agent decitabine-pretreated CD8+ progenitor Tex cells had enhanced cytolytic activity against tumors after anti-PD-1 treatment in vitro and could not reactivate the terminal Tex cells. Decitabine-plus-anti-PD-1 treatment promoted the activation and expansion of endogenous tumor-infiltrated CD8+ progenitor Tex cells and efficiently suppressed tumor growth in multiple mice tumor models. The single-cell RNA-sequencing, TCR-sequencing and ATAC-sequencing demonstrated that decitabine-plus-anti-PD-1 combination altered the transcriptional and epigenetic status of CD8+ Tex cells and markedly elevated the clonally expansion and effector function of progenitor Tex cells as compared with anti-PD-1 monotherapy, presenting increased expression of genes associated with T cell activation, proliferation, cytolytic activity, memory and mitochondrial metabolism. Strikingly, decitabine-plus-anti-PD-1 combination sustained the expression and activity of AP-1 transcription factor JunD, which was reduced following PD-1 blockade therapy. Suppressing JNK/AP-1 signaling in CD8+ T cells blunted decitabine-plus-anti-PD-1-induced activation of CD8+ T cells. Together, our findings show that the epigenetic therapy remodels CD8+ progenitor Tex subset, improves responsiveness to anti-PD-1 therapy and suppresses CD8+ T cell terminal differentiation. Overall design: scRNA-seq, scTCR-seq, ATAC-seq, and WGBS of T cells in the Control (C), decitabine(D), anti-PD-1(P), and decitabine-plus-anti-PD-1(DP) group.