肿瘤患者外周血（PB）中表达PD-1的T细胞具有治疗潜力；然而，PD-1 T 细胞的免疫抑制、PD1 触发信号通路和有限的增殖能力对其治疗应用提出了挑战。在这里，我们观察到 PD-1 和 PD-1-T 细胞在克隆重叠方面没有明显区别。然而，来自 PB 和肿瘤组织的 CD8 PD-1 T 细胞根据克隆大小表现出更紧密的聚类。单细胞RNA测序分析表明，与来自PB或肿瘤组织的PD-1-T细胞相比，来自PB的PD-1 T细胞高表达细胞毒性相关基因，并且富集T细胞激活相关通路。与此一致的是，PB衍生的PD-1 T细胞对自体肿瘤细胞和肿瘤细胞系表现出强烈的细胞毒性。为了增强PD-1 T细胞在体内对抗实体瘤的活性，我们将PD-1/CD28融合受体与CD19嵌合抗原受体（CAR）结合引入PD-1 T细胞，然后在体外进行扩增。修饰后的PD-1 T细胞在体外表现出优异的增殖和抗肿瘤能力。此外，四名癌症患者接受了自体 PD-1/CD28-CD19-CAR PD-1 T 细胞输注。这些患者均未出现严重副作用，其中一名黑色素瘤患者获得了完全缓解，并维持了 6.7 个月。其他三名患者病情稳定。总的来说，这些结果表明，使用修饰的 PB 衍生的 PD-1 T 细胞进行细胞治疗既安全又有效，并且可能为癌症患者构成一种有前景的治疗策略。

T cells expressing PD-1 in the peripheral blood (PB) of patients with tumors possess therapeutic potential; however, the immunosuppressive, PD1-triggered signaling pathway and limited proliferative capacity of PD-1+ T cells present challenges to their therapeutic application. Here, we observed no discernible distinction between PD-1+ and PD-1- T cells in terms of clonal overlap. However, CD8+PD-1+ T cells from PB and tumor tissues exhibited tighter clustering based on clone size. Single-cell RNA sequencing analysis showed that PD-1+ T cells from PB highly expressed cytotoxicity-related genes and were enriched for T cell activation-related pathways compared with PD-1- T cells from PB or tumor tissues. Consistent with this, PB-derived PD-1+ T cells exhibited strong cytotoxicity towards autologous tumor cells and tumor cell lines. To augment PD-1+ T-cell activity against solid tumors in vivo, we introduced a PD-1/CD28 fusion receptor combined with a CD19 chimeric antigen receptor (CAR) into PD-1+ T cells, which were then expanded in vitro. The modified PD-1+ T cells exhibited superior proliferation and antitumor abilities in vitro. In addition, four patients with cancer were infused with autologous PD-1/CD28-CD19-CAR PD-1+ T cells. None of these patients experienced severe side effects and one patient with melanoma achieved a complete response that was maintained for 6.7 months. The three other patients had stable disease. Collectively, these results suggested that cell therapy with modified PB-derived PD-1+ T cells is both safe and effective, and it may constitute a promising treatment strategy for cancer patients.