针对免疫检查点的单克隆抗体已广泛应用于胃肠道癌症免疫治疗。然而，各种单克隆抗体的全身给药通常不会产生逆转免疫抑制肿瘤微环境（TME）的持续效果，这可能是由于免疫检查点的时空动态变化所致。在此，我们报道了一种用于胃肠道癌症免疫治疗的新型免疫检查点重编程策略。它是通过顺序递送 siPD-L1（用于程序性细胞死亡配体 1 的 siRNA）和 pOX40L（用于 OX40 配体的质粒）来实现的，它们与两个阳离子聚合物刷接枝碳纳米管（密集短（DS）和密集长）复合(DL))根据核酸和刷状结构的结构特征而设计。在前三个剂量中给予 DL/pOX40L，然后在接下来的三个剂量中给予 DS/siPD-L1 后，TME 上调了树突状细胞 (DC) 上的刺激性检查点 OX40L，并下调了肿瘤细胞上的抑制性检查点 PD-L1和DC以顺序重编程方式。与其他联合治疗相比，这种序贯策略极大地促进了肿瘤部位 DC 的成熟和 CD8 细胞毒性 T 淋巴细胞的浸润。此外，它还可以增强局部抗肿瘤反应并改善肿瘤引流淋巴结中的 T 细胞浸润，从而逆转外周免疫抑制。我们的研究表明，通过个性化纳米平台的序贯核酸递送策略可以有效逆转肿瘤微环境和外周免疫景观中的免疫抑制状态，从而显着增强全身抗肿瘤免疫反应，建立针对胃肠道癌症的最佳免疫治疗策略。版权所有 © 2024 Elsevier B.V. All保留权利。

Monoclonal antibodies targeting immune checkpoints have been widely applied in gastrointestinal cancer immunotherapy. However, systemic administration of various monoclonal antibodies does not often result in sustained effects in reversing the immunosuppressive tumor microenvironment (TME), which may be due to the spatiotemporal dynamic changes of immune checkpoints. Herein, we reported a novel immune checkpoint reprogramming strategy for gastrointestinal cancer immunotherapy. It was achieved by the sequential delivery of siPD-L1 (siRNA for programmed cell death ligand 1) and pOX40L (plasmid for OX40 ligand), which were complexed with two cationic polymer brush-grafted carbon nanotubes (dense short (DS) and dense long (DL)) designed based on the structural characteristics of nucleic acids and brush architectures. Upon administrating DL/pOX40L for the first three dosages, then followed by DS/siPD-L1 for the next three dosages to the TME, it upregulated the stimulatory checkpoint OX40L on dendritic cells (DCs) and downregulated inhibitory checkpoint PD-L1 on tumor cells and DCs in a sequential reprogramming manner. Compared with other combination treatments, this sequential strategy drastically boosted the DCs maturation, and CD8+ cytotoxic T lymphocytes infiltration in tumor site. Furthermore, it could augment the local antitumor response and improve the T cell infiltration in tumor-draining lymph nodes to reverse the peripheral immunosuppression. Our study demonstrated that sequential nucleic acid delivery strategy via personalized nanoplatforms effectively reversed the immunosuppression status in both tumor microenvironment and peripheral immune landscape, which significantly enhanced the systemic antitumor immune responses and established an optimal immunotherapy strategy against gastrointestinal cancer.Copyright © 2024 Elsevier B.V. All rights reserved.