越来越多的证据表明，负责检测内源性RNA物种的RNA编辑酶ADAR1与免疫检查点抑制剂（ICB）治疗的差反应或抵抗力显著相关。因此，研发了一种基因工程纳米囊（siAdar1-LNP@mPD1）作为RNA干扰（RNAi）纳米工具，以克服肿瘤对ICB治疗的抵抗。小干扰RNA（siAdar1）被包装成脂质纳米粒子（LNP），进一步被覆盖在过表达PD1基因的基因工程细胞提取出的血浆膜上。siAdar1-LNP@mPD1可以通过呈现覆盖膜上的PD1蛋白来阻止PD1/PDL1免疫抑制通路。此外，设计的纳米囊可以有效将siAdar1传递到癌细胞中，沉默ADAR1表达，促进I/II型干扰素（IFN-β/γ）的产生，并使癌细胞对分泌的介导因子IFN-γ更敏感，导致细胞生长明显受阻。这些综合功能赋予siAdar1-LNP@mPD1强大而全面的抗肿瘤免疫力，在肿瘤免疫微环境的全面重塑下，表现出明显的肿瘤生长逆转、皮外肿瘤预防和肺转移有效抑制等优异的抗肿瘤能力。总之，我们提供了一种有前途的可转化策略，可同时沉默ADAR1和阻止PDL1免疫检查点，增强强大的抗肿瘤免疫力。 Copyright © 2023 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.

Growing evidences have proved that RNA-editing enzyme ADAR1, responsible for detecting endogenous RNA species, is significantly associated with poor response or resistance to immune checkpoint blockade (ICB) therapy. Here, a genetically engineered nanovesicle (siAdar1-LNP@mPD1) was developed as an RNA interference (RNAi) nano-tool to overcome tumor resistance to ICB therapies. Small interfering RNA against ADAR1 (siAdar1) was packaged into a lipid nanoparticle (LNP), which was further coated with plasma membrane extracted from the genetically engineered cells overexpressing PD1. siAdar1-LNP@mPD1 could block the PD1/PDL1 immune inhibitory axis by presenting the PD1 protein on the coating membranes. Furthermore, siAdar1 could be effectively delivered into cancer cells by the designed nanovesicle to silence ADAR1 expression, resulting in an increased type I/II interferon (IFN-β/γ) production and making the cancer cells more sensitive to secreted effector cytokines such as IFN-γ with significant cell growth arrest. These integrated functions confer siAdar1-LNP@mPD1 with robust and comprehensive anti-tumor immunity, as evidenced by significant tumor growth regression, abscopal tumor prevention, and effective suppression of lung metastasis, through a global remodeling of the tumor immune microenvironment. Overall, we provided a promising translatable strategy to simultaneously silence ADAR1 and block PDL1 immune checkpoint to boost robust antitumor immunity.Copyright © 2023 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.