色氨酸（Trp）代谢在癌症免疫中起着至关重要的作用。吲哚胺 2.3-双加氧酶 1 (IDO1) 是色氨酸降解为犬尿氨酸 (Kyn) 的代谢途径中的关键酶。 IDO1介导的色氨酸代谢物可抑制肿瘤免疫，促进癌细胞免疫逃避；因此，靶向IDO1是一种潜在的肿瘤免疫治疗策略。最近，许多IDO1抑制剂已作为癌症治疗的免疫治疗剂进入临床试验。然而，这些药物存在口服生物利用度低、起效慢和毒性高等缺点。随着纳米技术的不断发展，医学正逐步进入精准医疗时代。无机纳米粒子、脂质纳米粒子和聚合物纳米粒子（NPs）携带的纳米药物在肿瘤治疗方面显示出巨大的潜力，为克服肿瘤多样性和提高治疗效果提供了新的途径。与传统药物相比，纳米药物具有许多显着的优点，包括半衰期长、毒性低、靶向递送和响应释放。此外，基于这些纳米材料的物理化学特性（例如光热、超声响应和化学催化特性），已经开发了各种组合治疗策略来协同IDO1抑制剂的作用并增强其抗癌功效。本综述概述了 Trp-IDO1-Kyn 通路在肿瘤免疫逃逸中的作用机制。讨论了IDO1抑制剂的分类、临床应用和转化开发的障碍，总结了基于IDO1抑制剂的纳米药物递送系统作为联合治疗策略的应用，并阐明了其临床应用中面临的问题。我们期望该综述将为基于IDO1抑制剂的纳米粒子纳米药物的开发提供指导，从而克服当前治疗的局限性，提高癌症免疫治疗的疗效，并导致癌症免疫治疗领域的新突破。© 2024 Jiang et al等人。

Tryptophan (Trp) metabolism plays a vital role in cancer immunity. Indoleamine 2.3-dioxygenase 1 (IDO1), is a crucial enzyme in the metabolic pathway by which Trp is degraded to kynurenine (Kyn). IDO1-mediated Trp metabolites can inhibit tumor immunity and facilitate immune evasion by cancer cells; thus, targeting IDO1 is a potential tumor immunotherapy strategy. Recently, numerous IDO1 inhibitors have been introduced into clinical trials as immunotherapeutic agents for cancer treatment. However, drawbacks such as low oral bioavailability, slow onset of action, and high toxicity are associated with these drugs. With the continuous development of nanotechnology, medicine is gradually entering an era of precision healthcare. Nanodrugs carried by inorganic, lipid, and polymer nanoparticles (NPs) have shown great potential for tumor therapy, providing new ways to overcome tumor diversity and improve therapeutic efficacy. Compared to traditional drugs, nanomedicines offer numerous significant advantages, including a prolonged half-life, low toxicity, targeted delivery, and responsive release. Moreover, based on the physicochemical properties of these nanomaterials (eg, photothermal, ultrasonic response, and chemocatalytic properties), various combination therapeutic strategies have been developed to synergize the effects of IDO1 inhibitors and enhance their anticancer efficacy. This review is an overview of the mechanism by which the Trp-IDO1-Kyn pathway acts in tumor immune escape. The classification of IDO1 inhibitors, their clinical applications, and barriers for translational development are discussed, the use of IDO1 inhibitor-based nanodrug delivery systems as combination therapy strategies is summarized, and the issues faced in their clinical application are elucidated. We expect that this review will provide guidance for the development of IDO1 inhibitor-based nanoparticle nanomedicines that can overcome the limitations of current treatments, improve the efficacy of cancer immunotherapy, and lead to new breakthroughs in the field of cancer immunotherapy.© 2024 Jiang et al.