光敏纳米颗粒远程激活CAR-T细胞免疫应答规避脱靶效应研究

Despite promising clinical results, the engineered T cells can exhibit excessive activity that is difficult to control and can cause severe toxicity. This study designed "ON-switch" CARs targeting the human prostate-specific membrane antigen (hPSMA), that enable small-molecule control over T cell therapeutic functions while still retaining antigen specificity. The heterodimerizing small molecule (AP21967) and upconversion nanoparticles were encapsulated by using an amphiphilic block copolymer, near-infrared (NIR) light-responsive micelles which can be disrupted by illumination. Or, the heterodimerizing small molecule were made photo-labile by encapsulation of a NIR-triggerable photosensitizer; irradiation led to peroxidation of liposomal lipids, allowing drug release. In these split receptors, antigen-binding and intracellular signaling components assemble only in the presence of a heterodimerizing small molecule. This titratable pharmacologic regulation could allow physicians to precisely control the timing, location, and dosage of T cell activity, thereby mitigating toxicity. In vitro, the heterodimerizing small molecule was released upon NIR irradiation, which could be repeated a second time. In vivo, injection of nanoparticles containing heterodimerizing small molecule and the photosensitizer caused T cell therapeutic functions. The timing, intensity, and duration of T cell therapeutic functions could be controlled by adjusting the timing, irradiance, and duration of irradiation. Tissue reaction to this formulation and the associated irradiation was benign. This NIR-triggerable switch-on CAR system perfectly combined targeted control of drugs and engineered CAR-T cells delivery. This work developing cellular engineering with NIR control nanoparticles will yield safer therapeutic cells.

表达肿瘤特异性嵌合抗原受体的T细胞治疗技术进展迅猛，过继性细胞疗法在癌症治疗方面很有潜力，但脱靶效应引起的副作用非常严重。随着研究的深入，规避CAR-T细胞脱靶效应的方法取得了突破性的进展，新型CAR-T细胞ON-switch CAR能够靶向癌细胞，但是不激活任何免疫应答，但当暴露于二聚化诱导分子时显示同源靶细胞的选择性杀伤。这种设计为小分子化合物调控CAR-T细胞生物有效性提供了可能，也为纳米技术在这个领域的应用奠定了基础。为解决现有CAR-T细胞的脱靶效应和纳米制剂实体瘤靶向效率差的问题，本课题构建靶向前列腺癌的异源二聚化小分子激活CAR-T细胞，创新性地设计光敏纳米颗粒包封控制CAR-T细胞的二聚化诱导药物分子，CAR-T细胞携载这种光敏纳米颗粒同时达到肿瘤部位，近红外光照条件下在肿瘤部位启动CAR-T细胞免疫应答，精确控制T细胞的活性水平，处理好T细胞引起的各种副作用。

本课题构建靶向间皮素 （Mesothelin）的异源二聚化小分子激活CAR-T细胞，创新性地设计光敏纳米颗粒包封控制CAR-T细胞的二聚化诱导药物分子，CAR-T细胞携载这种光敏纳米颗粒同时达到肿瘤部位，近红外光照条件下在肿瘤部位启动CAR-T细胞免疫应答，精确控制T细胞的活性水平，处理好T细胞引起的各种副作用。这种二聚化小分子激活CAR的第一部分是胞外抗原结合结构域（单链可变片段，scFv），第二部分具有关键的下游信号元件：来自T细胞受体CD3ζ亚单位的免疫受体酪氨酸激活基序（ITAM）， ITAM基序在T细胞受体活化时被磷酸化，导致src同源区2（SH2）结构域效应子的募集并触发T细胞活化。新型CAR-T细受体的两个部分含有异源二聚化结构域，其在异源二聚化小分子结合时产生相互作用。这种T细胞能靶向癌细胞，除非患者服用二聚化诱导分子，否则不激活任何免疫应答。这种二聚化诱导分子药物负责启动CAR-T细胞，如果药物不再存在，这些T细胞就会恢复关闭状态。本课题采用光敏纳米颗粒携载能够控制CAR-T细胞的开/关的二聚化诱导分子，实现远程光控释药。默认关闭的新型CAR T细胞携载这种光敏纳米颗粒，同时达到肿瘤部位，光照条件下在肿瘤部位启动CAR-T细胞免疫应答。研究证实了携载光敏颗粒的CAR-T细胞动物体内外抗肿瘤效果，光照条件下实现光控的细胞免疫治疗。本项目构建的新型光敏纳米颗粒携载能够控制CAR-T细胞的二聚化小分子递药系统为细胞免疫治疗提供了一种新的方法，对细胞免疫的拓展具有一定的实用价值。本研究的科学意义在于以 CAR-T为细胞载体，通过构建新型的以 CAR-T细胞介导的局部高效治疗系统，为解决现有CAR-T细胞和纳米制剂体内实体瘤靶向效率差的现状的问题提供了重要的思路。