联合免疫治疗在中晚期HCC治疗中显示出巨大发展潜力，但目前的治疗方案存在较多局限性。针对免疫治疗现状，本项目拟构建基于CAR T细胞、免疫检查点抑制剂及NF-κB通路抑制剂（PDTC）的多层次联合治疗体系。先制备GPC3靶向修饰的CAR T细胞，赋予T细胞对HCC的靶向输送功能；制备双pH响应性纳米探针，负载PDTC和MRI显像剂，表面修饰PD-L1单链抗体，将探针吸附于CAR T细胞表面制备成纳米背囊。当背囊随CAR T细胞靶向输送至HCC后，在肿瘤pH6.5弱酸性环境中，背囊释放表面的抗PD-L1，与CAR T细胞共同发挥细胞外联合免疫治疗；同时，背囊被肿瘤及瘤旁细胞吞噬，在胞内pH5.5的酸性环境中裂解并释放PDTC，抑制NF-κB信号通路，下调免疫细胞因子表达，实现细胞内协同免疫治疗。该体系具HCC靶向输送、双pH响应智能控释、多层次协同免疫治疗及MRI可视化等功能，提高疗效。

Combined immunotherapy has shown great potential in the treatment of advanced hepatocellular carcinoma (HCC), but the current combined therapies still have some limitations. Aimed at the current situation of HCC immunotherapy, this project plans to build up a multi-level collaborative immunotherapy and monitoring system based on CAR T cells, checkpoint inhibitors and NF-κB signal inhibitor (PDTC). Firstly, GPC3-targeting CAR T cell were prepared to achieve HCC specific targeting ability; secondly, dual pH-responsive nanoprobes are prepared, loaded with PDTC and MRI imaging agent, and surface-modified with anti-PD-L1 scFv. Then the nanoprobes are attached to the surface of HCC-targeting GPC3-CAR T cells using nano-backpack technology. When the nanoprobes are delivered to the tumor tissue along with CAR T cells, anti-PD-L1 scFv are released in the tumor microenvironment at pH 6.5, which work together with the CAR T cells at the cellular level for immunotherapy. At the same time, the backpacks are released and internalized into tumor cells and adjacent cells through endocytosis. The backpacks release PDTC at pH 5.5 within the cell, inhibiting the expression of cytokines, to achieve intracellular molecular level of coordinated immunotherapy. The combined treatment system established by this project has multiple functions such as HCC- specific targeted drug delivery, dual pH-responsive smart controlled release, multi-level collaborative combined immunotherapy, and MRI visualization, providing an overall improvement in immunotherapy efficacy of HCC.