免疫检查点阻断剂已成为肿瘤免疫治疗的热点，开发靶向下调PD-L1的小分子药物是肺癌等恶性肿瘤免疫治疗的新方向。前期研究发现，我们自主创新、具有全新骨架结构的莲心碱类化合物IMB-29能显著下调肺癌细胞中PD-L1的表达，促进共培养的T/NK细胞对NSCLC细胞的杀伤作用，在小鼠体内也显示出较好的抗肿瘤活性，并具有较好的安全性。本项目拟在此原创性工作基础上，以PD-L1可发生溶酶体途径降解的新发现以及IMB-29调控PKCδ表达为依据，深入研究：（1）IMB-29通过溶酶体途径降解PD-L1；（2）IMB-29通过PKCδ-TFEB途径调控溶酶体生物合成的机制；（3）鉴定IMB-29的直接靶蛋白；（4）移植瘤及自发性小鼠肺癌模型评价IMB-29的体内抗肿瘤效果；（5）评价IMB-29的药代和安全性，为将IMB-29研发成靶向PD-L1的新型小分子肿瘤免疫治疗候选物奠定坚实的基础。

Among the most promising approaches to activating therapeutic antitumour immunity is the blockade of immune checkpoints. Programmed cell death protein-1 (PD-1) and programmed cell death ligand-1 (PD-L1) are key targets in the treatment of cancer, but current antibody-based drugs against this pathway have inherent drawbacks that may limit their effectiveness. Therefore, non-antibody, small moleculars cancer immunotherapies against PD-1/PD-L1 pathway is urgently demanded..During our screening program for natural anticancer drugs down-regulating PD-L1, we have recently discovered that IMB-29, a novel liensinine derivative, has potent anti- non-small cell lung cancer (NSCLC) activity. Our primary results demonstrated that IMB-29 significantly increased the cytotoxity of co-cultured T cells and NKcells by degradation of PD-L1 expressed on the NSLC cells. Meanwhile, we also found that IMB-29 regulated the lysosomal biogenesis in NSCLC cell by upregulation of the transcription activity of TFEB as well as controlling the expression of PKCδ. Therefore, we hypothesize that IMB-29 regulates lysosomal biogenesis through PKCδ-TFEB pathways. This proposal is novel, as it will demonstrate the effect of IMB-29-induced lysosomal-dependent PD-L1 degradation, delineate the molecular mechanism by which IMB-08B regulates TFEB activity through PKCδ-TFEB signaling pathway, investigate the target protein of IMB-29, evaluate the antitumor effect of IMB-29 in vivo, preliminary pharmacokinetics and safety of IMB-29 with the use of multiple cellular, molecular biotechnologies and animal models.This study will clarify a new role of IMB-29 in cancer immunotherapies against PD-1/PD-L1 pathway, and provide a theoretical basis for the mechanism study of liensinine derivatives against NSCLC.