CYP4F抑制剂重塑肿瘤相关成纤维细胞增敏抗PD-1/PD-L1治疗及机制研究

PD-1/PD-L1抑制剂抗肿瘤疗效显著，但总体应答率偏低。因此，研究新靶点和联合治疗策略是当前热点。本项目是在前期发现细胞色素P450（CYP）4F2在PIK3CA突变人癌组织中高表达并与癌相关成纤维细胞（CAFs）活化水平以及不良预后显著正相关的基础上，首先研究PIK3CA突变或CYP4F抑制对小鼠移植瘤花生四烯酸(AA)代谢,CAFs表型以及CD8+T细胞抗肿瘤免疫反应的影响。随后采用CAFs特异性敲除Gpr75小鼠和微流控芯片肿瘤与基质细胞共培养模型，研究CYP4F来源的20-HETE通过GPR75信号增强CAFs介导的血管异常化和CD8+T细胞无能和耗竭；最后采用肺癌类器官和人源化小鼠模型验证CYP4F抑制剂与PD-1/PD-L1单抗联用的治疗效能。阐明靶向抑制CYP4F催化的AA代谢抗CAFs介导的免疫逃逸作用及机理，确定新靶点、候选药物和联合疗法具有重要理论意义和临床价值。

PD-1/PD-L1 inhibitors have demonstrated remarkable efficacy in a wide range of advanced cancers, but the overall response rate is low. Therefore, the research on novel targets and combination therapy strategies is currently a hot spot. Our previous work demonstrates that cytochrome P450 (CYP) 4F2 is highly expressed in human cancer tissues with PIK3CA mutant and positively correlated with the level of tumor-associated fibroblasts (CAFs) and poor prognosis. We first investigate the effects of PIK3CA mutant or its combination with CYP4F2 inhibition on arachidonic acid metabolism in tumor cells, phenotype of CAFs and their expression of immunosuppressive molecules, and anti-tumor immune response of CD8+T cells in mouse Lewis lung cancer and 4T1 breast cancer. Subsequently, fibroblast-specific Gpr75-knockout mice and tumor-stroma cell co-culture in a microfluidic chip are used to study whether CYP4F2 promotes CAF-mediated vascular abnormalities and CD8+T cell inability and depletion through the activation of fibroblasts and their expression of immunosuppressive molecules via the 20-HETE-GPR75 signaling. Finally, a novel inhibitor of CYP4F is screened and the efficacy of its combination with PD-1/PD-L1 inhibitors is tested in organoid modeling of the lung cancer immune microenvironment and humanized mouse model. Together, targeting CYP4F-dependent arachidonic acid metabolism prevents CAF-mediated immunosuppression and improves anti-PD-1/PD-L1 therapy, and may serve as a potential therapeutic target and combination therapy strategies in human cancer, and thus have important theoretical significance and clinical value.