基于PSMA和TIM3的双特异性纳米抗体在前列腺癌的应用研究

New insights into the control of T cell activation and proliferation have led to the identification of checkpoint proteins that either up- or down modulate T cell reactivity. The blockade of immune check points have shown promising therapeutic outcomes in mice and humans with established cancers, highlighting the fact that cancer immunotherapy using T-cell checkpoint inhibitors is one of the most promising new therapeutic approaches. However, it remains relatively poorly studied in prostate oncology. Based on our previous study, T cell membrane protein 3 （TIM3）is an immune checkpoint receptor that suppresses the activation of T cell on engagement with ligand. So it is one of many similar inhibitory molecules that are gaining attention as targets. Moreover, we found that prostate specific membrane antigen (PSMA) was specifically expressed in prostate cancer. Thus, anti-PSMA agent shows prostate tumor targeting prospect. Therefore, we will manufacture a novel bispecific nanobody which targeted on PSMA for cancer navigation and TIM3 for T cell reactivation at same time. Furthermore，we will be further investigating the mechanism of action of anti-TIM3 and PSMA bispecific nanoboy against established experimental prostate tumor model, induced in SCID-beige mice by using human peripheral blood mononuclear cells and develop patient-derived tumor xenografts, that promote tumor specific T-cell activation, proliferation, effector function, and survival. In the end, this study aim to develop a novel bispecific nanobody with high efficiency and safe in treating prostate cancer, providing vital preclinical experimental results for its later clinical trials. The PDTXs would also sever as an important tool in the exploration of the underlying mechanisms of anti-TIM3 immunotherapy.

通过激活自身免疫系统而达到杀伤肿瘤细胞的抗肿瘤免疫疗法已经成为和外科手术，放化疗并重的肿瘤治疗手段，而靶向免疫检测点分子的抗肿瘤免疫治疗是其中新兴且有效地方法，但是仍然缺乏针对前列腺癌的靶向特异性免疫治疗手段。本项目将靶向前列腺癌特异性膜抗原(PSMA)和T细胞表面免疫检测点受体TIM3，构建特异性强，亲和力高且免疫源性低的抗PSMA-TIM3双特异性治疗纳米抗体，以人源化免疫重建SCID-beige小鼠的病人来源前列腺癌移植瘤模型为主要研究平台，研究该纳米抗体在前列腺癌治疗中的有效性和安全性。解决基于特异性阻断免疫检测点而重启T细胞免疫，开发一种安全、有效的新型抗前列腺癌靶向性免疫抗体药物这一科学问题，为抗TIM3免疫治疗的分子机制研究和抗PSMA-TIM3双特异性纳米抗体进入临床试验和应用提供重要动物实验结果。

来源于单链抗体的纳米小体是诊断、治疗和研究膜受体结构和功能的有力工具。我们开发了一系列的纳米体的噬菌体展示筛选从羊驼分离的淋巴细胞与重组人 T 细胞免疫球蛋白和粘蛋白域含蛋白 3 免疫（ TIM - 3 ）是一种表达于多种免疫细胞的免疫调节受体。我们使用一种商业化的 TIM - 3 抗体对前列腺癌活检标本中 TIM - 3 的表达进行免疫组化分析，发现 TIM - 3 在前列腺癌组织中的表达高于癌旁组织。生物筛选检索到的八个纳米抗体对 TIM - 3 ，观察到的最佳亲和力在76.02 nm 。荧光信号的分析表明，这些纳米抗体目标 TIM - 3 特异性。使用人类外周血单个核细胞，我们发现具有最佳亲和力的克隆改善 T 细胞免疫反应，增加γ干扰素的分泌。靶向 TIM - 3 的纳米抗体在功能研究、分子成像和治疗学方面可能是有用的。