胆道内多模态分子磁共振导航/射频增强恶性肿瘤介入基因治疗的基础研究

Pancreatobiliary malignancies have an extremely poor prognosis. Obstructive pancreatobiliary malignancies are often unresectable, while systemic chemotherapy does not permit delivery of sufficient drug doses at tumor sites, and it causes substantial undesired toxicities to other vital organs. . Gene therapy is a frontier of modern medicine, with nearly 1,000 on-going gene therapy trials worldwide. Gene-directed enzyme prodrug therapy (GDEPT) is currently the most promising strategy for genetic treatment of cancers. Among the candidate genes, herpes simplex virus thymidine kinase gene/gancyclovir prodrug (HSV-tk/GCV) represents a promising example of GDEPT. However, HSV-tk/GCV therapies are performed via a systemic gene delivery approach, with its low HSV-tk gene transfection and therefore low tumor kills. . Development of multi-modal molecular MRI-nevigated interventinal technology is a hot topic in interventional molecular imaging, which includes three basic compornents of (i) using molecular high-resolution MRI to precisely localize the target lesion; (ii) using real-time MRI to precisely guide the placement of interventional devices into the target; and (iii) using real-time MRI to precisely monitor the interventional delivery of therapeutics into the target. We have recently established an intraluminal MRI-guided/Radio-frenquency heat (RFH) system, with its key component being an FDA-approved MR imaging-heating-guidewire (MRIHG). This intraluminal MRI/RFH system has a unique “3-in-1” function of simultaneous imaging/guiding/heating, which cannot be achieved by other imaging modalities. In addtion, we have recently confirmed that motexafin gadolinium (MGd) is an unique multi-modal agent: a T1 MR agent for MRI, a red fluorescence emitter for optical imaging, an anti-tumor agent, and a gene therapy enhancer. In this project, we aim to overcome the obstacles associated with current medical/surgical treatments of obstructive pancreatobiliary malignancies. By fully applying advantages of intrabiliary MRI-nevigated interventions and MGd, we will perform a series of in vitro and in vivo basic investigations to establish groundworks for a new interventional oncologic technique, named “Intrabiliary multi-modal molecular MRI-nevigated/RFH-enhanced local gene therapy”. To this end, we propose two milestones: (i) to establish the “proof-of-principle” of the noval concept using MGd/RFH to enhance HSV-tk/GCV therapy of human cholangiocarcinomas in cell phatoms and mouse models; and (ii) to validate the feasbility of the intraluminal MRI-nevigated/RF-enhanced local gene therapy technology, which will be preclinically validated in a series of in vivo studies on pig models. . We strongly believe that the success of this project should open new avenues for both basic science and clinical practice in efficient management of obstructive pancreatobiliary malignancies by multi-modal molecular MR/RF-integrated interventional oncology and gene therapy..

多模态分子磁共振成像（MRI）联合肿瘤介入诊疗技术是目前介入分子影像的热点。MRI介入导航技术涵盖“定位-引导-监控”这三位一体的基本元素：既(i)高分辨MRI对靶部位精准定位；(ii)实时MRI精准引导介入操作；(iii)动态MRI精确监控治疗剂输送至靶部位。多模态莫特沙芬钆（Motexafin gadolinium, MGd）同时具有磁共振和光学分子成像、杀伤肿瘤及增强基因治疗等多项独特功能。腺相关病毒（AAV）载体介导的自杀基因治疗具低免疫原性及所携带基因长期表达等特性非常适用于基因治疗的临床转化。本项目将充分联合和发挥上述各先进技术的优点，通过一系列体外细胞实验和小鼠模型活体实验及近人类具胆道系统扩张大动物模型的临床前验证，为创建一项全新的“胆道内多模态MRI导航/射频增强肿瘤介入基因治疗”技术，提供理论基础和实践依据。

本课题严格按照重点项目要求进行，取得了一系列原创性的科研成果。具体如下：1.射频加热结合自杀基因治疗胆管癌体系的建立：热射频加热结合热休克蛋白启动子引导下自杀基因的联合治疗可以消除系统性基因治疗遇到的多重障碍，包括很低的基因转染效率和表达以及对正常细胞的错误杀伤。通过将大剂量治疗基因的影像引导与靶向递送及局部射频加热进行创新整合，该新技术可能为胆管癌的影像引导下的联合治疗开辟新途径。2.胆道MRI导航体系的建立：成功开发了MR兼容的介入器械，构建了射频加热系统，开发了MR引导下的介入导航。3.成功构建了与人类解剖结构和生理系统接近的大动物猪的胆道狭窄模型，并用此模型在临床前验证了我们的创新技术：胆道内MRI引导/射频加热体系增强HSV-tk/GCV 自杀基因系统治疗胆管癌疗效。本课题建立的MRI导航体系和射频加热结合病毒载体自杀基因治疗体系有望实现临床转化。