抗EGFRvⅢ抗体介导的聚合物胶束肿瘤靶向性及机理研究

In order to specially targeting deliver anti-tumor drugs, decrease side effects on normal tissues and improve the therapeutic effects, the mechanism of active targeting in solid tumors with antibody conjugated polymeric micells will be studied. Epidermal growth factor receptor variant Ⅲ (EGFRvⅢ) is the most common variant of epidermal growth factor receptor (EGFR) in tumor, which does not express in any regular organs and could be a special targeted site for anti-tumor drug delivery. High molecular weight polymeric micells could self-assemble in aqueous as nanoparticles to passively targeting deliver drug to tumor by enhanced permeability and retention effect (EPR). However, it is not an active targeting delivery. Therefore, in this project Poly(Poly(L-γ-glutamyl -glutamine))-Paclitaxel will be conjugated with the specially targeting anti-EGFRvⅢ antibody to be polymeric micells mAb-PGG-PTX. The effects of ligans, monoclone antibody, single-chain antibody, fragments of antibody and contents on the tumor targeting will be investigated both in EGFRvIII positive cells and mice bearing tumors.The endocytosis will be visualized in EGFRvIII positive cells. Furthermore, the content of this mAb-PGG-PTX polymeric micell in plasma and tissues will be determined and the pharmacokinetic parameters will be calculated to bulid up the relationship between the structure and the efficacy. The tumor inhibition and survival rate will be evaluated and compared between the active and passive targeting polymeric micells. Consequently, this project will build up a basic research to know how to actively targeting deliver anti-tumor drug to tumore by antibody-conjugated polymeric micells.

建立肿瘤特异性受体介导的靶向给药载体可能是提高抗肿瘤药物疗效并降低毒副作用的关键。表皮生长因子受体Ⅲ型变异体（EGFRvⅢ）是表皮生长因子受体（EGFR）在肿瘤中最常见的突变形式，未表达于任何正常组织，是一个肿瘤特异性靶点。高分子聚合物胶束以自组装携带抗肿瘤药物，可通过高通透性和滞留效应（EPR）被动积聚于肿瘤部位，但缺乏主动靶向性。因此，将聚合物胶束通过抗EGFRvⅢ抗体或抗体片断（包括单链抗体和Fab）修饰，研究不同修饰配体和不同修饰量与聚合物胶束理化性质、体内外肿瘤细胞靶向性、组织分布、药物代谢动力学、聚合物胶束在肿瘤细胞内亚结构的鉴定与识别以及肿瘤抑制效果等体内外构效关系，探索其实现主动靶向递药的构建规律，阐明抗体修饰聚合物胶束特异性主动靶向递送的机制，建立高靶向性，高肿瘤抑制率，低毒副作用的抗体修饰聚合物胶束mAb-PGG-PTX，并为其他配体修饰药物载体提供借鉴和依据。

传统的肿瘤化疗药物毒副作用比较大，载药纳米颗粒可以有效的降低化疗药物的毒副作用，但其肿瘤组织的靶向能力主要基于以EPR效应为基础的被动靶向，肿瘤组织药物聚集的效果还不够理想，需要建立更为高效的肿瘤靶向药物递送系统。表皮生长因子受体（EGFR）在多种肿瘤中高表达或者突变，是常用的肿瘤治疗靶点，其中突变体EGFRvIII更是具有高度的肿瘤组织特异性，利用 EGFR或EGFRvIII特异性的抗体、多肽等靶向元件引导化疗药物靶向肿瘤组织，在被动靶向的基础上引入主动靶向，增加药物肿瘤组织聚集，有望取得更好的治疗效果。. 本研究中我们主要制备了四种靶向EGFR或EGFRvIII的载药体系，包括靶向EGFRvIII的PGG-PTX聚合物纳米颗粒，靶向EGFR的PGG-PTX聚合物纳米颗粒，靶向EGFR的载阿霉素DSPE-PEG2000聚合物胶束，靶向EGFR的阿霉素多肽药肽共价偶联物。所制备的主动靶向体系在体外细胞毒性实验中，均可以对表达EGFR或EGFRvIII的肿瘤细胞系实现特异性杀伤，并在肿瘤移植瘤实验中表现出更好的肿瘤抑制效果。. 比如靶向EGFR的PGG-PTX-GE11，可将SMMC-7721移植瘤减小至约50%，而相应的游离紫杉醇组，无靶向的PGG-PTX组则分别减少了约16%，28%，说明主动靶向给药体系在原有基础上进一步增强了肿瘤抑制效果。. 所制备的四种靶向EGFR或EGFRvIII的载药体系，均可以有效的靶向杀伤肿瘤细胞，在降低化疗药物毒副作用的同时增强药物的肿瘤组织聚集，尤其是靶向EGFRvIII的PGG-PTX-GE11聚合物，在体内也表现出了很好的肿瘤靶向杀伤效果，具有较好的应用前景。