新型人源化抗RON单克隆抗体-药物偶联物对胰腺癌及其肝转移的抗癌效应

The clinical use of antibody-drug conjugates（ADC）is an important milestone in the development of anti-cancer biotherapeutics. During the last 20 years of studying RON in cancer biology, we were the first to demonstrate the biological basis of RON as a drug target and generated the first anti-RON antibody-DM1 conjugate in the world. Using advanced technology, we developed humanized anti-RON antibody, and generated a novel humanized and homogeneous labeled anti-RON antibody Zt/g4-drug maytansinoid conjugate (HHZG-DM1) using the chemically-modified disulfide-bridging technology. The objective of this project is to determine therapeutic efficacy and anti-cancer mechanism, pharmacokinetics, and toxic effect of HHZG-DM1 for targeted therapy of advanced pancreatic cancer，which should lay the foundation for potential clinical trial of this novel anti-cancer biotherapeutics. The hypothesis for this project is: by inducing cell-surface RON endocytosis in pancreatic cancer cells, humanized anti-RON antibody with homogeneous drug conjugation delivers highly-potent toxic DM1 to eradicate the xenograft tumor growth, leading to prevention of cancer hepatic invasive growth. Considering its potential clinical application，the project will focus on the following three specific aims: 1) to validate the anticancer therapeutic efficacy of HHZG-DM1 in pancreatic cancer xenograft and liver-metastatic models; 2) to establish the pharmacokinetic profiles of HHZG-DM1 and their dose-time relationships; and 3) to determine the in vivo tissue toxic profiles of HHZG-DM1 in animal models. The completion of this project should advance the development of novel targeted anti-pancreatic cancer biotherapeutics. It should also lay the biological and pharmacological foundations for potential preclinical study of this novel anti-RON ADC.

抗体-药物偶联物的临床应用是近年抗癌药物研发的重要里程碑。前期我们已阐明异常表达的RON在胰腺癌等恶性肿瘤中的致癌机理及其作为抗癌药靶的重要意义，研发了首个抗RON单抗-药物美登素偶联物并证实其显著的抗癌活性。进而将单抗人源化改造并建立化学桥式修饰标记技术，获得药物定向均匀标记的新型人源化抗RON单抗-药物偶联物HHZG-DM1。本研究目的是阐明HHZG-DM1的抗胰腺癌效应及机理、药代动力学和毒理作用。科学假设是：人源化抗RON单抗高效诱导胰腺癌细胞表面RON受体的胞浆内吞作用，在药物均匀标记下以靶向给药方式，杀伤癌细胞并抑制其在肝脏的侵袭性生长。研究内容：1)HHZG-DM1在胰腺癌及其肝转移模型中的抗癌效应；2)分析其在动物体内的药代动力学并建立剂量-时相药效模型；3)明确其对特定组织器官的毒理作用。本项目将为新型靶向抗癌药物HHZG-DM1的临床前研究奠定必要的科学基础。

项目背景：抗体-药物偶联物（ADC）的临床应用是近年抗癌药物研发的重要里程碑。前期我们已阐明异常表达的RON在胰腺癌等恶性肿瘤中的致癌机理及其作为抗癌药靶的重要意义。..主要研究内容：1）RON在不同病理类型的肿瘤组织中的表达特征；2）针对不同表位的抗RON单克隆抗体的筛选及人源化改造，人源化抗RON-ADC的制备及其理化分析；3）抗RON-ADC在小鼠及食蟹猴体内的药代动力学及体内外剂量-时相抗癌药效模型；4）明确抗RON-ADC对模型动物特定组织器官的毒理作用；5）抗RON-ADC在胰腺癌、乳腺癌等恶性肿瘤中的体内外抗癌效应及其药理机制。.重要结果：1）在胰腺癌、乳腺癌（包括三阴性乳腺癌）和大肠癌组织中，RON过表达率分别为33％、33.7%和32%，；2）通过CDR序列优化和改造获得人源化抗RON单抗H-Zt/g4，筛选和制备特异性识别丛蛋白-信号素-整合素（PSI）结构域的人源化抗RON单抗H5B14，并制备了系列人源化抗RON-ADC，偶联药物抗体比例（DAR）约为3.7：1，稳定性好，在人血浆中1个月毒素累积释放率小于5％；3）抗RON-ADC在小鼠和食蟹猴体内显示良好的稳定性和药代动力学特征，PK均符合两室模型，半衰期约为6.5天。4）抗RON-ADC在小鼠（≤60mg/kg）和食蟹猴（≤30mg/kg）中显示可控和可逆的毒性特征，未见严重的毒理学症状和与抗RON-ADC相关的组织病变，具有较好的安全性。5）动物实验显示抗RON-ADC通过内吞和旁观者效应发挥抗癌作用，抑制和清除RON阳性的胰腺癌细胞、胰腺癌干细胞等异种移植瘤以及胰腺癌患者肿瘤来源的原代癌细胞（PDX），其有效抑癌剂量为1-3mg/kg体重，并且癌细胞表面RON表达量与抗RON-ADC抗癌作用显著相关；6）靶向RON PSI域的人源化抗RON-ADC可以更高效地诱导癌细胞RON内吞，实现了在胰腺癌、三阴性乳腺癌、结直肠癌等多种异种移植瘤模型中更稳定的药物递送以及更强烈的靶向抑制和清除肿瘤作用。..科学意义：本项目创新性提出癌细胞异常表达的RON作为抗癌药靶的科学意义，证实人源化的抗RON-ADC对胰腺癌、三阴性乳腺癌等恶性肿瘤的显著抗癌效应，为抗RON-ADC的临床转化研究奠定必要的前期科学基础。