新型免疫毒素Anti-Trop2-LDM的制备及其抗肺癌活性研究

肺癌是目前导致癌症死亡的首要原因，因此，亟需开发新的抗肺癌药物。免疫毒素多由抗体和毒素分子组成，利用抗体的靶向性将毒素分子运送至肿瘤部位，直接杀死肿瘤细胞。滋养层细胞表面抗原2（Trop2）在肺癌等多种肿瘤中高表达，在正常组织限制性表达，是肿瘤治疗中有潜力的新靶点。力达霉素（LDM）是我所自主研发的新型烯二炔类抗生素，对肿瘤细胞和放化疗耐药的细胞具有强烈的杀伤活性。LDM由辅基蛋白和烯二炔发色团组成，二者可拆分和重组，活性不受影响。与传统毒素有较高的免疫原性不同，LDM在I期临床研究中未见免疫反应，因此是制备免疫毒素的理想分子。本项目首先采用杂交瘤技术获得全新的抗Trop2单抗并对其进行人源化，然后采用基因工程和分子重组技术，制备抗Trop2抗体和LDM的新型免疫毒素并研究其体内外抗肺癌活性和作用机制，为肺癌的靶向治疗提供全新的、安全有效的、具有自主知识产权的候选药物。

Lung cancer is the leading cause of cancer death, so there is an urgent need to develop new drugs to treat lung cancer. Immunotoxin is composed of antibody and toxin molecules, which can deliver the toxin molecules specific to the tumor site by tumor-targeting of antibody and then directly kill tumor cells. Trophoblast cell surface antigen 2 (Trop2) is highly expressed in a variety of tumors and restricted in normal tissues, which is a new target for tumor therapy. Lidamycin (LDM) is a new enediyne-containing antitumor antibiotic developed by our institute, demonstrated potent antitumor activity against cancer cells or those showed resistance to radioactivity and chemotherapy. LDM consists of an apoprotein and an enediyne chromophore AE, which can be divided and reconstituted in certain conditions. Compared with traditional toxins which show immunogenicity potential in human, there was no observed immune response in phase I clinical studies of LDM, so LDM is an attractive toxin for preparation of immunotoxins. In this project, a new anti-Trop2 monoclonal antibody was firstly obtained by hybridoma technique and then the antibody was humanized via CDR-grafting. Secondly, a novel immunotoxin anti-Trop2-LDM composed of anti-Trop2 antibody and LDM will be prepared by genetic engineering and “molecular recombination” technology. Then we will explore the anti-lung cancer activity and mechanism of the immunotoxin. Anti-Trop2-LDM will be a novel, safe, effective, promising candidate with independent intellectual property rights for targeted therapy of lung cancer.