新型双靶向抗体Cetu-R136 CrossMab 亲和力与其抗肿瘤活性及机理研究

Nowadays, epidermal growth factor receptor (EGFR) is an important therapeutic target for non-small-cell lung cancer (NSCLC) treatment. Both monoclonal antibodies (mAbs) targeting the extra-cellular domain of EGFR and small molecule tyrosine kinase inhibitors (TKIs) have been exploited pharmacologically to block EGFR activation. While the EGFR-TKIs erlotinib and gefitinib have been approved for advanced NSCLC, above all in patients with activating EGFR mutations (exon 19 deletion and mutation L858R in exon 21), the role of cetuximab (mAb) was recently clarified. Cetuximab (marketed as Erbitux) is a chimeric human/murine monoclonal immunoglobulin G1 antibody, that inhibits the receptor function, mediates antibody-dependent cell-mediated cytotoxicity, leading to the inhibition of EGFR activity. However, several clinical trials (including LUCAS, FLEX and SWOG S0342) recently have indicated that cetuximab failed to demonstrate a great and clinically significantly survival benefit when combined with chemotherapy regimens. The pursuit of improved reagents to replace cetuximab is intense, with several candidates currently under clinical evaluation.. The use of antibodies to block pathways inhibiting the endogenous immune response to cancer, known as checkpoint blockade therapy, has stirred up a great deal of excitement among scientists, physicians, and patients alike. Clinical trials evaluating the safety and efficacy of antibodies that block the T cell inhibitory molecules CTLA-4 and PD-1 have reported success in treating subsets of patients with metastatic melanoma and renal cell carcinoma. Antibodies targeting these pathways have been approved for clinical use, and patients once unresponsive to any sort of conventional treatment have shown good and stable clinical responses—some remaining free of disease progression for many years. NSCLC treatment through blockade of the transmembrane protein PD-L1 or its cell-surface receptor PD-1, has shown promise in preclinical experiments and now in clinical trials. In our previous studies, we have converted the EGFR antibody cetuximab and PD-1 antibody R136 we have previously generated into an IgG-like bispecific antibody (Cetu-R136 CrossMab) by using CrossMab technology, which exhibits potent anti-tumor efficacy against NSCLC. In the present study, we will design Cetu-R136 CrossMab variants with different binding affinity to the target protein EGFR or PD-1. After optimization of EGFR/PD-1 bispecific antibody by molecular dynamic simulation, the induction of tumor-specific immunity and anti-tumor activities of Cetu-R136 CrossMab against mouse lung carcinoma expressing human EGFR were evaluated through our in vitro and in vivo experiments. These studies will provide the theoretical evidence for development of novel therapeutic agents against NSCLC.

肺癌是世界上最常见的恶性肿瘤之一,由于缺少有效的靶向治疗药物,肺癌是病死率最高的恶性肿瘤。EGFR蛋白是非小细胞肺癌(NSCLC)靶向治疗的理想靶点,但是EGFR抗体Cetuxim ab的疗效有限。迫切需要设计新型抗体药物用于NSCLC的治疗。近期,抗体阻断PD-1免疫抑制信号在NSCLC临床试验中取得令人振奋的效果。我们借助计算机辅助设 计成功获得了新型双靶向抗体,既保留全抗体杀伤肿瘤的优势,又能够双靶向EGFR和PD-1分子,能够在特异性识别EGFR阳性肺癌细胞的同时,在肿瘤组织附近阻断PD-1免疫抑制信号通路,增强抗肿瘤免疫效应，表现出较好的抗肿瘤效果。本研究以EGFR和PD-1为靶点,采用计算机辅助设计具有不同亲和力的新型双靶向抗体，并系统研究新型抗体的亲和力与其有效激活抗肿瘤免疫之间的关系。

肺癌是世界上最常见的恶性肿瘤之一,由于缺少有效的靶向治疗药物,肺癌是病死率最高的 恶性肿瘤。EGFR蛋白是非小细胞肺癌(NSCLC)靶向治疗的理想靶点,但是EGFR抗体Cetuximab的疗效有限。迫切需要设计新型抗体药物用于NSCLC的治疗。近期,抗体阻断PD-1免疫抑制信号在 NSCLC临床试验中取得令人振奋的效果。在本项目研究中，我们设计了针对EGFR/PD-1的双靶向抗体。由于传统KIH的方法其组装效率不高，存在非特异性聚集的情况，极大限制了多靶向抗体的转化研究。在本研究中，我们借助计算机辅助设计的方法获得了比KIH具有更好组装效率的多靶向抗体关键技术。在此基础上，设计获得了EGFR/PD-1双靶向抗体。该新型多靶向抗体既保留全抗体杀伤肿瘤的优势,又能够双靶向EGFR和PD-1分子, 表现比亲本抗体联合使用更好的抗肿瘤效果。为后续具有更好疗效的新型多靶向抗体临床转化研究奠定基础。