Analysis of antigen to renal cell carcinoma and establishment of cancer specific antibody teratment

肾细胞癌（RCC）具有异质性的临床表现，在初始诊断时转移病例高达30%，在不同时间间隔的随访期间，最初器官受限的病例中有30%发生转移。近年来，针对特定分子的抗体已被应用于恶性疾病的临床治疗。虽然一些人源化的小鼠单克隆抗体（mab）已成为针对少数恶性肿瘤的有效治疗药物，但由于我们缺乏对哪些抗原（Ags）可以成为有用靶点的了解，治疗性抗体尚未可用于大多数人类癌症。在目前的研究中，我们建立了一种程序，通过广泛分离可能成为治疗的人单抗来全面鉴定这些Ags。利用噬菌体展示抗体文库，我们分离了大量与RCC细胞表面结合的人单克隆抗体。分别用免疫染色法对其进行筛选，选择对恶性细胞有优先和强烈染色的克隆。用免疫沉淀法分离出可识别的Ags，并用质谱法鉴定。我们分离到357个具有独特序列的单克隆抗体，鉴定出7个不同的单克隆抗体。Ags在几种癌中高度表达。制备完整的IgGi抗体后，进行体外抗体依赖性细胞介导细胞毒性（ADCC）实验和体内荷瘤胸腺小鼠抗肿瘤活性实验。转化为IgG1的单克隆抗体在体内显示出有效的ADCC和肿瘤活性。因此，在我们的研究中采用的程序使我们能够成功地全面鉴定肿瘤相关抗原（TAAs）和同时分离抗RCC的单克隆抗体。因此，我们相信在可预见的未来，一些检测到的Ags将成为癌症治疗的有用靶点，一些单克隆抗体将成为RCC的有用治疗剂。

Renal cell cancer (RCC) has a heterogeneous clinical presentation with up to 30% metastatic cases at initial diagnosis and 30% of initially organ-confined cases developing metastases during follow-up at variable intervals. Recently antibodies against specific molecules have been applied for clinical treatment to malignant diseases. Although several murine monoclonal antibodies (mAbs) which have been humanized became useful therapeutic agents against a few malignancies, therapeutic Abs are not yet available for the majority of the human cancers due to our lack of knowledge which antigens (Ags) can become useful targets. In the present study we established a procedure for comprehensive identification of such Ags through the extensive isolation of human mAbs that may become therapeutic. Using the phage-display Ab library we isolated a large number of human mAbs that bind to the surface of RCC cells. They were individually screened by immunostaining and clones that preferentially and strongly stained the malignant cells were chosen. The Ags recognized by those clones were isolated by immunoprecipitation and identified by mass spectrometry. We isolated 357 mAbs with unique sequences and identified 7 distinct. Ags highly expressed on several carcinomas. After preparing complete IgGi Abs the in vitro assay for antibody-dependent cell-mediated cytotoxicity (ADCC) and the in vivo assay in cancer-bearing athymic mice were performed to examine anti tumor activity. The mAbs converted to IgG1 revealed effective ADCC as well as and tumor activity in vivo. Thus, the procedure adopted in our study enabled us to succeed in comprehensive identification of tumor-associated antigens (TAAs) and simultaneous isolation of mAbs against RCC. Therefore, we believe that some Ags detected will be useful targets for cancer therapy and several mAbs will become useful therapeutic agents to RCC in the foreseeable future.