Antibody Therapy of Cancer

肝癌是世界上第五大常见癌症，也是导致癌症死亡的第三大原因。肝细胞癌（HCC）约占肝癌病例的75%，而肝内胆管癌（ICC）是第二常见的原发性肝脏肿瘤。目前迫切需要开发治疗肝癌的新药。项目一：靶向GPC3治疗肝癌及其他肿瘤GPC3是一种在HCC中高表达的硫酸肝素蛋白多糖，具有治疗肝癌的潜力。GPC3的生物学功能及其在肝脏肿瘤发生中的作用尚不清楚。我们的工作有助于揭示GPC3在肝癌细胞生长中的作用。我们生产并分析了一种重组可溶性GPC3(25-559)，它抑制HCC细胞的生长，并被认为与内源性glypican-3竞争，以结合癌细胞表面的生长因子。我们的实验室分离了一组小鼠单克隆抗体，包括YP7，可以识别GPC3的c -末端（511-560）。YP7结合GPC3对HCC具有高亲和力。它在低表达的卵巢透明细胞癌和黑色素瘤细胞中也能检测到GPC3，具有很高的敏感性。2013财年，GPC3小鼠单克隆抗体工作在《mab》杂志上报道（pmiid: 22820551）。最近，我们合成了一种人类单域抗体HN3，它对细胞表面相关的GPC3分子具有高亲和力。人抗体识别GPC3核心蛋白的独特构象表位。HN3可抑制肝癌细胞增殖，对小鼠肝癌异种移植瘤生长有显著抑制作用。HN3作用的潜在机制可能涉及通过yesassociated protein （YAP）信号传导在G1期阻滞细胞周期，提示gpc3靶向癌症治疗的新机制。2013财年，HN3抗体研究发表在Proc Natl Acad Sci USA （PMID: 23471984）。mesothelin在ICC、间皮瘤、卵巢癌等肿瘤中高水平表达。间皮素与MUC16（也称为CA125）之间的相互作用可能促进肿瘤的植入和扩散。我们在细胞表面间皮素n端建立了MUC16的64个氨基酸的功能结合域（IAB, 296-359）。HN125是一种免疫粘附素，由人抗体的IAB结构域和Fc部分组成，破坏由muc16 -间皮素相互作用介导的癌细胞粘附，并引发抗体依赖细胞介导的对muc16阳性肿瘤细胞的细胞毒性。随后，我们制备了HN1和SD1人单克隆抗体。HN1结合细胞表面间皮素的n端，破坏间皮素- muc16的相互作用，引发抗体依赖细胞介导的肿瘤细胞毒性。SD1是一种人单域抗体，可识别靠近细胞表面的间皮素c -末端（539-588），对肿瘤细胞具有补体依赖性的细胞毒性。2013年，在Mol Cancer Ther （PMID: 23371858）中报道了mesothelin的SD1人抗体。这种新的人类抗体显示出作为癌症治疗候选药物的潜力。

Liver cancer is the fifth most common cancer and the third leading cause of cancer mortality in the world. Hepatocelluar carcinoma (HCC) accounts for approximately 75% of liver cancer cases, while intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver tumor. There is an urgent need to develop new drugs for the treatment of liver cancer. Project 1: Targeting GPC3 in HCC and other cancers GPC3 is a heparan sulfate proteoglycan highly expressed in HCC and holds potential for liver cancer therapy. The biological functions of GPC3 and its role in liver tumorigenesis remain elusive. Our work helps uncover the role of GPC3 in liver cancer cell growth. We produced and analyzed a recombinant soluble GPC3 (25-559) that inhibited the growth of HCC cells and presumed to compete with endogenous glypican-3 for binding to growth factors on the cancer cell surface. Our lab isolated a panel of mouse monoclonal antibodies including YP7 that recognize the C-terminal end (511-560) of GPC3. YP7 binds GPC3 with high affinity for HCC. It is highly sensitive in that it also detects GPC3 in low expression ovarian clear cell carcinoma and melanoma cells. In FY13, the GPC3 mouse monoclonal antibody work was reported in the journal MAbs (PMID: 22820551). Recently, we generated a human single-domain antibody, HN3, with high affinity for cell-surface-associated GPC3 molecules. The human antibody recognizes a unique conformational epitope in the core protein of GPC3. HN3 inhibits proliferation of HCC cells and exhibits significant inhibition of HCC xenograft tumor growth in mice. The underlying mechanism of HN3 action may involve cell-cycle arrest at G1 phase through Yes-associated protein (YAP) signaling, suggesting a novel mechanism for GPC3-targeted cancer therapy. In FY13, the HN3 antibody research was published in Proc Natl Acad Sci USA (PMID: 23471984). Project 2: Targeting mesothelin in ICC and other cancers Mesothelin is expressed at high levels in ICC, mesothelioma, ovarian cancer, and other cancers. The interaction between mesothelin and MUC16 (also known as CA125) may facilitate the implantation and spread of tumors. We experimentally established the 64-amino acid functional binding domain (IAB, 296-359) in the N-terminus of cell surface mesothelin for MUC16. HN125, an immunoadhesin that consists of the IAB domain and the Fc portion of a human antibody, disrupts the cancer cell adhesion mediated by the MUC16-mesothelin interaction, and elicits antibody-dependent cell mediated cytotoxicity against MUC16-positive tumor cells. Subsequently, we generated the HN1 and SD1 human monoclonal antibodies. HN1 binds the N-terminal end of cell surface mesothelin, disrupts the mesothelin-MUC16 interaction and elicits antibody-dependent cell mediated cytotoxicity against tumor cells. SD1 is a human single-domain antibody that recognizes the C-terminal end (539-588) of mesothelin close to the cell surface and exhibits complement-dependent cytotoxicity against tumor cells. In FY13, the SD1 human antibody to mesothelin was reported in Mol Cancer Ther (PMID: 23371858). The new human antibodies show potential for use as cancer therapeutic candidates.