Novel Immunotherapy for Hepatocellular Carcinoma

描述（由申请人提供）： 肝细胞癌（HCC）是全球最常见的癌症形式之一，每年报告约1，000，000例新发病例和1，300，000例死亡。它是最致命的癌症形式之一，部分原因是HCC细胞对传统癌症疗法具有高度抗性。迫切需要新的治疗方法，并且是本申请的焦点。由连接至细胞毒性分子的肿瘤特异性靶向部分（例如抗体）组成的免疫毒素已经显示出用于癌症治疗的一些前景。然而，主要缺点包括对实体瘤的渗透性差和非人毒性部分的免疫原性。这项提议将开发一种克服这些问题的HCC特异性免疫毒素。来自HCC特异性杂交瘤的单链可变区抗体片段（scFv）将与称为“DNA片段化激活剂”（ADF）的具有强毒性的9kD新型人肽基因融合。将低纳摩尔浓度的重组ADF引入细胞对多种肿瘤细胞类型（包括HCC）是有毒的。此外，通过不同机制对化疗药物高度耐药的肿瘤细胞变体仍然与非耐药肿瘤细胞一样对ADF敏感。本申请的第一个目的是克隆和表达单独的抗HCC scFv并与ADF融合（命名为TH101）。将进行细胞结合和细胞毒性研究，以评价新构建体对各种肿瘤细胞系以及正常细胞类型的特异性。将进行初始研究以评价TH101在小鼠中的潜在急性毒性，以及缀合物在肝细胞瘤异种移植物中相对于正常组织的优先蓄积。II期研究将在HCC的小鼠异种移植治疗模型中测试TH101，并开发scFv构建体的人源化版本用于进一步的临床开发。该项目的成功完成将产生小的完全人HCC特异性免疫毒素，其与用大的完整抗体或免疫原性非人毒素部分制备的免疫毒素相比将具有显著的优势。 此外，由于ADF对多种耐药肿瘤类型具有如此强的毒性，因此它也可以在未来的应用中作为“子弹”广泛应用于武装对不同肿瘤细胞类型具有特异性的抗体。

DESCRIPTION (provided by applicant): Hepatocellular carcinoma (HCC) is one the most common forms of cancer worldwide, with approximately 1,000,000 new cases and 1,300,000 deaths reported annually. It is one of the most lethal forms of cancer, in part due to the fact that HCC cells are highly resistant to conventional cancer therapies. New approaches to therapy are desperately needed, and is the focus of the present application. Immunotoxins composed of a tumor specific targeting moiety, such as an antibody, attached to a cytotoxic molecule have shown some promise for cancer therapy. However, major drawbacks include poor penetration into solid tumors and the immunogenicity of non-human toxic moieties. This proposal will develop an HCC-specific immunotoxin that overcomes these problems. A single chain variable region antibody fragment (scFv) derived from a HCC-specific hybridoma will be genetically fused to a potently toxic 9 kD novel human peptide called "activator of DNA fragmentation" (ADF). Introduction of recombinant ADF at low nanomolar concentrations into cells is toxic to a wide variety of tumor cell types, including HCC's. Furthermore, tumor cell variants that are highly resistant to chemotherapeutic drugs through different mechanisms, are still just as sensitive to ADF as non-resistant tumor cells. The first aim of this application is to clone and express the anti-HCC scFv alone and fused to ADF (designated TH101). Cell binding and cytotoxicity studies will be performed to evalutate the specificity of the new construct on a variety of tumor cell lines as well as normal cell types. Initial studies will be performed to evaluate the potential acute toxicity of TH101 in mice, as well as the preferential accumulation of the conjugate in hepatoma xenografts as opposed to normal tissue. Phase II studies will test TH101 in mouse xenograft therapeutic models of HCC and develop a humanized version of the scFv construct for further clinical development. The successful completion of this project will result in a small completely human HCC-specific immunotoxin that will have significant advantages compared to immunotoxins prepared with bulky whole antibodies or immunogenic non-human toxin moieties. Furthermore, since ADF is so potently toxic to a wide variety of drug-resistant tumor types, it may also have wide application as a "bullet" to arm antibodies specific for different tumor cell types in future applications.