Cytotoxic Ribonucleases in Antibody-Drug Conjugates

描述（由申请人提供）：该项目的目标是利用一种逃避核糖核酸酶作为药物，开发一种安全而有效的抗体-药物偶联物（ADC）。EVade（tm）核糖核酸酶是哺乳动物酶的变体，在多种癌症类型的小鼠异种移植模型中有效，没有明显的毒性。虽然它们是有效的，但我们对提高EVade（tm）核糖核酸酶的效力以改善临床结果感兴趣。许多较新的靶向癌症疗法，如单克隆抗体，只被批准与其他药物联合使用，通常是小分子细胞毒素。小分子细胞毒素是有效的，但往往会引起严重的不良反应。小分子与靶向治疗的结合可以提高疗效，但会抵消靶向药物的任何安全性益处。我们希望寻求一种策略，既能增加成功治疗的机会，又不会增加毒副作用。我们将使用多种连接物将一种特性良好的抗体与一种独特的半胱氨酸结合起来，这种半胱氨酸是在一种有效的EVade（tm）核糖核酸酶中设计的。这些连接体对抗体（活化的酯或氢化物）和核糖核酸酶（马来酰亚胺、硫醇、卤代乙酰和2-吡啶二硫）的反应性不同。一些连接体可以在细胞中被切割，而另一些则保持稳定。抗体-核糖核酸酶结合物将被检测抗原结合和酶活性。活性偶联物将在体外（细胞增殖）对表达CEA和未知表达CEA的细胞系进行测试。有希望的候选人将在CEA过表达细胞系的小鼠异种移植模型中进一步筛选。该项目的最终目标是为医生治疗癌症患者开发一种安全有效的新工具。对于高效的癌症治疗方法有一个明确而未被满足的需求，我们的目标是为医生提供一种有效的新工具来治疗他们的癌症患者。2003年，美国国家癌症研究所估计，130万美国人将被新诊断为癌症，每天有1500多名美国人死于癌症。

DESCRIPTION (provided by applicant): The goal of this project is to develop a safe yet potent antibody-drug conjugate (ADC) by utilizing an EVade(tm) Ribonuclease as the drug. The EVade(tm) Ribonucleases are variants of mammalian enzymes that are effective in mouse xenograft models of multiple cancer types without exhibiting significant toxicity. While they are effective, we are interested in increasing the potency of the EVade(tm) Ribonucleases to improve clinical outcome. Many of the newer, targeted cancer therapies, such as monoclonal antibodies, are approved only in combination with other agents, typically small molecule cytotoxics. Small molecule cytotoxics are potent, but tend to cause serious adverse effects. The combination of the small molecules with the targeted therapies leads to improved efficacy but cancels out any safety benefits of the targeted drugs. We would like to pursue a strategy that would increase the chances of successful treatment without adding toxic side effects. We will conjugate a well characterized antibody reactive against CEA-expresssing cancer cells to a unique cysteine engineered in a potent EVade(tm) Ribonuclease using a variety of linkers. The linkers will be varied in their reactivity towards the antibody (activated ester or hyrdzide) and the ribonuclease (maleimide, thiol, haloacetyl, and 2- pyridyldithio). Some of the linkers can be cleaved in the cell while others will remain stable. The antibody-ribonuclease conjugates will be tested for antigen binding and enzymatic activity. Active conjugates will be tested in vitro (cell proliferation) against CEA-expressing and cell lines not known to express CEA. Promising candidates will then be further screened in a mouse xenograft model with a CEA overexpressing cell line. The ultimate goal of this project is to develop a new safe AND effective tool for physicians to treat patients with cancer. There is a clear and unfilled need for highly efficacious cancer therapeutics, and our goal is to provide an effective new tool for physicians to treat their patients who have cancer. In the year 2003, the National Cancer Institute estimated that 1.3 million Americans will be newly diagnosed with cancer and that more than 1,500 Americans died from cancer each day.