Catch and Release Immunotoxins: CAR-Bombs for Cancer

摘要 美国癌症协会估计，2016年将有170万新确诊癌症病例和 美国有60万人死于癌症。尽管在治疗癌症方面取得了进展 随着手术、放疗、化疗和生物制剂的出现，迫切需要开发新的治疗方法。 有希望提高选择性、效力和有效性的方法。该项目引入了一种新的和 以前未经测试的平台策略，以提高向细胞质输送大分子的效率 目标细胞的数量。该战略的核心部分是使用“即捕即放”的单抗 抗体(CAR)，与pH依赖的受体结合。CAR抗体结合到高度有效的 大分子毒素(CAR-毒素)和内容体逃逸多肽(CAR-EEP)。联合用药 CAR-毒素和CAR-EEP结合物允许高效、靶向地在体内传递和释放毒素 细胞质，具有高度选择性和强大的抗癌功效。为了推进这一项目，我们有 研制了一种新型捕捉和释放抗癌胚抗原抗体(10H6)，具有高亲和力 CEA在生理pH下结合，在酸性pH下结合显著减少。初步数据显示 来评估10H6的结合、细胞毒性和药代动力学，总而言之，它强烈地 支持这项工作的可行性。已经组建了一个跨学科的团队来评估这一方法， 有三个实验目标：(1)检查和优化捕获物和释放物的效用 大分子的细胞质输送到体外的癌细胞，(2)检验关于肿瘤的假说 抗体结合物体内处置的选择性，以及(3)评价该抗体结合物的安全性和有效性。 捕捉和释放单抗结合物在治疗荷人异种移植瘤小鼠中的作用该项目，如果 成功，将建立一个新的目标概念，具有潜在的效用，提高效率 几乎任何大分子的细胞质递送到任何类型的癌症。

Abstract The American Cancer Society estimates that in 2016 there will be 1.7 million new cancer cases diagnosed and 600,000 cancer deaths in the United States. Although advances have been made in the treatment of cancer with surgery, radiation, chemotherapy, and with biologics, there is a critical need to develop novel treatment approaches with promise for improved selectivity, potency, and efficacy. This project introduces a new and previously untested platform strategy to enhance the efficiency of delivery of macromolecules to the cytoplasm of targeted cells. The central component of the strategy is the use of “catch-and-release” monoclonal antibodies (CAR), with pH-dependent receptor binding. The CAR antibodies are conjugated to highly potent macromolecular toxins (CAR-toxin) and to endosome escape peptides (CAR-EEP). Combined administration of CAR-toxin and CAR-EEP conjugates allows efficient, targeted delivery and release of the toxin in the cytoplasm, enabling highly selective and potent anti-cancer efficacy. To pursue this project, we have developed a novel catch-and-release anti-carcinoembryonic antigen (CEA) antibody (10H6), with high affinity CEA binding at physiological pH, and with dramatically reduced binding at acidic pH. Preliminary data have been generated to assess the binding, cytotoxicity, and pharmacokinetics of 10H6, which in sum, strongly support the feasibility of the work. An interdisciplinary team has been assembled to evaluate this approach, with three experimental aims that will: (1) examine and optimize the utility of catch and release conjugates for cytoplasmic delivery of macromolecules to cancer cells in vitro, (2) test hypotheses regarding the tumor selectivity of in vivo disposition of the antibody conjugates, and (3) evaluate the safety and efficacy of the catch-and-release mAb conjugates in the treatment of mice bearing human xenograft tumors. The project, if successful, will establish a new targeting concept, with potential utility in enhancing the efficiency of cytoplasmic delivery of virtually any macromolecule to any type of cancer.