Systemic Delivery of CpG Oligonucleotides

描述(申请人提供)：细菌提取物通常具有抗肿瘤作用。直到最近才发现，在这种定义不明确的癌症治疗中，活性成分是细菌DNA，而不是蛋白质、碳水化合物或脂肪。与人类基因组DNA不同，细菌DNA显示的是未甲基化的胞苷-胍二核苷酸序列，通常被称为CpG。我们身体的宿主防御系统已经进化到这样一种方式，每当在身体中发现CpG时，它就是一个“危险”的信号。由此产生的先天免疫可以被利用来对抗肿瘤的生长。最吸引人的是，一旦肿瘤相关抗原从肿瘤中脱落，由CpG激活的树突状细胞可以对其进行处理，并呈现给T淋巴细胞，从而杀死肿瘤细胞。简而言之，基于CpG的免疫治疗不仅可以利用其先天免疫反应，还可以利用随后的获得性免疫反应。因此，CpG已成为近年来最令人兴奋的免疫疗法之一。然而，在动物模型中，该方法仅适用于肿瘤内或肿瘤周围的给药途径。在第二阶段的人体研究中，静脉注射无效，皮下注射仅产生轻微效果。综上所述，这些相当令人失望的结果可以归因于CpG在体内的糟糕传递。最近，我们展示了一种在交付过程中绕过这一关键问题的方法。我们的方法是基于这样一个事实，即免疫复合体只要不引发抗原交联，就可以在血液中长时间循环。在荷瘤小鼠身上，我们的配方显示在血液中的半衰期为几天，在肿瘤组织中累积的剂量高达20%。根据这一良好的药代动力学，静脉注射CpG成功地延缓了实体瘤的生长。最近，我们还发现一种皮下途径也同样有效。我们对这些令人兴奋的结果有自己的解释，这项提议旨在检验这些假设。这一部分构成了提案的一个方面。提案的另一部分涉及两个新系统的开发，这两个系统将不需要一个在动物研究中可能可以接受但在人类身上可能不能接受的步骤。拟议研究的成功结果无疑将加速基于CpG的免疫癌症治疗，并将为治疗癌症与其他现有治疗方法一起提供另一种可行的选择。 公共卫生相关性：多年来，人们已经知道细菌DNA片段具有抗肿瘤作用。为了有效，必须在肿瘤生长的地方引入它们。这项提案涉及开发一种方便的静脉或皮下给药途径，将药物输送到肿瘤组织的策略。

DESCRIPTION (provided by applicant): Bacterial extracts often show anti-tumor effect. It was only recently discovered that the active component in the ill-defined cancer treatment is bacterial DNA, not protein, carbohydrate, or lipid. In contrast to human genomic DNA, bacterial DNA shows unmethylated cytidine-guanidine dinucleotide sequences, commonly referred to as CpG. Our own body's host defense system has evolved such a way that whenever CpG is found in the body, it serves as a "danger" signal. Resulting innate immunity can be harnessed to fight against tumor growth. Most attractively, once tumor-associated antigens are shed from the tumor, dendritic cells activated by CpG can process them and present to T lymphocytes that can kill the tumor cells. In short, CpG-based immunotherapy can exploit not only its innate immune response but also subsequent adaptive immune response. Thus CpG has become one of the most exciting immunotherapies in recent years. However, the approach works only with intra-tumoral or peri-tumoral route of administration in animal models. In Phase II human studies, intravenous route was ineffective while subcutaneous administration produced only minor effects. Taken together these rather disappointing outcomes can be attributed to poor delivery of the CpG in vivo. Recently we were able to demonstrate a way to circumvent this critical problem in delivery. Our approach was based on the fact that immune complexes can circulate in the blood for a long time so long as they do not trigger antigen crosslinking. In tumor-bearing mice our formulation showed a half-life of several days in the blood and as much as 20% of the dose accumulated in tumor tissue. In accordance with this favorable pharmacokinetic, intravenously administered CpG successfully retarded solid tumor growth. More recently we also discovered that a subcutaneous route was as effective. We have our own explanations of these exciting results and this proposal is designed to test these hypotheses. This portion constitutes one aspect of the proposal. The other portion of the proposal is concerned with development of two new systems that will not require a step that may be acceptable in animal studies but may not be in humans. Successful outcome of the proposed studies will undoubtedly accelerate CpG-based immunocancer therapy and will provide another viable option in treating cancer along with other existing treatments. Public Health Relevance: It has been known for many years that bacterial DNA fragments exert anti-tumor effect. To be effective, they must be introduced where tumor is growing. This proposal deals with strategies for developing a convenient intravenous or subcutaneous route of administration that will deliver the agents to the tumor tissue.