Overcoming Drug Resistance to Nucleoside Analogs by Tumor-Targeted Active Nanofor

描述（由申请人提供）：通过肿瘤靶向活性药物纳米制剂克服对核苷类似物的耐药性细胞毒性核苷类似物（NA）是单药或多药化疗方案的重要组成部分。然而，在肿瘤和病毒感染的治疗中，对治疗性NA的耐药性成为持续的临床挑战。耐药的主要机制包括药物转运缺陷和NA转化为活性药物形式5'-三磷酸（NATP）的激酶依赖性活化。我们的中心假设是，在癌细胞的细胞质中直接递送NATP将足以绕过许多耐药机制并有效地根除耐药肿瘤。这种方法还可以减少化疗的毒性后果。我们专门设计了用于封装NATP的纳米载体，可生物降解的纳米凝胶阳离子网络，能够可逆地结合NATP，在肿瘤部位的癌细胞内递送和释放活性药物。在初步研究中，NATP-nanogel制剂在许多正常和耐药癌细胞和动物模型中表现出比NA显著改善的治疗效果。纳米制剂的全身循环和肿瘤蓄积将通过在纳米级上修饰纳米凝胶结构和用对过表达的肿瘤EGF受体或肿瘤淋巴管具有高亲和力的多种选择的肽装饰纳米凝胶表面来优化。纳米凝胶在组织中降解，形成无毒的聚合物缀合物。NATP-纳米凝胶制剂保留了它们的性质，并且可以以冻干形式储存。这种方法提供了额外的前景，多药化疗的耐药肿瘤，通过管理两个NA分子与不同的细胞目标。肽修饰纳米凝胶的全身给药建议将增强药物在播散性转移灶中的蓄积和对转移性肿瘤的治疗功效。我们的具体目标1是开发有效的肿瘤靶向纳米凝胶载体，这些载体被优化用于将NATP全身递送到肿瘤。具体目标2是在体外评估药物纳米制剂在收集对NA耐药的癌细胞系中的细胞毒性作用。收集具有NA抗性的特定机制的细胞系将使我们能够确定用于消除耐药癌细胞的载体、载体和药物的最有效组合。在具体目标3中，我们将在人类乳腺癌和淋巴瘤异种移植动物模型中通过选定的纳米制剂实现对耐药肿瘤的有效治疗，并评估使用具有单独细胞靶点的两种NATP的多重化疗方法的可行性。简而言之，这种方法开发了一种新的基于纳米技术的治疗耐药肿瘤的策略。 公共卫生相关性：许多常见癌症对治疗药物（包括核苷类似物）的抗性代表了对化学疗法的非常严重的临床挑战。对细胞毒性核苷类似物（单药和多药癌症治疗中的一线药物）的耐药性包括药物转运和细胞药物活化核苷5'-三磷酸的缺陷。我们在此提出直接应用肿瘤靶向纳米凝胶包封的核苷5'-三磷酸（nanoNATP）来将活性药物递送到癌细胞内并克服癌细胞防御绕过耐药机制。NanoNATP被发现可以数百至数千倍地恢复对核苷类似物具有抗性的癌细胞的敏感性。这种应用包括彻底的化学工程和通过肿瘤结合肽对纳米载体进行表面修饰，以增加其在肿瘤部位和转移灶中的积累。所建议的nanoNATP制剂提供了一种额外的治疗选择，用于全身施用一种或两种协同药物治疗难治性癌症。这将大大改善患者的生活质量;他们将只接受一次低剂量，而不是接受高剂量或两次不同药物的给药。该应用开发了创新的纳米技术方法来治疗耐药肿瘤。

DESCRIPTION (provided by applicant): Overcoming drug resistance to nucleoside analogs by tumor targeted active drug nanoformulations cytotoxic nucleoside analogs (NA) are important components of single-drug or multidrug chemotherapeutic regimens. However, drug resistance to therapeutic NA became constant clinical challenge in the treatment of tumors and viral infections. The principle mechanisms of resistance include deficiencies in drug transport and kinase-dependent activation of NA into 5'-triphosphates (NATP), an active drug form. Our central hypothesis is that direct delivery of NATP in the cytoplasm of cancer cells would be sufficient to bypass many mechanisms of drug resistance and efficiently eradicate drug-resistant tumors. This approach would also allow for decreasing toxic consequences of chemotherapy. We have specially designed nanocarriers for encapsulation of NATP, biodegradable nanogel cationic networks, which are capable to reversibly bind NATP, deliver and release the active drug inside cancer cells in tumor sites. In preliminary studies, NATP-nanogel formulations demonstrated significantly improved over NA therapeutic effect in many normal and drug-resistant cancer cells and animal models. Systemic circulation and tumor accumulation of nanoformulations will be optimized by modifying nanogel structure on nanoscale and decorating nanogel surface with multiple selected peptides having high affinity to overexpressed tumor EGF receptors or tumor lymphatic vessels. Nanogels degrade in tissues with the formation of non-toxic polymer conjugates. NATP-nanogel formulations retain their properties and can be stored in lyophilized form. This approach provides additional prospects for multidrug chemotherapy of drug-resistant tumors by administration of two NA molecules with different cellular targets. Systemic administration suggested for peptide-decorated nanogels would enhance drug accumulation in disseminated metastases and therapeutic efficacy against metastatic tumors. Our Specific Aim 1 is to develop efficient tumor-targeted nanogel carriers that are optimized for systemic delivery of NATP to tumors. Specific Aim 2 is to evaluate cytotoxic effect of drug nanoformulations in vitro in the collection of resistant to NA cancer cell lines. The collection of cell lines with specific mechanisms of resistance to NA will allow us to determine the most efficient combinations of vector, carrier and drug for elimination of drug-resistant cancer cells. In Specific Aim 3 we are going to achieve efficient therapy of drug-resistant tumors by selected nanoformulations in human breast cancer and lymphoma xenograft animal models and evaluate the feasibility of polychemotherapeutic approach using two NATP having separate cellular targets. Concisely stating, this approach develops a novel nanotechnology-based strategy of treating drug-resistant tumors. PUBLIC HEALTH RELEVANCE: Resistance of many common cancers to therapeutic drugs, including nucleoside analogs, represents a very serious clinical challenge to chemotherapy. The drug resistance to cytotoxic nucleoside analogs, the first line drugs in single- and multidrug cancer therapies, includes deficiencies in drug transport and cellular drug activation to nucleoside 5'-triphosphates. We propose here direct application of tumor-targeted nanogel- encapsulated nucleoside 5'-triphosphates (nanoNATP) to deliver the active drug inside of cancer cells and overcome the cancer cell defense bypassing the drug resistance mechanisms. NanoNATP was found to restore sensitivity of cancer cells resistant to nucleoside analogs in hundreds to thousand times. This application includes thorough chemical engineering and surface decoration of nanocarriers by tumor-binding peptides to increase their accumulation in tumor sites and metastases. The suggested nanoNATP formulations provide an additional therapeutic option for systemic administration of one or two synergistic drugs at the treatment of poorly treatable cancers. This would greatly improve quality of life of patients; instead of receiving high doses or two administrations of different drugs, they would receive only one low dose. This application develops innovative nanotechnological approach to treat drug-resistant tumors.