Metabolic Engineering of Cancer for Immunotargeting

描述（由申请人提供）：癌症是世界上最臭名昭著的健康问题之一。该项目旨在通过免疫疗法找到有效的癌症治疗方法，即用抗癌抗体或能激发抗癌免疫的治疗性癌症疫苗治疗患者，由于其潜在的高疗效和低毒性，被认为是癌症的理想疗法。在这方面，肿瘤相关糖抗原（TACA），由肿瘤表达的异常聚糖，是重要的分子基序和靶标。然而，大多数TACA的主要问题之一是它们的免疫耐受性，即，它们的免疫原性差或无免疫原性，这是一个通常难以通过简单地将TACA偶联到载体蛋白上来克服的问题。另一方面，耐受的TACA通常是肿瘤细胞上相对丰富和重要的抗原，使它们成为癌症疫苗开发的非常有吸引力的靶标。该项目旨在建立一种策略来克服对TACA的免疫耐受问题，并使用该策略来设计和开发新的基于TACA的癌症免疫疗法。所提出的策略的基本概念是用衍生自TACA的非天然类似物的疫苗免疫癌症患者，然后用非天然糖治疗患者，所述非天然糖可以糖工程肿瘤细胞以表达非天然TACA类似物代替天然TACA。预刺激的免疫系统随后将识别并破坏糖工程改造的肿瘤。预期由非天然TACA类似物制成的疫苗可以容易地激发抗肿瘤免疫。该项目的先前研究已经证明了该策略的两个先决条件，即非天然TACA类似物具有高度免疫原性以诱导强烈的T细胞依赖性免疫应答，并且肿瘤细胞可以被有效地糖工程化以表达非天然TACA类似物。该提案将继续测试各种糖缀合物作为新免疫策略的疫苗，验证其他相关问题，并在体外和体内评估治疗黑色素瘤，乳腺癌和结肠癌的新免疫疗法。本研究的具体目标是：1）合成和研究新的偶联疫苗，其中非天然TACA类似物连接到单磷酰脂质A和肽T细胞表位; 2）开发一种方法来定量分析由于糖工程而导致的非天然TACA类似物在细胞上的表达，并在体外评估各种抗体靶向和杀死糖工程化肿瘤细胞的效力和选择性;以及3）在体内研究和评估基于抗体和疫苗治疗的新免疫疗法治愈癌症和预防肿瘤转移的功效。预计通过所提出的研究，可以确定有希望的癌症免疫疗法用于临床试验，并最终开发成用于黑色素瘤和乳腺癌或结肠癌的有用疗法。此外，免疫耐受问题的解决方案可能对癌症免疫学和其他相关领域产生重大影响。公共卫生相关性：该研究项目旨在建立一种新的癌症免疫治疗策略，即，使用抗癌抗体或治疗性癌症疫苗来治疗肿瘤，这被认为是癌症的“理想疗法”。为此目的，将制备由癌细胞表达的特殊碳水化合物抗原的非天然类似物并将其偶联至载体分子以产生高度免疫原性的疫苗，所述疫苗可用于激发特异性免疫应答或制备针对非天然抗原的特异性抗体。然后用非天然糖处理接种疫苗的动物，这种糖可以诱导癌细胞上非天然抗原的表达。随后，激发的免疫系统或特异性抗体将识别并消除标记的肿瘤。该提案的具体目的是确定用于动物（或患者）免疫的有效疫苗和标记肿瘤细胞的适当条件，并验证新的免疫疗法治愈癌症的功效。

DESCRIPTION (provided by applicant): Cancer is one of the most notorious health problems worldwide. This project aims to find effective cures for cancer by immunotherapy, namely to treat patients with anticancer antibodies or with therapeutic cancer vaccines that can provoke anticancer immunities, which is considered the ideal therapy for cancer due to its potentially high efficacy and low toxicity. In this regard, tumor-associated carbohydrate antigens (TACAs), the abnormal glycans expressed by tumors, are important molecular motifs and targets. However, one of the major issues for the majority of TACAs is their immune tolerance, i.e., they are poorly or nonimmunogenic, a problem that is frequently difficult to overcome by simply coupling TACAs to a carrier protein. On the other hand, the tolerated TACAs are often the relatively rich and important antigens on tumor cells, rendering them very attractive targets for cancer vaccine development. This project aims to establish a strategy to overcome the problem of immune tolerance to TACAs and use the strategy to design and develop new TACA-based immunotherapies for cancer. The basic concept of the proposed strategy is to immunize cancer patients with a vaccine derived from an unnatural analog of a TACA and then treat the patients with an unnatural sugar that can glycoengineer tumor cells to express the unnatural TACA analog in place of the natural TACA. The pre-stimulated immune system will subsequently recognize and destroy the glycoengineered tumors. It is anticipated that vaccines made of unnatural TACA analogs can easily provoke antitumor immunities. Previous studies of this project have proved the two prerequisites for the strategy, namely that unnatural TACA analogs are highly immunogenic to induce strong T cell dependent immune responses and that tumor cells can be effectively glycoengineered to express unnatural TACA analogs. This proposal will continue to test various glycoconjugates as vaccines for the new immunotherapeutic strategy, verify other related issues, and evaluate in vitro and in vivo the new immunotherapy for treating melanoma, breast and colon cancer. The specific aims of this proposal are: 1) to synthesize and study new conjugate vaccines with the unnatural TACA analogs linked to monophosphoryl lipid A and a peptidic T cell epitope; 2) to develop a method to quantitatively analyze the expression of unnatural TACA analogs on cells as a result of glycoengineering, and to evaluate in vitro the efficacy and the selectivity of various antibodies to target and kill glycoengineered tumor cells; and 3) to study and evaluate in vivo the efficacy of the new immunotherapy to cure cancer and prevent tumor metastasis based on antibody and vaccine treatments. It is expected that through the proposed studies promising cancer immunotherapies can be identified for clinical trials and, ultimately, be developed into useful therapies for melanoma and breast or colon cancer. Moreover, a solution to the immune tolerance problem may have a significant impact on cancer immunology and other related areas as well. PUBLIC HEALTH RELEVANCE: This research project aims to establish a new strategy for cancer immunotherapy, i.e., to treat tumors using anticancer antibodies or therapeutic cancer vaccines, which is considered the "ideal cure" for cancer. For this purpose, unnatural analogs of the special carbohydrate antigens expressed by cancer cells will be prepared and coupled to carrier molecules to create highly immunogenic vaccines that can be used to provoke specific immune responses or prepare specific antibodies against the unnatural antigens. The vaccinated animals will be then treated with an unnatural sugar which can induce the expression of the unnatural antigens on cancer cells. Subsequently, the provoked immune system or the specific antibodies will recognize and eliminate the labeled tumors. The specific aims of this proposal are to identify the effective vaccines for immunization of animals (or patients) and the appropriate conditions for labeling of tumor cells and to verify the efficacies of the new immunotherapies to cure cancer.