Collaborative Research: Integrative Adaptation of Dendrimer-peptide Conjugates for Cancer Immunotherapy

非技术性概述免疫疗法，利用患者自身的免疫系统来治疗疾病，已经彻底改变了癌症治疗。临床上使用的大多数免疫抑制药物都是基于生物制剂，如抗体（仅与特定抗原结合的蛋白质），可以增强对肿瘤细胞的免疫监视。 然而，这种基于抗体的药物是昂贵的，并且通常导致令人失望的临床结果，特别是当单独使用时。使用肽（由20-30个氨基酸的链制成的大分子）将是一种有前景的替代方案;然而，它们比相应的抗体更弱的结合被认为是一个主要的弱点。最近，提出这项工作的合作团队已经证明，小球状聚合物（尺寸为人类头发厚度的1/10，000），称为聚（酰胺胺）（PAMAM）树状聚合物，可以被工程化以显着提高肽的结合强度高达一百万倍。在这项提案中，研究小组假设，与计算优化的肽连接的树枝状聚合物可以增强免疫系统攻击肿瘤细胞，从而最大限度地提高其免疫效果。在成功完成该项目后，该团队将致力于开发一种与各种免疫肽兼容的新技术。结合研究工作，本项目包括各种教育活动，招收研究生，本科生和高中生。 这些活动不仅有助于高级学位学生积极参与尖端科学，还能激发大学预科学生对STEM的兴趣，这将对我国保持世界科学和工程的领先地位产生深远的影响。技术概述研究活动的总体目标是整合计算和实验方法来设计基于树枝状聚合物的纳米颗粒平台-用于增强癌症免疫治疗的肽缀合物。合作团队已经证明，聚（酰胺胺）（PAMAM）树枝状聚合物是多价结合效应的优秀介质，如通过显着增强小分子，抗体和肽的结合亲和力所观察到的。这种用于结合增强的纳米工程方法可以直接适用于改善依赖于有效阻断免疫细胞和肿瘤细胞之间结合的癌症免疫疗法。鉴于与靶免疫检查点蛋白（如程序性死亡配体1（PD-L1）、程序性细胞死亡蛋白-1（PD-1）和细胞毒性T淋巴细胞相关蛋白4（CTLA-4））的强结合是有效诱导检查点阻断所必需的，迄今为止FDA批准的所有免疫检查点抑制剂（ICI）都是基于具有强结合亲和力的抗体。不幸的是，这种基于抗体的治疗剂是昂贵的，并且通常导致令人失望的临床结果，特别是当单独使用时。该团队假设，树状聚合物与靶向T细胞上多个免疫检查点受体的计算优化肽的结合将大大提高其他弱结合肽的结合强度，从而最大限度地提高其免疫效率。肽的使用将是有利的，因为与完整抗体相比，它们具有成本效益并且适合于各种工程化策略。所提出的树枝状聚合物-肽缀合物（DPC）系统由用肽官能化的工程化PAMAM树枝状聚合物组成，与其他常用的纳米颗粒药物递送系统相比相对简单。然而，DPC系统是独特的和创新的，因为：i）肽可以通过高通量计算进行调整和优化; ii）树状聚合物多聚化肽以利用强的多价结合效应（亲合力）; iii）折叠的肽可以稳定在树状聚合物表面上，进一步有助于结合增强;和iv）该方法实际上与任何肽相容，为各种组合提供模块化平台。成功完成本项目后，我们将对肽设计/合成、聚合物工程、DPC的结合动力学和生物学行为有基本的了解。该项目将扩大代表性不足的少数民族和妇女在各级教育中参与STEM研究。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical SummaryImmunotherapy, utilization of a patient’s own immune system to treat diseases, has revolutionized cancer treatment. Most of the immunotherapeutic drugs that are being used in the clinic are based on biologics, such as antibodies (proteins that bind to specific antigens only), that boost immune surveillance against tumor cells. However, such antibody-based drugs are expensive and often result in disappointing clinical outcomes, particularly when used alone. The use of peptides (macromolecules made from a chain of 20-30 amino acids) would be a promising alternative; however, their weaker binding than the corresponding antibodies has been recognized as a major weakness. Recently, the collaborative team proposing this work have demonstrated that small ball-shaped polymers (size of 1/10,000 of human hair thickness), called poly(amidoamine) (PAMAM) dendrimers, can be engineered to dramatically improve the binding strength of the peptides up to a million times. In this proposal, the team hypothesizes that dendrimers attached with computationally optimized peptides can boost up the immune system to attack tumor cells, thereby maximizing their immunotherapeutic effect. Upon successful completion of this project, the team will contribute to developing a new technology that would be compatible with various immunotherapeutic peptides. Integrated with the research effort, this project includes various educational activities that recruit graduate students, undergraduate students, and high school students. These activities will not only help advanced degree students be actively involved in cutting-edge science but also stimulate STEM interests of pre-college students, which will have profound impact on our nation to maintain the position as the world leader of science and engineering.Technical SummaryThe overarching goal of the research activities is to integrate computational and experimental methods to engineer a nanoparticle platform based on dendrimer-peptide conjugates for enhanced cancer immunotherapy. The collaborative team has demonstrated that poly(amidoamine) (PAMAM) dendrimers are excellent mediators for multivalent binding effects, as observed by dramatically enhanced binding avidities of small molecules, antibodies, and peptides. This nanoengineering approach for binding enhancement could be directly applicable for improving cancer immunotherapy that relies on efficient blocking of binding between immune and tumor cells. Given that strong binding to the target immune checkpoint proteins, such as programmed death-ligand 1 (PD-L1), programmed cell death protein-1 (PD-1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), is necessary to effectively induce the checkpoint blockade, all the FDA-approved immune checkpoint inhibitors (ICIs) to date are based on antibodies with strong binding affinities. Unfortunately, such antibody-based therapeutics are expensive and often result in disappointing clinical outcomes, particularly when used alone. The team hypothesizes that dendrimer conjugation with computationally optimized peptides that target multiple immune checkpoint receptors on T cells would substantially improve the binding strength of otherwise weakly binding peptides, which in turn would maximize their immunotherapeutic efficiency. The use of peptides would be advantageous, as they are cost-effective and amenable to various engineering strategies, in contrast to whole antibodies. The proposed dendrimer-peptide conjugate (DPC) systems, consisting of engineered PAMAM dendrimers functionalized with peptides, are relatively simple in comparison to other commonly used nanoparticle drug delivery systems. Yet, the DPC systems are unique and innovative in that: i) peptides can be adapted and optimized via a high-throughput computation; ii) dendrimers multimerize peptides to exploit strong multivalent binding effects (avidity); iii) folded peptides can be stabilized on the dendrimer surface, further contributing for binding enhancement; and iv) this approach is compatible with virtually any peptides, providing a modular platform for various combinations. Upon successful completion of this project, we will have obtained fundamental understanding in peptide design/synthesis, polymer engineering, and binding kinetics and biological behaviors of the DPCs. The project will broaden participation of underrepresented minorities and women in STEM research at various educational levels.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.