Yip Theresa, Tu Xinyi, Qi Xiaodong, Yan Hao, Chang Yung
School of Life Sciences, Arizona State University, Tempe, AZ 85281, USA.
Biodesign Center for Molecular Design and Biomimetics, Biodesign Institute, Arizona State University, Tempe, AZ 85281, USA.
Vaccines (Basel). 2025 May 25;13(6):560. doi: 10.3390/vaccines13060560.
BACKGROUND/OBJECTIVES: Cancer peptide vaccines represent a promising strategy to develop targeted and personalized treatments for cancer patients. While tumor peptides alone are insufficient in mounting effective immune responses, the addition of adjuvants can enhance their immunogenicity. Nanoparticle delivery systems have been explored as vaccine carriers to incorporate both adjuvants and peptides. One such nanoparticle is RNA origami (RNA-OG), a nucleic acid nanostructure that is programmed to form different sizes and shapes. Our designed RNA-OG can incorporate various biomolecules and has intrinsic adjuvant activity by acting as a toll-like receptor 3 agonist. We previously showed that the RNA-OG functions as an adjuvanted, carrier-free vaccine platform to assemble peptides. Although effective, only a fixed number of peptides (13) could be covalently linked to each RNA-OG.
Here, we developed a simple physical assembly strategy to attach polylysine-linked neopeptides onto RNA-OG so that the number of peptides per RNA-OG could be readily tuned and tested for their immunogenicity.
Although the vaccines with a high number of peptides, i.e., 100-200 peptides/RNA-OG, led to greater peptide presentation by bone marrow-derived dendritic cells, they failed to mount effective CD8 T cell responses against engrafted tumor cells, probably owing to an induction of early T cell exhaustion. Interestingly, the same vaccine format with a low number of peptides, i.e., 10-15 peptides/RNA-OG, enhanced CD8 T cell responses without provoking T cell exhaustion in tumor-bearing mice, leading to strong protective anti-tumor immunity. In comparison, the covalently assembled RNA-OG-peptide vaccine, having a similarly low peptide dosage, offered the highest therapeutic efficacy. Thus, our RNA-OG nanostructure provides a simple and tunable platform for peptide loading to optimize vaccine efficacy.
Our findings have significant implications for peptide vaccine design regarding peptide dosages and structural stability of RNA-OG complexed with peptides, which could guide the development of more effective peptide vaccines for cancer immunotherapy.
背景/目的：癌症肽疫苗是为癌症患者开发靶向性和个性化治疗方法的一种有前景的策略。虽然单独的肿瘤肽不足以引发有效的免疫反应，但添加佐剂可以增强其免疫原性。纳米颗粒递送系统已被探索用作疫苗载体，以同时包含佐剂和肽。一种这样的纳米颗粒是RNA折纸（RNA-OG），一种被设计成形成不同大小和形状的核酸纳米结构。我们设计的RNA-OG可以结合各种生物分子，并通过作为Toll样受体3激动剂具有内在佐剂活性。我们之前表明，RNA-OG作为一种佐剂化的、无载体疫苗平台来组装肽。虽然有效，但每个RNA-OG只能共价连接固定数量的肽（13个）。
在此，我们开发了一种简单的物理组装策略，将聚赖氨酸连接的新肽附着到RNA-OG上，以便每个RNA-OG上的肽数量可以很容易地调整，并测试其免疫原性。
虽然含有大量肽（即100 - 200个肽/RNA-OG）的疫苗导致骨髓来源的树突状细胞呈现更多肽，但它们未能引发针对移植肿瘤细胞的有效CD8 T细胞反应，这可能是由于早期T细胞耗竭的诱导。有趣的是，相同疫苗形式但含有少量肽（即10 - 15个肽/RNA-OG），在荷瘤小鼠中增强了CD8 T细胞反应而不会引发T细胞耗竭，从而产生强大的保护性抗肿瘤免疫力。相比之下，具有相似低肽剂量的共价组装RNA-OG - 肽疫苗具有最高的治疗效果。因此，我们的RNA-OG纳米结构为肽负载提供了一个简单且可调节的平台，以优化疫苗效果。
我们的发现对于肽疫苗设计中肽剂量以及与肽复合的RNA-OG的结构稳定性具有重要意义，这可以指导开发更有效的用于癌症免疫治疗的肽疫苗。
