A Cobalt Porphyrin Nanoliposome Adjuvant for MHC-I-Restricted Cancer Peptide Vaccines

项目摘要 MHC I类（MHC-I）限制性肽癌症疫苗仅保留最少量的生化信息 这是产生抗原特异性T细胞以引发抗肿瘤应答所需的。自身免疫， 最小的肽表位不能提供令人满意的应答，因此通常长肽或缀合的肽表位不能提供令人满意的应答。 必须有运载系统。然而，这些方法克服了短合成肽的直接性， 疫苗。一种新的肽疫苗免疫模式将被引入，基于组合（通过简单的 混合）MHC-I肽表位与诱导自发纳米脂质体-抗原的疫苗佐剂 颗粒化（SNAP）。含有少量钴卟啉-磷脂（CoPoP）的脂质体快速 通过His-标签自发插入双层结合短His-标签肽（8- 9聚体）。这引起 到在生物介质中稳定的颗粒化。His标记的肽与CoPoP脂质体简单混合 在接种疫苗时（无需进一步纯化）将这些充分表征的肽转化为100 nm的 粒子这种方法在产生抗原特异性CD 8 + T细胞方面是潜在有效的。AH 1是MHC-IH-2Ld 来源于gp 70鼠白血病病毒抗原的模型CD 8+表位。可以使用AH 1衍生肽 用SNAP免疫以产生大量抗原特异性CD 8 + T细胞。SNAP免疫接种， 低纳克剂量的肽完全保护小鼠免受随后的肿瘤攻击， 肺转移的治疗性疫苗模型。将评估SNAP免疫的不同组成部分， 包括his-标签长度、共掺入的浓度和剂量（MPLA和QS-21;两者都是GSK的一部分）。 疫苗佐剂AS 01），以确定它们对Ag特异性CD 8+应答的影响。Ag特异性的产生 将评估CD 44 + CD 62 L+细胞以确定这样的中央记忆细胞是否更有效地抑制CD 44 + CD 62 L+细胞。 根除肿瘤将在多种预防和治疗性局部和转移中测试疫苗效力 肿瘤模型将评估大肿瘤的治疗性治疗与环磷酰胺的影响， 检查站封锁。将通过评估递送的肽如何到达MHC来探索机制见解- I.假设His标签肽与CoPoP脂质体结合，并经历血清稳定转运至引流 淋巴结在那里，它们被树突状细胞吞噬，吞噬体的还原环境 也被怀疑诱导肽从CoPoP脂质体中释放。双层Toll样受体 被推测上调吞噬体内MHC-I的表达。进一步的研究将评估 SNAP免疫和抗原多路复用作为肽微文库体内筛选工具的可行性 使用已建立的肿瘤相关抗原和新抗原， 测序最后，将评估系统的安全性和钴反应。这些研究将提供 用于癌症治疗的短的、MHC-I限制性肽基癌症疫苗的实质性进展， 免疫原性表位筛选。

PROJECT SUMMARY MHC class I (MHC-I) -restricted peptide cancer vaccines hold the minimal amount of biochemical information required for generating antigen-specific T cells to elicit anti-tumor responses. On their own, immunization with minimal peptide epitopes does not provide a satisfactory response, so typically long peptides or conjugated delivery systems are necessitated. However, such approaches defeat the directness of short synthetic peptide vaccines. A new peptide vaccine immunization paradigm will be introduced, based on combining (via simple mixing) MHC-I peptide epitopes with a vaccine adjuvant that induces spontaneous nanoliposome-antigen particleization (SNAP). Liposomes that contain small amounts of cobalt porphyrin-phospholipid (CoPoP) rapidly bind short his-tagged peptides (8-9mers) via spontaneous insertion of the his-tag into the bilayer. This gives rise to particleization that is stable in biological media. His-tagged peptides are simply mixed with CoPoP liposomes at the time of vaccination (without further purification) to convert these well-characterized peptides into a 100 nm particle. This approach is potently effective in generating antigen-specific CD8+ T cells. AH1 is a MHC-I H-2Ld model CD8+ epitope derived from the gp70 murine leukemia virus antigen. An AH1-derived peptide can be used with SNAP immunization to generate high numbers of antigen specific CD8+ T cells. SNAP immunization with low nanogram doses peptides completely protects mice from subsequent tumor challenge, and eradicates 100% of lung metastases in a therapeutic vaccine model. Varying components of SNAP immunization will be assessed, including the his-tag length, the density and dose of co-incorporated (MPLA and QS-21; both part of GSK’s vaccine adjuvant AS01) to determine their impact the Ag-specific CD8+ response. Generation of Ag-specific CD44+ CD62L+ cells will be assessed to determine whether such central memory cells are more effective in eradicating tumors. Vaccine efficacy will be tested in multiple prophylactic and therapeutic local and metastasis tumor models. Therapeutic treatment of large tumors will be assessed with the impact of cyclophosphamide and checkpoint blockade. Mechanistic insights will be probed by assessing how the delivered peptide reaches MHC- I. It is hypothesized that his-tag peptides bind to CoPoP liposomes, and undergo serum-stable transit to draining lymph nodes. There, they are phagocytosed by dendritic cells where the reductive environment of phagosomes is also suspected to induce the release of the peptide from the CoPoP liposomes. Toll-like receptor in the bilayer are hypothesized to upregulate the expression of MHC-I within the phagosome. Further studies will assess the viability of SNAP immunization and antigen multiplexing as an in vivo screening tool for peptide microlibraries using established tumor-associated antigens and neoantigens that will be identified with next-generation sequencing. Finally, the safety and cobalt response of the system will be assessed. These studies will provide substantial advancement for short, MHC-I-restricted peptide-based cancer vaccines for cancer therapy and immunogenic epitope screening.