临床补铁药Ferumoxytol大幅增强“新生抗原疫苗”抗“晚期大肿瘤”效果的实验研究

Vaccines based on neoantigen, which derived of tumor mutations, have demonstrated "exciting" clinical efficacy in advanced "hot" tumors, but the efficacy needs to be improved, especially in "cold " tumors that with heavy immunosuppression, according to recent proof-of-concept clinical trials data. We have designed and screened a liposomal nanovaccine that formulated by co-encapsulating multiple-neoantigens and two danger signals, Lipo-neo-PA, which was significantly superior to current-used vaccine formulation. To our surprise, we found pretreatment combination with iron-supplement drug ferumoxytol, which was reported shifting tumor-associated macrophage (TAM) to M1 polarization, substantially improved lipo-neo-PA vaccine efficacy in established large tumors (eradication rate rising from 2/8 to 6/8). In this project, CT-26 tumor neoantigen therapeutic system will be used to (1) establish the quantitative relationship between serum-iron-concentration parameter and vaccine therapeutic efficacy; and (2) to analyze ferumoxytol induced M1-polarization in shaping tumor and lymph node microenvironment, further to elucidate which stage (priming or effector, or both) of vaccine-induced immune response are the targets of ferumoxytol using techniques such as flow cytometry and ELISpot. This program will provide reference data for clinical use ferumoxytol in tumor combination vaccine immunotherapy, and will reveal the rate-limiting step of tumor vaccine in immunesuppression situation, which will be helpful in vaccine design.

最近临床试验结果证明，肿瘤突变产生的新生抗原疫苗在“热免疫” 肿瘤中具有“令人兴奋”的临床效果，但在免疫抑制的“冷免疫”肿瘤中的效果亟待改善。本课题在设计筛选得到一个显著优于现有疫苗形式的“双佐剂新生抗原脂质体疫苗”Lipo-neo-PA的基础上，惊喜发现，临床补铁药Ferumoxytol(Fer)预处理联合，极大提高疫苗治疗“晚期大肿瘤”的效果（疫苗对大肿瘤的清除率由2/8变为6/8）。本项目利用CT-26等荷瘤模型的新生抗原疫苗治疗体系，拟1）建立Fer用药、“血铁浓度”、最佳疫苗效果的定量关系；2）利用流式细胞术、ELISpot等技术，分析Fer诱导的M1极化对疫苗活化阶段（priming，淋巴结）及效应阶段（effector，肿瘤组织）的影响，揭示Fer增强疫苗治疗效果的关键环节，为临床试验及疫苗优化提供依据。

治疗性疫苗是免疫治疗的重要策略，在肿瘤和持续性感染疾病中展现出良好的临床获益苗头；其治疗效力受到多方面因素影响。如何提高治疗性疫苗的治疗效力是亟待解决的重要问题。临床试验结果证明，基于新生抗原的肿瘤治疗性疫苗在“热免疫”肿瘤中具有“令人兴奋”的临床效果。我们在治疗性疫苗效力的提升研究中，主要从抗原设计和免疫应答调节剂方向展开。.主要研究内容、重要结果和关键数据.1. 研究了基于模拟抗原策略设计的纳米颗粒治疗性疫苗设计策略的效力。通过一个随机、多中心、安慰剂对照的2期临床试验，揭示了纳米颗粒治疗性疫苗的εPA-44临床效果；研究结果显示，该疫苗单用能够实现病人的临床获益，900微克εPA-44治疗组的临床应答率是38.8%，疗效显著高于安慰剂组（20.2%）。.2.多肽疫苗存在种属MHC限制性问题，本项目在小鼠疫苗基础上，制备了一个重要的人用新生抗原疫苗，即靶向KRAS G12突变的模拟抗原肿瘤疫苗。该疫苗形式能够产生更强大的抗肿瘤免疫应答，具有更为强大的抗肿瘤效果。基于上述治疗性疫苗设计策略，制备了一个HPV感染相关肿瘤预防性疫苗，即HPV感染治疗性疫苗。初步利用利用TC-1小鼠模型，进行效力评价。.3. 初步阐述了以临床补铁药Ferumoxytol为代表的纳米氧化铁颗粒提高肿瘤治疗性疫苗效力是多机制的，诱导肿瘤微环境的M1细胞极化是其机制之一。纳米氧化铁的铁离子具有直接调控T细胞功能的机制。鉴定了与铁离子诱导M1极化具有协同作用的靶标。阐明了肿瘤生长过程中血清铁离子浓度的动力学。.科学意义.本项目的研究内容概念证明了纳米颗粒疫苗策略的优越性，设计并研发了新的人源肿瘤治疗性疫苗，发现了治疗性疫苗效力调控的影响因素。