The changing neoantigen landscape and associated immune response during immune checkpoint blockade in recurrent glioblastoma: a pathway to personalized tumor immunotherapy

每年有数以千计的胶质母细胞瘤(GBM)患者被诊断出来，尽管目前 最大限度手术切除、放疗和化疗的标准治疗，中位存活率较低 比15个月还多。虽然免疫检查点抑制剂(ICIS)已经显著提高了小鼠的存活率 尽管系统性癌症的数量很多，但它们在GBM中的有效性并不那么显著。预测性指标 确定哪些患者对ICIS会有更好的反应，而GBM缺乏有效的免疫治疗靶点。 这项应用的总体目标是识别免疫基因组学决定因素对ICIS的反应 以确定最有可能从这些疗法中受益的患者。中心假设是 GBM新抗原的免疫原性和新抗原特异性免疫反应的时间变化 ICI治疗与临床疗效相关。这个项目的基本原理是更好地识别 对ICIS有反应的患者将提高靶向免疫治疗的疗效，并允许 开发新的个性化治疗方法。这项提议将利用肿瘤和匹配的血液样本 从NIH资助的一项研究联合ICIS在GBM中的有效性的试验中，追求以下具体目标： 1)识别可引起新抗原特异性T细胞克隆扩增的新抗原，并确定 IC阻断过程中丢失或获得的新抗原的免疫原性；(2)鉴定共有的新抗原特异性T细胞 血液和肿瘤之间的克隆，并用IC阻断来量化这些克隆的时间变化，以及 (3)确定这些共享克隆的多样性和增殖与对ICIS的反应之间的关系。 假定的新抗原将通过整个外显子组测序和新抗原的应用来鉴定 治疗前肿瘤及其免疫原性的预测平台将通过评估 新一代TcR-VβCDR3区测序扩增新抗原特异性T细胞克隆 在体外多肽刺激后。利用这一新的检测和生物信息学平台，TCR-VβCDR3 区域将被用作条形码来识别血液和血液之间共享的新抗原特异性T细胞克隆 肿瘤，用IC阻断追踪和量化这些克隆的增殖或耗尽，并确定 这些克隆的多样性和增殖与对ICIS的反应之间的关系。这项研究建议在 这个应用程序的创新之处在于它使用了一种新的、定量的、敏感的和特定的技术来确定 新抗原的免疫原性是常规检测不能检测到的。拟议的研究是 意义重大，因为它将确定哪些新抗原与T细胞增殖和 确定ICI反应的免疫基因组生物标志物。这样的知识将允许最大限度地选择患者 可能从ICI疗法中受益，并为基于免疫的新型个性化疗法提供新的靶点。通过 在进行这项研究时，杰克逊博士将接受研究设计、方法学和 研究计划是成为一名熟练的外科科学家和神经外科肿瘤学的领导者所必需的。

There are thousands of patients with glioblastoma (GBM) being diagnosed each year and despite current standard therapy of maximal surgical resection, radiation, and chemotherapy, have a median survival of less than 15 months. While immune checkpoint inhibitors (ICIs) have led to significant improvements in survival in a number of systemic cancers, their effectiveness has been less dramatic in GBM. Predictive metrics to determine which patients will better respond to ICIs, and effective immunotherapy targets are lacking in GBM. The overall objective of this application is to identify immunogenomic determinants of response to ICIs in order to identify patients who are most likely to benefit from these therapies. The central hypothesis is that the immunogenicity of GBM neoantigens, and temporal changes in neoantigen-specific immune responses during ICI therapy are correlated with clinical response. The rationale for this project is that better identification of patients who will respond to ICIs will improve the efficacy of targeted immunotherapy and allow for development of novel personalized therapies. This proposal will leverage tumor and matched blood specimens from a NIH-funded trial studying the efficacy of combination ICIs in GBM to pursue the following specific aims: 1) identify neoantigens that elicit expansion of neoantigen-specific T cell clones and determine the immunogenicity of lost or gained neoantigens during IC blockade, (2) identify shared neoantigen-specific T cell clones between the blood and tumor and quantify the temporal changes of these clones with IC blockade, and (3) determine the association of the diversity and proliferation of these shared clones with response to ICIs. Putative neoantigens will be identified through whole exome sequencing and application of a neoantigen prediction platform of pre-treatment tumors and their immunogenicity will be assessed by evaluating the expansion of neoantigen-specific T cell clones using next-generation sequencing of the TCR-Vβ CDR3 region following in vitro peptide stimulation. Utilizing this novel assay and bioinformatics platform, the TCR-Vβ CDR3 region will be used as a barcode to identify shared neoantigen-specific T cell clones between the blood and tumor, track and quantify the proliferation or depletion of these clones with IC blockade, and determine the association of the diversity and proliferation of these clones with response to ICIs. The research proposed in this application is innovative in that it uses a novel, quantitative, sensitive, and specific technique to determine immunogenicity of neoantigens at a frequency undetectable by conventional assays. The proposed research is significant because it will identify which neoantigens are most strongly associated with T cell proliferation and identify immunogenomic biomarkers of ICI response. Such knowledge will allow for selection of patients most likely to benefit from ICI therapy and offer new targets for novel personalized immune-based therapies. By performing this research, Dr. Jackson will receive the rigorous training in study design, methodology, and research planning necessary to become a skilled surgeon-scientist and a leader in neurosurgical oncology.