Neoantigen-Targeted Vaccines in Combination with Immune Checkpoint Inhibitors for Pancreatic Cancer

项目总结 免疫检查点抑制剂(ICIS)在大约20%的癌症患者中提供了持久的临床反应，但 对缺乏肿瘤内T细胞的癌症有最小的影响。将耗尽T细胞的癌症转化为 需要吸引高质量T细胞的细胞才能使这些对ICIS不敏感的癌症变得敏感。肿瘤包含 编码肿瘤特异性突变蛋白的体细胞突变，这些突变蛋白在正常细胞上不表达 (称为新抗原)。具有最高突变负担的癌症，如黑色素瘤，更有可能 对单一代理ICIS做出回应。然而，大多数癌症，包括胰腺导管腺癌(PDAC)， 突变负荷较低，导致抗原性较低，内源性T细胞谱系较弱，T细胞较少 肿瘤内有细胞渗入。PDAC还具有免疫抑制肿瘤微环境(TME)，包括 表达T细胞抑制信号的单核细胞、B细胞和T细胞。临床前研究表明，一种突变的 高表达mKRASG12D基因工程小鼠(KPC小鼠)接种ICIS KRAS疫苗 抑制癌前病变进展到PDAC(PMID：24607504)。我对Panc02细胞的研究表明 一种新抗原靶向疫苗，PancVAX，12个20聚体新抗原肽的混合物，当配对时 使用IC调节剂清除了Panc02荷瘤小鼠的肿瘤，并提高了存活率(PMID：30333318)。在这 我们将测试以mKRAS新抗原为靶点的多肽疫苗的假设，或者 个性化的患者肿瘤特异性新抗原将触发高质量的新抗原特异性效应器和 效应器记忆T细胞，然后可以被ICIS进一步激活并导致肿瘤 拒绝。因此，我们将进行两项早期临床试验，以测试针对mKRAS(特定目标1)或 患者肿瘤特异性新抗原(特异性靶点2)与ICIS ipilimumab和nivolumab联合应用 PDAC切除和转移者分别为2例。在这两种情况下，我们都将评估三元组的安全性 组合，对外周血进行深入的免疫表型分析，包括T细胞数量、质量和 曲目，并研究TME的细胞结构。尖端技术的补充 包括单细胞RNA-Seq和TCR-Seq，以及多光谱免疫荧光。在漫长的岁月里 长期而言，这些研究应该为PDAC患者未来的联合免疫治疗方法提供信息，并且在 短期内，将为我提供重要的生物信息学、人类免疫学和早期临床试验方面的新技能 设计。我的顾问团队的杰出指导，约翰霍普金斯大学丰富的科学环境，以及 大量的可用资源应该使我能够实现我的目标，成为一个有资金的、独立的 转化型肿瘤学的研究人员在此授权期结束前。

PROJECT SUMMARY Immune checkpoint inhibitors (ICIs) provide durable clinical responses in about 20% of cancer patients, but have minimal effects in cancers lacking intra–tumoral T cells. Approaches that turn T–cell–deplete cancers into ones that attract high–quality T cells are needed to sensitize these unresponsive cancers to ICIs. Tumors contain somatic mutations that encode for mutant proteins that are tumor–specific and not expressed on normal cells (termed neoantigens). Cancers, such as melanoma, with the highest mutational burdens are more likely to respond to single agent ICIs. However, most cancers, including pancreatic ductal adenocarcinoma (PDAC), have lower mutational loads, resulting in lower antigenicity, weaker endogenous T cell repertoires, and fewer T cells infiltrating the tumor. PDACs also have an immunosuppressive tumor microenvironment (TME) consisting of monocytes, B cells and T cells that express T cell inhibitory signals. Preclinical studies show that a mutated KRAS (mKRAS) vaccine given with ICIs to genetically–engineered mice overexpressing mKRASG12D (KPC mice) inhibits premalignant lesions from progressing to PDAC (PMID: 24607504). My work with Panc02 cells showed that a neoantigen–targeted vaccine, PancVAX, a mixture of twelve 20–mer neoantigen peptides, when paired with IC modulators cleared tumors in Panc02–bearing mice with a survival benefit (PMID: 30333318). In this proposal we will test the hypothesis that peptide vaccines targeting ‘shared’ mKRAS neoantigens, or ‘personalized’ patient–tumor–specific neoantigens will trigger high–quality neoantigen–specific effector and effector memory T cells, which will then become available for further activation by ICIs and result in tumor rejection. We will thus conduct two early clinical trials to test vaccines targeting mKRAS (Specific Aim 1) or patient–tumor–specific neoantigens (Specific Aim 2) in combination with the ICIs ipilimumab and nivolumab in patients with resected and metastatic PDAC, respectively. In both instances, we will assess safety of the triple combinations, perform in–depth immune phenotyping of peripheral blood to include T cell number, quality and repertoire, and study the cellular architecture of the TME. A complement of state–of–the–art technologies including single cell RNA–Seq and TCR–Seq, and multispectral immunofluorescence will be utilized. In the long term, these studies should inform future combination immunotherapy approaches in PDAC patients, and, in the short term, will provide me with vital new skillsets in bioinformatics, human immunology, and early clinical trial design. The outstanding mentorship of my Advisory Team, the rich scientific environment at Johns Hopkins, and the vast array of available resources should poise me to achieve my goal of becoming a funded, independent investigator in translational oncology by the end of this grant period.