The role of Albumin-Flt3L-induced cross-presenting dendritic cell expansion in antitumor immunity

项目摘要/摘要 能够在多种癌症类型中介导抗肿瘤反应的癌症治疗策略仍然存在 即使检查点封锁等新的免疫疗法发展迅速，也是有限的。这个 不堪重负的癌症对新的、广泛有效的公共卫生负担产生了巨大的需求 免疫疗法。基本上所有癌症治疗策略成功的核心是产生 肿瘤特异性细胞毒性CD8+T细胞免疫需要树突状细胞呈递强大的抗原 (DC)，因为肿瘤细胞不能有效地提供相关的CD8+T细胞表位。DC必须摄取肿瘤细胞 或肿瘤抗原和交叉递呈免疫刺激多肽给CD8+T细胞。然而，DC存在的数量 亚群，大多数人进行低于平均水平的交叉陈述。CD103+和CD8a+DC以其 能够处理外源抗原，并有效地交叉呈现给CD8+T细胞。正因为如此，战略以 增强交叉呈递DC亚群可能在许多癌症类型的治疗中具有治疗潜力。 FMS样酪氨酸激酶3配体(Flt3L)是一种扩增和分化DC前体细胞的细胞因子。 表达CD103+和CD8a+树突状细胞，但Flt3L的半衰期短，治疗潜力有限 和体内的全球分布。我们已经通过产生基因融合克服了Flt3L的上述问题 从白蛋白(Alb)到Flt3L，命名为白蛋白-Flt3L(Alb-Flt3L)。白蛋白的半衰期很长，这是由于新生儿Fc受体- (FcRN)介导的跨细胞循环，并作为无处不在的血清运输到淋巴系统 蛋白。新型免疫治疗性Alb-Flt3L融合蛋白的半衰期延长和选择性 与天然Flt3L相比，Flt3L在引流淋巴中的积聚。Alb-Flt3L能够扩展交叉连接 在体内呈现DC群体，从而产生强大的抗原特异性CD4+和CD8+T细胞 和B细胞在蛋白免疫后的反应。在本研究中，Alb-Flt3L诱导抗原的能力 通过扩增交叉呈递的DC和随后的肿瘤控制而产生的特异性抗肿瘤免疫 被调查。小鼠结肠腺癌模型和人乳头瘤病毒相关癌模型的治疗 Alb-Flt3L联合靶向放射治疗释放肿瘤抗原和增强细胞功能 渗透性。随后的抗肿瘤CD4+和CD8+T细胞和交叉递呈的DC免疫反应和 将对肿瘤控制进行评估。Alb-Flt3L介导其免疫刺激功能的机制 也将使用适当的缺陷小鼠模型进行讯问。成功完成这项提案将 产生关于Alb-Flt3L治疗潜力的有价值的临床前和机制数据 免疫疗法具有潜在的疗效，可作为治疗多种癌症的通用策略。建议数 研究将由奖学金申请者在赞助下进行为期3年的研究 约翰·霍普金斯大学医学院吴天昌博士的指导。调查结果将以以下形式提交 在研究金培训期结束前向全国会议提交摘要并出版。

Project Summary/Abstract Cancer treatment strategies capable of mediating antitumor response in a wide array of cancer types remain limited, even with the rapid development of novel immunotherapeutics such as checkpoint blockade. The overwhelming public health burden of cancer has created great demand for novel, broadly effective immunotherapeutics. Central to the success of essentially all cancer treatment strategies is the generation of tumor specific cytotoxic CD8+ T cell immunity, which requires potent antigen presentation by dendritic cells (DCs) since tumor cells do not efficiently present relevant CD8+ T cell epitopes. DCs must uptake tumor cells or tumor antigen and cross-present immunostimulatory peptides to CD8+ T cells. However, DCs exist as many subpopulations, and most perform subpar cross-presentation. CD103+ and CD8a+ DCs are known for their ability to process exogenous antigen and potently cross-present to CD8+ T cells. Because of this, strategies to enhance cross-presenting DC subsets could have therapeutic potential in the treatment of many cancer types. FMS-like tyrosine kinase 3 ligand (Flt3L) is a cytokine that expands and differentiates DC precursors to cross- presenting CD103+ and CD8a+ DCs, but therapeutic potential of Flt3L is limited because of its short half-life and global distribution in vivo. We have overcome the described issues of Flt3L by generating a genetic fusion of Albumin (Alb) to Flt3L named Albumin-Flt3L (Alb-Flt3L). Alb has a long half-life due to neonatal Fc receptor- (FcRn)-mediated transcytolic recycling, and exhibits trafficking to the lymphatic system as a ubiquitous serum protein. The novel immunotherapeutic Alb-Flt3L fusion protein exhibits increased half-life and selective accumulation in the draining lymph node compared to native Flt3L. Alb-Flt3L is able to expand cross- presenting DC populations in vivo, and consequently engenders potent antigen specific CD4+ and CD8+ T cell and B cell responses following protein immunization. In this study, the ability of Alb-Flt3L to induce antigen specific antitumor immunity through the expansion of cross-presenting DCs and subsequent tumor control will be investigated. Murine model of colon adenocarcinoma and model of HPV-associated cancer with be treated using Alb-Flt3L in combination with targeted radiation therapy to release tumor antigen and enhance cellular permeability. Subsequent antitumor CD4+ and CD8+ T cell and cross-presenting DC immune responses and tumor control will be evaluated. The mechanism by which Alb-Flt3L mediates its immunostimulatory function will also be interrogated using appropriate deficient mouse models. Successful completion of this proposal will generate valuable preclinical and mechanistic data regarding the therapeutic potential of Alb-Flt3L, a novel immunotherapeutic with potential efficacy as a universal strategy to treat many types of cancer. The proposed research will be conducted over a period of 3 years by the fellowship applicant under the sponsorship and guidance of Dr. T.-C. Wu at the Johns Hopkins University School of Medicine. The findings will be submitted as abstracts to national meetings as well as for publication prior to the end of the fellowship training period.