Combinatorial Protein Transfer for Cancer Therapeutics

这项建议集中在我们最近开发的一种新的FC融合蛋白转移方法的应用上，该方法用于癌症的联合治疗。拟议研究的结构基于三个假设。首先，除了通过T细胞共刺激分子转移将肿瘤细胞转化为专业的APC以直接激活CTL(直接启动)外，通过同时促进旁观者宿主抗原提呈细胞(APC)，特别是树突状细胞(DC)启动CTL(间接启动)，可能更有效地激发抗肿瘤免疫。因此，人们可以开始思考T细胞本身之外的问题，并同时着眼于DC功能的增强。其次，鉴于DC在体内的存活时间较短，可以通过在肿瘤微环境中促进DC的寿命，最大限度地提高肿瘤抗原致敏的DC诱导的T细胞活化程度来增强抗肿瘤免疫。第三，在提高DC寿命的同时，促进DC向肿瘤部位的募集，可进一步优化抗肿瘤免疫。在这些假说的推动下，我们的初步数据证明了通过原位蛋白转移“四共刺激分子”组合来激发系统的、长期的抗肿瘤免疫的可行性，该组合被选择来激活T细胞和APC。在这些初步数据的基础上，拟议的研究试图利用我们的Fc融合蛋白转移方法作为加深我们对T细胞激活和DC寿命调节的理解的一种手段，并反过来利用所获得的见解来优化体内的抗肿瘤免疫。这三个具体目标是：1)评估T细胞共刺激分子之间的协同/合作，共刺激信号本身以及共刺激信号和抗原信号之间的空间需求，以及共刺激分子在促进T细胞有丝分裂中的协同作用；2)确定DC激活剂和DC抑制物之间在调节DC寿命方面的定量相互作用；以及3)评估共刺激分子协同作用、增强DC寿命和增加DC数量与更有效的抗肿瘤反应的相关性。

This proposal centers upon the application of a novel Fc fusion protein transfer method that we have recently developed to combination therapy for cancer. The configuration of the proposed studies has been based upon three hypotheses. First, in addition to converting tumor cells to professional APCs via T cell costimulator transfer in order to directly activate CTLs (direct priming), anti-tumor immunity may be more efficiently elicited by simultaneously promoting bystander host antigen- presenting cells (APCs), dendritic cells (DCs) in particular, to prime CTLs (indirect priming). Hence, one can begin to think beyond T cells per se and look to the potentiation of DC function in parallel. Second, in light of the short life span of DCs in vivo, anti-tumor immunity may be enhanced by promoting DC longevity in tumor microenvironment, maximizing the extent of T cell activation inducible by limited number of tumor antigen- pulsed DCs. Third, anti-tumor immunity may be further optimized by, in addition to improving DC longevity, simultaneously promoting the recruitment of DCs to tumor site. Driven by these hypotheses, our preliminary data demonstrate the feasibility of eliciting a systemic, long-term anti-tumor immunity via in situ protein transfer of a "tetra-costimulator" combination, chosen to activate T cells as well as APCs. Building upon these preliminary data, the proposed studies seek to exploit our Fc fusion protein transfer method as a means to deepen our understanding of the regulations of T cell activation and DC longevity and, in turn, use the gained insights to optimize anti- tumor immunity in vivo. The three specific aims are: 1) To assess synergy/cooperation among T cell costimulators, spatial requirements among costimulatory signals themselves as well as between costimulatory and antigenic signals, and costimulator synergy in promoting T cell mitosis; 2) To determine the quantitative interplay between DC activators and DC inhibitors in modulating DC longevity; and 3) To assess the relevance of costimulator synergy, enhanced DC longevity, and increased DC quantity to more effective anti-tumor response.