Combinatorial Protein Transfer for Cancer Therapeutics

本提案的中心是我们最近开发的一种新的Fc融合蛋白转移方法在癌症联合治疗中的应用。拟议研究的结构是基于三个假设。首先，除了通过T细胞共刺激剂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呈递细胞（apc），特别是树突状细胞（dc），以启动ctl（间接启动），可以更有效地激发抗肿瘤免疫。因此，人们可以开始考虑超越T细胞本身，并同时考虑DC功能的增强。其次，鉴于DC在体内的寿命较短，通过促进DC在肿瘤微环境中的寿命，使有限数量的肿瘤抗原脉冲DC诱导的T细胞活化程度最大化，可以增强抗肿瘤免疫。第三，在提高DC寿命的同时，促进DC向肿瘤部位的募集，可以进一步优化抗肿瘤免疫。在这些假设的推动下，我们的初步数据证明了通过“四共刺激剂”组合的原位蛋白转移诱导系统性、长期抗肿瘤免疫的可行性，该组合可以激活T细胞和apc。在这些初步数据的基础上，拟议的研究寻求利用我们的Fc融合蛋白转移方法作为加深我们对T细胞活化和DC寿命调节的理解的手段，反过来，利用所获得的见解来优化体内抗肿瘤免疫。三个具体目的是：1)评估T细胞共刺激因子之间的协同/合作，共刺激信号本身之间以及共刺激信号与抗原信号之间的空间要求，以及共刺激因子在促进T细胞有丝分裂中的协同作用；2)确定直流活化剂和直流抑制剂在调节直流寿命中的定量相互作用；3)评估共刺激剂协同作用、延长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.