Novel Biologics Designed to Mobilize HIV-specific CTL for Sustained HIV Remission

该应用程序高度响应RFA（AI-18-017）的主要目标，以支持开发 具有免疫调节作用的下一代生物制剂，可能导致长期的艾滋病毒缓解。 HIV感染的功能性治愈由于HIV感染者的免疫系统的无能而受到阻碍。 个体在重新激活后有效地消除潜伏感染的细胞，导致复发， 停止抗逆转录病毒治疗后出现病毒血症。我们建议利用我们对精确的 信号和分子，调动有效的T细胞反应和复杂的蛋白质设计和工程 构建由高度稳定的二聚IgG Fc融合蛋白组成的新型免疫刺激生物制剂的原理 蛋白质，称为synTacs。这些生物制剂通过MHC介导的确定的抗原呈递来模拟APC功能。 在一些实施方案中，本发明提供了通过递送共刺激和/或细胞因子信号将肽递送至TCR的方法。synTac的关键元素 该结构是使用单链MHC分子，共价连接到定义的HIV衍生肽作为抗原。 靶向模块，其触发所述初级TCR激活信号。与此同时，synTac通过共价键 将共刺激配体或细胞因子连接到靶向的HIV特异性CD 8 + T细胞，以提供共刺激配体或细胞因子。 在一些实施方案中，所述细胞因子信号包括用于完全激活T细胞的细胞因子信号或用于驱动T细胞增殖和/或分化的细胞因子信号。我们有 通过构建靶向HLA-A*0201限制性HIV Gag表位的synTac来验证该方法， SL 9，与特异性激活和扩增原代细胞的共刺激性CD 28或4-1BBL分子连接， 来自HIV感染个体的SL 9特异性CD 8 + T细胞。我们建议开发艾滋病毒特异性synTac， 鉴定最佳的共刺激和/或细胞因子信号以使它们能够作为靶向生物制剂发挥作用 能够刺激、扩增和选择性分化患者来源的HIV特异性CD 8 + T细胞， 最有效的能力，以消除艾滋病毒感染的T细胞。我们将确定synTac的体内能力， 活化、扩增和分化HIV特异性CD 8 + T细胞的生物制剂， 我们使用一种新的人源化小鼠模型， 开发作为一种替代方法，我们还建议利用HIV特异性CAR的潜在潜力， T细胞，其识别具有重组免疫受体（如scFv）的抗原，而不是MHC限制性抗原。 TCR，通过开发一种替代的生物学，synTac样分子，与CAR-T免疫受体结合， 递送最佳的共刺激和/或细胞因子信号以放大HIV特异性CAR-T细胞的体内功能。

This application is highly responsive to the major goal of the RFA (AI-18-017) to support the development of next-generation biologics with immune-modulating effects that may lead to long-lasting HIV remission. Functional cure of HIV infection has been stymied by the inability of the immune system of HIV-infected individuals to eliminate effectively latently infected cells following reactivation, resulting in the recurrence of viremia after stopping antiretroviral therapy. We propose to exploit our increasing understanding of the precise signals and molecules that mobilize potent T cell responses and sophisticated protein design and engineering principles to construct novel immunostimulatory biologics consisting of highly stable dimeric IgG Fc-fusion proteins, termed synTacs. These biologics mimic APC functions by MHC-mediated presentation of defined peptides to TCRs with delivery of costimulatory and/or cytokine signals. The key element of the synTac architecture is the use of a single chain MHC molecule, covalently linked to a defined HIV-derived peptide as a targeting module that triggers the primary TCR activation signal. In parallel, the synTac delivers covalently linked costimulatory ligands or cytokines to the targeted HIV-specific CD8+ T cells to provide a costimulatory signal to activate fully the T cells or a cytokine signal to drive T cell proliferation and/or differentiation. We have validated this approach by constructing synTacs which target the HLA-A*0201-restricted HIV Gag epitope, SL9, linked to the costimulatory -CD28 or 4-1BBL molecules that specifically activated and expanded primary SL9-specific CD8+ T cells from HIV-infected individuals. We propose to develop HIV-specific synTacs and identify the optimal costimulatory and/or cytokine signals to enable them to function as targeted biologics capable of stimulating, expanding and differentiating selectively patient-derived HIV-specific CD8+ T cells with the most potent capacity to eliminate HIV-infected T cells. We will determine the in vivo capacity of synTac biologics to activate, expand and differentiate HIV-specific CD8+ T cells capable of preventing recurrent viremia by eliminating reactivated latently infected cells using a novel humanized mouse model we have developed. As an alternative approach, we also propose to harness the potential potency of HIV-specific CAR- T cells, which recognize antigen with recombinant immunoreceptors such as scFv rather than MHC-restricted TCRs, by developing an alternative biologic, synTac-like molecules that bind to the CAR-T immunoreceptor to deliver the optimal costimulatory and/or cytokine signals to amplify HIV-specific CAR-T cell in vivo function.