Targeting immunosuppression blockade to T cells for cancer immunotherapy

描述(申请人提供)：基于细胞的免疫疗法正在积极开发用于癌症治疗，而体外激活/扩增T细胞的过继细胞疗法(ACT)是目前在患者中测试的最有前途的疗法之一。在ACT中，自体肿瘤反应性T细胞在体外被激活/扩增，然后回输以对抗转移的肿瘤。然而，需要采取策略保护T细胞免受肿瘤产生的高度免疫抑制环境的影响，以提高客观反应的频率和持久性。我们最近证明，在转移到肿瘤受体之前，通过在体外将细胞因子负载的纳米颗粒(NPs)连接到T细胞表面，ACT的有效性可以显著增强(Stephan等人)。纳特。地中海医院。2010)。与T细胞结合的颗粒为转移的细胞提供了伪自分泌药物输送，极大地增加了佐剂细胞因子的有效效力，同时消除了全身暴露于药物中。然而，这种方法的局限性是干预的一次性性质：ACT T细胞在转移之前只能负载一次佐剂药物，刺激的持续时间固有地受到体内细胞群体扩张的限制。需要的是一种策略，在体内用纳米药物载体武装T细胞，直接在血液或组织中，以便转移到患者体内的单个抗肿瘤淋巴细胞群体可以被针对该细胞群体的支持辅助药物重复刺激。我们提出了一套实现这一目标的方法，基于注射携带免疫抑制阻断辅助药物的纳米颗粒，这些纳米颗粒旨在与肿瘤细胞和/或ACT T细胞结合，并可以随意重新给药，以在ACT治疗期间持续向淋巴细胞提供支持信号。作为概念验证，我们将重点介绍关键T细胞磷酸酶SHP1的小分子抑制剂的交付，它是肿瘤微环境中广泛的负面调控信号的下游靶点，包括IL-10、转化生长因子β、CTLA-4和PD-1。我们建议测试三种不相互排斥的主要策略：(I)通过硫醇反应颗粒将NPs非特异性地原位靶向肿瘤细胞和淋巴细胞；(Ii)抗体靶向将SHP抑制剂特异性地输送到ACT T细胞；以及(Iii)联合共刺激和靶向ACT T细胞，通过刺激配体将携带SHP抑制剂的NPs靶向ACT T细胞，既将NPs靶向T细胞，又向受体细胞提供激活/共刺激信号。AS 最后一个目标是，我们将测试这些方法中最有效的方法是否可以与疫苗接种协同作用，使内源性T细胞反应具有抗肿瘤效果，从而消除过继转移T细胞以实现有效的肿瘤排斥反应的需要。

DESCRIPTION (provided by applicant): Cell-based immunotherapies are in active development for treatment of cancer, and adoptive cell therapy (ACT) with ex vivo activated/expanded T-cells is one of the most promising treatments currently being tested in patients. In ACT, autologous tumor-reactive T-cells are activated/expanded ex vivo and then reinfused to combat metastatic tumors. However, strategies to protect T-cells from the highly immuno-suppressive environment generated by tumors are needed to increase the frequency and durability of objective responses. We recently demonstrated that the efficacy of ACT can be dramatically enhanced by conjugation of cytokine- loaded nanoparticles (NPs) to the surfaces of T-cells ex vivo prior to transfer into tumor-bearing recipients (Stephan et al. Nat. Med. 2010). T-cell-bound particles provided pseudo-autocrine drug delivery to the transferred cells that greatly increased the effective potency of adjuvant cytokines while simultaneously eliminating systemic exposure to the drug. However, a limitation of this approach is the one-time nature of the intervention: ACT T-cells can only be loaded once with a cargo of adjuvant drug prior to transfer, and the duration of stimulation is inherently limited by expansion of the cell population in vivo. What is needed is a strategy to arm T-cells with nanoparticle drug carriers in vivo, directly in th blood or tissues, so that a single population of anti-tumor lymphocytes transferred into a patient could be repeatedly stimulated with supporting adjuvant drugs that are targeted to this cell population. We propose a set of approaches to achieve this goal, based on the injection of nanoparticles that carry immunosuppression-blocking adjuvant drugs, which are designed to bind to tumor cells and/or ACT T-cells, and which could be re-administered at will to continuously provide supporting signals to lymphocytes during ACT therapy. As a proof of concept, we will focus on delivery of a small-molecule inhibitor of the key T-cell phosphatase Shp1, which is a downstream target of a broad spectrum of negative regulatory signals in the tumor microenvironment including IL-10, TGF-¿, CTLA-4, and PD-1. We propose to test 3 major strategies, which are not mutually exclusive: (i) non-specific in situ targeting of NPs to tumor cells and lymphocytes via thiol-reactive particles; (ii) antibody-targeted NP delivery of Shp inhibitors specifically to ACT T-cells; and (iii) combined costimulation and targeting of ACT T-cells, by targeting Shp inhibitor-carrying NPs to ACT T-cells via stimulatory ligands that both target NPs to the T-cells and provide an activating/costimulatory signal to the recipient cells. As a final goal we will test whether the most potent of these approaches can synergize with vaccination to allow endogenous T-cell responses to have anti-tumor efficacy, thereby eliminating the need for adoptive transfer of T-cells for potent tumor rejection.