Targeting immunosuppression blockade to T cells for cancer immunotherapy

描述（由申请人提供）：基于细胞的免疫疗法正在积极开发用于治疗癌症，体外活化/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希望的治疗方法之一。在ACT中，自体肿瘤反应性t细胞在体外被激活/扩增，然后再输注以对抗转移性肿瘤。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，以增加客观反应的频率和持久性。我们最近证明，在转移到荷瘤受体之前，将细胞因子负载的纳米颗粒（NPs）结合到t细胞的体外表面，可以显著增强ACT的功效（Stephan等）。Nat. Med. 2010)。t细胞结合颗粒向转移的细胞提供伪自分泌药物递送，大大增加了辅助细胞因子的有效效力，同时消除了全身暴露于药物。然而，这种方法的局限性在于干预的一次性：在转移之前，ACT t细胞只能装载一次辅助药物，并且刺激的持续时间本质上受到体内细胞群扩增的限制。我们需要的是一种策略，在体内，直接在血液或组织中，用纳米颗粒药物载体武装t细胞，这样，转移到患者体内的单个抗肿瘤淋巴细胞群就可以被针对该细胞群的辅助药物反复刺激。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，这些药物被设计成与肿瘤细胞和/或ACT t细胞结合，并且可以随意重新给药，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，我们将专注于递送关键t细胞磷酸酶Shp1的小分子抑制剂，Shp1是肿瘤微环境中广泛的负调控信号的下游靶点，包括IL-10、TGF-¿、CTLA-4和PD-1。我们建议测试3种主要策略，它们并不相互排斥：(i)通过巯基反应性颗粒将NPs非特异性地原位靶向肿瘤细胞和淋巴细胞；（ii）抗体靶向NP递送Shp抑制剂特异性靶向ACT t细胞；（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靶向到ACT t细胞，这些配体既靶向t细胞的NPs，又向受体细胞提供激活/共刺激信号。作为

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.