Targeting Stat3 to Improve Immunotherapy

摘要 肿瘤微环境严重限制了各种免疫疗法的疗效。 对于过继性T细胞疗法，需要选择/工程化和扩增具有靶向性的T细胞。 抗原特异性，同时仍保留其效应子功能和归巢能力 带来了额外的挑战。我们和其他人已经证明，Stat 3，一个关键， 在多种癌细胞中组成性激活的致癌转录因子， 对肿瘤细胞存活很重要，也在肿瘤基质免疫细胞中被激活， 有效的免疫抑制我们的初步研究表明，靶向Stat 3基因 髓样细胞中的消融导致肿瘤DC活化、肿瘤Treg细胞减少和 CD 8 + T细胞在肿瘤中的大量浸润，导致有效的抗肿瘤免疫 应答此外，在具有Stat 3-/-髓样区室的小鼠中，过继性 转移的CD 8 + T细胞增殖良好，并且在肿瘤引流中高度活化。 淋巴结我们还能够通过多光子共聚焦 转移的Stat 3-/-CD 8 + T细胞有效浸润肿瘤的显微镜下， 增殖，导致肿瘤抗原特异性免疫应答的激活。我们有 我开始了解细胞和分子机制，使Stat 3在这两个 肿瘤髓样细胞和T细胞以阻碍T细胞介导的抗肿瘤免疫。在这 应用，我们建议进一步定义这些细胞和分子机制， 从而鉴定另外的靶点以优化Stat 3靶向和T细胞治疗。到 为了促进未来潜在的临床翻译，我们还将测试两种试剂，这两种试剂都 已经显示出对肿瘤免疫环境的积极影响，因为它们具有 改善T细胞疗法。一种是新的Toll样受体（TLR）激动剂-siRNA 缀合物，我们最近开发的一种技术平台，能够免疫 激活和靶向基因沉默所需的免疫检查点，如Stat 3 在骨髓和B细胞中。另一种是FDA批准的酪氨酸激酶抑制剂舒尼替尼， 我们的初步数据表明，它抑制肿瘤细胞中的Stat 3， 树突状细胞和髓源性抑制细胞。此外，我们将测试抗肿瘤 通过用慢病毒-siRNA离体沉默T细胞中的Stat 3来观察疗效。拟议的研究 可能导致新的策略，以扩大和激活转移的T细胞在体内， 克服T细胞治疗面临的几个主要障碍，并显着提高其 癌症治疗的功效。

Abstract The tumor microenvironment severely limits the efficacy of various immunotherapies. For adoptive T cell therapy, the need to select/engineer and expand T cells with targeted antigen specificity while still preserving their effector function and homing capacities poses additional challenges. We and others have demonstrated that Stat3, a key oncogenic transcription factor constitutively activated in diverse cancer cells and important for tumor cell survival, is also activated in tumor stromal immune cells and potently immunosuppressive. Our preliminary studies show that targeted Stat3 gene ablation in myeloid cells results in tumor DC activation, tumor Treg cell reduction and heavy infiltration of CD8+ T cells in tumors, leading to effective antitumor immune responses. Furthermore, in mice with a Stat3-/- myeloid compartment, adoptively transferred CD8+ T cells proliferate well and are highly activated in the tumor draining lymph nodes. We were also able to capture live images by multi-photon confocal microscopy of transferred Stat3-/- CD8+ T cells efficiently infiltrating tumors, where they proliferate, leading to activation of tumor antigen-specific immune responses. We have begun to understand the cellular and molecular mechanisms that allow Stat3 in both tumor myeloid cells and T cells to impede T-cell mediated antitumor immunity. In this application, we propose to further define these cellular and molecular mechanisms and thereby identifying additional targets to optimize Stat3 targeting and T cell therapy. To facilitate potential future clinical translation, we will also test two reagents, both of which have shown positive effects on the tumor immunologic environment, for their potential to improve T cell therapies. One is a novel Toll-like receptor (TLR) agonist-siRNA conjugate, a technology platform we have recently developed, and is capable of immune activation and targeted gene silencing of desired immunologic checkpoints such as Stat3 in myeloid and B cells. The other is an FDA-approved tyrosine kinase inhibitor, sunitinib, as our preliminary data suggested it inhibited Stat3 in tumor cells, tumor-infiltrating dendritic cells and myeloid-derived suppressor cells. Additionally, we will test antitumor efficacy by silencing Stat3 in T cells ex vivo with lentiviral-siRNAs. The proposed studies may lead to new strategies to expand and activate transferred T cells in vivo, thereby overcoming several major hurdles facing T cell therapy, and significantly improve its efficacy for cancer treatment.