Novel PD-L1 signals regulating anti-tumor immunity and immunotherapy responses

 描述(申请人提供)：肿瘤微环境中的因素促进免疫抑制，使肿瘤逃脱免疫破坏。我们的研究表明，肿瘤PD-L1(CD274，B7-H1)是肿瘤炎性淋巴细胞(TIL)浸润的主要调节因子。PD-L1在许多肿瘤中广泛表达，是两种成功的癌症免疫治疗新方法的靶点，但不能很好地预测治疗效果。我们定义了肿瘤内在PD-L1信号对肿瘤增殖、肿瘤干细胞特性、体内生长独立于抗肿瘤免疫的新作用，以及mTOR信号和自噬的调节。我们通过更深入和详细地研究肿瘤固有PD-L1如何改变抗肿瘤免疫来扩展获得性免疫抵抗的概念，而不是目前仅关注肿瘤PD-L1杀伤抗肿瘤T细胞能力的研究。尽管已知PD-L1在免疫抑制中的作用以及αPD-L1治疗的潜在临床益处，但对于肿瘤PD-L1通过肿瘤内在信号在αPD-L1反应、免疫修饰和致瘤潜力中的作用的理解仍然存在重大差距。我们建议的研究将通过使用PD-L1+的卵巢癌和黑色素瘤细胞的小鼠模型以及PD-L1lo或PD-L1-的工程版本，以及异质肿瘤PD-L1表达的新模型来测试我们的总体假设，即抗肿瘤免疫和对αPD-L1治疗的反应是由肿瘤固有的PD-L1信号指导的。我们将以以下特定目标来解决这一假说：特定目标1：验证抗肿瘤免疫和对αPD-L1治疗的反应受异质性肿瘤PD-L1表达调控的假说。我们研究了卵巢和黑色素瘤的小鼠模型，这些肿瘤是PD-L1+的，以及PD-L1lo、PD-L1KO或PD-L1hi的工程化版本。我们将使用B16黑色素瘤和ID8卵巢癌，以及PD-L1KO小鼠，确定αPD-L1治疗对抗肿瘤TIL数量和功能的作用机制，并确定αPD-L1对PD-L1LO/NEG肿瘤的治疗作用与抗肿瘤免疫的哪些方面有关。我们还将利用αPD-L1治疗的特定目标2：测试肿瘤PD-L1对肿瘤内在mTOR和自噬的调节影响抗肿瘤免疫和临床结果的假设，以确定由异质性肿瘤PD-L1表达改变的免疫细胞转运和T调节抑制效应。我们将根据初步数据重点控制肿瘤mTOR和自噬(可能相关)，通过使用封闭抗体和基因干预评估下游效应分子(例如CCL2、CCL9、CXCL12)来确定免疫后果，并评估其对体内抗肿瘤免疫的影响。我们将通过在体外和体内验证的方法来确定干细胞发育中的PD-L1信号，以确定这些特性是否是PD-L1通过mTOR和自噬调节肿瘤内在信号的结果。

 DESCRIPTION (provided by applicant): Factors in the tumor microenvironment promote immunosuppression that permits tumor escape from immune destruction. Our data show that tumor PD-L1 (CD274, B7-H1) is a major regulator of tumor inflammatory lymphocyte (TIL) infiltrate. PD-L1 is widely expressed in many tumors and is the target of two successful new cancer immunotherapy approaches, but is a poor predictor of treatment efficacy. We define novel effects of tumor intrinsic PD-L1 signaling on tumor proliferation, cancer stem cell properties, in vivo growth independent of anti-tumor immunity, and regulation of mTOR signals and autophagy. We extend the concept of adaptive immune resistance by studying how tumor intrinsic PD-L1 alters anti-tumor immunity in vastly greater depth and detail than current studies that solely focus on the capacity of tumor PD-L1 to kill anti- tumor T cells. Despite the known role for PD-L1 in immunosuppression and the promising clinical benefits of αPD-L1 therapy, there remain significant gaps in understanding the role of tumor PD-L1 in the αPD-L1 response, immune modification, and tumorigenic potential through tumor intrinsic signaling. Our proposed studies will address these gaps by employing mouse models for ovarian cancers and melanoma cells that are PD-L1+ and engineered versions that are PD-L1lo or PD-L1-, and novel models of heterogeneous tumor PD-L1 expression to test our overarching hypothesis that anti-tumor immunity and response to αPD-L1 therapy are directed by tumor-intrinsic PD-L1 signals. We will address this hypothesis with the following specific aims: Specific Aim 1: Test the hypothesis that anti-tumor immunity and response to αPD-L1 therapy are modulated by heterogeneous tumor PD-L1 expression. We study mouse models for ovarian and melanoma tumors that are PD-L1+ and engineered versions that are PD-L1lo, PD-L1KO or PD-L1hi. We will employ B16 melanoma and ID8 ovarian cancer, along with PD-L1 KO mice, to define the mechanism of αPD-L1 therapy on anti-tumor TIL quantity and function, and determine which aspects of anti-tumor immunity are responsible for treatment effects of αPD-L1 in PD-L1lo/neg tumors. We will also define immune cell trafficking and T regulatory suppression effects altered by heterogeneous tumor PD-L1 expression with αPD-L1 therapy Specific Aim 2: Test the hypothesis that tumor PD-L1 regulation of tumor intrinsic mTOR and autophagy affects anti-tumor immunity and clinical outcomes. We will focus on control of tumor mTOR and autophagy (which are likely related) based on preliminary data, determining immune consequences by evaluating downstream effector molecules (e.g., CCL2, CCL9, CXCL12) using blocking antibodies and genetic interventions, and evaluate the impact on anti-tumor immunity in vivo. We will determine PD-L1 signals in stem cell development using validated in vitro and in vivo assays whether these properties are the result of PD-L1 regulation of tumor intrinsic signaling through mTOR and autophagy.