Targeted MEK inhibition to enhance immunotherapy in cholangiocarcinoma

胆管癌（CC）是一种侵袭性癌症，对大多数化疗或靶向化疗都是难治性的。 剂.我们的目标是将免疫治疗的成功扩展到CC，并确定相关的生物标志物。 approach.该提案将转化临床前研究结果，表明MEK抑制剂（MEKi）可增强浸润 的CD 8 + T效应细胞，防止其彻底的凋亡性细胞死亡，并增强抗PD-L1抗体在 肿瘤模型我们假设MEKi将与PD-L1阻断剂协同作用，通过以下途径引发抗肿瘤反应： 改变促进CD 8 + T细胞浸润和存活的细胞因子和趋化因子特征， 肿瘤微环境（TME）中的免疫抑制细胞。我们将进行一项创新的随机 2期临床试验，以检查MEKi（cobimetinib）与以下抑制剂组合的安全性和功效： PD-L1（atezolizumab）和atezolizumab单药治疗不可切除的CC患者。本试验将 在我们批准的NCI赞助的UM 1临床试验资助的背景下进行。同期研究将 阐明MEKi作用于T细胞和骨髓细胞的机制，并增强PD-L1阻断的功效。 该试验将提供来自可触及肿瘤患者的配对活检，其中我们可以验证我们的机制 使用创新的多光谱成像的发现。这将是CC二线最大的临床研究。 我们将追求三个具体目标：1）进行PD-L1抑制剂的随机2期临床试验 atezolizumab联合MEKi cobimetinib与atezolizumab单药治疗受试者中 不可切除的CC。我们已通过NCI癌症治疗评估计划（CTEP）完成批准 在76名可评价受试者中进行这项随机、多中心临床试验，这些受试者至少接受过一次既往 化疗如果成功的话，这种方案有可能成为第二代CC的标准治疗方法。 线本试验将提供样本以评价MEKi对TME中关键生物标志物的影响。2)以确定 MEKi如何改变TME以改善对抗PD-L1治疗的反应。一组独特的人类CC细胞系 将用于研究MEKi如何调节调节T细胞迁移的肿瘤衍生趋化因子。使用临床 试验活检，我们将评估CD 8 + T细胞浸润和PD-L1表达作为综合生物标志物。多- 光谱IHC将表征治疗对免疫亚群和耗竭性T细胞死亡标志物的影响 (i.e. Nur 77）在TME中的作用以及对免疫抑制性T调节细胞和髓源性T细胞的影响。 抑制细胞3)为了确定系统性细胞因子和免疫细胞群在应答中的作用， MEKi和PD-L1阻断。体内模型将测试MEKi +抗PD-L1治疗的功效是否依赖于 IFN-γ，T细胞功能和趋化因子介导的运输的关键细胞因子调节剂。体外研究将定义 如果MEKi改变肿瘤来源的细胞因子（例如IL-6、GM-CSF）对肿瘤细胞的分化或功能的影响， 抑制性骨髓细胞最后，使用患者外周血样本，我们将确定 细胞因子表达和各种免疫细胞表型与临床结果的关系。

Cholangiocarcinoma (CC) is an aggressive cancer that has been refractory to most chemotherapeutic or targeted agents. Our goal is to extend success of immunotherapy to CC, and identify relevant biomarkers for this approach. This proposal will translate pre-clinical findings showing that MEK inhibitors (MEKi) enhance infiltration of CD8+ T effector cells, prevent their exhaustive apoptotic cell death, and enhance efficacy of anti-PD-L1 Ab in tumor models. We hypothesize that MEKi will synergize with PD-L1 blockade to elicit anti-tumor responses via altering cytokine and chemokine signatures that promote CD8+ T cell infiltration and survival and decreased immunosuppressive cells in the tumor microenvironment (TME). We will conduct an innovative randomized phase 2 clinical trial to examine safety and efficacy of a MEKi (cobimetinib) in combination with an inhibitor of PD-L1 (atezolizumab) and atezolizumab monotherapy in patients with unresectable CC. This trial will be performed in the context of our approved NCI-sponsored UM1 clinical trials grant. Concurrent studies will elucidate the mechanism by which MEKi acts on T and myeloid cells, and augments efficacy of PD-L1 blockade. The trial will provide paired biopsies from patients with accessible tumor in which we can validate our mechanistic findings using innovative multi-spectral imaging. This will be the largest clinical study of CC in the second line. We will pursue three Specific Aims: 1) To conduct a randomized phase 2 clinical trial of the PD-L1 inhibitor atezolizumab in combination with the MEKi cobimetinib versus atezolizumab monotherapy in participants with unresectable CC. We have completed approval through the NCI Cancer Therapy Evaluation Program (CTEP) to conduct this randomized, multicenter clinical trial in 76 evaluable subjects who have received at least one prior chemotherapy. If successful, this regimen has potential to become the standard of care for CC in the second line. This trial will provide samples to evaluate the effect of MEKi on key biomarkers in the TME. 2) To determine how MEKi alter the TME to improve the response to anti-PD-L1 therapy. A unique panel of human CC cell lines will be used study how MEKi modulates tumor-derived chemokines that regulate T cell migration. Using clinical trial biopsies, we will evaluate CD8+ T cell infiltration and PD-L1 expression as integrated biomarkers. Multi- spectral IHC will characterize the impact of treatment on immune subsets and markers of exhaustive T cell death (i.e. Nur77) in the TME as well as the impact on immunosuppressive T regulatory cells and myeloid-derived suppressor cells. 3) To determine the role of systemic cytokines and immune cell populations in the response to MEKi and PD-L1 blockade. In vivo models will test if the efficacy of MEKi + anti-PD-L1 therapy is dependent on IFN-, a key cytokine regulator of T cell function and chemokine-mediated trafficking. In vitro studies will define if MEKi alters the impact of tumor-derived cytokines (e.g. IL-6, GM-CSF) on differentiation or function of suppressive myeloid cells. Finally, using patient peripheral blood samples we will determine the relevance of relationships between cytokine expression and various immune cell phenotype with clinical outcome.