Augmenting Pancreatic Cancer Immunotherapy via TGFβ Pathway Inhibition

项目摘要/摘要 逃避免疫介导的细胞毒作用是肿瘤发生的一个显著特征。为此，治疗性的 抑制免疫检查点程序性细胞死亡蛋白1(PD-1)已显示出相当大的前景 在几种恶性肿瘤的治疗中。然而，在胰腺癌中，尽管有很强的联系 在PD-1配体(PD-L1)的表达和低存活率之间，检查点抑制剂表现出有限的 作为一种单一疗法的疗效。因此，最近的努力集中在确定肿瘤中的其他因素上。 调节PD-L1/PD1表达的微环境，希望改善药物反应。我们的团队已经 先前发现的基质衍生转化生长因子β(β)是一种重要的抗肿瘤生长因子抑制因子 肿瘤免疫功能，特别是在细胞毒性T淋巴细胞方面。尽管有这些观察， 在临床试验中，药物抑制转化生长因子β信号也是无效的。当检查一个小的 在胰腺癌患者的队列中，我们发现PD-L1的表达与 Smad4，转化生长因子β信号的下游靶点。根据这些观察，外源性转化生长因子β1 抑制PD-L1的体外获得。同样，基因消融转化生长因子β的小鼠肿瘤模型 信号导致胰腺中PD-L1表达增加，并未能建立全面的抗肿瘤免疫 回应。使用已建立的转移性胰腺癌模型，我们因此给予 PD-1(Invivomab)和/或TGFBR1(Galunisertib)的药理抑制剂。虽然两种单一疗法都没有 两个月后的结果是，同时接受Invivomab和Galunisertib治疗的小鼠没有明显的疾病证据。 组织学上，这些小鼠的胰腺肿瘤几乎完全消退，有异常组织。 表现为淋巴细胞浸润增多、颗粒酶沉积、细胞凋亡。综合来看，这些数据 提示阻断转化生长因子β通路可增强免疫关卡抑制，可能是一种合理的 临床上克服耐药的途径。鉴于这种方法在临床前的显著疗效，它 对于进一步了解转化生长因子β和PD-L1/PD-1信号被调控的方式是至关重要的，因为 以及在选定的患者群体中抑制它们的优点。通过本文件中详细介绍的实验 提案，我们将对这些事件获得有价值的见解，希望延长寿命和减少癌症- PDAC患者的相关发病率。

Project Summary/Abstract The evasion of immune-mediated cytotoxicity is a hallmark feature of tumorigenesis. To this end, therapeutic inhibition of the immune checkpoint Programmed Cell Death Protein 1 (PD-1) has shown considerable promise in the management of several malignancies. In pancreatic cancer, however, despite a strong association between expression of the PD-1 ligand (PD-L1) and poor survival, checkpoint inhibitors have shown limited efficacy as a monotherapy. Recent efforts have therefore focused on identifying additional factors in the tumor microenvironment that modulate PD-L1/PD1 expression in hopes of improving drug response. Our group has previously identified stromal-derived Transforming Growth Factor Beta (TGFβ) as a crucial repressor of anti- tumor immune function, particularly with respect to cytotoxic T lymphocytes. Despite these observations, pharmacologic inhibition of TGFβ signaling has also been ineffective in clinical trials. When examining a small cohort of pancreatic cancer patients, we found an inverse association between PD-L1 expression and that of SMAD4, a downstream target of TGFβ signals. In accordance with these observations, exogenous TGFβ1 repressed the acquisition of PD-L1 in vitro. Similarly, neoplastic mouse models with genetic ablation of TGFβ signaling developed increased PD-L1 expression in the pancreas, and failed to mount a full anti-tumor immune response. Using an established model of metastatic pancreatic cancer, we therefore administered pharmacologic inhibitors of PD-1 (Invivomab) and/or TGFBR1 (Galunisertib). While neither monotherapy had an effect, after two months, mice receiving both Invivomab and Galunisertib had no overt evidence of disease. Histologically, the pancreata of these mice had near complete regression of neoplasms, with abnormal tissues displaying increased lymphocyte infiltration, Granzyme deposition, and apoptosis. Combined, these data suggest that TGFβ pathway blockade augments immune checkpoint inhibition, and may be a reasonable approach to overcome drug resistance in the clinic. Given the substantial preclinical efficacy of this approach, it is essential to further understand the means through which TGFβ and PD-L1/PD-1 signals are regulated, as well as the merits to their inhibition in select patient populations. Through the experiments detailed in this proposal, we will gain valuable insight into these events in hopes of extending survival and reducing cancer- associated morbidity in PDAC patients.