Priming pancreatic ductal adenocarcinoma using blood thinners to sensitize the efficacy of checkpoint immunotherapy

项目总结： 癌症和间质细胞共存于一个复杂的微环境中，以缺氧、酸中毒、 和高间质压力；所有这些都会对T细胞的渗透产生物理屏障。因此，它的功效 免疫疗法取决于许多重要因素，包括检查点抑制物灌流和 扩散通过细胞外基质(ECM)，穿梭于血流较少的血管或间质，衰减 免疫抑制的微环境，最后，识别杀灭癌细胞。胰管 腺癌(PDAC)对化疗和免疫治疗的反应很差，主要是因为 肿瘤间质致密，缺乏免疫调节T细胞和细胞因子 微环境(TME)。然而，基质减少剂的使用并不成功，因为 产生间质的肌成纤维细胞的耗尽与免疫抑制和生存无关 胰腺癌的发病率。因此，有一种尚未得到满足的需要，即确定能够使TME敏感的新战略 PDAC，并提高免疫检查点抑制剂的效率。一个很大程度上被忽视，但潜在的主导地位 肿瘤药物输送的障碍是在肿瘤血管和间质空间内形成的小凝块， 称为肿瘤内凝块。瘤内纤维蛋白凝块在大多数实体肿瘤中是常见的，其中PDAC表现为 广泛的纤维蛋白原和纤维蛋白凝块遍及肿瘤间质和肿瘤细胞周围。然而， 肿瘤内血栓对血液灌流和缺氧的影响以及在抑制抗肿瘤免疫方面的作用 被大大低估了。此外，还没有一种策略可以用来击败凝块- 诱导免疫屏障，尽管抗凝剂长期以来一直被用于治疗癌症患者的血栓形成。 我们假设肿瘤内的血块起到了运输屏障的作用，启动了PDAC以产生抑制作用 有助于逃避免疫监视的微环境。我们还假设增强的血流灌注会 抗凝可以缓解低氧，使PDAC TME转变为免疫支持性TME，这也将 有益于免疫治疗的疗效。为了验证我们的假设，我们设计了三个具体目标：(1)研究 纤维蛋白沉积调节PDAC免疫抑制微环境的临床和临床前意义 和肿瘤进展；(2)检测血液稀释剂对T细胞和巨噬细胞的影响 体外PDAC亚型；(3)评估血液稀释剂增强抗PD-1疗效的能力 在KPC和人源化小鼠中联合化疗时给予抗体。成功 这项研究的完成将对结合现成的新治疗策略的开发产生积极影响 血液稀释剂和现有检查点抑制物溶栓治疗胰腺肿瘤无效 去接受免疫治疗。

Project Summary: Cancer and stromal cells co-exist within a complex microenvironment that is characterized by hypoxia, acidosis, and high interstitial pressure; all of which generate a physical barrier to T cells' infiltration. Thus, the efficacy of an immunotherapy depends on many vital factors, including the ability of the checkpoint inhibitor to perfuse and diffuse through the extracellular matrix (ECM), shuttle through the less perfused vessels or interstitia, attenuate the immunosuppressive microenvironment and finally, recognize cancer cells to kill. Pancreatic ductal adenocarcinomas (PDACs) are poorly responsive to both chemo- and immunotherapies, mainly because of the presence of dense stroma and absence of immunomodulatory T-cells and cytokines in the tumor microenvironment (TME). However, the use of stroma-reducing agents has not been successful because of the fact that depletion of stroma-producing myofibroblasts did not correlate with immunosuppression and survival rate in pancreatic cancers. Thus, there is an unmet need to identify new strategies that can sensitize the TME of PDAC and increase the efficiency of immune checkpoint inhibitors. A largely overlooked, but potentially dominant barrier to tumoral drug delivery, are the small clots that form within the tumor vasculature and interstitial space, called intratumoral clots. Intratumoral fibrin clots are common in the most solid tumors, where PDACs exhibit extensive fibrinogen and fibrin clots throughout the tumor stroma and surrounding of the tumor cells. However, the impact of intratumoral clots on blood perfusion and hypoxia and in dampening the anti-tumor immunity has been immensely underestimated. Furthermore, no strategies have been in use that can outmaneuver clot- induced immune-barriers although anticoagulants have long been used to treat thrombosis in cancer patients. We hypothesize that intratumoral clots act as a transport barrier and prime the PDACs to create a suppressive microenvironment that helps to escape immune surveillance. We also hypothesize that enhanced perfusion sue to anticoagulation can alleviate hypoxia and alter the PDAC TME into an immune-supportive one, which will also benefit the efficacy of immunotherapy. To test our hypothesis, we designed three specific aims: (1) To study the clinical and pre-clinical relevance of fibrin deposition on regulating PDAC immunosuppressive microenvironment and tumor progression in PDAC; (2) To test the effects of blood thinners on T cells and macrophages against PDAC subtypes, in vitro; and (3) To assess the ability of blood thinners in potentiating the efficacy of anti-PD-1 antibody when administered in combination with chemotherapy in KPC and humanized mice. Successful completion of this study will positively affect the development of new treatment strategy combining ‘off-the-shelf’ blood thinners and thrombolytic with existing checkpoint inhibitors for pancreatic tumors, which are unresponsive to immunotherapy.