Modulation of Tumor Microenvironment for Improved Therapy of Pancreatic Cancer

摘要 对治疗药物的耐药性是胰腺癌高致死率的主要原因。 血流不足和不均匀以及促结缔组织间质梗阻是主要原因。 阻碍治疗药物的输送和在肿瘤内的分布，是外在决定因素 PC的治疗耐药情况。PC细胞固有的化疗耐药是由一组独特的药物决定的 抗药性癌症干细胞。因此，对血流和细胞外基质的选择性调节可以导致 改善治疗药物进入肿瘤的输送，而消除肿瘤干细胞可以提高对 对肿瘤细胞进行化疗。内皮素-1水平升高与两种ET受体的过度表达 (ETAR和ETBR)在肿瘤中观察到。重要的是，ET-1是一种强大的血管调节剂，并诱导 通过ETAR的血管收缩被认为是导致肿瘤血流不均匀的重要因素 肿瘤。我们的初步研究表明，ET轴的成分在胰腺肿瘤中表达。 TME的各种成分包括肿瘤细胞、血管和基质细胞以及CSCs。此外，目标明确 特异性抑制剂BQ123对ETAR的选择性增强灌流和减少异种移植物的缺氧 对原发肿瘤(KPC小鼠模型)内ET轴的抑制作用。 双特异性抑制剂波生坦对促结缔组织生长有明显的抑制作用。我们还观察到ET- 1通过ETBR对小鼠胰腺星状细胞发挥促纤维化作用。我们假设：“顺序的 抑制ETBR和ETAR可以调节基质和灌注，以增强递送、分布和疗效 在治疗药物和临床上，亚伯拉沙和吉西他滨的联合应用将更有效 ET轴的调制“。提出了三个具体目标。目标1中的研究将确定选择性 ETAR和ETBR拮抗剂BQ123和BQ788对大分子(ABX)和 基于小分子(GEM)的治疗剂。将研究放射性标记的ABX和GEM的生物分布 用于对肿瘤摄取的定量估计。进一步，我们将破译ET轴介导的机制作用 在结缔组织增生的背景下，PC中的癌细胞和基质细胞之间的相互作用。目标2中建议的研究将 确定ET轴靶向在体外对ABX+GEM疗效的影响(使用独特的癌细胞- 星状细胞共培养和肿瘤器官培养)和体内使用基因工程小鼠(KPC) PC的模型。最后，Aim 3被设计用于临床安全性评估和进行疗效的初步筛选 将ET轴拮抗剂博森坦与FDA批准的联合疗法吉西他滨(GEM)PLUS联合使用 阿不来生(ABX)对PC患者的治疗。总之，拟议的研究将证明临床前的可行性 通过靶向单一信号轴消除治疗耐药性的外部和内在决定因素 临床确定ET轴拮抗剂与批准的化疗方案联合应用的安全性 PC机这三个AIMS产生的数据将构成未来致命性PC的1/II期临床试验的基础。

ABSTRACT Resistance to therapeutic agents is the predominant cause of high lethality of pancreatic cancer (PC). Inadequate and heterogeneous blood flow and obstructive desmoplastic stromal compartment are the major impediments to the delivery and intratumoral distribution of therapeutic agents and are the extrinsic determinants of therapy resistance in PC. Intrinsic chemoresistance of PC cells is dictated by a unique population of drug resistant cancer stem cells. Hence selective modulation of blood flow and extracellular matrix can lead to improved delivery of therapeutic agents into the tumors, while elimination of CSCs can improve the sensitivity of tumor cells to chemotherapy. Elevated endothelin (ET)-1 levels and overexpression of the two ET receptors (ETAR and ETBR) are observed in tumors. Importantly, ET-1 is a strong vasomodulator and induces vasoconstriction via ETAR is believed to be an important contributor to the tumor blood flow heterogeneity in tumors. Our preliminary studies indicate that the components of ET-axis are expressed in pancreatic tumors in various components of TME including tumor cells, blood vessel and stromal cells and CSCs. Further, targeting of ETAR with a specific inhibitor BQ123 selectively enhanced perfusion and reduced hypoxia in xenograft PC tumors, while prolonged inhibition of ET-axis in autochthonous tumors (in KPC mouse model of PC) with dual specificity inhibitor (Bosentan) resulted in marked inhibition of desmoplasia. We also observed that ET- 1 exerts pro-fibrogenic effects on murine pancreatic stellate cells via ETBR. We hypothesize that: “Sequential inhibition of ETBR and ETAR can modulate stroma and perfusion for enhanced delivery, distribution and efficacy of therapeutic agents and clinically, combination of abraxane and gemcitabine will be more efficacious with the modulation of ET axis”. Three specific aims are proposed. Studies in Aim 1 will determine the effect of selective ETAR and ETBR antagonists BQ123 and BQ788, on the delivery and distribution of macromolecule (ABX) and small molecule-based (GEM) therapeutic agents. Biodistribution of radiolabeled ABX and GEM will be studied for quantitative estimation of tumor uptake. Further, we will decipher the mechanistic role of ET-axis-mediated cross-talk between cancer and stromal cells in PC in the context of desmoplasia. Studies proposed in Aim 2 will determine the impact of ET-axis targeting on the efficacy of ABX+GEM both in vitro (using unique cancer cell- stellate cell co-cultures and tumor organoid cultures) and in vivo using genetically engineered mouse (KPC) model of PC. Finally, Aim 3 is designed to clinically evaluate the safety and perform initial screening for efficacy of combining the ET-axis antagonist Bosentan with FDA-approved combination therapy Gemcitabine (GEM) plus Abrexane (ABX) in PC patients. Altogether, the proposed studies will demonstrate the preclinical feasibility of eliminating both extrinsic and intrinsic determinants of therapy resistance by targeting a single signaling axis and clinically determine the safety of combining ET-axis antagonism with approved chemotherapeutic regimens of PC. The data generated from the three aims will form the basis of future Phase 1/II clinical trials in lethal PC.