TAS102联合Regorafenib治疗结肠癌及靶向肿瘤干细胞的作用及机制研究

Cancer stem cells (CSCs) account for tumor self-renewal, plasticity and heterogeneity. As a result, they contribute to tumorigenesis, progression and tumor resistance to chemoradiotherapies. TAS-102 is an oral formulation consisting of trifluridine (TFT) and tipiracil hydrochloride (TPI) .Trifluridine, like 5-FU, is a thymidine-based nucleoside analogue, which can impede DNA synthesis and induce DNA damage. Tipiracil hydrochloride is an inhibitor of thymidine phosphorylase, which protects degradation of trifluiridine and increases its bioavailability. TAS102 is a therapeutic effect for 5-FU-resistant metastatic colon cancer. Regorafenib, a novel multitargeted tyrosine kinase inhibitor, deregulates the activities of VEGFR2 and 3, Ret, Kit, PDGFR and Raf kinases and results in the inhibition of tumor angiogenesis and cell proliferation. Both TAS102 and Regorafenib have been approved to the treatment of metastatic colorectal cancer by FDA. We have reported that 5-FU in combination with regorafenib is effective in treatment of 2 patients with refractory metastatic colon cancer. However, the therapeutic effects and mechanisms of TAS102 in combination regorafenib have not been reported in colon cancer. Our data showed that TAS102 can synergize with regorafenib against colon cancer in vitro and in vivo. TAS102 can significantly alleviate the formation of colonosphere. Consequently, the project is aim at these directions as followed: 1) The therapeutic effects of TAS102 in combination with regorafenib against colon cancer in vitro and in vivo; 2) The single and combined effects of TAS102 and regorafenib on colorectal cancer stem cells. 3) To demonstrate the underlying mechanisms of TAS102 synergy with regorafenib. Collectively, we will demonstrate the therapeutic effects and mechanisms of TAS102 in combination with regorafenib in vitro and in vivo and the study’s insight is expected to provide a novel and effective therapy strategy in treatment of refractory metastatic colon cancer.

肿瘤干细胞决定了肿瘤自我更新及异质性并诱导了治疗耐受。TAS102由类似5-FU的曲氟尿苷（TFT）和胸苷磷酸化酶抑制剂达克罗宁（TPI）组成，TFT抑制了胸苷酸合酶活性，阻碍DNA的合成。TPI有效提高了TFT的生物利用度。其对5-FU治疗耐受的转移性结肠癌患者有效。Regorafenib（瑞格菲尼）是多靶点酪氨酸激酶抑制剂。二者近年被FDA批准用于耐药性转移性结肠癌治疗。我们报道了5-FU协同瑞格菲尼有效延长了难治性晚期结肠癌患者生存期。但TAS102联合瑞格菲尼治疗策略及对肿瘤干细胞作用还未见报道。前期研究发现TAS102和瑞格菲尼具有一定联合效应且TAS102显著抑制了肿瘤干细胞的生长。本课题拟开展如下研究：1）体内外实验评估二者单独及联合使用的治疗效应；2）二者单独及联合使用对肿瘤干细胞生长的影响；3)体内外实验分析二者联合用药的分子机制；以期为进展期结肠癌治疗提供新的策略。

TAS102及Regorafenib是新近报道的治疗晚期复发性转移性消化道恶性肿瘤的新药。TAS-102是一种口服配方，由trifluridine (FTD)和胸苷磷酸化酶抑制剂盐酸替吡拉西(TPI)组成。Regorafenib是一种多靶点酪氨酸激酶抑制剂，它抑制VEGFR2和3、Ret、Kit、PDGFR和Raf激酶的活性，从而抑制肿瘤血管生成和细胞增殖。TAS102或regorafenib单药治疗可使既往接受常规化疗和靶向治疗的转移性结直肠癌(mCRC)患者的总生存期延长。TAS102联合贝伐珠单抗(一种抗血管内皮生长因子a (VEGF-A)的单克隆抗体)与结直肠癌无进展生存的显著临床相关改善相关。FTD可与nintedanib协同抑制结直肠癌异种移植瘤的生长。我们之前报道在多耐药mCRC患者的病例报告中，瑞格非尼联合氟嘧啶可延缓肿瘤进展。本研究发现TAS102联合regorafenib在体外对包括结直肠癌和胃癌在内的多种GI癌症具有协同活性。TAS102抑制colonosphere形成，regorafenib增强了这种作用。TAS102加regorafenib的体内抗肿瘤作用似乎是由于抗增殖作用，坏死和血管生成抑制。TAS102联合regorafenib均可抑制异种移植肿瘤的生长，其中野生型p53可观察到更强的肿瘤抑制作用。Regorafenib显著抑制TAS102诱导的异种移植肿瘤血管生成和微血管密度，并抑制TAS102诱导的ERK1/2激活，而与体内RAS或BRAF状态无关。因此，TAS102和regorafenib在GI癌临床前模型中是一种协同药物组合，regorafenib抑制TAS102诱导的微血管密度增加和p-ERK是其作用机制。这种药物组合可能会进一步在胃癌和其他胃肠道癌症中进行测试。