Preclinical development of CXCR6 antagonists to target sorafenib resistance in Hepatocellular Carcinoma

项目摘要/摘要 索拉非尼(Nexavar®)是FDA批准的第一种治疗晚期肝细胞癌的靶向药物 癌症(HCC)患者和一线治疗。然而，它只提供了适度的生活 约40%的晚期不能切除的肝细胞癌患者因应答率低而延长，严重 不良事件和后天抵抗力。一些与肝细胞癌相关的细胞通路 病情发展和预后不良也是造成对索拉非尼耐药的原因。了解哪些内容 途径将通过提供肝细胞癌特异的临床反应生物标志物而产生重大影响 以及开发新的治疗靶点。其中一个这样的途径在50%的肝癌细胞中表达失调 是由Ras/Raf/β/Erk信号通路引起的WnT/MEK-连环蛋白的激活 (索拉非尼靶向)、PI3K/AKT/TOR和p38MAPK导致GSK-3β激酶失活。 GSK-3β磷酸化和蛋白酶体降解后β-连环蛋白的逃逸 在细胞核内积聚并激活几种致癌蛋白的转录。 索拉非尼无效，促进无节制的抗细胞凋亡，细胞增殖，血管生成， 急救和入侵。我们提出的一种对抗索拉非尼耐药性的新策略包括 抑制趋化因子受体CXCR6的过度激活。CXCR6及其配体的信号转导 CXCL16通过下游激酶驱动对索拉非尼的耐药性，并在Ser-9处达到顶峰 磷酸化-GSK3-β/β-连环蛋白激活。CXCR6在SK-Hep-1等肝癌细胞中的表达下调 LINES与p38活性降低，GSK3β活性升高，膜分离 β-连环蛋白与核内β-连环蛋白转录活性的下调。我们有 开发了一种一流的小分子铅，SBI-457，它能拮抗CXCR6受体，是 小鼠口服生物利用度和抑制30d小鼠肿瘤生长的效果 无不良反应的晚期肝癌异种移植模型。由于CXCR6/CXCL16不是很高 SBI-457在非癌肝细胞和其他肝组织中表达，预期无毒。 在高剂量和长期暴露下的活体。因为临床上还没有已知的CXCR6拮抗剂 到目前为止，将主药SBI-457优化为治疗晚期肝癌的单一药剂将是第一个创新 我们应用程序的一个方面。第二个重大创新是优化的CXCR6组合 了解和克服索拉非尼拮抗剂对肝癌耐药细胞的主要作用 化疗耐药的瓶颈。因此，小分子CXCR6拮抗剂先导化合物在此发展起来 应用具有扩大索拉非尼和其他靶向药物临床应用的潜力 通过重新致敏，改善反应和降低剂量，从而减少毒性和 不良事件的风险。

PROJECT SUMMARY/ABSTRACT Sorafenib (Nexavar®) is the first FDA approved targeted drug for advanced hepatocellular carcinoma (HCC) patients and a first-line treatment. However, it offers only a moderate life extension in about 40% of advanced unresectable HCC patients due to low response rate, serious adverse events and acquired resistance. Some of the cellular pathways associated with HCC development and poor prognosis also cause resistance to sorafenib. Understanding which pathway will have monumental impact by providing HCC specific clinical biomarkers of response and the development of new therapeutic targets. One such pathway dysregulated in 50% of HCCs is the activation of Wnt/β-catenin, induced by kinase cascades, notably the Ras/Raf/Mek/Erk (targeted by sorafenib), PI3K/AKT/TOR and p38 MAPK leading to inactivation of GSK-3β kinase. Post its escape from phosphorylation by GSK-3β and proteasomal degradation, β-catenin accumulates in the nucleus and activates transcription of several oncogenic proteins rendering sorafenib ineffective and promotes unchecked anti-apoptosis, cell proliferation, angiogenesis, EMT and invasion. A novel strategy proposed by us for combating resistance to sorafenib involves inhibiting hyperactivation of a chemokine receptor CXCR6. Signaling from CXCR6 and its ligand CXCL16 drives resistance to sorafenib through the downstream kinases and culminates at Ser-9 phospho-GSK3β/β-catenin activation. CXCR6-knockdown in SK-Hep-1 and other hepatoma cell lines is correlated with lower p38 activity, increased GSK3β activity, membrane sequestration of β-catenin and downregulation of β-catenin transcriptional activity in the nucleus. We have developed a first-in-class small molecule lead, SBI-457, that antagonizes the CXCR6 receptor, is orally bioavailable in mice and efficacious at attenuating tumor growth in a 30-day mouse xenograft model for advanced HCC with no adverse effects. Since CXCR6/CXCL16 are not highly expressed in non-cancerous hepatocyte and other liver tissue, SBI-457 is expectedly non-toxic in vivo under high dose and chronic exposure. Since there are no known clinical CXCR6 antagonists to date, optimization of lead SBI-457 as a single agent in advanced HCC will be the first innovative aspect of our application. A second major innovation is a combination of optimized CXCR6 antagonists with sorafenib in resistant HCC cells to understand and then overcome the major bottleneck of chemoresistance. Hence small molecule CXCR6 antagonist leads developed in this application have the potentially to expand the clinical use of sorafenib and other targeted agents by re-sensitization, improved response, and lowering of the dose thereby reducing toxicity and risk of adverse events.