选择性FGFR4降解剂的设计合成及其抗肝癌活性研究

Aberrant signaling through FGF19/FGFR4 is the oncogenic driver for hepatocellular carcinoma (HCC) and is associated with poor prognosis. Proof of concept studies in mice using FGFR4 inhibitors or FGF19 antibodies to block this pathway have demonstrated that FGFR4 is an effective target for HCC treatment. Several selective FGFR4 irreversible-covalent inhibitors BLU9931, BLU554 and H3B-6527 have been entered clinical studies. However, recent studies show that FGFR4 protein can be resynthesized rapidly (half-life <2 h), leading a re-evaluation of the suitability of the irreversible-covalent approach for the treatment of HCC. Reversible-covalent inhibitors of FGFR4 become a new strategy to block the FGFR4 signaling pathway, but which still need to maintain high concentrations of drugs in the tumor tissue to play an effectively role. Proteolysis targeting chimeras (PROTAC) is a new technology in drug research that introduced as promoters of cellular protein degradation. Compared with traditional small molecule drugs, PROTAC may induce target protein degradation at a catalytic amount and fully antagonize the biological functions of the target protein..We have successfully designed and synthesized a series of 2-aminopyrimidine derivatives as new selective FGFR4 inhibitors. One of the most promising compound D2785 tightly binds to FGFR4 with a Kd value of 3.3 nM and inhibits FGFR4 with a IC50 value of 2.6 nM, and completely spared EGFR1/2/3 with IC50 values of >10 μM. Furthermore, D2785 exhibited extraordinary target specificity in a Kinome-wide screen against 468 kinases with S (35) and S (10) selectivity scores of 0.01 and 0.007 at 1. 0 μM, respectively. In this project, we will continue design and synthesis of new generation of FGFR4 reversible-covalent inhibitors and FGFR4 PROTAC degradation agents based on the lead compound D2785. Besides, we will also investigate the SARs and mechanism of action of newly discovery FGFR4 degradation agents, and the potential applications of FGFR4 inhibitors for the treatment of HCC.

FGF19/FGFR4通路过度激活促进肿瘤的发生和发展，FGFR4成为抗肝癌药物研究的新靶标。多个FGFR4非可逆抑制剂已进入临床研究。但最新研究表明FGFR4的快速再合成（速率<2h）导致非可逆抑制剂的药效受到质疑。可逆共价抑制剂成为抑制FGFR4快速合成的新策略，但仍需要在肿瘤组织保持高浓度才能发挥作用。新兴起的蛋白降解靶向嵌合分子（PROTAC）在催化剂量下可诱导蛋白降解，拮抗蛋白生物功能。课题组已获得全新的选择性FGFR4抑制剂，代表分子D2785抑制FGFR4的IC50为2.6nM，Kd为3.3nM，抑制FGFR1/2/3的IC50>10μM，选择性超过1000倍。本项目拟在前期研究的基础上，进行系统的结构优化获得高选择性FGFR4可逆共价抑制剂，并以此为基础设计合成FGFR4降解剂，利用体内外模型研究其作用机制和抗肝癌活性，为进一步发展靶向FGFR4的抗肝癌药物提供候选分子。

肝癌成为严重威胁我国人民健康的重大疾病。多靶点激酶抑制剂索拉菲尼（Sonafinib）和瑞戈非尼（Regorafenib）被批准用于晚期肝癌的靶向药物。鉴于其脱靶引起的副作用（如：腹泻、手足皮肤病和低磷血症等）以及有限的治疗效果，临床上迫切需要更加安全有效的新型抗肝癌药物，寻找肝癌治疗新靶点并开发相应高选择性的靶向药物具有重要的临床意义。根据FGFR4激酶对肝细胞癌的发生发展中的作用，利用合理药物设计技术，总计合成3-氨基吲唑和5-醛基杂环酰胺两大类具有全新结构的高活性和高选择性的FGFR4小分子抑制剂，并进行构效关系研究，以及初步的成药性研究。总计合成了两大类约120个FGFR4小分子抑制剂，并进行的体外活性测试和作用机制研究，针对2个优选分子分别进行药代动力学或体内活性研究，为抗肝癌药物的研究提供候选分子。执行期内，发表SCI论文8篇，申请发明专利3项(PCT1项)。总计培养博士研究生1名，硕士研究生4名。项目负责人获得国家自然科学基金优秀青年基金项目资助。