Fibroblast growth factor receptor 4 (FGFR4) has been proved to be an effective target for cancer therapy. Aberration in FGF19/FGFR4 signaling is oncogenic driving force in human hepatocellular carcinoma (HCC). FGFR4 gatekeeper mutations induced acquired resistance remains an unmet clinical challenge for HCC treatment. In this study, a series of 1H-indazole derivatives were designed and synthesized as new irreversible inhibitors of wild-type and gatekeeper mutant FGFR4. These new derivatives showed significant FGFR4 inhibitory and antitumor activities, among which compound 27i was demonstrated to be the most potent compound (FGFR4 IC₅₀ = 2.4 nM). Remarkably, compound 27i exhibited no activity against a panel of 381 kinases at 1 μM. Additionally, compound 27i displayed nanomolar IC₅₀s against huh7 (IC₅₀ = 21 nM) and two mutant cell lines, BaF3/ETV6-FGFR4-V550L and BaF3/ETV6-FGFR4-N535K (IC₅₀ = 2.5/171 nM). Meanwhile, compound 27i exhibited potent antitumor potency (TGI: 83.0%, 40 mg/kg, BID) in Huh7 xenograft mouse models with no obvious toxicity observed. Overall, compound 27i was identified as a promising preclinical candidate for overcoming FGFR4 gatekeeper mutations for HCC treatment.

成纤维细胞生长因子受体4（FGFR4）已被证明是癌症治疗的有效靶点。FGF19/FGFR4 信号传导异常是人类肝细胞癌 (HCC) 的致癌驱动力。FGFR4 看门人突变引起的获得性耐药仍然是 HCC 治疗中尚未解决的临床挑战。在本研究中，设计并合成了一系列1H-吲唑衍生物作为野生型和守门突变体FGFR4的新型不可逆抑制剂。这些新衍生物表现出显着的FGFR4抑制和抗肿瘤活性，其中化合物27i被证明是最有效的化合物（FGFR4 IC ₅₀  = 2.4 nM）。值得注意的是，化合物27i在 1 μM 浓度下对一组 381 种激酶没有表现出活性。此外，化合物27i对 huh7 (IC ₅₀  = 21 nM) 和两种突变细胞系 BaF3/ETV6-FGFR4-V550L 和 BaF3/ETV6-FGFR4-N535K (IC ₅₀  = 2.5/171 nM)显示纳摩尔 IC _{50 s。}同时，化合物27i在Huh7异种移植小鼠模型中表现出有效的抗肿瘤效力（TGI：83.0％，40mg/kg，BID），并且没有观察到明显的毒性。总体而言，化合物27i被确定为克服 HCC 治疗中 FGFR4 看门人突变的有前途的临床前候选药物。