Design, synthesis and biological evaluation of 5-amino-1H-pyrazole-4-carboxamide derivatives as pan-FGFR covalent inhibitors.

The aberrant activation of FGFRs plays a critical role in various cancers, leading to the development of several FGFR inhibitors in clinic. However, the emergence of drug resistance, primarily due to gatekeeper mutations in FGFRs, has limited their clinical efficacy. To address the unmet medical need, a series of 5-amino-1H-pyrazole-4-carboxamide derivatives were designed and synthesized as novel pan-FGFR covalent inhibitors targeting both wild-type and the gatekeeper mutants. The representative compound 10h demonstrated nanomolar activities against FGFR1, FGFR2, FGFR3 and FGFR2 V564F gatekeeper mutant in biochemical assays (IC50 = 46, 41, 99, and 62 nM). Moreover, 10h also strongly suppressed the proliferation of NCI-H520 lung cancer cells, SNU-16 and KATO III gastric cancer cells with IC50 values of 19, 59, and 73 nM, respectively. Further X-ray co-crystal structure revealed that 10h irreversibly binds to FGFR1. The study provides a new promising point for anticancer drug development medicated by FGFRs.

Design, Synthesis, and Biological Evaluation of 5-Formyl-pyrrolo[3,2-b]pyridine-3-carboxamides as New Selective, Potent, and Reversible-Covalent FGFR4 Inhibitors.

The FGF19-FGFR4 signaling pathway has been extensively studied as a promising target for the treatment of hepatocellular carcinoma (HCC). Several FGFR4-selective inhibitors have been developed, but none of them receives approval. Additionally, acquired resistance caused by FGFR4 gatekeeper mutations is emerging as a serious limitation for these targeted therapies. Herein, we report a novel series of 5-formyl-pyrrolo[3,2-b]pyridine derivatives as new reversible-covalent inhibitors targeting wild-type and gatekeeper mutant variants of FGFR4 kinase. The representative compound 10z exhibited single-digit nanomolar activity against wild-type FGFR4 and the FGFR4V550L/M mutant variants in biochemical and Ba/F3 cellular assays, while sparing FGFR1/2/3. Furthermore, 10z showed significant antiproliferative activity against Hep3B, JHH-7, and HuH-7 HCC cells with IC50 values of 37, 32, and 94 nM, respectively. MALDI-TOF-MS and X-ray protein crystallography studies were consistent with 10z acting as a reversible-covalent inhibitor of FGFR4, serving as a promising lead compound for further anticancer drug development.

Investigation of Covalent Warheads in the Design of 2-Aminopyrimidine-based FGFR4 Inhibitors.

Covalent kinase inhibitors are rapidly emerging as a class of therapeutics with clinical benefits. Herein we report a series of selective 2-aminopyrimidine-based fibroblast growth factor receptor 4 (FGFR4) inhibitors exploring different types of cysteine-targeting warheads. The structure-activity relationship study revealed that the chemically tuned warheads α-fluoro acrylamide, vinylsulfonamide, and acetaldehyde amine were suitable as covalent warheads for the design of selective FGFR4 inhibitors. Compounds 6a, 6h, and 6i selectively suppressed FGFR4 enzymatic activity with IC50 values of 53 ± 18, 45 ± 11, and 16 ± 4 nM, respectively, while sparing FGFR1/2/3. X-ray crystal structure and MALDI-TOF studies demonstrated that compound 6h bearing the α-fluoro acrylamide binds to FGFR4 with an irreversible binding mode, whereas compound 6i with an acetaldehyde amine binds to FGFR4 with a reversible covalent mode. 6h and 6i might provide some fundamental structural information for the rational design of new selective FGFR4 inhibitors.