Lenvatinib is an oral multikinase inhibitor that selectively inhibits vascular endothelial growth factor (VEGF) receptors 1 to 3 and other proangiogenic and oncogenic pathway-related receptor tyrosine kinases. To elucidate the origin of the potency of lenvatinib in VEGF receptor 2 (VEGFR2) inhibition, we conducted a kinetic interaction analysis of lenvatinib with VEGFR2 and X-ray analysis of the crystal structure of VEGFR2-lenvatinib complexes. Kinetic analysis revealed that lenvatinib had a rapid association rate constant and a relatively slow dissociation rate constant in complex with VEGFR2. Co-crystal structure analysis demonstrated that lenvatinib binds at its ATP mimetic quinoline moiety to the ATP binding site and to the neighboring region via a cyclopropane ring, adopting an Asp-Phe-Gly (DFG)-"in" conformation. These results suggest that lenvatinib is very distinct in its binding mode of interaction compared to the several approved VEGFR2 kinase inhibitors.

Unresectable hepatocellular carcinoma (uHCC) is one of the most lethal and prevalent cancers worldwide, and current systemic therapeutic options for uHCC are limited. Lenvatinib, a multiple receptor tyrosine kinase inhibitor targeting vascular endothelial growth factor receptors (VEGFRs) and fibroblast growth factor receptors (FGFRs), recently demonstrated a treatment effect on overall survival by statistical confirmation of noninferiority to sorafenib in a phase 3 study of uHCC. Here, we investigated mechanisms underlying the antitumor activity of lenvatinib in preclinical HCC models. In vitro proliferation assay of nine human HCC cell lines showed that lenvatinib selectively inhibited proliferation of FGF signal‐activated HCC cells including FGF19‐expressing Hep3B2.1‐7. Lenvatinib suppressed phosphorylation of FRS2, a substrate of FGFR1–4, in these cells in a concentration‐dependent manner. Lenvatinib inhibited in vivo tumor growth in Hep3B2.1‐7 and SNU‐398 xenografts and decreased phosphorylation of FRS2 and Erk1/2 within the tumor tissues. Lenvatinib also exerted antitumor activity and potently reduced tumor microvessel density in PLC/PRF/5 xenograft model and two HCC patient‐derived xenograft models. These results suggest that lenvatinib has antitumor activity consistently across diverse HCC models, and that targeting of tumor FGF signaling pathways and anti‐angiogenic activity underlies its antitumor activity against HCC tumors.

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f152A1 was isolated from a fermentation broth of Curvularia verruculosa and characterized as a potent inhibitor of TNFalpha transcription, with anti-inflammatory activity. f152A1 and several analogues displayed inhibitory activity against the MAP kinases ERK2 and MEK1 in in vitro kinase assays. Through SAR studies on f152A1 and analogues prepared via total synthesis, we have identified structural features that contribute to inhibitory activity. To rationalize these results and to aid in the discovery process, a combination of high temperature molecular dynamics and MOPAC AM1 semiempirical molecular orbital method studies was used in studies that yielded a postulated active conformation, M1(8). This active conformation M1(8) reflects a high degree of conformational similarity among f152A1 and its more potent analogues. In view of the highly reactive cis-enone moiety in the flexible 14-membered resorcylic acid lactone ring of f152A1, the chemical reactivities of the enone moieties in various analogues were assessed by molecular orbital calculations. The enone reactivity analyses suggested that these inhibitors were prone to Michael addition at the alpha,beta-unsaturated ketone moiety and might chemically react with cysteine residues in the ATP-binding site of MAP kinases. Reactivity of the cis-enone moiety and the M1(8) conformation make important contributions to the inhibitory activity of MAP kinases.