Phosphorylation State-Dependent High Throughput Screening of the c-Met Kinase

High-throughput screening (HTS) of ~50,000 chemical compounds against phosphorylated and unphosphorylated c-Met, a tyrosine kinase receptor for hepatocyte growth factor (HGF), was carried out in order to compare hit rates, hit potencies and also to explore scaffolds that might serve as potential leads targeting only the unphosphorylated form of the enzyme. The hit rate and potency for the confirmed hit molecules were higher for the unphosphoryalted form of c-Met. While the target of small molecule inhibitor discovery efforts has traditionally been the phosphorylated form, there are now examples of small molecules that target unphosphorylated kinases. Screening for inhibitors of unphosphorylated kinases may represent a complementary approach for prioritizing chemical scaffolds for hit-to-lead follow ups

INCB054828 (pemigatinib), a potent and selective inhibitor of fibroblast growth factor receptors 1, 2, and 3, displays activity against genetically defined tumor models.

Alterations in fibroblast growth factor receptor (FGFR) genes have been identified as potential driver oncogenes. Pharmacological targeting of FGFRs may therefore provide therapeutic benefit to selected cancer patients, and proof-of-concept has been established in early clinical trials of FGFR inhibitors. Here, we present the molecular structure and preclinical characterization of INCB054828 (pemigatinib), a novel, selective inhibitor of FGFR 1, 2, and 3, currently in phase 2 clinical trials. INCB054828 pharmacokinetics and pharmacodynamics were investigated using cell lines and tumor models, and the antitumor effect of oral INCB054828 was investigated using xenograft tumor models with genetic alterations in FGFR1, 2, or 3. Enzymatic assays with recombinant human FGFR kinases showed potent inhibition of FGFR1, 2, and 3 by INCB054828 (half maximal inhibitory concentration [IC50] 0.4, 0.5, and 1.0 nM, respectively) with weaker activity against FGFR4 (IC50 30 nM). INCB054828 selectively inhibited growth of tumor cell lines with activation of FGFR signaling compared with cell lines lacking FGFR aberrations. The preclinical pharmacokinetic profile suggests target inhibition is achievable by INCB054828 in vivo with low oral doses. INCB054828 suppressed the growth of xenografted tumor models with FGFR1, 2, or 3 alterations as monotherapy, and the combination of INCB054828 with cisplatin provided significant benefit over either single agent, with an acceptable tolerability. The preclinical data presented for INCB054828, together with preliminary clinical observations, support continued investigation in patients with FGFR alterations, such as fusions and activating mutations