ABSTRACT
FGF19 signaling through the FGFR4/ß-klotho receptor complex has been shown to be a key driver of growth and survival in a subset of hepatocellular carcinomas, making selective FGFR4 inhibition an attractive treatment opportunity. A kinome-wide sequence alignment highlighted a poorly conserved cysteine residue within the FGFR4 ATP-binding site at position 552, two positions beyond the gate-keeper residue. Several strategies for targeting this cysteine to identify FGFR4 selective inhibitor starting points are summarized which made use of both rational and unbiased screening approaches. The optimization of a 2-formylquinoline amide hit series is described in which the aldehyde makes a hemithioacetal reversible-covalent interaction with cysteine 552. Key challenges addressed during the optimization are improving the FGFR4 potency, metabolic stability, and solubility leading ultimately to the highly selective first-in-class clinical candidate roblitinib.
Subject(s)
Piperazines/chemistry , Protein Kinase Inhibitors/chemistry , Pyridines/chemistry , Receptor, Fibroblast Growth Factor, Type 4/antagonists & inhibitors , Amino Acid Sequence , Animals , Binding Sites , Cell Line, Tumor , Cell Proliferation/drug effects , Cysteine/chemistry , Dogs , Drug Design , Half-Life , Hepatocytes/cytology , Hepatocytes/drug effects , Hepatocytes/metabolism , Liver Neoplasms/drug therapy , Mice , Microsomes, Liver/metabolism , Molecular Dynamics Simulation , Piperazines/metabolism , Piperazines/pharmacology , Piperazines/therapeutic use , Protein Kinase Inhibitors/metabolism , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic use , Pyridines/metabolism , Pyridines/pharmacology , Pyridines/therapeutic use , Rats , Receptor, Fibroblast Growth Factor, Type 4/metabolism , Structure-Activity Relationship , Xenograft Model Antitumor AssaysABSTRACT
Taking the pyrrolopyrimidine derived IGF-1R inhibitor NVP-AEW541 as the starting point, the benzyl ether back-pocket binding moiety was replaced with a series of 2-cyclic ether methyl ethers leading to the identification of novel achiral [2.2.1]-bicyclic ether methyl ether containing analogues with improved IGF-1R activities and kinase selectivities. Further exploration of the series, including a fluorine scan of the 5-phenyl substituent, and optimisation of the sugar-pocket binding moiety identified compound 33 containing (S)-2-tetrahydrofuran methyl ether 6-fluorophenyl ether back-pocket, and cis-N-Ac-Pip sugar-pocket binding groups. Compound 33 showed improved selectivity and pharmacokinetics compared to NVP-AEW541, and produced comparable in vivo efficacy to linsitinib in inhibiting the growth of an IGF-1R dependent tumour xenograft model in the mouse.
