regorafenib and Gastrointestinal-Stromal-Tumors

Gastrointestinal stromal tumors (GISTs) are prototypes of stem cell factor receptor (c-KIT)-driven cancer. Two receptor tyrosine kinases, c-KIT and fms-tyrosine kinase (FLT3), are frequently mutated in acute myeloid leukemia (AML) patients, and these mutations are associated with poor prognosis. In this study, we discovered a multitargeted tyrosine kinase inhibitor, compound

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Proliferation; Female; fms-Like Tyrosine Kinase 3; Gastrointestinal Neoplasms; Gastrointestinal Stromal Tumors; Humans; Leukemia, Myeloid, Acute; Male; Mice; Mice, Inbred ICR; Mice, Inbred NOD; Mice, Nude; Mice, SCID; Mutation; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-kit; Pyrimidines; Rats, Sprague-Dawley; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

While the treatment of gastrointestinal stromal tumors (GISTs) has been revolutionized by the application of targeted tyrosine kinase inhibitors capable of inhibiting KIT-driven proliferation, diverse mutations to this kinase drive resistance to established therapies. Here we describe the identification of potent pan-KIT mutant kinase inhibitors that can be dosed without being limited by the tolerability issues seen with multitargeted agents. This effort focused on identification and optimization of an existing kinase scaffold through the use of structure-based design. Starting from a series of previously reported phenoxyquinazoline and quinoline based inhibitors of the tyrosine kinase PDGFRα, potency against a diverse panel of mutant KIT driven Ba/F3 cell lines was optimized, with a particular focus on reducing activity against a KDR driven cell model in order to limit the potential for hypertension commonly seen in second and third line GIST therapies. AZD3229 demonstrates potent single digit nM growth inhibition across a broad cell panel, with good margin to KDR-driven effects. Selectivity over KDR can be rationalized predominantly by the interaction of water molecules with the protein and ligand in the active site, and its kinome selectivity is similar to the best of the approved GIST agents. This compound demonstrates excellent cross-species pharmacokinetics, shows strong pharmacodynamic inhibition of target, and is active in several in vivo models of GIST.

Topics: Drug Discovery; Gastrointestinal Neoplasms; Gastrointestinal Stromal Tumors; Humans; Models, Molecular; Mutant Proteins; Mutation; Protein Conformation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-kit; Quinazolines; Tissue Distribution; Triazoles; Tumor Cells, Cultured