ABSTRACT
Somatic PIK3CA mutations are frequently found in solid tumors, raising the hypothesis that selective inhibition of PI3Kα may have robust efficacy in PIK3CA-mutant cancers while sparing patients the side-effects associated with broader inhibition of the class I phosphoinositide 3-kinase (PI3K) family. Here, we report the biologic properties of the 2-aminothiazole derivative NVP-BYL719, a selective inhibitor of PI3Kα and its most common oncogenic mutant forms. The compound selectivity combined with excellent drug-like properties translates to dose- and time-dependent inhibition of PI3Kα signaling in vivo, resulting in robust therapeutic efficacy and tolerability in PIK3CA-dependent tumors. Novel targeted therapeutics such as NVP-BYL719, designed to modulate aberrant functions elicited by cancer-specific genetic alterations upon which the disease depends, require well-defined patient stratification strategies in order to maximize their therapeutic impact and benefit for the patients. Here, we also describe the application of the Cancer Cell Line Encyclopedia as a preclinical platform to refine the patient stratification strategy for NVP-BYL719 and found that PIK3CA mutation was the foremost positive predictor of sensitivity while revealing additional positive and negative associations such as PIK3CA amplification and PTEN mutation, respectively. These patient selection determinants are being assayed in the ongoing NVP-BYL719 clinical trials.
Subject(s)
Antineoplastic Agents/pharmacology , Phosphoinositide-3 Kinase Inhibitors , Thiazoles/pharmacology , Animals , Antineoplastic Agents/pharmacokinetics , Cell Line, Tumor , Class I Phosphatidylinositol 3-Kinases , Disease Models, Animal , Drug Evaluation, Preclinical , Drug Resistance, Neoplasm/genetics , Female , Humans , Inhibitory Concentration 50 , Mice , Mutation , Neoplasms/drug therapy , Neoplasms/genetics , Neoplasms/metabolism , PTEN Phosphohydrolase/genetics , PTEN Phosphohydrolase/metabolism , Phosphatidylinositol 3-Kinases/genetics , Rats , Thiazoles/pharmacokinetics , Xenograft Model Antitumor AssaysABSTRACT
The overall power of kinase inhibitors is substantially overshadowed by the acquisition of drug resistance. To address this issue, we systematically assessed the potential of secreted proteins to induce resistance to kinase inhibitors. To this end, we developed a high-throughput platform for screening a cDNA library encoding 3,432 secreted proteins in cellular assays. Using cancer cells originally dependent on either MET, FGFR2, or FGFR3, we observed a bypass of dependence through ligand-mediated activation of alternative receptor tyrosine kinases (RTK). Our findings indicate a broad and versatile potential for RTKs from the HER and FGFR families as well as MET to compensate for loss of each other. We further provide evidence that combined inhibition of simultaneously active RTKs can lead to an added anticancer effect.
Subject(s)
Neoplasms/metabolism , Proto-Oncogene Proteins c-met/metabolism , Receptor, ErbB-2/metabolism , Receptor, Fibroblast Growth Factor, Type 2/metabolism , Receptor, Fibroblast Growth Factor, Type 3/metabolism , Animals , Cell Line, Tumor , Cell Proliferation/drug effects , Drug Resistance, Neoplasm/genetics , ErbB Receptors/antagonists & inhibitors , ErbB Receptors/genetics , ErbB Receptors/metabolism , High-Throughput Screening Assays , Humans , Mice , Mutation , Neoplasms/drug therapy , Neoplasms/genetics , Neoplasms/pathology , Phosphorylation/drug effects , Protein Kinase Inhibitors/pharmacology , Receptor, ErbB-2/genetics , Signal Transduction/drug effects , Transplantation, HeterologousABSTRACT
Caveolae appear in a multitude of processes encompassing growth regulation and trafficking. We demonstrate the abundant presence of ESA/reggie-1/flotillin-2, ATP synthase beta subunit and annexin V in endothelial caveolae by immunopurification of caveolae from vascular endothelial membrane. Five proteins are abundant in a caveolin-1 protein complex, analyzed by sucrose gradient velocity sedimentation following octyl-beta-D-glucopyranoside extraction. Caveolin-1 alpha interacts with caveolin-1beta, caveolin-2, actin, the microsomal form of NADH cytochrome B5 reductase and ESA/reggie-1/flotillin-2 as shown by co-immunoprecipitation. We propose the concept that ATP biosynthesis in caveolae regulates mechanosignaling and is induced by membrane depolarization and a proton gradient. Pressure stimuli and metabolic changes may trigger gene regulation in endothelial cells, involving a nuclear conformer of caveolin-1, shown here with an epitope-specific caveolin-1 antibody, and immediate response of ion channel activity, regulated by ESA/reggie-1/flotillin-2.
