buparlisib and Biliary-Tract-Neoplasms

There are currently no clinically validated therapeutic targets for biliary tract cancer (BTC). Despite promising results in other cancers, compounds targeting the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, alone or in combination with Ras/Raf/MEK pathway inhibitors, have not been evaluated in BTC. Here, we examined the effects of a pan-PI3K inhibitor (BKM120) with or without a MEK inhibitor (MEK162), on eight human BTC cell lines carrying mutations in K-Ras and/or the PI3K catalytic subunit, PI3KCA. BKM120 inhibited the colony-forming ability and migration of BTC cells carrying wild-type (WT) PI3KCA and either mutant (MT) or WT K-Ras, but not of cells carrying mutations in both genes. In K-Ras-WT cells, BKM120 decreased the phosphorylation of Akt, its downstream effector kinase p70S6K, and the translational repressor 4E-BP1. Interestingly, BKM120 did not induce cell cycle arrest or suppress PI3K signaling via restoration of p-4E-BP1 in cells with PIK3CA and K-Ras double mutations. Notably, the resistance of dual K-Ras/PI3KCA-mutant cells to BKM120 was overcome by treatment with a combination of BKM120 and MEK162. Our findings thus support the clinical development of BKM120 monotherapy or BKM120/MEK162 combination therapy for the treatment of BTC.

Topics: Aminopyridines; Antineoplastic Combined Chemotherapy Protocols; Benzimidazoles; Biliary Tract Neoplasms; Cell Line, Tumor; Cell Movement; Drug Resistance, Neoplasm; Drug Synergism; Humans; MAP Kinase Signaling System; Morpholines; Phosphatidylinositol 3-Kinases; raf Kinases; ras Proteins; Signal Transduction