ribociclib + buparlisib + letrozole

Ribociclib + buparlisib + letrozole is a combination regimen designed to treat hormone receptor-positive, HER2-negative, locally advanced or metastatic breast cancer. Ribociclib is an oral small molecule inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6), arresting proliferation of cancer cells dependent on this pathway. Buparlisib (BKM120) is an oral pan-class I phosphoinositide 3-kinase (PI3K) inhibitor that targets the PI3K/AKT/mTOR pathway, which can be aberrantly activated in breast cancer. Letrozole is an oral nonsteroidal aromatase inhibitor that reduces estrogen production, limiting growth of estrogen-dependent cancer cells. This triple combination was investigated for potential synergistic antitumor activity via simultaneous inhibition of CDK4/6, PI3K, and estrogen receptor pathways.