A drug used with an aromatase inhibitor (a type of hormone therapy) to treat hormone-receptor positive (HR+), HER2 negative (HER2-) breast cancer. It is used in postmenopausal women whose cancer is advanced or has spread to other parts of the body. It is also being studied in the treatment of other types of cancer. Ribociclib blocks certain proteins, which may help keep cancer cells from growing. It is a type of cyclin-dependent kinase inhibitor. Also called Kisqali.