TRENTON, N.J. >> U.S. regulators have approved a new drug as an initial treatment for postmenopausal women with a type of advanced breast cancer.

The drug, called Kisqali, is a pill that works to slow the spread of cancer by blocking two proteins that can stimulate growth and division of cancer cells. It’s for women who have metastatic breast cancer known as HR+/HER2-.

The U.S. Food and Drug Administration confirmed the drug’s approval on Monday. Swiss drugmaker Novartis AG, which developed the treatment, said there are no firm statistics on how many U.S. patients get this type of breast cancer.

“This is an important therapy for these patients,” who have limited options, said Dr. Vas Narasimhan, chief medical officer and head of drug development at Novartis, which has its U.S. headquarters in East Hanover, New Jersey.

Kisqali is taken along with an older cancer drug called letrozole that works differently.

Kisqali, part of the drug class called kinase inhibitors, is taken daily for three weeks, followed by a one-week break. Meanwhile, patients also take either letrozole or another medication in the same drug class, called aromatase inhibitors, depending on characteristics of their disease for the entire four weeks.

A four-week supply of Kisqali, or 21 pills, will have a list price of $10,950 for the strongest dose — 600 milligrams. The 400- milligram dose will cost $8,760 and the 200-milligram dose $4,380, Novartis said.

Patients often need to switch doses and the smaller doses will save patients and insurance companies money. Novartis said it will offer patients several types of financial assistance and many won’t have to make copayments.

A study of 668 women funded by Novartis found that Kisqali and letrozeole together reduced the risk of death or the cancer worsening by 44 percent, compared to those receiving only letrozole.

Kisqali, known chemically as ribociclib, can have side effects, ranging from potentially fatal abnormal heartbeat, serious liver problems and severe infections to nausea, hair loss and fatigue. It cannot be taken by women who are pregnant or breastfeeding.