On September 28, the Food and Drug Administration (FDA) approved Verzenio (abemaciclib), a kinase inhibitor that disrupts cancer growth, for people with certain types of advanced or metastatic breast cancer that has progressed despite hormone therapy. The approval was supported by data from a Phase III trial that showed that women who took Verzenio plus the estrogen blocker Faslodex (fulvestrant) after hormone therapy stopped working held off disease progression for nearly twice as long as those who took a placebo. Breast cancer is classified by the kind of receptors it expresses. A majority of breast tumors carry hormone receptors for estrogen or progesterone (known as HR-positive). Estrogen and progesterone encourage the growth of HR-positive breast cancer, and treatment usually includes hormone-blocking drugs.

Other tumors express a receptor called HER2 (human epidermal growth factor receptor 2). Triple-negative breast cancer doesn’t express any of these receptors. The FDA approved Verzenio for adults with HR-positive/HER2-negative advanced or metastatic (spread elsewhere in the body) breast cancer that has progressed after taking hormone blockers. More than 70 percent of all breast cancers are HR-positive and HER2-negative, according to the American Cancer Society. Verzenio is taken by mouth twice daily. It can be given with Faslodex for patients whose cancer has progressed on hormone therapy or given alone for people previously treated with hormone therapy and chemotherapy after their cancer has spread. Verzenio, made by Eli Lilly, is a cyclin-dependent kinase inhibitor that blocks both CDK4 and CDK6. These proteins play a role in regulating cell division, and blocking their action can slow the growth of cancer cells. Two other drugs in this class, Pfizer’s Ibrance (palbociclib) and Novartis’s Kisqali (ribociclib), were previously approved for some types of breast cancer.