FDA Approves New CDK4/6 Inhibitor for Certain Advanced or Metastatic Breast Cancers

The U.S. Food and Drug Administration (FDA) today approved abemaciclib (Verzenio) to treat adult patients who have hormone receptor–positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer that has progressed after endocrine therapy. Abemaciclib is approved to be given either in combination with fulvestrant (Faslodex) after the cancer had progressed on endocrine therapy, or on its own, if patients were previously treated with endocrine therapy and prior chemotherapy in the metastatic setting.

"[Abemaciclib] provides a new targeted treatment option for certain patients with breast cancer who are not responding to treatment, and unlike other drugs in the class, it can be given as a stand-alone treatment to patients who were previously treated with endocrine therapy and chemotherapy," said Richard Pazdur, MD, Director of the FDA’s Oncology Center of Excellence and Acting Director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research.

Abemaciclib works by blocking cyclin-dependent kinases (CDK) 4 and 6, which are involved in promoting the growth of cancer cells. This is the third CDK 4/6 inhibitor approved for patients with breast cancer; palbociclib (Ibrance) was approved in February 2015, and ribociclib (Kisqali) was approved in March 2017.

Breast cancer is the most common form of cancer in the United States. The National Cancer Institute at the National Institutes of Health estimates approximately 252,710 women will be diagnosed with breast cancer this year, and 40,610 will die of the disease. Approximately 72% of patients with breast cancer have tumors that are hormone receptor–positive and HER2-negative.

Safety and Efficacy

The safety and efficacy of abemaciclib in combination with fulvestrant were studied in a randomized trial of 669 patients with hormone receptor–positive, HER2-negative breast cancer that had progressed after treatment with endocrine therapy and who had not received chemotherapy once the cancer had metastasized. The primary endpoint of the study was progression-free survival; the median progression-free survival for patients taking abemaciclib with fulvestrant was 16.4 months compared to 9.3 months for patients taking a placebo with fulvestrant.

The safety and efficacy of abemaciclib as a stand-alone treatment were studied in a single-arm trial of 132 patients with hormone receptor–positive, HER2-negative breast cancer that had progressed after treatment with endocrine therapy and chemotherapy after the cancer metastasized. The study measured the percent of patients whose tumors completely or partially shrank after treatment (objective response rate). In the study, 19.7% of patients taking abemaciclib experienced complete or partial shrinkage of their tumors for a median 8.6 months.

Common side effects of abemaciclib include diarrhea, neutropenia and leukopenia, nausea, abdominal pain, infections, fatigue, anemia, decreased appetite, vomiting, and headache. Serious side effects of abemaciclib include diarrhea, neutropenia, elevated liver blood tests, and deep venous thrombosis/pulmonary embolism. Women who are pregnant should not take abemaciclib because it may cause harm to a developing fetus.

The FDA granted this application Priority Review and Breakthrough Therapy designations. The FDA granted the approval of abemaciclib to Eli Lilly and Company.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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