FDA Approval Announcement
September 28, 2017 -- The U.S. Food and Drug Administration (FDA) approved Verzenio (abemaciclib) to treat adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer that has progressed after endocrine therapy. The approved indications are as follows:
In combination with fulvestrant (an endocrine therapy) for patients whose cancer progressed on prior endocrine therapy.
As monotherapy for patients who were previously treated with endocrine therapy and chemotherapy after the cancer metastasized.
Expert Statement
Richard Pazdur, M.D., 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, stated that Verzenio provides a new targeted treatment option for certain non-responsive breast cancer patients. Unlike other drugs in the same class, it can be used as a stand-alone treatment for patients who have received prior endocrine therapy and chemotherapy.
Mechanism of Action
Verzenio works by blocking cyclin-dependent kinases 4 and 6 (CDK4/6), molecules that promote cancer cell growth. It belongs to the same class as two other FDA-approved drugs for breast cancer: palbociclib (approved in February 2015) and ribociclib (approved in March 2017).
Clinical Background of Breast Cancer
Breast cancer is the most common form of cancer in the United States. According to the National Cancer Institute (NIH):
Approximately 252,710 women will be diagnosed with breast cancer in 2017.
Approximately 40,610 women will die of the disease in 2017.
About 72% of breast cancer patients have HR-positive, HER2-negative tumors.
Clinical Trial Data
1. Verzenio in Combination with Fulvestrant
Trial Design: Randomized trial involving 669 patients with HR-positive, HER2-negative breast cancer that progressed after endocrine therapy (no prior chemotherapy for metastatic disease).
Primary Endpoint: Progression-free survival (PFS).
Results: Median PFS was 16.4 months in the Verzenio + fulvestrant group, compared to 9.3 months in the placebo + fulvestrant group.
2. Verzenio as Monotherapy
Trial Design: Single-arm trial involving 132 patients with HR-positive, HER2-negative breast cancer that progressed after endocrine therapy and chemotherapy for metastatic disease.
Primary Endpoint: Objective response rate (ORR, defined as complete response [CR] plus partial response [PR]).
Results: 19.7% of patients achieved CR or PR, with a median duration of response of 8.6 months.
Adverse Reactions
Common Side Effects
Diarrhea, neutropenia, leukopenia, nausea, abdominal pain, infections, fatigue, anemia, decreased appetite, vomiting, and headache.
Serious Side Effects
Diarrhea, neutropenia, elevated liver function tests, and blood clots (deep venous thrombosis/pulmonary embolism).
Special Warning
Pregnant women should not take Verzenio, as it may cause harm to the developing fetus.
