What Is Verzenio™ (abemaciclib)?

Reviewed by: HU Medical Review Board | Last reviewed: June 2023

Verzenio™ (abemaciclib) is a targeted therapy used to treat certain people with early, advanced, or metastatic breast cancer that is hormone receptor-positive and human epidermal growth factor receptor 2 (HER2) negative. It may be used in combination with certain hormone therapies or alone (monotherapy).1

What are the ingredients in Verzenio?

The active ingredient in Verzenio is abemaciclib.1

How does abemaciclib work?

Breast cancer cells that are hormone receptor-positive are stimulated by the presence of hormones like estrogen, which can increase the activity of CDK4 and 6, which are proteins involved in a cell’s growth and division. Overactivity of CDK4 and CDK6 can cause breast cancer cells to grow uncontrollably.

Abemaciclib targets and blocks the proteins CDK4 and CDK6. By blocking these two proteins, abemaciclib can help slow the growth and division of breast cancer cells, but it may also interfere with the normal growth and division of healthy cells.1,2

What are the possible side effects?

The most common side effects of abemaciclib include:1,3

  • Nausea, vomiting, decreased appetite
  • Abdominal pain
  • Infections
  • Fatigue
  • Hair thinning or loss
  • Headache
  • Lowered white blood cells, red blood cells (anemia), or platelet counts
  • Diarrhea

Abemaciclib may also cause serious side effects, including:1,3

  • Diarrhea, which can cause dehydration or infection
  • Lowered white blood cell counts, which can cause serious infections and symptoms like fever and/or chills
  • Liver problems, which can cause symptoms like fatigue, abdominal pain, more bleeding or bruising than normal, and loss of appetite
  • Blood clots, which can cause pain or swelling in the arms or legs, shortness of breath, chest pain, fast breathing, or a fast heart rate
  • Lung problems, which can cause difficulty breathing, chest pain, and/or cough

If you have any signs of serious side effects, contact your doctor right away.

These are not all the possible side effects of abemaciclib. Talk to your doctor about what to expect when taking abemaciclib. You also should call your doctor if you have any changes that concern you when taking abemaciclib.

Things to know about abemaciclib

Avoid eating grapefruit, drinking grapefruit juice, or consuming products that have grapefruit while taking abemaciclib. These products may increase the levels of abemaciclib in the body, which can increase the potential for side effects.1,3

Your doctor will monitor your white blood cell counts and liver function before and during treatment with abemaciclib.1,3

Before taking abemaciclib, tell your doctor if you have:1,3

  • Liver problems
  • Kidney problems
  • Fever, chills, or other signs of infection
  • Lung problems
  • Ever had a blood clot

Abemaciclib can harm an unborn baby. If you can become pregnant, you should use birth control during treatment and for some time after the last dose of abemaciclib. You should also not breastfeed during treatment with abemaciclib and for some time after the last dose. Talk to your doctor about your options for birth control and breastfeeding while taking abemaciclib.1,3

Before beginning treatment for breast cancer, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

For more information, read the full prescribing information of abemaciclib.

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