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What is Verzenio™ ? (abemaciclib)

Verzenio is a prescription medication classified as a targeted therapy to treat 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 (as monotherapy). Abemaciclib is manufactured by Eli Lilly and Company.

What is the ingredient in Verzenio?

The active ingredient in Verzenio is abemaciclib, a kinase inhibitor that targets cyclin dependent kinase (CDK) 4 and 6.1

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 some of the possible side effects of abemaciclib?

Abemaciclib may cause serious side effects, including:

  • Diarrhea, which can lead to dehydration or infection
  • Lowered white blood cell counts (neutropenia), which may lead to serious infections and cause symptoms such as fever and/or chills – any signs of infection should be reported immediately to a doctor
  • Liver problems, which can cause symptoms such as fatigue, abdominal pain on the right side, more bleeding or bruising than normal, and/or a loss of appetite – any of these symptoms should be reported immediately to a doctor
  • Blood clots, which may cause pain or swelling in the arms or legs, shortness of breath, chest pain, fast breathing, or a fast heart rate – any of these symptoms should be reported immediately to a doctor1,3

The most common side effects experienced by patients taking abemaciclib in clinical trials include:

  • Nausea
  • Infections
  • Decreased appetite
  • Headache
  • Abdominal pain
  • Diarrhea
  • Fatigue
  • Vomiting
  • Hair thinning or loss
  • Lowered white blood cells, red blood cells (anemia), or platelet counts1,3

Things to know about abemaciclib

Because abemaciclib can lower white blood cell levels, it should not be used in patients who already have lowered white blood cell counts. Levels of white blood cells should be checked prior to starting treatment with abemaciclib and throughout treatment.1

Before starting treatment with abemaciclib, patients should talk to their doctor about all their medications (prescription and over-the-counter), herbal supplements, and vitamins they are taking. Some medications or supplements may interfere with each other and may cause side effects.1,3

Before starting treatment with abemaciclib, patients should also discuss with their doctor if they are pregnant, planning to become pregnant, breastfeeding, or planning to breastfeed. Abemaciclib can cause harm to an unborn fetus and should not be used in pregnant women. Women who can become pregnant are advised to use effective contraception while taking abemaciclib and for at least three weeks after stopping treatment with abemaciclib.1,3

It is not known if abemaciclib passes through breastmilk. Women should not breastfeed while taking abemaciclib and for at least 3 weeks after treatment with abemaciclib is finished.1,3

In addition, it should be noted that although it is rare, treatment with abemaciclib can cause severe inflammation of the lungs. Patients should notify their health care professional right away if they have any new or worsening symptoms involving their lungs, as they may indicate a rare but life-threatening condition that can lead to death.4

People taking abemaciclib should avoid eating grapefruit, drinking grapefruit juice, or consuming grapefruit containing products, as grapefruit products may increase the levels of abemaciclib in the body, which can increase the potential for side effects.1,3

Blood tests to monitor liver function should be performed during treatment with abemaciclib.1

Dosing information

Abemaciclib comes in tablets in several different strengths: 50 mg, 100 mg, 150 mg, and 200 mg. Your healthcare provider will determine the appropriate abemaciclib dosing regimen for you. The tablets can be taken with or without food.1

The dosage of abemaciclib may be reduced or stopped by the patient’s doctor depending on how the individual patient tolerates the treatment.1Patients should take their medication as prescribed by their doctor. Patients should talk to their doctor if they have any questions, or if they have questions regarding their abemaciclib regimen.

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

Written by: Editorial Team | Last reviewed: October 2019.
  1. Verzenio prescribing information. Eli Lilly and Company. Available at Accessed 7/13/18.
  2. CDK4/6 inhibitors: where they are now and where they are headed in the future. ASCO Post. Available at Accessed 7/12/18.
  3. Verzenio product website. Eli Lilly and Company. Available at Accessed 7/13/18.
  4. US FDA. FDA warns about rare but severe lung inflammation with Ibrance, Kisqali, and Verzenio for breast cancer. Available at Accessed 10/10/19.