Abemaciclib (Verzenio) is a targeted therapyinfo-icon approved by the Food and Drug Administrationinfo-icon to treat hormone receptorinfo-icon-positive metastaticinfo-icon breast cancer. It is a cyclin-dependent kinase 4/6 (CDK 4/6) inhibitor, which means it targets two specific kinases, or proteins, that help tumorinfo-icon cells reproduce. Those kinases are CDK 4 and CDK 6.

CDK 4/6 inhibitors are relatively new treatments. The first, palbociclib, was approved by the FDAinfo-icon in 2015. Another, ribociclib, was approved in early 2017. Abemaciclib is the third medicineinfo-icon of this type to be approved for hormone receptor-positive, HER2-negative metastatic breast cancer.

How Abemaciclib Works

Cyclin-dependent kinases 4 and 6 are two proteins that help some breast cancers to grow. Medicines like abemaciclib are called CDK 4/6 inhibitors because they block these proteins from telling cancer cells to multiply, which helps slow the growth or spread of the cancer.

Who Gets Abemaciclib

Abemaciclib is approved for two uses in people with hormone receptorinfo-icon-positive, HER2-negative metastaticinfo-icon breast cancer:

  • It is given with an aromatase inhibitorinfo-icon as the first treatment for metastatic breast cancer if you are a postmenopausalinfo-icon woman.
  • It is given alone if you have already been treated with hormonal therapyinfo-icon and chemotherapyinfo-icon for metastatic breast cancer.
  • It is given with fulvestrantinfo-icon (Faslodexinfo-icon) if you have taken hormonal therapy for early-stageinfo-icon or metastatic breast cancer, but have not had chemotherapy since being diagnosed with metastatic breast cancer.

How Abemaciclib is Given

Abemaciclib is a pill, usually taken twice a day. The recommended doseinfo-icon depends on whether you are taking it alone, with an aromatase inhibitorinfo-icon or with fulvestrantinfo-icon. Unlike other CDK 4/6 inhibitors, which are taken in cycles with regular breaks, abemaciclib is taken every day through treatment.

Side Effects and Things to Remember

The most common side effectinfo-icon for abemaciclib is diarrheainfo-icon. In a clinical trialinfo-icon, more than 80 percent of women experienced diarrhea, but most cases were controlled with anti-diarrheal medicines and lowering the doseinfo-icon, if necessary. It also may cause neutropeniainfo-icon, a low white blood cellinfo-icon count that makes infectioninfo-icon more likely. Your doctor will watch your blood counts closely, especially during the first two months on the treatment. Other side effects included:

  • low red blood cell countinfo-icon, which can lead to fatigueinfo-icon
  • low blood platelet count, which can cause abnormalinfo-icon bleeding
  • nauseainfo-icon and vomiting
  • abdominal pain
  • small sores or ulcers in the mouth or on the lips
  • fatigue
  • headache
  • low appetite
  • hair loss
  • itching
  • swelling in the limbs

Tell your doctor about any medicines, supplements or remedies you are taking before starting abemaciclib. You should avoid eating grapefruit and any food or drinks that have grapefruit in them while taking this medicineinfo-icon.

Tell your doctor if you are pregnant, breastfeeding or planning to do either. Abemaciclib may be dangerous to a fetus so it is recommended that you not take this medicine while pregnant and not get pregnant until at least 3 weeks after you have stopped treatment. It is not known if abemaciclib is transferred through breast milk, so you should also not breastfeed while taking abemaciclib or for 3 weeks after you stop.

Talk to your doctor about any side effects you experience and how to manage them. You can also visit our Side Effects page to learn more.

April 2, 2018