Abemaciclib is used in combination with tamoxifen (Soltamox) or an aromatase inhibitor such as anastrozole (Arimidex), exemestane (Aromasin), or letrozole (Femara) to treat a certain type of hormone receptor-positive, early breast cancer. Abemaciclib is also used along with fulvestrant (Faslodex) to treat a certain type of hormone receptor-positive, advanced breast cancer (breast cancer that depends on hormones such as estrogen to grow) or breast cancer that has spread to other parts of the body after treatment with an antiestrogen medication such as tamoxifen. Abemaciclib is also used along with anastrozole (Arimidex), exemestane (Aromasin), or letrozole (Femara) as a first treatment of hormone receptor-positive, advanced breast cancer or breast cancer that has spread to other parts of the body. Abemaciclib is also used alone to treat a certain type of hormone receptor-positive, advanced breast cancer or breast cancer that has spread to other parts of the body in people who have already been treated with an antiestrogen medication and chemotherapy. Abemaciclib is in a class of medications called kinase inhibitors. It works by blocking the action of an abnormal protein that signals cancer cells to multiply. This helps slow or stop the spread of cancer cells.

Abemaciclib comes as a tablet to take by mouth. It is usually taken twice daily with or without food. Take abemaciclib at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take abemaciclib exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the tablets whole; do not split, chew, or crush them. Do not take tablets that are broken, cracked, or damaged in any way.

If you vomit after taking abemaciclib, do not take another dose. Continue your regular dosing schedule.

Your doctor may decrease your dose or temporarily or permanently stop your treatment if you experience certain side effects. This depends on how well the medication works for you and the side effects you experience. Be sure to tell your doctor how you are feeling during your treatment with abemaciclib.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

Before taking abemaciclib,

• tell your doctor and pharmacist if you are allergic to abemaciclib, any other medications, or any of the ingredients in abemaciclib tablets. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• The following nonprescription or herbal products may interact with abemaciclib: St. John’s wort. Be sure to let your healthcare provider know that you are taking this medication before you start taking abemaciclib. Do not start this medication while taking abemaciclib without talking to your healthcare provider..
• tell your doctor if you have a fever, chills, or any other signs of an infection or if you have or have ever had blood clots, including a pulmonary embolism (PE; a blood clot in the lung); lung or breathing problem; or liver or kidney disease.
• tell your doctor if you are pregnant or plan to become pregnant. You will need to take a pregnancy test before you start treatment and should use birth control to prevent pregnancy during your treatment and for at least 3 weeks after your final dose. If you become pregnant while taking abemaciclib, call your doctor immediately. Abemaciclib may harm the fetus.
• tell your doctor if you are breastfeeding or plan to breastfeed. You should not breastfeed while taking abemaciclib and for at least 3 weeks after your final dose.
• you should know that this medication may decrease fertility in men. Talk to your doctor about the risks of taking abemaciclib.
• you should know that abemaciclib often causes diarrhea, which can be severe. Your doctor will probably tell you to drink plenty of liquids and to take anti-diarrhea medication to prevent dehydration (loss of too much water from your body) when you first experience diarrhea or loose stools. Call your doctor immediately if you experience any of the following symptoms of dehydration: extreme thirst, dry mouth or skin, decreased urination, or fast heartbeat.

Do not eat grapefruit or drink grapefruit juice while taking this medication.

Skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

Abemaciclib may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• nausea
• vomiting
• stomach pain
• constipation
• sores on the lips, mouth, or throat
• decreased appetite
• weight loss
• hair loss
• itching
• rash
• headache
• changes in taste
• dizziness
• joint pain

Some side effects can be serious. If you experience any of these symptoms or any in the SPECIAL PRECAUTIONS section, call your doctor immediately:

• tiredness
• pain in the upper right part of the stomach
• yellowing of the skin or eyes
• loss of appetite
• bleeding or bruising easily
• pain in arms or legs
• swelling of the hands, feet, legs or ankles
• difficulty breathing or shortness of breath
• cough with or without mucus
• chest pain
• rapid breathing
• fast, irregular, or pounding heartbeat
• fever, chills, cough or other signs of infection
• pale skin

Abemaciclib may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests before and during your treatment to check your body’s response to abemaciclib.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

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