Abemaciclib belongs to a class of medications called kinase inhibitors. Abemaciclib 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 is used in combination with 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 can cause severe diarrhea, which can lead to dehydration or infection. Call your doctor right away if you have diarrhea. Drink extra fluids and start taking anti-diarrhea medicine such as loperamide (Imodium).

Abemaciclib can cause blood clots, liver problems, and even serious or fatal infections. Call your doctor right away if you have symptoms such as: fever, chills, easy bruising or bleeding, unusual tiredness, loss of appetite, right-sided upper stomach pain, chest pain, shortness of breath, rapid breathing, fast heartbeats, or pain or swelling in your arms or legs.

Take abemaciclib exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Take the medicine at the same time each day, with or without food.

Swallow the tablet whole and do not crush, chew, or break it. Do not use a cracked, broken or damaged tablet.

If you vomit shortly after taking abemaciclib, do not take another dose. Take your next dose as scheduled.

Call your doctor if you have diarrhea while taking abemaciclib. Start taking anti-diarrhea medicine such as loperamide (Imodium) to quickly treat diarrhea. Drink extra fluids and call your doctor.

Your blood will need to be tested often and your cancer treatments may be delayed based on the results.

Store at room temperature away from moisture and heat.

Usual Adult Dose of Abemaciclib for Breast Cancer:

IN COMBINATION WITH FULVESTRANT OR AN AROMATASE INHIBITOR:
150 mg orally 2 times a day

MONOTHERAPY:
200 mg orally 2 times a day

Duration of Therapy: Until disease progression or unacceptable toxicity

Comments:
-If using this drug in combination with fulvestrant on pre/perimenopausal women, treat these patients with a gonadotropin-releasing hormone agonist according to current clinical practice standards.
-When used in combination with this drug, the recommended dose of fulvestrant is 500 mg on Days 1, 15, and 29, then once monthly thereafter; refer to the manufacturer product information for fulvestrant.

Uses:
-In combination with an aromatase inhibitor as initial endocrine-based therapy for postmenopausal women with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer
-In combination with fulvestrant for women with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer with disease progression following endocrine therapy
-As monotherapy for adult patients with HR-positive, HER2-negative advanced or metastatic breast cancer with disease progression following endocrine therapy and prior chemotherapy in the metastatic setting

Tell your doctor and pharmacist if you are allergic to abemaciclib, any other medications, or any of the ingredients in abemaciclib tablets.

To make sure abemaciclib is safe for you, tell your doctor if you have ever had:

• a fever, chills, or other signs of infection;

• lung or breathing problems;

• blood clots; or

• liver or kidney disease.

Abemaciclib may harm an unborn baby. You may need a pregnancy test to make sure you are not pregnant. Use effective birth control while using abemaciclib and for at least 3 weeks after your last dose. Tell your doctor right away if you become pregnant.

It may be harder for you to get a woman pregnant while you are using abemaciclib.

You should not breastfeed while using this medicine and for at least 3 weeks after your last dose.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

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.

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

Grapefruit may interact with abemaciclib and cause side effects. Avoid consuming grapefruit products.

Get emergency medical help if you have signs of an allergic reaction to abemaciclib: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Abemaciclib may cause serious side effects. Call your doctor at once if you have:

• severe or ongoing diarrhea;

• signs of infection - fever, chills, sore throat, body aches, unusual tiredness, loss of appetite, bruising or bleeding;

• liver problems - loss of appetite, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

• low blood cell counts - fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath;

• signs of inflammation in the lungs - sudden chest pain, wheezing, dry cough or hack, feeling short of breath; or

• signs of a blood clot deep in the body or in the lung - chest pain, sudden cough or shortness of breath, dizziness, coughing up blood, or pain, swelling, or warmth in your arms or legs.

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Common abemaciclib side effects may include:

• diarrhea, nausea, vomiting, stomach pain;

• loss of appetite;

• hair loss;

• infections;

• feeling tired;

• headache; or

• low blood cell counts.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Sometimes it is not safe to use certain medicines at the same time. Some drugs can affect your blood levels of other drugs you use, which may increase side effects or make the medicines less effective.

Tell your doctor about all your other medicines, especially:

• ketoconazole.

This list is not complete. Other drugs may affect abemaciclib, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

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.