Care During Chemotherapy and Beyond


(too KA tinib)

Trade Name(s): Tukysa®

Tucatinib is the generic name for the trade name drug Tukysa®. In some cases, health care professionals may use trade name or the generic name when referring to the drug.

Drug Type: Tucatinib is a targeted therapy. Tucatinib is classified as a tyrosine kinase inhibitor (for more detail, see "How this drug works" below).

What Tucatinib Is Used For

  • Treatment of patients with advanced breast cancer that is human epidermal growth factor receptor 2 (HER2)-positive and cannot receive surgery or has spread to other parts of the body.

Note: If a drug has been approved for one use, physicians may elect to use this same drug for other problems if they believe it may be helpful.

How Tucatinib Is Given

  • Tucatinib is a tablet to be taken by mouth. The usual dose is 300 mg to be taken by mouth twice daily.
  • Your doctor may reduce this dose. It is important to take tucatinib exactly as instructed by your doctor.
  • Tablets come in two different dosage strengths, 50 mg or 150 mg.
  • Tucatinib should be taken as close to every 12 hours as possible, with or without food.
  • Tucatinib tablets should be swallowed whole. Do not chew, crush, or split tablets.
  • If you are taking tucatinib with capecitabine, you may take tucatinib at the same time as capecitabine on those days capecitabine is also scheduled.
  • If you miss a dose of tucatinib, take it as soon as you remember that day. If you miss a day, do not double your dose the next day. In this case, skip your dose and go back to your normal schedule. Call your healthcare provider if you are not sure what to do.
  • Store tucatinib tablets at room temperature between 68ºF to 77ºF.
  • Tucatinib should be given to you in its original container only. Keep the medication in this container closed tightly and do not throw away desiccant packet that is given with it.
  • Once the medication bottle is open, use tucatinib within 3 months. Throw away any medications remaining after this time if unused.
  • Keep out of the reach of children.

The amount of tucatinib that you will receive depends on many factors, including your your general health or other health problems, and the type of cancer or condition you have. Your doctor will determine your exact dosage and schedule.

Side Effects

Important things to remember about the side effects of tucatinib:

  • Most people will not experience all of the tucatinib side effects listed.
  • Tucatinib side effects are often predictable in terms of their onset, duration, and severity.
  • Most tucatinib side effects will improve after therapy is complete.
  • There are many options to minimize or prevent the side effects of tucatinib.
  • There is no relationship between the presence or severity of side effects and the effectiveness of tucatinib.

The following side effects are common (occurring in greater than 30%) for patients taking tucatinib:

These are less common side effects (occurring in 10-29%) for patients receiving tucatinib:

These are rare serious side effects for patients receiving tucatinib:

Not all side effects are listed above. Side effects that are very rare -- occurring in less than about 10 percent of patients -- may not be listed here. But you should always inform your health care provider if you experience any unusual symptoms.

When to Contact Your Doctor or Health Care Provider

Contact your health care provider immediately, day or night, if you should experience any of the following symptoms:

  • Fever of 100.4º F (38º C) or higher, chills (possible signs of infection)
  • Shortness of breath, wheezing, difficulty breathing, closing up of the throat, swelling of facial features, hives (possible allergic reaction).

The following symptoms require medical attention, but are not an emergency. Contact your health care provider within 24 hours of noticing any of the following:

  • Nausea (interferes with ability to eat and unrelieved with prescribed medication)
  • Vomiting (vomiting more than 4-5 times in a 24 hour period)
  • Diarrhea (4-6 episodes in a 24-hour period)
  • Unusual bleeding or bruising
  • Black or tarry stools, or blood in your stools
  • Blood in the urine
  • Pain or burning with urination
  • Extreme fatigue (unable to carry on self-care activities)
  • Mouth sores (painful redness, swelling or ulcers)
  • Rash, hives, or blistered and peeling skin
  • Redness or irritation of the palms of hands or soles of feet
  • Burning or numbness feeling
  • Liver problems like dark urine, fatigue, lack of appetite, nausea, abdominal pain, light-colored stools, vomiting, or yellow skin or eyes
  • Electrolyte problems like mood changes, confusion, muscle pain or weakness, abnormal heartbeat, seizures, lack of appetite, or severe nausea or vomiting
  • Unable to eat or drink for 24 hours or have signs of dehydration: tiredness, thirst, dry mouth, dark and decrease amount of urine, or dizziness

Always inform your health care provider if you experience any unusual symptoms.


  • Before starting tucatinib treatment, make sure you tell your doctor about any other medications you are taking (including prescription, over-the-counter, vitamins, herbal remedies, etc.). Do not take aspirin or products containing aspirin unless your doctor specifically permits this.
  • Tucatinib interacts with many common medications. Be sure to notify your doctor before starting any new medications.
  • Inform your health care professional if you are pregnant or may be pregnant prior to starting this treatment. This drug must not be given to a pregnant woman or a woman who intends to become pregnant. If you become pregnant while taking tucatinib, stop taking the medication immediately and call your doctor for further instructions.
  • For both men and women: Use contraceptives, and do not conceive a child (get pregnant) while taking tucatinib. Barrier methods of contraception, such as condoms, are recommended. Use effective contraception during treatment and for at least 1 week after the last dose.
  • Do not breast feed while taking tucatinib and for at least 1 week after the last dose.

Self-Care Tips

  • Drink at least two to three quarts of fluid every 24 hours, unless you are instructed otherwise.
  • Follow regimen of anti-diarrheal medication as prescribed by your health care professional.
  • Eat foods that may help reduce diarrhea (for more information see - managing side effects - diarrhea).
  • Prevention of hand-foot syndrome: modification of normal activities of daily living to reduce friction and heat exposure to hands and feet, as much as possible during treatment with tucatinib (for more information see - managing side effects: hand foot syndrome).
  • You may be at risk of infection so try to avoid crowds or people with colds, and report fever or any other signs of infection immediately to your health care provider.
  • Wash your hands often.
  • To help treat/prevent mouth sores, use a soft toothbrush, and rinse three times a day with 1 teaspoon of baking soda mixed with 8 ounces of water.
  • Use an electric razor and a soft toothbrush to minimize bleeding.
  • Avoid contact sports or activities that could cause injury.
  • To reduce nausea, take anti-nausea medications as prescribed by your doctor, and eat small, frequent meals.
  • Avoid sun exposure. Wear SPF 30 (or higher) sunblock and protective clothing.
  • In general, drinking alcoholic beverages should be kept to a minimum or avoided completely. You should discuss this with your doctor.
  • Get plenty of rest.
  • Maintain good nutrition.
  • Remain active as you are able. Gentle exercise is encouraged such as a daily walk.
  • If you experience symptoms or side effects, be sure to discuss them with your health care team. They can prescribe medications and/or offer other suggestions that are effective in managing such problems.

Monitoring and Testing While Taking Tucatinib

You will be checked regularly by your doctor while you are taking tucatinib, to monitor side effects and check your response to therapy. Periodic blood work will be obtained to monitor your complete blood count (CBC) as well as the function of other organs (such as your kidneys and liver) will also be ordered by your doctor.

How Tucatinib Works

Cancer is a disease caused by changes, also known as mutations, in DNA that change the way cells grow and divide. Cancer cells can be destroyed using many different types of medications that work in very different ways. Examples of medications that destroy cancer cells include cytotoxic chemotherapy, targeted therapy, immunotherapy, and antibody-drug conjugates.

Targeted therapy is about identifying other features of cancer cells. Scientists look for specific differences in the cancer cells and the normal cells. This information is used to create a targeted therapy to attack the cancer cells without damaging the normal cells, thus leading to fewer side effects. Each type of targeted therapy works a little bit differently but all interfere with the ability of the cancer cell to grow, divide, repair and/or communicate with other cells.

There are different types of targeted therapies, defined in three broad categories. Some targeted therapies focus on the internal components and function of the cancer cell. These targeted therapies use small molecules that can get into the cell and disrupt the function of the cells, causing them to die. There are several types of targeted therapy that focus on the inner parts of the cells. Other targeted therapies target receptors that are on the outside of the cell. Antiangiogenesis inhibitors target the blood vessels that supply oxygen to the cells, ultimately causing the cells to starve.

Tucatinib belongs to the signal transduction inhibitor category of targeted therapies. It particularly interferes with the protein-tyrosine kinases; Epidermal Growth Factor Receptor (EGFR [ErbB1]) and of Human Epidermal Receptor type 2 (HER2 [ErbB2]).

Note: We strongly encourage you to talk with your health care professional about your specific medical condition and treatments. The information contained in this website is meant to be helpful and educational, but is not a substitute for medical advice. is designed to provide the latest information about chemotherapy to patients and their families, caregivers and friends. For information about the 4th Angel Mentoring Program visit