What Is Tukysa® (tucatinib)?

Reviewed by: HU Medical Review Board | Last reviewed: June 2023

Tukysa® (tucatinib) is a drug used to treat some types of breast cancer.

It is used together with trastuzumab and Xeloda® (capecitabine) to treat HER2 positive breast cancer that has been previously treated with at least 1 other therapy that targets HER2, and is either:1

  • Metastatic (breast cancer that has spread to other parts of the body like the liver, bones, or brain), or
  • Advanced and cannot be surgically removed, such as breast cancer that has spread to tissue near the breast but not to other parts of the body away from the breast

Breast cancer can be classified as HER2+ or HER2-. HER2 is a protein that helps cells grow. When found in high amounts in breast cancer cells, HER2 can contribute to increased cancer cell growth and potential spread. All breast cancers are generally tested for HER2 status.2

  • HER2+ tumors have a lot of HER2 protein
  • HER2- tumors have little or normal amounts of HER2 protein

What are the ingredients in Tukysa?

The active ingredient in Tukysa is tucatinib.1

How does Tukysa work?

Tukysa is a type of targeted therapy. Targeted therapy drugs work by interfering with specific areas of cancer cells involved in cell growth or by focusing on specific features unique to cancer cells. Targeted therapy drugs work differently than chemotherapy drugs, though some of the side effects may be similar. Targeted therapy drugs can get to almost anywhere in the body. This helps them treat cancers that have spread throughout the body. HER2-positive breast cancers usually grow and spread more aggressively, so researchers have developed drugs to target the HER2 protein. Targeted therapy drugs that target the HER2 protein work on HER2+ tumors but not HER2- tumors.2,3

HER2 is a kinase. Kinases are proteins that tell the cells to grow. Kinase inhibitors are drugs that block kinases. Tukysa is a kinase inhibitor, also called a tyrosine kinase inhibitor. By blocking the kinases involved in this communication pathway, the growth of HER2-positive breast cancer cells may be slowed or stopped.3

What are the possible side effects?

The most common side effects of Tukysa include:1

  • Nausea
  • Vomiting
  • Diarrhea
  • Liver problems
  • Mouth sores
  • Loss of appetite
  • Hand-foot syndrome (redness, pain, swelling on the palms of hands and/or soles of feet)
  • Rash
  • Anemia (low amounts of red blood cells)

Tykysa may also cause serious side effects, including:1

  • Diarrhea – If you have diarrhea, tell your doctor right away. Diarrhea can become severe, causing dehydration, low blood pressure, and serious kidney problems.
  • Liver problems – Tell your doctor if you have dark urine, yellowing skin or eyes, or if you bruise or bleed more frequently than usual.

These are not all the possible side effects of Tukysa. Talk to your doctor about what to expect or if you experience any changes that concern you during treatment with Tukysa.

Other things to know

Your doctor will monitor your liver function before and during treatment with Tukysa.1

Tukysa can harm an unborn baby. If you or your partner can become pregnant, you should use birth control during treatment and for some time after the last dose of Tukysa. You should also not breastfeed during treatment with Tukysa and for some time after the last dose. Talk to your doctor about your options for birth control and breastfeeding while taking Tukysa.1

Certain drugs interact with Tukysa. Before beginning treatment for breast cancer, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

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

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