What Is Enhertu® (fam-trastuzumab deruxtecan-nxki)?

Reviewed by: HU Medical Review Board | Last reviewed: April 2022 | Last updated: October 2022

Enhertu® (fam-trastuzumab deruxtecan-nxki) is used to treat adults with human epidermal growth factor receptor-2 (HER2) positive breast cancer. It may be used to treat those with HER2+ breast cancer that:1,2

  • Cannot be removed by surgery or has spread to other parts of the body (metastatic), and
  • Has been previously treated with at least 2 other therapies that target HER2

What are the ingredients in Enhertu?

The active ingredient in Enhertu is fam-trastuzumab deruxtecan-nxki.1,2

How does Enhertu work?

The fam-trastuzumab portion of Enhertu is a monoclonal antibody. This means it is designed to seek out and attach to a very specific cell in the body. In this case, the target is HER-2 positive breast cancer cells.1,2

The other part of Enhertu is the deruxtecan-nxki. This drug is a type of chemotherapy called a topoisomerase inhibitor. The antibody and chemotherapy drugs work together. The antibody portion helps find and attach to HER2+ breast cancer cells. Once attached, the chemotherapy portion is released to attack the cancer cell.1,2

What are the possible side effects?

The most common side effects of Enhertu in breast cancer treatment include:1,2

  • Nausea
  • Fatigue
  • Hair loss
  • Vomiting
  • Low red blood cell and platelet levels
  • Diarrhea
  • Constipation
  • Decreased appetite
  • Cough
  • Low potassium levels
  • Changes in tests monitoring liver function/li>

Enhertu may also cause serious side effects, including:1,2

  • Low white blood cell counts (neutropenia), which can increase your risk of infections. Symptoms may include fever or chills.
  • Heart problems, with symptoms like cough, irregular heartbeat, sudden weight gains, and dizziness. If you develop any of these symptoms, let your doctor know right away.

Enhertu has a boxed warning, the strictest warning from the U.S. Food and Drug Administration (FDA). This is because it may cause severe, life-threatening lung problems. Tell your doctor right away if you have any of the following symptoms:1,2

  • Cough
  • Trouble breathing
  • Fever
  • Other new or worsening breathing symptoms, like chest tightness or wheezing

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

Other things to know

Your doctor will check your heart function before and during treatment with Enhertu.1,2

Before taking Enhertu, tell your doctor if you have:1,2

  • Lung or breathing problems
  • Signs or symptoms of an infection
  • Heart problems

Enhertu 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 Enhertu. You should also not breastfeed during treatment with Enhertu and for some time after the last dose. Talk to your doctor about your options for birth control and breastfeeding while taking Enhertu.1,2

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 Enhertu.

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