Enhertu (fam-trastuzumab deruxtecan-nxki)

Reviewed by: HU Medical Review Board | Last reviewed: September 2023 | Last updated: September 2023

Enhertu® (fam-trastuzumab deruxtecan-nxki) is a targeted therapy used to treat adults who have non-small cell lung cancer (NSCLC) that:1

  • Has a certain mutation in the HER2 gene, and
  • Cannot be removed by surgery or has spread to other parts of the body (metastatic), and
  • Has been previously treated

NSCLC accounts for about 85 percent of all lung cancers. But only about 3 percent of these have activated HER2 mutations.2

What are the ingredients in Enhertu?

The active ingredients in Enhertu are fam-trastuzumab and deruxtecan-nxki.1

How does Enhertu work?

Enhertu is an antibody-drug conjugate (ADC). This means it has 2 main working parts. The first working part is a monoclonal anti-HER2 antibody called fam-trastuzumab. This part seeks out and binds to mutated HER2 on the surface of a cancer cell. The second part is a cancer cell-destroying agent called deruxtecan-nxki.1

Fam-trastuzumab and deruxtecan-nxki are connected by a linker molecule that breaks apart after the fam-trastuzumab binds to the mutated HER2. After the deruxtecan-nxki enters the cell, it damages the cell's DNA. This triggers a process called cellular death.1

After destroying a cancer cell, deruxtecan-nxki keeps working. Once the first cell is killed and its outer layer (membrane) breaks down, the deruxtecan-nxki moves to a nearby cell. The drug then enters that cell, damages its DNA, and again triggers its death. This is called the bystander effect.1

Because the the fam-trastuzumab antibody brings deruxtecan-nxki directly to specific cancer cells, this is called a targeted therapy. Targeted therapies are meant to affect as few healthy cells as possible.1

What are the possible side effects?

The most common side effects of Enhertu in NSCLC treatment include:1

  • Nausea, vomiting
  • Low red or white cell counts
  • Low platelet counts
  • Fatigue
  • Increased liver function tests
  • Hair loss
  • Constipation
  • Muscle or bone pain
  • Decreased appetite
  • Low levels of blood potassium
  • Diarrhea
  • Cough

Enhertu has a boxed warning, the strictest warning from the US Food and Drug Administration (FDA). It has this warning because:1

  • People who take Enhertu have a risk of developing severe lung problems including interstitial lung disease (ILD) and pneumonitis. ILD and pneumonitis can be life-threatening. Tell your doctor right away if you experience any of the following symptoms:1
    • Cough
    • Shortness of breath
    • Fever
    • Other breathing problems, like wheezing or chest tightness
  • 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.

These are not all the possible side effects of Enhertu. Talk to your doctor about what to expect when taking Enhertu. You also should call your doctor if you have any changes that concern you when taking Enhertu.

Other things to know

Before starting treatment with Enhertu, tell your doctor if you have:1

  • Lung or breathing problems
  • Signs or symptoms of an infection
  • Current or previous heart problems

Your doctor will check your white blood cell counts before starting treatment with Enhertu and before starting each dose.1

Your doctor will check your heart function before starting treatment with Enhertu.1

Before beginning treatment for lung 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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