Trastuzumab deruxtecan
Say it: tras-TOO-zoo-mab deh-RUX-teh-kan · Brand names: Enhertu
Trastuzumab deruxtecan is a targeted medicine that delivers a strong cancer drug straight to cancer cells that have a protein called HER2.
What it is
It is made of two parts joined together: an antibody that finds a protein called HER2 on cancer cells, and a strong cancer medicine. The antibody carries the medicine straight to the cancer cell, so more of it reaches the cancer and less reaches healthy cells. It can work even when cancer cells have only small amounts of HER2.
Often used for
- breast cancer with high, low, or very low HER2
- lung cancer with a change in the HER2 gene
- stomach cancer with HER2
- some other solid tumors with high HER2
How you get it
You get it as an infusion into a vein at a clinic. The first infusion takes about 90 minutes, and later ones take about 30 minutes if you do well. Most people get it once every 3 weeks. Your schedule may be different.
Common side effects and what helps
- Nausea and vomiting. Take your anti-nausea medicine just as your team tells you, even before you feel sick.
- Feeling tired. Rest when you need to and try short walks.
- Hair thinning or hair loss. A soft hat or scarf can help you stay comfortable.
- Constipation. Drink fluids and ask your team about a stool softener.
- Lower appetite. Try small meals and snacks more often.
- Low blood counts, which can raise your risk of infection. Wash your hands often.
- Diarrhea. Drink plenty of fluids and tell your team if it lasts.
Call your care team right away if you have
- New or worse cough, shortness of breath, or chest pain
- A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher
- Chills, sore throat, or other signs of infection
- Vomiting or diarrhea that keeps you from drinking fluids
- Swelling in your legs, a racing heartbeat, or trouble breathing when lying down
- Feeling very dizzy or faint
Before you start, tell your team
- If you have ever had lung problems, such as scarring or swelling of the lungs
- If you have heart problems
- If you are pregnant, may become pregnant, or are breastfeeding
- All the medicines, vitamins, and herbal products you take
Good to know
- This medicine can cause a serious lung problem called pneumonitis (swelling and scarring in the lungs). It can be life threatening. Tell your team about any new breathing problems right away.
- You will have blood tests to check your blood counts before each dose.
- You will have heart tests before and during treatment to check how well your heart pumps.
- This medicine can harm an unborn baby. Ask your team about birth control during treatment and for months after it ends.
Questions to ask
- What should I do if I start to cough or feel short of breath?
- Which anti-nausea medicines should I take at home, and when?
- How will you check my lungs and heart during treatment?
- How long will I be on this medicine?
Side effect guides
- Fatigue (tiredness)
- Nausea and vomiting
- Diarrhea
- Constipation
- Appetite loss and weight loss
- Hair loss
- Low white blood cells and infection risk
Sources
Quick answers
- What is Trastuzumab deruxtecan?
- Trastuzumab deruxtecan is a targeted medicine that delivers a strong cancer drug straight to cancer cells that have a protein called HER2. Brand names: Enhertu.
- What is Trastuzumab deruxtecan used for?
- breast cancer with high, low, or very low HER2; lung cancer with a change in the HER2 gene; stomach cancer with HER2; some other solid tumors with high HER2.
- How is Trastuzumab deruxtecan given?
- You get it as an infusion into a vein at a clinic. The first infusion takes about 90 minutes, and later ones take about 30 minutes if you do well. Most people get it once every 3 weeks. Your schedule may be different.
- What are the common side effects of Trastuzumab deruxtecan?
- Nausea and vomiting. Feeling tired. Hair thinning or hair loss. Constipation. Lower appetite. Low blood counts, which can raise your risk of infection. Diarrhea.
- When should I call my care team while taking Trastuzumab deruxtecan?
- New or worse cough, shortness of breath, or chest pain; A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher; Chills, sore throat, or other signs of infection; Vomiting or diarrhea that keeps you from drinking fluids; Swelling in your legs, a racing heartbeat, or trouble breathing when lying down; Feeling very dizzy or faint.
Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.