Description and Brand Names

Drug information provided by: IBM Micromedex

US Brand Name

  1. Enhertu


Fam-trastuzumab deruxtecan-nxki injection is used to treat HER2-positive metastatic (cancer that has spread to other parts of the body) breast cancer or whose cancer cannot be removed with surgery in patients who have previously received two or more anti-HER2-based regimens in the metastatic setting.

Fam-trastuzumab deruxtecan-nxki injection is also used to treat HER-2 positive metastatic (cancer that has spread to other parts of the body) or locally advanced (cancer that has spread to areas near the stomach) stomach cancer called gastric or gastroesophageal junction (GEJ) adenocarcinoma in patients who have previously received trastuzumab-based regimen.

HER2 protein is produced by some tumors. Fam-trastuzumab deruxtecan-nxki interferes with the growth of this protein which also prevents tumor growth. The tumor cells will then be destroyed by the body.

This medicine is to be given only by or under the immediate supervision of your doctor.

This product is available in the following dosage forms:

  • Powder for Solution

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies have not been performed on the relationship of age to the effects of Enhertu® in the pediatric population. Safety and efficacy have not been established.


Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of Enhertu® in the elderly. However, elderly patients are more likely to have unwanted side effects which may require caution in patients receiving this medicine.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Congestive heart failure or
  • Heart disease, history of or
  • Interstitial lung disease or
  • Neutropenia (low number of white blood cells) or
  • Pneumonitis (lung disease) or—Use with caution. May make these conditions worse.

Proper Use

Medicines used to treat cancer are very strong and can have many side effects. Before receiving this medicine, make sure you understand all the risks and benefits. It is important for you to work closely with your doctor during your treatment.

A doctor or other trained health professional will give you this medicine in a medical facility. It is given through a needle placed into one of your veins. The medicine must be given slowly, so the needle will have to stay in place for at least 30 to 90 minutes. The injection is usually given once every 3 weeks.


It is very important that your doctor check your progress closely while receiving the medicine and at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to receive it. Blood tests may be needed to check for unwanted effects.

Receiving this medicine while you are pregnant can harm your unborn baby. It may also cause birth defects if the father is receiving it when his sexual partner becomes pregnant. If you are a woman who can get pregnant, your doctor may do tests to make sure you are not pregnant before starting treatment. Female patients should use effective birth control during treatment with this medicine and for 7 months after the last dose. Male patients who have female partners should use effective birth control during treatment with this medicine and for 4 months after the last dose. If you think you have become pregnant while receiving the medicine, tell your doctor right away.

Talk with your doctor before receiving this medicine if you plan to have children. Some men who receive this medicine have become infertile (unable to have children).

Tell your doctor right away if you are having chest pain or tightness, chills, cough, fever, general feeling or discomfort or illness, thickening of bronchial secretions, or trouble breathing while receiving this medicine. These could be symptoms of a serious lung problem (eg, interstitial lung disease or pneumonitis).

This medicine can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

  • If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
  • Check with your doctor immediately if you notice any unusual bleeding or bruising, black, tarry stools, blood in the urine or stools, or pinpoint red spots on your skin.
  • Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
  • Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
  • Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
  • Avoid contact sports or other situations where bruising or injury could occur.

This medicine may cause heart failure. Your doctor may test your heart before and during treatment. Contact your doctor right away if you have chest pain, increased coughing, trouble breathing, rapid weight gain, or swelling in your ankles or legs. These could be symptoms of heart failure.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur:

More common

  1. Black, tarry stools
  2. bloody nose
  3. chest pain or tightness
  4. chills
  5. cough
  6. decreased urine output
  7. difficult breathing
  8. dilated neck veins
  9. dry mouth
  10. fever
  11. general feeling of discomfort or illness
  12. increased thirst
  13. irregular breathing
  14. irregular heartbeat
  15. loss of appetite
  16. lower back or side pain
  17. mood changes
  18. muscle pain or cramps
  19. nausea or vomiting
  20. numbness or tingling in the hands, feet, or lips
  21. painful or difficult urination
  22. pale skin
  23. seizures
  24. sneezing
  25. sore throat
  26. swelling of the face, fingers, feet, or lower legs
  27. thickening of bronchial secretions
  28. trouble breathing
  29. ulcers, sores, or white spots in the mouth
  30. unusual bleeding or bruising
  31. unusual tiredness or weakness
  32. weight gain

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  1. Acid or sour stomach
  2. belching
  3. constipation
  4. decreased appetite
  5. diarrhea
  6. dizziness
  7. dry eyes
  8. hair loss or thinning of the hair
  9. headache
  10. heartburn
  11. indigestion
  12. rash
  13. stomach discomfort, upset, or pain
  14. swelling or inflammation of the mouth

Incidence not known

  1. Bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.