Fam-trastuzumab deruxtecan-nxki (Intravenous)

Fam-trastuzumab deruxtecan-nxki injection is used to treat HER2-positive metastatic (cancer that has spread to other parts of the body) or unresectable (cancer that cannot be removed with surgery) breast cancer in patients who have already received an anti-HER2 breast cancer treatment for metastatic disease or have breast cancer that has returned during or within 6 months of finishing treatment for early-stage breast cancer.

Fam-trastuzumab deruxtecan-nxki injection is also used to treat HER2-low metastatic (cancer that has spread to other parts of the body) or unresectable (cancer that cannot be removed with surgery) breast cancer in patients who have already received treatment for metastatic disease or have breast cancer that has returned during or within 6 months of finishing treatment (after surgery).

Fam-trastuzumab deruxtecan-nxki injection is also used to treat metastatic (cancer that has spread to other parts of the body) or unresectable (cancer that cannot be removed with surgery) non-small cell lung cancer (NSCLC) in patients whose cancer has an abnormal HER2 gene and who have already received treatment.

Fam-trastuzumab deruxtecan-nxki injection is also used to treat HER2-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 already received a trastuzumab-based regimen.

Your doctor will test for the presence of the HER2 gene. 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.

It is very important that your doctor checks your progress closely while you are receiving this medicine and during regular visits. This will help your doctor see if the medicine is working properly and decide if you should keep receiving 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, a general feeling of discomfort or illness, thickening of bronchial secretions, or trouble breathing while receiving this medicine. These could be symptoms of a serious lung problem (e.g., 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.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the benefits. This is a decision you and your doctor will make together. For this medicine, consider the following:

Allergies

Inform your doctor if you have ever had any unusual or allergic reactions to this medicine or any other medicines. Also, let your healthcare professional know about any other allergies you have, such as to foods, dyes, preservatives, or animals. For non-prescription products, carefully read the label or package ingredients.

Pediatric

There have not been appropriate studies on how Enhertu® affects children. Safety and effectiveness have not been established for the pediatric population.

Geriatric

Studies conducted so far have not shown any specific problems in older adults that would limit the use of Enhertu®. However, older patients are more likely to experience unwanted side effects, which may require caution when using this medicine.

Breast Feeding

There are no adequate studies in women to determine the risk to infants when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before using this medication while breastfeeding.

Interactions with Medicines

Some medicines should never be used together, while in other cases, two different medicines may be used together even if an interaction could occur. In such situations, your doctor may adjust the dose or take other precautions. Inform your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicines.

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be taken around mealtime or with specific types of food due to potential interactions. Using alcohol or tobacco with certain medicines may also lead to interactions. Discuss with your healthcare professional about using your medicine with food, alcohol, or tobacco.

Other Medical Problems

Having other medical problems may impact the use of this medicine. Make sure to inform your doctor if you have any other medical issues, 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 worsen these conditions.

Along with its necessary effects, this medicine may cause some unwanted effects. Not all of these side effects may happen, but if they do, they may require medical attention.

Contact your doctor or nurse right away if any of the following side effects occur:

More common

• Black, tarry stools
• Bloody nose
• Bone or muscle pain
• Burning, numbness, tingling, or painful sensations
• Chest pain or tightness
• Chills
• Cough
• Decreased urine output
• Difficulty breathing
• Dilated neck veins
• Dry mouth
• Fever
• General feeling of discomfort or illness
• Increased thirst
• Irregular breathing
• Irregular heartbeat
• Loss of appetite
• Lower back or side pain
• Mood changes
• Muscle cramps
• Nausea or vomiting
• Numbness or tingling in the hands, feet, or lips
• Painful or difficult urination
• Pale skin
• Seizures
• Sneezing
• Sore throat
• Swelling of the face, fingers, feet, or lower legs
• Thickening of bronchial secretions
• Trouble breathing
• Ulcers, sores, or white spots in the mouth
• Unsteadiness or awkwardness
• Unusual bleeding or bruising
• Unusual tiredness or weakness
• Weakness in the arms, hands, legs, or feet
• Weight gain

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

More common

• Acid or sour stomach
• Belching
• Constipation
• Decreased appetite
• Diarrhea
• Dizziness
• Dry eyes
• Hair loss or thinning of the hair
• Headache
• Heartburn
• Indigestion
• Rash
• Stomach discomfort, upset, or pain
• Swelling or inflammation of the mouth

Less common

• Bloated
• Change in taste
• Darkening of the skin
• Excess air or gas in the stomach or intestines
• Full feeling
• Loss of taste
• Passing gas

Incidence not known

• 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, consult 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.

In the U.S.

• Enhertu

Available Dosage Forms:

• Powder for Solution

Therapeutic Class: Antineoplastic Agent

Pharmacologic Class: Antibody Drug Conjugate

Find detailed information on biosimilars for this medication.

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.

You may also receive other medicines to help prevent nausea and vomiting.

• How well does Enhertu work in metastatic breast cancer?
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