What is ENHERTU?
ENHERTU is a prescription medicine used to treat adults who have:

• Human epidermal growth factor receptor 2 (HER2)-positive breast cancer that cannot be removed by surgery or that has spread to other parts of the body (metastatic), and who have received a prior anti-HER2 breast cancer treatment:  
  • for metastatic disease, or 
  • have breast cancer that has come back during or within 6 months of completing treatment for their early-stage breast cancer.  
• HER2-low breast cancer that cannot be removed by surgery or that has spread to other parts of the body (metastatic), and who have received a prior chemotherapy
  • for metastatic disease, or 
  • whose disease has returned during or within 6 months of completing adjuvant chemotherapy (after surgery). 

Your healthcare provider will perform a test to make sure ENHERTU is right for you.

• Hormone receptor (HR)-positive, HER2-low or HR-positive, HER2-ultralow, breast cancer that cannot be removed by surgery or that has spread to other parts of the body (metastatic), and who have received one or more endocrine treatments for metastatic disease. Your healthcare provider will perform a test to make sure ENHERTU is right for you.
• Non-small cell lung cancer (NSCLC) that has a certain mutation in the HER2 gene and cannot be removed by surgery or has spread to other parts of your body (metastatic), and who have received a prior treatment. Your healthcare provider will perform a test to make sure ENHERTU is right for you.
  • ENHERTU was FDA approved for this use based on a clinical study that measured how many patients responded and how long they responded. ENHERTU is still being studied
• Stomach cancer called gastric or GEJ adenocarcinoma that is HER2-positive and has spread to areas near your stomach (locally advanced) or that has spread to other parts of your body (metastatic), and who have received a prior trastuzumab-based regimen. 
• Solid tumors that are HER2-positive (IHC 3+) and that cannot be removed by surgery or have spread to other parts of your body (metastatic), and who have received a prior treatment and have no other satisfactory treatment options. Your healthcare provider will perform a test to make sure ENHERTU is right for you.
  • ENHERTU was FDA approved for this use based on clinical studies that measured how many patients responded and how long they responded. ENHERTU is still being studied to confirm these results. 

It is not known if ENHERTU is safe and effective in children.

Important Safety Information  
What is the most important information I should know about ENHERTU?
ENHERTU can cause serious side effects, including:

• Lung problems that may be severe, life-threatening or that may lead to death. If you develop lung problems your healthcare provider may treat you with corticosteroid medicines. Tell your healthcare provider right away if you get any of the following signs and symptoms:
  • Cough
  • Trouble breathing or shortness of breath
  • Fever
  • Other new or worsening breathing symptoms (such as chest tightness, wheezing)
• Low white blood cell count (neutropenia). Low white blood cell counts are common with ENHERTU and can sometimes be severe. Your healthcare provider will check your white blood cell counts before starting ENHERTU and before starting each dose. Tell your healthcare provider right away if you develop any signs or symptoms of an infection or have fever or chills during treatment with ENHERTU.
• Heart problems that may affect your heart's ability to pump blood. Your healthcare provider will check your heart function before starting treatment with ENHERTU. Tell your healthcare provider right away if you get any of the following signs and symptoms:
  • New or worsening shortness of breath
  • Coughing
  • Feeling tired
  • Swelling of your ankles or legs
  • Irregular heartbeat
  • Sudden weight gain
  • Dizziness or feeling light-headed
  • Loss of consciousness

Your healthcare provider will check you for these side effects during your treatment with ENHERTU. Your healthcare provider may reduce your dose, delay treatment or completely stop treatment with ENHERTU if you have severe side effects.

• Harm to your unborn baby. Tell your healthcare provider right away if you become pregnant or think you might be pregnant during treatment with ENHERTU.
  • If you are able to become pregnant, your healthcare provider should do a pregnancy test before you start treatment with ENHERTU.
  • Females who are able to become pregnant should use effective birth control (contraception) during treatment with ENHERTU and for 7 months after the last dose.
  • Males who have female partners that are able to become pregnant should use effective birth control (contraception) during treatment with ENHERTU and for 4 months after the last dose.

Before you receive ENHERTU, tell your healthcare provider about all of your medical conditions, including if you:

• Have lung or breathing problems.
• Have signs or symptoms of an infection.
• Have or have had any heart problems.
• Are breastfeeding or plan to breastfeed. It is not known if ENHERTU passes into your breast milk. Do not breastfeed during treatment with ENHERTU and for 7 months after the last dose.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

How will I receive ENHERTU?

• You will receive ENHERTU into your vein through an intravenous (IV) line by your healthcare provider.
• ENHERTU is given 1 time every three weeks (21-day treatment cycle).
• Your healthcare provider will decide how many treatments you need.
• Your healthcare provider will give you medicines before your infusion to help prevent nausea and vomiting.
• Your healthcare provider may slow down or temporarily stop your infusion of ENHERTU if you have an infusion-related reaction, or permanently stop ENHERTU if you have severe infusion reactions.
• If you miss a planned dose of ENHERTU, call your healthcare provider right away to schedule an appointment. Do not wait until the next planned treatment cycle.

What are the possible side effects of ENHERTU?

ENHERTU can cause serious side effects. See "What is the most important information I should know about ENHERTU?"

The most common side effects of ENHERTU, when used in people with metastatic breast cancer, HER2-mutant non-small cell lung cancer, and other HER2-positive solid tumors, include: 

• Low white blood cell counts
• Nausea
• Low red blood cell counts
• Feeling tired
• Low platelet counts
• Increased liver function tests
• Vomiting
• Hair loss
• Constipation
• Low levels of blood potassium
• Decreased appetite
• Diarrhea
• Muscle or bone pain

The most common side effects of ENHERTU, when used in people with HER2-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma, include: 

• Low red blood cell counts 
• Low white blood cell counts 
• Low platelet counts 
• Nausea
• Decreased appetite
• Increased liver function tests 
• Feeling tired 
• Diarrhea
• Low levels of blood potassium
• Vomiting 
• Constipation
• Fever
• Hair loss 

ENHERTU may cause fertility problems in males, which may affect the ability to father children. Talk to your healthcare provider if you have concerns about fertility.

These are not all of the possible side effects of ENHERTU. Call your doctor for medical advice about side effects. You may report side effects to Daiichi Sankyo at 1-877-437-7763 or to FDA at 1-800-FDA-1088.

Please see full Prescribing Information, including Boxed WARNINGS, and Medication Guide.

--Brand Name--
US Brand Name: Enhertu

--Description--
Fam-trastuzumab deruxtecan-nxki injection is used to treat HER2-positive (IHC 3+ or ISH 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 previously received an anti-HER2 breast cancer treatment for metastatic disease or have breast cancer that has come back during or within 6 months of completing 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 previously received treatment for metastatic disease or have breast cancer that has come back during or within 6 months of completing treatment (after surgery). This medicine is also used to treat HR-positive, HER2-low or HR-positive, HER2-ultralow breast cancer that has spread to other parts of the body cannot be removed with surgery in patients who have received one or more endocrine treatments.

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 previously received treatment.

Fam-trastuzumab deruxtecan-nxki injection is also used to treat HER2-positive (IHC 3+ or IHC 2+/ ISH 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.

Fam-trastuzumab deruxtecan-nxki injection is also used to treat HER2-positive (IHC 3+) metastatic (cancer that has spread to other parts of the body) or unresectable (cancer that cannot be removed with surgery) solid tumors in patients who have previously received treatment that did not work well.

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.

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:

Allergies
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.

Pediatric
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.

Geriatric
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.

Breastfeeding
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. When you are receiving this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

• Bacillus of Calmette and Guerin Vaccine, Live
• Dengue Tetravalent Vaccine, Live
• Measles Virus Vaccine, Live
• Mumps Virus Vaccine, Live
• Rubella Virus Vaccine, Live
• Smallpox Monkeypox Vaccine
• Typhoid Vaccine
• Varicella Virus Vaccine, Live
• Yellow Fever Vaccine

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Adenovirus Vaccine Type 4, Live
• Adenovirus Vaccine Type 7, Live
• Cholera Vaccine
• Ebola Zaire Vaccine, Live
• Influenza Virus Vaccine, Live
• Rotavirus Vaccine, Live

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 an IV catheter that is placed into one of your veins. The medicine must be given slowly, so the IV 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.

--Precautions--
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 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 male patients 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 have 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

• Black, tarry stools
• bloody nose
• bone or muscle pain
• burning, numbness, tingling, or painful sensations
• chest pain or tightness
• chills
• cough
• decreased urine output
• diarrhea
• difficult breathing
• dilated neck veins
• dry mouth
• fever
• general feeling of discomfort or illness
• headache
• increased thirst
• irregular breathing
• irregular heartbeat
• loss of appetite
• lower back or side pain
• mood changes
• muscle cramps
• nausea or vomiting
• new loss of taste or smell
• numbness or tingling in the hands, feet, or lips
• painful or difficult urination
• pale skin
• seizures
• sneezing
• sore throat
• stuffy or runny nose
• 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

Less common

• Difficulty swallowing
• dizziness
• fast heartbeat
• flushing
• hives, itching, skin rash
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue

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

• Acid or sour stomach
• belching
• constipation
• decreased appetite
• dry eyes
• hair loss or thinning of the hair
• headache
• heartburn
• indigestion
• 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
• 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, 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.