Fam-trastuzumab deruxtecan is not a pill or capsule. It must be given by a nurse or doctor at a hospital or cancer treatment center.

Steps for Use:

• The patient is seated comfortably.
  
  
• An IV line is inserted into a vein in the arm.
  
  
• The medicine is given slowly through the drip.
  
  
• The first dose is given slowly to monitor for allergic reactions.
  
  
• After the infusion, patients may be observed for 30 minutes or more to check for side effects.
  
  

Do not eat or drink anything unusual before the treatment unless told by your doctor. Follow all instructions given before each treatment visit.

Fam-trastuzumab deruxtecan works like a targeted missile against cancer cells. First, the trastuzumab part of the medicine finds and attaches to HER2 proteins on cancer cells. HER2 is like a signal that tells the cancer to grow. By attaching to it, trastuzumab blocks this signal, which helps to slow or stop the growth of the cancer.

Once the medicine has found the cancer cell, it delivers the deruxtecan part, which is a strong chemotherapy drug. This part goes inside the cancer cell and destroys it from within. Since the medicine targets only HER2-positive cells, it reduces damage to healthy cells in the body. This makes the treatment more effective and slightly less harsh than general chemotherapy.

Fam-trastuzumab deruxtecan is known as an antibody-drug conjugate (ADC). This means it uses a special technology that combines the accuracy of targeted therapy with the power of chemotherapy. The combination increases the chances of killing cancer cells and reduces the risk of cancer coming back.

Like most cancer treatments, Fam-trastuzumab deruxtecan can cause side effects. Some are mild and go away with time, while others may need medical attention.

Common Side Effects

• Nausea or vomiting
  
  
• Hair thinning or hair loss
  
  
• Tiredness or weakness
  
  
• Diarrhea
  
  
• Low white blood cell count
  
  
• Loss of appetite
  
  
• Mouth sores
  
  

Serious Side Effects

• Lung problems (Interstitial Lung Disease): Symptoms may include coughing, shortness of breath, or chest pain. This needs immediate medical care.
  
  
• Heart problems: Trastuzumab can sometimes affect the heart. Patients may experience chest pain, swelling, or shortness of breath.
  
  
• Low blood cell counts: Can lead to infections or bleeding. Doctors monitor blood levels regularly.
  
  
• Allergic reactions: Rare but serious. May include swelling, rash, or difficulty breathing during or after infusion.
  
  

Patients should report any unusual symptoms to their healthcare team immediately.

Before starting Fam-trastuzumab deruxtecan, inform your doctor about any health conditions or allergies. This medicine may not be suitable for everyone.

Medical Conditions to Watch

• Lung disease
  
  
• Heart problems
  
  
• Liver issues
  
  
• Weak immune system
  
  
• Recent infections
  
  

Pregnancy and Breastfeeding
Fam-trastuzumab deruxtecan can harm an unborn baby. Women must use effective birth control during treatment and for at least 7 months after the last dose. Men should also use protection for at least 4 months after treatment. Do not breastfeed during treatment or for 7 months after the last dose.

Regular Monitoring
During treatment, you’ll need regular:

• Blood tests
  
  
• Heart checks
  
  
• Chest scans (to monitor lungs)
  
  

Avoid alcohol and smoking, as they may increase side effects or reduce the effectiveness of the medicine.

 While taking Fam-trastuzumab deruxtecan, it’s important to avoid medicines that can weaken the immune system unless prescribed. Also, combining it with other chemotherapy drugs or radiation must be done carefully.

Always inform your doctor about any other medications you’re taking, including:

• Antibiotics
  
  
• Painkillers
  
  
• Antidepressants
  
  
• Herbal supplements
  
  

Some drugs may affect how Fam-trastuzumab deruxtecan works or increase side effects. Never start or stop medicines without talking to your doctor first.

The starting dose is usually 5.4 mg/kg of body weight every 3 weeks. However, your doctor may adjust this based on how your body responds and any side effects.

Adjustments May Be Needed If:

• You develop lung symptoms
  
  
• Your white blood cells drop too low
  
  
• You experience severe nausea or vomiting
  
  
• Your liver tests become abnormal
  
  

Missed Doses
If you miss a scheduled treatment, contact your clinic as soon as possible. Do not try to make up for it yourself.

Do not increase or skip doses without medical guidance.

• You will need blood tests and imaging scans.
  
  
• The doctor will confirm HER2 status using a biopsy or lab test.
  
  
• Your medical history will be reviewed, especially any lung, heart, or liver conditions.
  
  

During Treatment:

• Keep all appointments.
  
  
• Get regular lab tests.
  
  
• Report side effects quickly.
  
  

This medicine must be stored and handled by professionals. Never try to use or store it at home. Always follow your doctor’s advice carefully.

• What is Fam-trastuzumab deruxtecan used for?
  It is prescribed to treat certain HER2-positive cancers, including:

  • HER2-positive metastatic breast cancer

  • HER2-low metastatic breast cancer

  • HER2-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma

  • Other HER2-expressing solid tumors (in specific cases)

• What is the brand name?
  Enhertu®.

• What type of drug is it?
  It is an antibody-drug conjugate (ADC), combining a HER2-targeting antibody with a chemotherapy payload.

• How does it work?

  • The trastuzumab part binds to HER2 receptors on cancer cells.

  • The deruxtecan (chemotherapy agent) is released inside the cell, killing it.

  • It can also kill neighboring cancer cells via a “bystander effect”.

• How is it given?
  Administered by intravenous (IV) infusion every 3 weeks in a clinic or hospital.

• Who is eligible for treatment?
  Patients with confirmed HER2-positive or HER2-low cancers who have already received other treatments.

• What are the common side effects?
  Nausea, vomiting, fatigue, decreased appetite, constipation, hair loss, low blood counts, and cough.

• Are there serious side effects?
  Yes, including:

  • Interstitial lung disease (ILD)/pneumonitis (can be life-threatening)

  • Severe low white blood cells (neutropenia)

  • Heart problems (like other trastuzumab products)

  • Severe infusion reactions

• Why is lung monitoring important with Enhertu?
  Because interstitial lung disease (ILD) is a serious risk—patients need to report new cough, shortness of breath, or fever immediately.

• Do patients need heart monitoring?
  Yes, like other HER2 therapies, it may affect left ventricular ejection fraction (LVEF), requiring regular heart tests.

• Is Fam-trastuzumab deruxtecan chemotherapy or targeted therapy?
  It is a targeted therapy linked with chemotherapy—an antibody-drug conjugate.

• Is it used alone or with other drugs?
  Typically used as a single-agent infusion, not combined with traditional chemo in most cases.

• Can men receive this treatment?
  Yes, if they have HER2-positive cancers (such as gastric or breast cancer in men).

• Is it safe during pregnancy?
  No—can cause serious harm to an unborn baby. Effective birth control is required.

• Can I use it while breastfeeding?
  Not recommended, as it may harm a nursing infant.

• Does it interact with other medications?
  Some drug interactions are possible—patients should always provide a full medication list.

• How effective is Enhertu?
  Clinical trials have shown significant improvements in progression-free survival and overall survival in HER2-positive and HER2-low breast cancer.

• How long will treatment continue?
  Treatment is usually continued until disease progression or unacceptable side effects.

• Where can patients get this treatment?
  At oncology infusion centers, hospitals, or specialty cancer clinics.