Enhertu 100mg Injection is used for certain cancers in which HER2 (human epidermal growth factor receptor 2) is overexpressed or has specific activating mutations.

It may be used for:

• HER2-positive breast cancer: Certain early, unresectable or metastatic breast cancers depending on the treatment setting and previous therapy.

• HER2-low or HER2-ultralow breast cancer: Certain unresectable or metastatic breast cancers in eligible patients.

• HER2-mutant non-small cell lung cancer: Certain unresectable or metastatic cases with activating HER2 mutations after previous systemic treatment.

• HER2-positive gastric or gastroesophageal junction cancer: Locally advanced or metastatic disease after previous trastuzumab-based treatment.

• Certain HER2-positive solid tumours: Unresectable or metastatic HER2-positive solid tumours in patients who have received previous systemic treatment and have no satisfactory alternative treatment options.

The exact indication depends on the cancer type, HER2 test results, previous treatment and the approved product label.

Enhertu contains Trastuzumab Deruxtecan, which has two main components. The trastuzumab portion recognises and attaches to the HER2 protein on cancer cells.

After binding to HER2, the medicine is taken into the cancer cell. The deruxtecan component is then released and inhibits topoisomerase I, an enzyme needed for DNA replication. This causes DNA damage and can lead to the death of the cancer cell.

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

• Other anticancer medicines: Enhertu may be used with specific anticancer medicines in some treatment regimens. Do not add or stop anticancer treatment without your oncologist's advice.

• Medicines that affect the bone marrow: Other treatments that lower blood cell counts may increase the risk of neutropenia, anaemia or thrombocytopenia and may require closer monitoring.

• Medicines that affect the lungs: Tell your doctor about medicines or treatments that may affect lung function, particularly if you have a history of lung disease.

• Other medicines: Your oncology team should review all medicines before treatment because Enhertu can cause serious adverse effects that may require treatment interruption or dose adjustment.

• Store Enhertu 100mg Injection in a refrigerator at 2°C to 8°C.

• Keep the vial in the original carton to protect it from light until reconstitution.

• Do not freeze.

• Do not shake the reconstituted or diluted solution.

• The medicine is a hazardous drug and should be handled and disposed of according to appropriate procedures.

• Reconstituted or diluted solution should be handled within the time limits specified in the product information.

Enhertu 100mg Injection is given only by intravenous infusion under the supervision of a qualified healthcare professional.

The 100mg vial is not the patient's individual dose. The required dose is calculated according to body weight and cancer type, then the vial is reconstituted and diluted before administration.

Do not inject Enhertu directly into a vein as a bolus or intravenous push. The first infusion is generally given over 90 minutes. If it is well tolerated, subsequent infusions may be given over 30 minutes according to the prescribed regimen.

Common side effects may include:

• Nausea

• Fatigue

• Vomiting

• Decreased appetite

• Constipation

• Diarrhoea

• Hair loss

• Reduced white blood cell count

• Reduced neutrophil count

• Reduced haemoglobin

• Reduced platelet count

• Changes in liver function tests

• Decreased blood potassium

• Musculoskeletal pain

Serious side effects:

• Interstitial lung disease or pneumonitis: New or worsening cough, shortness of breath, fever or breathing difficulty needs prompt medical attention.

• Severe neutropenia: A low neutrophil count can increase the risk of serious infections. Fever or chills during treatment should be reported immediately.

• Left ventricular dysfunction: New or worsening breathlessness, swelling of the ankles or legs, palpitations, sudden weight gain, dizziness or fainting require urgent medical attention.

• Severe infusion-related or allergic reactions

• Severe embryo-fetal toxicity if used during pregnancy.

Seek medical attention promptly for adverse symptoms.

• Enhertu should be given only under the supervision of an oncology team.

• Keep all scheduled blood tests and heart-function assessments recommended by your doctor.

• Report new cough, breathing difficulty or fever promptly rather than waiting for the next treatment visit.

• Tell your doctor about previous lung disease or breathing problems before starting treatment.

• Do not replace Enhertu with trastuzumab or ado-trastuzumab emtansine unless specifically prescribed.

• Follow the prescribed treatment schedule even if you feel well.

• Tell your doctor immediately if you become pregnant during treatment.