Herceptin

Herceptin is a prescription monoclonal antibody whose active ingredient is trastuzumab, provided as a subcutaneous injection (strength not specified) for use in the European Union. It belongs to the antineoplastic class and functions as a HER2 receptor antagonist. The product is indicated for HER2‑positive cancers and is administered by a healthcare professional, often in combination with chemotherapy or other targeted therapies as part of a treatment regimen.

Herceptin is used in clinical practice for several HER2‑positive malignancies, where it targets the HER2 receptor to improve outcomes.

- Treatment of HER2‑positive metastatic breast cancer, often with chemotherapy. - Adjuvant therapy for HER2‑positive early‑stage breast cancer after surgery. - Management of HER2‑positive gastric or gastroesophageal adenocarcinoma. - Combined with taxane‑based chemotherapy in advanced disease settings. - Neoadjuvant use before surgery to increase pathological response rates. - Maintenance therapy following initial response in metastatic HER2‑positive disease. - Combined with pertuzumab to provide dual HER2 blockade in selected regimens.

Herceptin may cause a range of adverse reactions, which are generally categorized as common or serious.

Common: - Infusion‑related reactions such as fever, chills, flushing, or nausea during or shortly after administration. - Fatigue or generalized weakness that may affect daily activities. - Diarrhea or abdominal discomfort, sometimes with mild cramping. - Rash or mild skin irritation at the injection site, often presenting as redness or itching.

Serious: - Cardiac dysfunction, including reduced left ventricular ejection fraction, which may cause shortness of breath or edema. - Severe allergic reactions (anaphylaxis) with respiratory distress, hypotension, or urticaria requiring immediate medical attention. - Thrombocytopenia or neutropenia leading to increased risk of bleeding or infection, possibly necessitating treatment interruption.

When prescribing Herceptin, clinicians should consider several precautions to minimize risks and ensure safe use.

- Assess baseline cardiac function (e.g., left ventricular ejection fraction) before initiating therapy. - Monitor cardiac function periodically during treatment, especially in patients with prior heart disease. - Evaluate for pregnancy and advise appropriate contraception, as safety in pregnancy is not established. - Screen for active infections, including hepatitis B, before starting therapy. - Use caution in patients with known hypersensitivity to trastuzumab or any component of the formulation. - Adjust or discontinue treatment if severe adverse reactions or significant laboratory abnormalities occur.

Herceptin may interact with other medicines, and certain combinations should be avoided or used with caution.

Avoid: - Concurrent use with other HER2‑targeted monoclonal antibodies not studied, due to potential additive toxicity. - Live vaccines during treatment, because immunosuppression may reduce vaccine efficacy and increase infection risk.

Use with caution: - Anthracycline chemotherapy (e.g., doxorubicin) given sequentially, as combined cardiotoxicity may be increased. - Cardiotoxic agents such as trastuzumab‑emtansine or pertuzumab, requiring close cardiac monitoring. - Medications that prolong QT interval, which may exacerbate cardiac effects. - Hormonal therapies (e.g., tamoxifen) may have overlapping metabolic pathways; monitor for potential interactions.