Herceptin (Trastuzumab)

Herceptin is indicated for the treatment of cancers that overexpress the human epidermal growth factor receptor 2 (HER2).

• HER2‑positive breast cancer, as adjuvant or neoadjuvant therapy.
• HER2‑positive metastatic breast cancer.
• HER2‑positive gastric or gastro‑esophageal adenocarcinoma.
• Combination with chemotherapy in early‑stage disease.
• Post‑surgical maintenance in selected patients.

• Trastuzumab binds with high affinity to the extracellular domain IV of the HER2 receptor on tumor cells. This binding blocks ligand‑independent HER2 signaling, prevents receptor dimerization, and inhibits downstream pathways such as PI3K/AKT and MAPK. In addition, the Fc region of the antibody recruits immune effector cells, leading to antibody‑dependent cellular cytotoxicity (ADCC) that contributes to tumor cell elimination. The overall effect reduces tumor proliferation and survival.

Adverse reactions to Herceptin vary in frequency and severity.

Common

• Fever or chills during or after injection.
• Nausea or vomiting.
• Injection site reactions (redness, swelling, pain).

Serious

• Cardiac dysfunction, including decreased left ventricular ejection fraction.
• Severe allergic reactions (anaphylaxis).
• Pulmonary toxicity (interstitial lung disease).

Before initiating Herceptin therapy, clinicians assess several safety considerations to minimize risk.

• Baseline cardiac evaluation (ejection fraction) and periodic monitoring during treatment.
• Avoid use in patients with known hypersensitivity to trastuzumab or its components.
• Caution in patients with pre‑existing cardiac disease or risk factors.
• Monitor for signs of infusion‑related reactions, especially during the first administration.
• Assess liver function tests periodically.
• Consider pregnancy risk; use only if potential benefit justifies potential fetal exposure.

Herceptin may interact with other agents, influencing safety or efficacy.

Avoid

• Concurrent use with anthracycline chemotherapy (e.g., doxorubicin) due to increased cardiac toxicity risk.

Use with caution

• Combination with other HER2‑targeted agents (pertuzumab, lapatinib) requires cardiac monitoring.
• Co‑administration with live vaccines is generally discouraged.
• Concurrent use of medications that prolong QT interval may require ECG monitoring.
• Concomitant use with immunosuppressive drugs may affect antibody activity.