Herwenda (Trastuzumab)

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

• HER2-positive breast cancer, either as adjuvant therapy or in combination with chemotherapy.
• HER2-positive metastatic breast cancer that has progressed after prior therapy.
• HER2-positive gastric or gastro‑esophageal junction adenocarcinoma.
• HER2-positive metastatic gastric cancer in patients who have not received prior HER2‑targeted therapy.
• Use in clinical trials evaluating HER2-directed regimens for other solid tumors.

• Trastuzumab is a humanized IgG1 monoclonal antibody that binds with high affinity to the extracellular domain IV of the HER2 (ErbB2) receptor. This binding blocks ligand‑independent HER2 dimerization, inhibits downstream signaling pathways such as PI3K/AKT and MAPK, and reduces cellular proliferation. Additionally, the Fc region of trastuzumab engages immune effector cells, promoting antibody‑dependent cellular cytotoxicity (ADCC) against HER2‑overexpressing tumor cells.

Adverse reactions to Herwenda have been observed in clinical practice and may vary in frequency and severity. The frequency of each event depends on patient factors and treatment duration.

Common

• Fever, chills, or flu‑like symptoms during or shortly after infusion.
• Nausea, vomiting, or mild gastrointestinal upset.
• Fatigue or headache.
• Infusion‑related reactions such as flushing, rash, or mild hypotension.

Serious

• Cardiac dysfunction, including decreased left ventricular ejection fraction or heart failure.
• Severe infusion reactions with bronchospasm, angioedema, or anaphylaxis.
• Thromboembolic events such as deep‑vein thrombosis or pulmonary embolism.
• Hepatotoxicity presenting as elevated liver enzymes or hepatitis.

Healthcare providers should assess patients carefully before initiating Herwenda and monitor them throughout therapy to mitigate risks.

• Baseline and periodic cardiac evaluation (e.g., echocardiogram) due to risk of cardiotoxicity.
• Monitor for signs of infusion‑related reactions; be prepared to manage severe hypersensitivity.
• Assess hepatic function before treatment and during therapy, especially in patients with pre‑existing liver disease.
• Use caution in patients with a history of thromboembolic events or clotting disorders.
• Adjust or withhold therapy in the presence of uncontrolled infection or severe neutropenia.
• Consider pregnancy and lactation status; trastuzumab may cross the placenta and is excreted in breast milk.

Herwenda may interact with other agents that affect cardiac function, immune response, or drug clearance.

Avoid

• Concurrent use of anthracycline chemotherapy (e.g., doxorubicin) due to additive cardiotoxic risk.
• Live vaccines during treatment, as immunosuppression may reduce vaccine efficacy and increase infection risk.

Use with caution

• Other HER2‑targeted therapies (e.g., pertuzumab, lapatinib) may increase cardiac toxicity; monitor closely.
• Medications that prolong QT interval or affect cardiac conduction should be used cautiously.
• Concomitant corticosteroids can mask infusion‑related reactions; monitor patient closely.