Herwenda (Trastuzumab)

Herwenda is prescribed for patients whose tumors overexpress the human epidermal growth factor receptor 2 (HER2). It is used as part of a treatment plan that may include chemotherapy, surgery, or radiation.

• HER2‑positive breast cancer (early‑stage or metastatic)
• HER2‑positive gastric or gastro‑esophageal junction adenocarcinoma
• Adjuvant therapy following surgical resection of HER2‑positive breast cancer
• Neoadjuvant therapy to shrink HER2‑positive tumors before surgery
• Combination regimens with taxane‑based chemotherapy in metastatic disease

• Trastuzumab binds with high affinity to the extracellular domain IV of the HER2 receptor on tumor cells. This binding blocks ligand‑independent HER2 dimerization, inhibits downstream signaling pathways such as PI3K/AKT and MAPK, and promotes antibody‑dependent cellular cytotoxicity (ADCC) by recruiting immune effector cells, leading to reduced tumor proliferation and survival. It also interferes with HER2‑mediated angiogenic signaling and may enhance the efficacy of concomitant chemotherapeutic agents.

Adverse reactions to Herwenda are reported across clinical studies and may vary in frequency and severity. The frequency of each event depends on patient factors and treatment duration.

Common

• Infusion‑related reactions (fever, chills, nausea)
• Fatigue or asthenia
• Diarrhea or abdominal discomfort
• Rash or mild skin irritation
• Headache
• Upper respiratory symptoms
• Elevated liver enzymes

Serious

• Cardiac dysfunction, including decreased left ventricular ejection fraction
• Severe hypersensitivity reactions such as anaphylaxis
• Thromboembolic events (deep vein thrombosis, pulmonary embolism)
• Interstitial lung disease
• Hepatotoxicity

Before initiating Herwenda, clinicians should evaluate patient history and monitor specific parameters throughout therapy.

• Baseline and periodic assessment of cardiac function (e.g., echocardiogram)
• Review of prior infusion reactions or hypersensitivity to monoclonal antibodies
• Caution in patients with pre‑existing cardiac disease or reduced ejection fraction
• Monitor liver function tests during treatment
• Avoid use in pregnant or breastfeeding women unless benefits outweigh risks
• Adjust therapy in patients with severe renal impairment if applicable

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

Avoid

• Concurrent use with anthracyclines (e.g., doxorubicin) due to increased cardiotoxicity risk
• Live vaccines during treatment because of immunosuppression

Use with caution

• Other HER2‑targeted therapies (pertuzumab, lapatinib) as combined cardiotoxic potential
• Medications that prolong QT interval
• Concomitant chemotherapy agents that may exacerbate infusion reactions
• Steroids that may mask early signs of hypersensitivity