Adverse Event Profile of Trastuzumab

Infusion‑Related Reactions

• Approximately 40–50 % of patients experience chills and fever during the first trastuzumab infusion; these reactions are typically mild‑to‑moderate, begin within 1–2 weeks of treatment initiation, and resolve after a few days. 1

Cardiotoxicity

• When trastuzumab is administered concurrently with anthracyclines, about 27 % of patients develop symptomatic or asymptomatic left‑ventricular dysfunction. 2, 3, 4
• Concurrent anthracycline‑trastuzumab therapy leads to heart‑failure (NYHA class III–IV) in roughly 16 % of patients. 2
• Sequential (non‑concurrent) anthracycline administration or trastuzumab without anthracyclines reduces the incidence of heart‑failure to 1.7–4.1 %. 2, 3, 4

Gastrointestinal Toxicity with Pertuzumab

• Adding pertuzumab to trastuzumab markedly increases diarrhea incidence to 67 % (any grade) compared with 46 % when trastuzumab is used alone. 5

Comparative Safety of Other HER2‑Targeted Agents

Lapatinib

• Lapatinib is associated with substantially more diarrhea and rash but considerably lower cardiotoxicity (≈1.6 % cardiac events, 0.2 % symptomatic). 2, 6

Pertuzumab

• Pertuzumab demonstrates cardiac safety comparable to control arms, with cardiac adverse events occurring in 14.5 % of patients versus 16.4 % in controls. 2, 3

Clinical Considerations

• Although infusion‑related reactions are the most frequent adverse events, cardiotoxicity is the primary driver of treatment modifications and long‑term morbidity. 1, 7
• The risk of cardiac complications varies dramatically with the chemotherapy schedule; concurrent anthracycline‑trastuzumab regimens carry a far higher risk than sequential administration. 2, 4