Cardiotoxic effects of trastuzumab

Breast cancer with overexpression of the HER2 receptor is an aggressive type of breast cancer with poor prognosis. Trastuzumab (Herceptin) is a monoclonal antibody that binds to the HER2 receptor on the cell surface blocking the signals that promote cell-growth proliferation. Trastuzumab treatment has almost halved the risk of relapse, when given as an adjuvant, and has improved the overall survival in metastatic breast cancer. However, when given alone or in combination with cardiotoxic chemotherapy, especially anthracyclines, trastuzumab may lead to congestive heart failure of varying severity.

The article is a non-systematic review of articles from clinical trails, basic research, and recommendations by Norwegian and international expert panels.

The cardiotoxic effects of trastuzumab and anthracycline in combination were already reported in the pivotal trials. Over ten years of research have revealed the mechanisms of cardiotoxicity with trastuzumab. Risk factors have been identified and recommendations drawn up for cardiac surveillance and treatment of patients with signs of heart failure. By following these recommendations the incidence of heart failure is reduced to approximately five per cent of treated patients.

In summary, the favourable effects of trastuzumab are convincing, but cardiotoxicity is a significant challenge in treatment. Risk factors for side effects indicate extra vigilance, but the side effects are unpredictable and all patients treated with trastuzumab must undergo regular cardiac surveillance.