United States of America - The manufacturer of trastuzumab (Herceptin®, Genentech) has warned of 62 postmarketing reports of serious adverse events related to the use of their product indicated for the treatment of breast cancer. To date, 25 000 women have been treated with trastuzumab which the FDA approved in 1998.

Adverse events include hypersensitivity reactions (anaphylaxis), infusion reactions, and pulmonary events (adult respiratory distress syndrome). A total of 15 fatal outcomes were reported. In the majority of patients the symptoms occurred with the first dose of trastuzumab or within 12 hours of infusion. Most patients with fatal outcome had significant pre-existing pulmonary comprimise secondary to intrinsic lung disease and/or malignant pulmonary involvement.

Such patients should be treated with extreme caution. Any patients experiencing symptoms should be discontinued immediately and be closely monitored until complete resolution of symptoms. Patients should also be informed of the possibility of delayed severe reactions.

Reference: Letter from Genentech dated 3 May 2000 at www.fda.gov/medwatch