Target and mechanism of action: it is a humanized IgG1 monoclonal antibody against the receptor of epidermal growth factor 2 (HER2). By blocking this receptor, Trastuzumab inhibits the proliferation of human tumor cells that overexpress this receptor. Overexpression of HER2 is observed in 20%-30% of primary breast cancers.
Indications: trastuzumab is indicated for the treatment of patients with metastatic breast cancer whose tumors overexpress HER2:
- monotherapy for the treatment of patients who received at least two chemotherapy regimens for metastatic disease,
- in combination with paclitaxel for the treatment of patients who were receiving chemotherapy for metastatic disease and for which no treatment is indicated with anthracyclines.
The HER2 testing is mandatory prior to initiation of therapy with trastuzumab. It is detected using an immuno-histochemical sections of fixed tumor. Recently the drug has shown to be effective in the adjuvant setting, or after radical surgery, enough to be in the process of approval for this indication and it often used in these patients. Currently there are numerous studies to evaluate the use of the drug for other indications in breast cancer or other cancers (e.g. Gastric carcinomas…).
Mode of administration: it is administered intravenously on a weekly basis.
Most common side effects: skin reactions (acneiform rash), nausea/vomiting, diarrhea, infusion reactions, hypersensitivity, chills and/or fever. A serious adverse event is very rare but serious cardiotoxicity.
Trade name: Herceptin (Roche pharmaceutical company)