3 The Technology
3.1 Trastuzumab is a recombinant humanised monoclonal antibody that specifically targets the HER2 protein. It is licensed for two indications for the treatment of MBC overexpressing HER2 at level 3+. Firstly, it is licensed in combination with paclitaxel for patients with MBC who have not received chemotherapy for metastatic disease and in whom an anthracycline is unsuitable. Secondly, it is licensed as a monotherapy for patients who have received at least two chemotherapy regimens for MBC; prior chemotherapy must have included at least an anthracycline and a taxane, unless these treatments are inappropriate; patients who are oestrogen receptor-positive must also have failed to respond to appropriate hormonal therapy.
3.2 Trastuzumab is administered intravenously. Following an initial loading dose of 4 mg per kg body weight, patients receive a weekly dose of 2 mg per kg body weight until disease progression. Side-effects associated with trastuzumab have been noted to include cardiotoxicity and infusion-related reactions.
3.3 The basic NHS price according to the British National Formulary (September 2001) for trastuzumab is £407 per 150 mg vial. For a typical patient, a 38-week course of combination therapy costs approximately £15,500 for trastuzumab and £9,600 for paclitaxel. The cost of a 12-week course of treatment with trastuzumab monotherapy is approximately £5,300.
3.4 There are costs of testing a woman's suitability for treatment and of monitoring in addition to the cost of administering treatment. HER2 levels must be assessed in patients who are potentially eligible for treatment with trastuzumab, and patients receiving trastuzumab should have left ventricular ejection fraction measured before and during treatment.