3.1
Lapatinib (Tyverb, GlaxoSmithKline) is a protein kinase inhibitor that blocks the tyrosine kinase components of the epidermal growth factor receptors (ErbB1 and ErbB2), which are implicated in the growth of various tumours. Lapatinib has conditional marketing authorisation (that is, further evidence on this medicinal product is being awaited) in the UK. Lapatinib is 'indicated for the treatment of patients with breast cancer, whose tumours overexpress HER2 (ErbB2); in combination with an aromatase inhibitor for postmenopausal women with hormone receptor positive metastatic disease, not currently intended for chemotherapy'. The summary of product characteristics (SPC) states that 'patients in the registration study were not previously treated with trastuzumab or an aromatase inhibitor'.