In the absence of a submission from the holder of the marketing authorisation, lapatinib (Tyverb®) cannot be endorsed for use within NHS Wales for the treatment of patients with breast cancer, whose tumours overexpress HER2 (ErbB2) in combination with trastuzumab for patients with hormone receptor-negative metastatic disease that has progressed on prior trastuzumab therapy(ies) in combination with chemotherapy.