BIBW 2992 in combination with vinorelbine will provide a suitable combination to test the hypothesis that patients with metastatic breast cancer whose tumours are HER2 2+ by immunohistochemistry, but negative by fluorescence in-situ hybridisation (FISH) will benefit from a combination of a cytotoxic agent, i.e. vinorelbine, plus the dual irreversible EGFR/HER2-tyrosine kinase inhibitor BIBW 2992.