The combination of AEE788 (a dual TKI of EGFR/HER-2 and inhibitor of the VEGF receptor) and letrozole has been shown to enhance growth inhibition in ER+ breast cancer cell lines compared with either drug alone (Hauge-Evans et al, 2004), but this activity may be restricted to tumours that overexpress EGFR and/or HER-2. Here, ERBB2 is linked to breast cancer.