Erlotinib in combination with capecitabine and docetaxel in patients with metastatic breast cancer: a dose-escalation study

Capecitabine added to docetaxel extends survival in metastatic breast cancer (MBC) and shows additive efficacy with erlotinib in pre-clinical studies. This study aimed to determine the maximum-tolerated dose (MTD) of capecitabine/docetaxel with erlotinib and assess tolerability, anti-tumour activity and potential pharmacokinetic interactions. Three treatment cohorts were assessed, using different dosing regimens. A total of 24 women with MBC were enrolled sequentially. The regimen comprising erlotinib 100mg/day continuously, capecitabine 825mg/m2 bid on days 1 to 14 and docetaxel 75mg/m2 intravenously every 3 weeks on day 1 was well tolerated and was established as the MTD. Overall response rate was 67%, comprising two complete and 12 partial responders in 21 assessable patients. The most common treatment-related adverse events were gastrointestinal disorders and skin toxicities. Pharmacokinetic studies showed that exposure to the three drugs was not reduced when given in combination. These encouraging preliminary results warrant further trials of the combination in MBC.