Capecitabine after anthracycline and taxane exposure in HER2-negative metastatic breast cancer patients: response, survival and prognostic factors.

BACKGROUND Capecitabine is a widely accepted option in pre-treated metastatic breast cancer (MBC) patients. However, little is known about specific activity in molecularly defined subgroups of patients. Here, response, survival and prognostic factors were examined in a prospectively characterized cohort of human epidermal growth factor receptor 2 (HER2) negative MBC patients receiving capecitabine following anthracycline and taxane failure. PATIENTS AND METHODS Medical records from 75 HER2-negative MBC pre-treated with anthracycline and/or taxane and receiving capecitabine monotherapy at the Institut Paoli-Calmettes between 2002 and 2009 were reviewed. Univariate and multivariate analysis according the Cox regression model were employed to identify factors predictive for response, progression-free survival (PFS) and overall survival (OS). RESULTS Overall, the objective response rate (ORR) was 29.3% (95% CI: 20-40). The ORR in HER2-negative/hormonal receptor (HRe) positive and HER2-negative/HRe-negative patients were 37% (95% CI: 26-50) and 0% (95% CI: 0-19), respectively, (p=0.003, Fisher's test). With a median follow-up of 35.2 months after capecitabine initiation, median PFS was 6.6 months (95% CI: 4.7-10.4) and median OS was 18.4 months (95% CI:14.1-24.9). In univariate analysis, HRe-negative status was the strongest prognostic factor for PFS (hazard ratio (HR)=2.09; p-value=0.015, log-rank test). In multivariate analysis, only three variables (HRe-negative status, initial disease-free interval <24 months and extra-regional lymph node involvement) were considered independently associated with poor PFS, while five variables (grade 2/3, initial disease-free interval <24 months, central nervous system metastases, interval between diagnosis of metastases and capecitabine initiation <24 months, and number of metastatic sites on capecitabine initiation) were associated with poor OS. CONCLUSION The median OS of pretreated patients with HER2-negative MBC receiving capecitabine is approximately 18 months, but HER2-negative/HRe-negative patients have a low probablility of response/disease control to capecitabine and require innovative therapies.