Capecitabine and cisplatin (XP) combination systemic chemotherapy in heavily pre-treated HER2 negative metastatic breast cancer

Purpose/Objective(s) After taxane and anthracycline failure, no standard chemotherapy regimen is established in metastatic breast cancer (MBC). Capecitabine and cisplatin (XP) combination shows promising results in gastrointestinal cancer, but there are relatively scarce data in MBC. We reviewed the clinical outcome of XP regimen in anthracycline and taxane resistant, heavily pretreated MBC patients. Materials/Methods Between Jan. 2010 to Feb. 2016, 48 HER2 negative MBC patients who failed anthracycline and taxane based chemotherapy were enrolled. In 43.8% of patients, more than 4 regimens were administrated before XP. Thirty-four patients (70.8%) were hormone receptor (HR) positive MBC. Patients were treated with XP (capecitabine [2000mg/m₂ per oral; day 1-14] plus cisplatin [60mg/m₂ IV; day 1], every 3 weeks) regimen. Results Median progression-free survival (PFS) in total population was 4.33 months (range 1.1∼ 33.57 months). HR positive patients showed trends for superior PFS compared to triple negative breast cancer (TNBC), without statistical significance (6.53 vs. 3.83 months, P = 0.168). In HR positive group, patients receiving 3 or less lines of chemotherapy showed superior PFS compared to others (10.1 vs. 3.0 months, P = 0.039). In multivariate analysis, HR positive patients receiving 3 or less lines of regimens still showed superior PFS (HR = 2.624, 95% CI; 1.071∼6.43, P = 0.032). Most common toxicity was grade 3-4 neutropenia, without treatment-related deaths. Conclusions XP combination regimen showed clinical benefit with tolerable toxicity in heavily pretreated patients, including HR positive patients. After anthracycline and taxane failure, early administration of XP regimen in selected patients may have improve clinical outcome in breast cancer.