Ixabepilone plus capecitabine in metastatic breast cancer patients with reduced performance status previously treated with anthracyclines and taxanes: a pooled analysis by performance status of efficacy and safety data from 2 phase III studies.

Patients with metastatic breast cancer (MBC) previously treated with anthracyclines and taxanes often have decreased performance status secondary to extensive tumor involvement. Here, we report the pooled analysis of efficacy and safety data from two similarly designed phase III studies to provide a more precise estimate of benefit of ixabepilone plus capecitabine in MBC patients with Karnofsky's performance status (KPS) 70-80. Across the studies, anthracycline/taxane-pretreated MBC patients were randomized to receive ixabepilone plus capecitabine or capecitabine alone. Individual patient data for KPS 70-80 subset (n = 606) or KPS 90-100 subset (n = 1349) from the two studies were pooled by treatment. Analysis included overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and safety. In patients with reduced performance status (KPS 70-80), ixabepilone plus capecitabine was associated with improvements in OS (median: 12.3 vs. 9.5 months; HR, 0.75; P = 0.0015), PFS (median: 4.6 vs. 3.1 months; HR, 0.76; P = 0.0021) and ORR (35 vs. 19\%) over capecitabine alone. Corresponding results in patients with high performance status (KPS 90-100) were median OS of 16.7 versus 16.2 months (HR, 0.98; P = 0.8111), median PFS of 6.0 versus 4.4 months (HR, 0.58; P = 0.0009), and ORR of 45 versus 28\%. The safety profile of combination therapy was similar between the subgroups. Ixabepilone plus capecitabine appeared to show superior efficacy compared to capecitabine alone in MBC patients previously treated with anthracyclines and taxanes, regardless of performance status, with a possible OS benefit favoring KPS 70-80 patients (ClinicalTrials.gov identifiers: NCT00080301 and NCT00082433).