Phase III trial of ixabepilone plus capecitabine compared to capecitabine alone in patients with metastatic breast cancer (MBC) previously treated or resistant to an anthracycline and resistant to taxanes

Abstract
1006 Background: Patients with MBC who have progressed after anthracyclines and taxanes have limited treatment options. Ixabepilone, a novel epothilone B analog, is active in resistant breast cancer. Methods: In this large multinational phase III trial, patients with MBC who were anthracycline pretreated and met predefined resistance criteria to taxanes were randomized to ixabepilone (40mg/m2 IV over 3h Q3w) + capecitabine (1,000mg/m2 PO BID Q14d) or capecitabine (1,250mg/m2 PO BID Q14d). The primary endpoint was progression-free survival (PFS); secondary endpoints included objective response rate (ORR), safety, and overall survival (available after 2007). Response and progression were assessed by an independent review committee (IRC) and the investigators (INV). Results: 752 patients were randomized. Median age was 53; 84% had visceral disease, 48% and 43% had 1 and =2 prior metastatic regimens. Median of 5 and 4 cycles of ixabepilone + capecitabine and capecitabine were administered. Ixabepilone + capecitabine was superior to capecitabine. Significant benefit was consistently maintained across predefined subgroups, including HER2-/ER- /PR- and HER2+. *Primary analysis of PFS; hazard ratio= 0.75. Grade (G) 3/4 adverse events included neuropathy (ixabepilone + capecitabine 23% vs capecitabine 0%), hand-foot syndrome (18% vs 17%), and fatigue (9% vs 3%). Neuropathy was cumulative and reversible (median time to resolution of G3/4 to baseline/G1 was 6 weeks). G3 and 4 neutropenia were reported in 32% and 36% vs 9% and 2%, respectively; febrile neutropenia was 5% with ixabepilone + capecitabine. Toxic death rate was 3% vs 1%. Patients with liver dysfunction were at greater risk. Conclusions: Ixabepilone + capecitabine has superior efficacy to capecitabine across endpoints and has a manageable safety profile in this heavily pretreated population. It offers a new potential option for patients with MBC. [Table: see text] No significant financial relationships to disclose.

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