Final overall survival (OS) analysis of PHEREXA: A randomized phase III trial of trastuzumab (H) + capecitabine (X) ± pertuzumab (P) in patients with HER2-positive metastatic breast cancer (MBC) who experienced disease progression during or after H-based therapy.

1013Background: In PHEREXA (NCT01026142), adding P to H + X did not significantly improve independent review facility-assessed progression-free survival (IRF-PFS; primary endpoint) in patients with HER2-positive MBC who received a prior taxane and progressed during or after H-based therapy (hazard ratio [HR] 0.82; 95% confidence interval [CI] 0.65–1.02; p= .0731). An 8-month increase in median OS to 36.1 months was observed with P, but due to hierarchical testing of IRF-PFS, and subsequently of OS, statistical significance could not be claimed. No new safety signals were identified. We now report the final prespecified analysis. Methods: Randomization arms were A: intravenous H 8 mg/kg→6 mg/kg every 3 weeks (q3w) + oral X 1250 mg/m2 twice daily (2 weeks on, 1 week off q3w) and B: intravenous P 840 mg→420 mg q3w + intravenous H per Arm A + oral X 1000 mg/m2 (same schedule as Arm A). Treatment was given until disease progression, unmanageable toxicity, or patient request for discontinuation. OS and investig...