Trastuzumab plus capecitabine with or without pertuzumab in patients with HER2-positive MBC whose disease has progressed during or following trastuzumab-based therapy for first-line metastatic disease: A multicenter, randomized, two-arm, phase II study (PHEREXA).

TPS118 Background: Pertuzumab (P) is a promising new anti-HER2 antibody which has shown both activity and good tolerability when combined with trastuzumab (H) in patients with HER2-positive breast cancer. Capecitabine (X) in combination with H has been shown to be more efficacious than X alone as second-line treatment of patients with HER2-positive metastatic breast cancer (MBC). The PHEREXA study is designed to investigate the potential benefit of administering P and H combined with X in patients with HER2-positive MBC whose disease has progressed during or following H-based therapy for first-line MBC. Methods: In this multicenter, open-label, Phase II trial (NCT01026142), patients are randomized 1:1 to Arm A (H: 8 mg/kg loading dose followed by a 6 mg/kg maintenance dose; X: 1250 mg/m2 twice daily for 14d q3w) or Arm B (H: 8 mg/kg loading dose followed by a 6 mg/kg maintenance dose; X: 1000 mg/m2 twice daily for 14d; P: 840 mg loading dose and 420 mg thereafter q3w). Enrolment began in January 2010 and ...