Phase III trial of non-pegylated liposomal doxorubicin (M) in combination with trastuzumab (T) and paclitaxel (P) in HER2+ metastatic breast cancer (MBC).

517 Background: M in combination with T has shown promising activity and cardiac safety in MBC patients (pts). We conducted a randomized Phase III trial of first-line M plus T and P (MTP) versus T plus P (TP) in HER2+ MBC pts. Methods: Pts with HER2+ (by FISH) MBC ≥ 18 years and ECOG 0-1, who had received no prior chemotherapy for metastatic disease, were eligible. Left ventricular ejection fraction should be within normal institutional limits. Prior (neo-) adjuvant anthracyclines, T or P were permitted, if completed >1 year before the start of the study. Pts received M 50 mg/m2 q3w for 6 cycles, T 4 mg/kg loading dose followed by 2 mg/kg qw, and P 80 mg/m2qw, or T+P at the same doses until progression or toxicity. Primary outcome was progression-free survival (PFS). Enrollment of 332 pts would provide 80% power with a 5% significance to detect an improvement in PFS with MTP, assuming a median PFS of 8 months in TP and a hazard ratio (HR) of 0.70. Results: 363 pts enrolled (MTP 181, TP 183), 360 received ...