Non-pegylated liposomal doxorubicin combined with gemcitabine as first-line treatment for metastatic or locally advanced breast cancer. Final results of a phase I/II trial

Doxorubicin and gemcitabine are active as single agents in breast cancer, have different mechanisms of action, and mainly have non-overlapping side effects. Dose-dependent doxorubicin-related cardiac toxicity is the principal limitation in the metastatic setting. This open, multicenter, single-arm phase I/II study assessed the safety and activity of gemcitabine in combination with non-pegylated liposomal doxorubicin (Myocet), a more cardiac-friendly anthracycline, in the first-line treatment of patients with advanced breast cancer. We aimed to determine the optimal recommended dose (RD) of gemcitabine combined with Myocet in a population, with performance status >or=2 and LVEF >or=50%. A formal phase II study was performed afterwards. A total of 53 patients were recruited. Gemcitabine 900 mg/m(2) intravenously day 1 and 8 combined with Myocet 55 mg/m(2) intravenously day 1, every 21 days, was the final RD. The principal toxicity observed was hematological, and 48% of patients developed grade 3-4 neutropenia. Other toxicities were mild and infrequent, including nausea and vomiting. There were no symptomatic cardiac events despite the fact that 36% of the patients had received prior treatment with adjuvant anthracyclines. Objective responses were observed in 51.1% of 47 evaluable patients (95% CI: 36-66%), including two complete response. In addition, 14 patients (29.8%) demonstrated stable disease. The combination of Myocet and gemcitabine at the RD is safe and has encouraging clinical activity in patients with advanced breast cancer, without apparent cardiac toxicity in anthracycline-pretreated patients. These data support further development of this combination.