Phase II Study of Pirarubicin in Metastatic Breast Cancer

Pirarubicin is a more lipophilic derivative of doxorubicin, with a higher uptake rate of cells, lower cardiotoxicity and better antitumor efficacy in preclinical models. Thirty-four patients with metastatic breast cancer were treated in a multicenter phase II study with pirarubicin (THP) using a dosage of 75 mg/m2/every 3 weeks. The patients had a median age of 56 years (range 41-73) and a performance status of WHO grade 0-2. Patients pretreated with anthracyclines, or who were older than 75 years and without sufficient bone marrow reserve were excluded. The 32 evaluable patients received a median number of 4 cycles (range 2-8). The myelosuppression was dose-limiting and led to infections (grades 1 and 2) in 5 patients. Twenty-eight patients developed leukocytopenia grade 3 and 4 toxicity and 7 patients experienced thrombocytopenia grade 1 and 2. The drug was subjectively well tolerated and nausea, vomiting and alopecia were mild. One complete remission with a duration of 15.4 months (67 weeks) and 7 partial remissions with a median duration of 9.3 months (40 weeks) were achieved, which resulted in an overall response rate of 25%. Twenty-one patients were stable for 17 weeks (median) under the treatment with pirarubicin.