EORTC 10968: a phase I clinical and pharmacokinetic study of polyethylene glycol liposomal doxorubicin (Caelyx, Doxil) at a 6-week interval in patients with metastatic breast cancer. European Organization for Research and Treatment of Cancer.

BACKGROUND We performed a phase I study of polyethylene glycol (pegylated, Stealth) liposomal doxorubicin (Caelyx, Doxil) using a prolonged (6-week) dose interval to reduce the incidence of skin toxicity that was dose-limiting at more conventional dose intervals, and which appeared to be schedule dependent. PATIENTS AND METHODS Eligible for the study were metastatic breast cancer patients who had received a maximum of one prior therapy for metastatic disease. The defined dose levels were 60, 70, 80 and 90 mg/m2. RESULTS Twenty patients were assessed at starting doses of 60 mg/m2 (n = 9) or 70 mg/m2 (n = 11). The dose-limiting toxicity was mucositis. Severe skin toxicity was not observed at the 60 mg/m2 dose level, and occurred in only one patient treated at 70 mg/m2. Significant neutropenia, alopecia, and nausea and vomiting were rare events. No clinical cardiac events occurred, despite a median cumulative doxorubicin dose of 323 mg/m2 (range 5-630 mg/m2). Partial responses were documented in five patients. Pharmacokinetics were assessed in 15 patients, and confirmed the long terminal half-life of the agent (median 77 h) demonstrated in earlier studies. CONCLUSIONS The recommended dose of Caelyx/Doxil using this schedule is 60 mg/m2 every 6 weeks. This is a safe and effective regimen that permits prolonged administration of anthracycline to patients with metastatic breast cancer.