Doxil (Caelyx): An Exploratory Study with Pharmacokinetics in Patients with Hormone-Refractory Prostate Cancer

In a pilot study conducted 24 years ago, Doxil, a doxorubicin formulation encapsulated in polyethylene glycol-coated liposomes, was tested on 15 patients with hormone-refractory prostate cancer (HRPC). The study administered Doxil intravenously at two different dose intensities: 45 mg/m^2 every 3 weeks or 60 mg/m^2 every 4 weeks. Plasma levels of doxorubicin were analyzed in 10 of these patients. The study found that the most common side effect was stomatitis, particularly at the higher dose, while hand-foot syndrome was more frequent and severe at the lower dose but more frequent schedule. Out of the 15 patients, 3 responded to the treatment and 2 had stable disease, with the best results observed at the 60 mg/m^2 dose given every 4 weeks. Pharmacokinetic analysis indicated a dose-proportional increase in plasma drug levels and a long circulation time with half-lives around 3 days. Despite some activity against HRPC, severe mucocutaneous toxicities at the 60 mg/m^2 dose level prevented further exploration of this regimen.