Pharmacokinetics and adverse reactions of a new liposomal cisplatin (Lipoplatin): phase I study

Lipoplatin, a new liposomal cisplatin formulation, is formed from cisplatin and liposomes composed of dipalmitoyl phosphatidyl glycerol (DPPG), soy phosphatidyl choline (SPC-3), cholesterol and methoxy-polyethylene glycol-distearoyl phosphatidylethanolamine (mPEG2000-DSPE). Following intravenous infusion, the nanoparticles (110 nm) are distributed into tissues and concentrate preferentially at tumor sites supposedly via extravasation through the leaky tumor vasculature. This study was designed to investigate the pharmacokinetics and the toxicity of this new liposomal cisplatin in patients with pretreated advanced malignant tumors. The drug was infused for 8 h every 14 days at escalating doses. Twenty-seven patients were included and 3-5 patients were selected for each dosage level; levels started at 25 mg/m2 and were increased by 25 to 125 mg/m2. Three patients were also treated at higher dose levels, one each at 200, 250 and 300 mg/m2. Blood was taken at certain time intervals in order to estimate total platinum plasma levels. At level 5 (125 mg/m2), grades 1 and 2 GI tract and hematological toxicities were detected. No nephrotoxicity was observed. Seven additional patients were added at the 4th level (100 mg/m2) for further pharmacokinetic evaluation. Measurement of platinum levels in the plasma of patients as a function of time showed that a maximum platinum level is attained at 6-8 h. The half-life of Lipoplatin was 60-117 h depending on the dose. Urine excretion reached about 40% of the infused dose in 3 days. The data demonstrate that Lipoplatin up to a dose of 125 mg/m2 every 14 days has no nephrotoxicity and it lacks the serious side effects of cisplatin.