Phase I and pharmacokinetic study of intraperitoneal ormaplatin

Ormaplatin is a cisplatin analog which has demonstrated activity against cisplatin-resistant tumors in preclinical studies. We delivered 28 cycles to 14 patients in a phase I trial of intraperitoneal ormaplatin given every 28 days. The maximum tolerated dose was 88.4 mg/m2 and acute dose-limiting toxicity was abdominal pain. Other toxicities include nausea, emisis, fever, and severe neuropathy seen in 1 patient at a cumulative dose of 399 mg/m2. No objective responses were observed. Hematologic toxicity was mild. The dose recommended for future trials of intraperitoneal ormaplatin is 66.5 mg/m2. Pharmacokinetic analysis performed at a dose of 66.5 mg/m2 demonstrated that the initial phase of elimination from the peritoneal cavity follows first-order kinetics with k = 0.69 hr-1 and half-life of 1.4 hr. Plasma pharmacokinetic behavior is best described by biexponential model with k1 = 0.369 hr-1, k2 = 0.107 hr-1, and first half-life of 2.9 hr and second half-life of 8.4 hr. Pharmacologic advantage, calculated by ratio of peritoneal to plasma AUC, is 17.1. If site-specific activity is demonstrated, then the intraperitoneal route of administration of ormaplatin at 66.5 mg/m2 may be beneficial.