Background: Bis-acetato-ammine-dichloro-cyclohexylamine-platinum(IV) (JM216) is the first orally given platinum complex that shows in vitro cytotoxicity comparable to that of cisplatin and in vivo cytotoxicity superior to those of cisplatin and carboplatin.
Methods: We conducted an escalating-dose (50, 75, 100, 120 mg/m2) phase I study of JM216 administered orally once a day for five consecutive days in patients with solid tumors to establish the toxicity profile, maximum tolerated dose (MTD) and pharmacokinetic profile. Twenty-three patients were enrolled and all were assessable for toxicity.
Results: The MTD was 120 mg/m2/day and the dose-limiting toxicities were leukopenia, thrombocytopenia, anemia and diarrhea. Because of the delayed hematological toxicities, it was difficult to repeat cycles every 26 days in some patients. Tumor shrinkage was observed in two patients with breast cancer, both of whom were resistant to doxorubicin. A pharmacokinetic study showed that the areas under the concentration-time curve (AUC) and peak plasma concentrations (Cmax) for total platinum (Pt) on days 1 and 5 and ultrafiltered Pt (UF-Pt) on day 1 increased in proportion to the dose of JM216. The AUCs for both total and UF-Pt on day 5 were higher than the AUCs on day 1. The AUC for UF-Pt on day 5 showed the best correlation with percentage reduction in leukocyte count and in absolute neutrophil count.
Conclusion: The recommended dose for phase II studies is 100 mg/m2/day every 4-6 weeks. The observation of tumor shrinkage in previously heavily treated breast cancer patients supports a phase II investigation.