A pharmacologically guided phase I study of carboplatin in combination with methotrexate and vinblastine in advanced urothelial cancer.

Carboplatin is an alternative for cisplatin in the treatment of urothelial cancers. A pharmacologically guided phase I study of carboplatin in combination with methotrexate (30 mg/m2) and vinblastine (4 mg/m2) was conducted in ten patients by increment of the area under the plasma concentration versus time curve (AUC) for ultrafilterable carboplatin using the Calvert formula. The maximal tolerated AUC was 5 mg ml-1 min, with neutropenia being the dose-limiting toxicity. There was a significant linear correlation between the percentage of decrease in neutrophil count and the carboplatin AUC. Determination of the glomerular filtration rate by the isotopic method allowed us to adapt the dose of carboplatin given to patients suffering from urothelial cancer, who frequently have impaired renal function. The recommended AUC for phase II study is 4 mg ml-1 min.