Phase 1/2 Study of Intravenous Paclitaxel and Oral Cyclophosphamide in Pretreated Metastatic Urothelial Bladder Cancer Patients

BACKGROUND: To the authors' knowledge, no previous studies have been reported with the combination of paclitaxel and oral cyclophosphamide in patients with metastatic bladder cancer. A phase 1/2 study was conducted of paclitaxel in combination with oral cyclophosphamide for patients with advanced urothelial bladder cancer who had been previously treated with gemcitabine/cisplatin chemotherapy as first-line metastatic treatment. METHODS: This was a single-arm phase 1/2 study. Patients were treated with paclitaxel and oral cyclophosphamide at 3-week intervals until disease progression or irreversible toxicity occurred. Primary endpoints were to determine the maximum tolerated doses (MTD) and objective response rate; secondary endpoints were safety, time to disease progression (TTP), and overall survival (OS). RESULTS: Forty-four patients were enrolled. Dose levels of paclitaxel of 175 mg/m(2) (Day 1) and cyclophosphamide of 50 mg (Days 1-7 orally) (dose level 1) of a 21-day cycle were tolerated without close-limiting toxicities (DLTs). At a cyclophosphamide dose of 100 mg (dose level 11) the MTD was exceeded; 3 of 6 patients experienced a DLT (grade 3 constipation and grade 4 neutropenia and thrombocytopenia [toxicities were graded using National Cancer Institute Common Toxicity Criteria (version 3,0)]). Dose level I was expanded and determined to be the MTD. A total of 32 patients were treated at dose level I in the phase 2 portion. Partial responses were observed in 31% of patients (10 of 32 patients; 95% confidence interval [95% CI], 17%-45%). Grade 1/2 vomiting, peripheral neuropathy, and neutropenia were the most common side effects, noted in 11 (34%), 8 (25%), and 10 (31%) patients, respectively. The median TTP was 5 months (95% CI, 2 months-7.5 months) and the median OS was 8 months (95% CI, 4 months-14 months). CONCLUSIONS: The combination of paclitaxel and cyclophosphamide is well tolerated and associated with promising efficacy. Further trials are needed to confirm these preliminary results. Cancer 2009;115:517-23. (c) 2008 American Cancer Society.