Phase II Study of Pazopanib and Paclitaxel in Patients With Refractory Urothelial Cancer

The present phase II study of paclitaxel with an antiangiogenic agent for refractory urothelial cancer resulted in a high objective response rate with limited toxicity. Introduction Currently, no standard treatments are available for relapsed or refractory urothelial carcinoma (UC). Paclitaxel has demonstrated efficacy in the treatment of UC when used alone or combined with other cytotoxic therapies. We designed a phase II trial combining paclitaxel with pazopanib, a commonly used antiangiogenic agent with significant antitumor activity in various solid tumors. Patients and Methods We enrolled 32 patients with refractory UC who had demonstrated disease progression after 2 previous chemotherapeutic regimens. The patients received paclitaxel 80 mg/m² on days 1, 8, and 15 of a 28-day cycle and oral pazopanib 800 mg daily. The primary endpoint was the overall response rate (ORR). The secondary endpoints included progression-free survival, overall survival, and a safety assessment of the combination. Results Of the 28 evaluable patients, a complete response was observed in 3 patients and a partial response in 12, with an ORR of 54% (95% confidence interval, 33.9-72.5). The median progression-free and overall survival was 6.2 and 10 months, respectively. The most frequent side effects noted (all grades) were fatigue (63%), diarrhea (44%), and nausea and vomiting (41%). Hematologic toxicities were common and included (all grades) anemia (69%), neutropenia (38%), and thrombocytopenia (47%). Growth factor support was required for 44% of the patients. Conclusion The combination of paclitaxel and pazopanib resulted in a promising ORR of 54% in patients with advanced pretreated UC. This represents a greater response rate and median survival than found with other existing second-line regimens for UC and is worthy of further study.