Phase II trial of pazopanib and weekly paclitaxel in metastatic urothelial cancer (UC).

Abstract

299 Background: Currently, there are no standard treatments for relapsed or refractory urothelial carcinoma (UC). Discouraging results have been achieved in trials evaluating drugs as single agents or in combination regimens. Paclitaxel has activity when used alone and in combination in urothelial cancer, and pazopanib is active in solid tumors secondary to its potent anti-angiogenic effect. We report the results of an ongoing multicenter phase II study evaluating the combination of paclitaxel with pazopanib in refractory UC. Methods: Patients (pts) eligible for the study have histologically confirmed UC, with relapse after receiving up to 2 chemotherapeutic regimens. Pazopanib (800 mg) is administered daily, with weekly paclitaxel (80mg/m2) for 3 weeks in a 28 day cycle. Treatment is continued until disease progression or unacceptable toxicity. Primary endpoint of the study is the response-rate (RR) based on RECIST criteria. Secondary endpoints include safety, and progression free-survival (PFS). For designing the study, Simon’s two-stage method was applied, and 9 pts were recruited in the first stage. After having ≥1 response in the first group, a full enrollment of 32 pts has been initiated. Results: 25 pts were enrolled from April 2010 to September 2013. Their median age was 67 years (47-89), with a median ECOG performance status of 1 (0-2). 10 pts (40%) had UC of the upper urinary tract and 15 had primary bladder/ureter tumors. All pts had multiple metastatic sites, including 11 (44%) with liver metastases. Median number of prior cytotoxic regimens was 2, and 50% were considered cisplatin responsive. Based on RECIST (v1.1) criteria,13 pts (52%) had partial response (PR), 5 (20%) had stable disease (SD), and 2 (8%) had complete response (CR) (80% clinical benefit). The side effects included grade 3 hypertension (n=2), grade 3 fatigue (n=4), grade 3 thrombosis (n=2) and grade 4 neutropenia (n=2). 14 pts required growth factor support. Conclusions: Our phase II study combining paclitaxel and pazopanib demonstratedsignificant anti-tumor activity of combining paclitaxel in relapsed/refractory UC. This combination is safe, and is worthy of evaluation in larger studies. Clinical trial information: 1108055.