Pazopanib for the Treatment of Non-clear Cell Renal Cell Carcinoma: A Single-Arm, Open-Label, Multicenter, Phase II Study

Purpose The optimal treatment strategy for patients with metastatic non-clear cell type renal cell carcinoma (nccRCC) remains unclear. Although several inhibitors of vascular endothelial growth factor have recently shown efficacy against nccRCC, the clinical benefit of pazopanib in nccRCC has not been analyzed. We therefore designed a single-arm, open-label, phase II study to determine the efficacy and safety of pazopanib in patients with nccRCC. Materials and Methods Patients with locally advanced or metastatic nccRCC, except for collecting duct or sarcomatoid type, received 800 mg/day of pazopanib daily until progression of disease or intolerable toxicity. One cycle was defined as 4 weeks and tumor response was evaluated every two cycles. The primary objective was overall response rate (ORR). Results A total of 29 eligible patients were enrolled at nine centers in Korea from December 2012 and September 2014. The median age of the patients was 58 years (range, 27 to 76 years) and 21 patients (72%) were male. Regarding histology type, 19 patients had papillary, three had chromophobe, two had unclassified and five had unknown non-clear cell type. Of 28 evaluable patients, eight achieved a confirmed partial response with ORR of 28%. The median progression-free survival was 16.5 months (95% confidence interval, 10.9 to 22.1) and median overall survival was not reached. Sixteen patients (55%) experienced treatment-related toxicity of grade 3 or more, but most adverse events were overcome through dose reduction and delay. Conclusion In this prospective phase II study, pazopanib demonstrated promising activity and tolerable safety profile in patients with metastatic nccRCC.