Combining Sunitinib and Bevacizumab for the Management of Advanced Renal Cell Carcinoma: A Phase I/II Trial

BACKGROUND: Tyrosine kinase inhibitors remain a cornerstone in managing metastatic clear cell renal cell carcinoma (RCC). The 4 weeks on/2 weeks off intermittent sunitinib schedule could result in rebound angiogenesis and tumor progression in the 2-week rest period. We propose using bevacizumab during this period for continuous antiangiogenic effects. METHOD: This was a phase I/II study of patients with advanced clear cell RCC. Sunitinib was given 50 mg daily on a 4-week on/2-week off schedule. Bevacizumab was given on day 29 of each sunitinib cycle. The bevacizumab starting dose was 5 mg/kg, and the dose was escalated to 10 mg if there was no dose-limiting toxicity. The primary endpoints were response rate and progression-free survival (PFS). RESULTS: Twenty-five patients were recruited. The study was closed prematurely because of poor accrual. No dose-limiting toxicity was observed with 5 mg bevacizumab. One patient achieved a complete response, and 12 achieved a partial response (52% response rate). At a median follow-up of 42.2 months (95%, confidence interval (CI) 32.9 to 51.4), the median PFS duration was 16.5 months (95% CI 4.1-28.8), and the median overall survival time was 33.3 months (95% CI 19.4-47.3). Twenty-two patients (88%) had at least one grade 3 or 4 toxicity; the most common were thrombocytopenia (32%), lymphopenia (32%), hypertension (28%), and fatigue (24%). CONCLUSION: Continuous angiogenesis blockade by adding bevacizumab to the sunitinib on/off regimen for advanced RCC yields significant antitumor activity with manageable increased toxicity.