e15547 Background: To evaluate the efficacy and safety of Sunitinib as post-operative adjuvant therapy in patients with high-risk renal cell carcinoma (RCC). Methods: A total of 60 patients with resected, histologically confirmed clear cell RCC were enrolled in this study. Patients received orally Sunitinib either at a dose of 50mg on treatment schedule 4/2 (once daily for 4 weeks followed by 2 weeks off) or at a dose of 37.5mg once daily for three 6-week cycles from 1 month after surgery. Results: All 60 patients tolerated Sunitinib treatment well and no patient discontinued treatment due to adverse events. Most adverse events were grade 1 to 2. The most frequently reported adverse events were neutropenia (56.7%), thrombocytopenia (53.3%), leucopenia (48.3%), hand-foot syndrome (46.7%) and hypertension (36.7%). The most frequently reported grade 3 or 4 toxicities were thrombocytopenia (25%), neutropenia (15%), hand-foot syndrome (11.7%) and leucopenia (8.3%). The majority of adverse events occurred within the first 1-2 cycles of Sunitinib treatment, and was ameliorated 1 month after 3 cycles finished. No irreversible adverse event was observed. As of January 31, 2013, recurrence occurred in 3 of 60 (5%) patients except one death due to cerebrovascular accident unrelated to treatment, with 12-month disease-free survival (DFS) rate of 96.6% (RCC recurred 7 months after surgery in 2 patients and recurred 14 months after surgery in 1 patient). Conclusions: Myelosuppression occurred less frequently in high-risk RCC patients treated with Sunitinib as operative adjuvant therapy than in advanced RCC patients, with a better benefit trend. Long-term follow-up data are needed to further confirm the efficacy of Sunitinib in the adjuvant setting.