Prolonged Complete Responses and Near-Complete Responses to Sunitinib in Metastatic Renal Cell Carcinoma

Sunitinib is a tyrosine kinase inhibitor with activity against vascular endothelial growth factor (VEGF) receptor and platelet-derived growth factor receptor recently approved by the FDA for the treatment of advanced renal cell carcinoma (RCC). Complete responses (CRs) to sunitinib have been documented in the literature. However, a detailed description and analysis of these patients is lacking. Seventy-four patients receiving sunitinib at the Cleveland Clinic in first-, second-, and third-line clinical trials were reviewed to determine the number of patients with Response Evaluation Criteria in Solid Tumors (RECIST)– defined CRs and patients who have achieved near CRs (nCRs) with a > 90% reduction in composite tumor volume or residual disease of ≤ 1 cm only. Two patients (2.7%) achieved investigator-assessed, RECIST-defined CRs and have had prolonged responses lasting > 22 months while on maintenance sunitinib. The patients who obtained CRs had nonbulky pulmonary metastases, had favorable or intermediate Memorial Sloan-Kettering Cancer Center risk profiles, were treated with sunitinib in the first-line setting, and had a significant reduction in composite tumor measurements within the first 2 cycles. Two additional patients achieved nCRs, including a patient who had previously progressed on bevacizumab. Finally, 1 patient achieved sufficient downstaging and reduction of tumor volume such that the remaining lesion could be excised to produce a surgical CR. Sunitinib is capable of producing durable CRs in patients with cytokine-naive, metastatic RCC who have nonbulky pulmonary metastases. Additionally, nCRs can be seen despite nonpulmonary metastatic sites and previous VEGFtargeted therapy.