Phase II trial of sunitinib in bevacizumab-refractory metastatic renal cell carcinoma (mRCC): Updated results and analysis of circulating biomarkers

5035 Background: Sunitinib malate is an oral, multitargeted tyrosine kinase inhibitor with antiangiogenic and antitumor activity. This study evaluated the safety and activity of sunitinib in mRCC patients (pts) previously treated with the VEGF-neutralizing antibody, bevacizumab. Levels of angiogenic biomarkers, including plasma VEGF and soluble VEGFR-3 (sVEGFR-3), were assessed for predictive significance with clinical response. Methods: Pts were required to have mRCC with disease progression following bevacizumab- based therapy, measurable disease, ECOG performance status 0 or 1, and adequate organ function. Pts were treated with sunitinib 50 mg daily in 6-week cycles (4 weeks on, followed by 2 weeks off). The primary endpoint was objective response according to RECIST. Plasma VEGF and sVEGFR-3 levels were measured in pre-treatment samples and at multiple timepoints on study. Results: A total of 61 pts were enrolled. The objective partial response rate was 23% (95% CI: 13%, 36%); 35 pts (57%) demonstrate...