Correlation of pathologic findings after brief neoadjuvant sorafenib with results of dynamic-contrast enhanced (DCE) and diffusion-weighted magnetic resonance imaging (DW-MRI) in patients with locally advanced or metastatic clear cell renal cell carcinoma (RCC).

466 Background: Many pts receiving tyrosine kinase inhibitors for RCC manifest stable disease as their best response by RECIST criteria. We hypothesized that tumor necrosis by DCE and DW-MRI after brief treatment with neoS may correlate with pathologic findings. We investigated in a pilot study whether these MRI changes may serve as an imaging biomarker predictive of clinical outcome. Methods: Pts with locally advanced or metastatic clear cell RCC undergoing nephrectomy or metastastectomy were treated with neoS 400mg PO bid for 28 days prior to surgery. The feasibility and safety of neoS was determined. Tumor necrosis detected by DCE and DW MRI’s pre- and post-neoS were compared and correlated with survival and pathologic findings at surgery. RECIST/WHO criteria were also compared. Results: 9 pts were enrolled, and all underwent surgery after neoS, 4 weeks (n=7) or less for toxicity (n=2). Clear cell/sarcomatoid histology was noted in 8 pts, and papillary in 1. All pts had T3 or T4 disease. 7 had M1 disea...