852PCAN RADIOLOGICAL PARAMETERS PREDICT THE OUTCOME IN METASTATIC RENAL CELL CARCINOMA (MRCC) PATIENTS TREATED WITH SUNITINIB? USEFULNESS OF NORMALIZED ARTERIAL DENSITY AND BLOOD FLOW

ABSTRACT Aim: Despite of the efforts, clinically useful biomarkers in mRCC remain unknown. The aim is to determine if radiological parameters can be useful to predict mRCC outcome to sunitinib. Methods: Twenty-six mRCC patients treated with first-line sunitinib were enrolled in this study. A volumetric study (21 cm) with perfusion-CT (Flash Definition, Siemens, Erlangen, Germany) was done in these patients before starting the treatment, 1 and 4 months after treatment initiation. Baseline size, normalized arterial (NAD) and venous density, and perfusion parameters (blood flow (BF), blood volume (BV) and permeability) and changes on these parameters were analysed. Results: 80.8% of the patients were men with a median age of 59.8 years (35.8 – 75.4). Clear cell carcinoma was the most frequent histology (73%) and 58% of the patient had a good prognosis according to MSKCC classification. According to RECIST criteria, 8 patients achieve a partial response (30.7%), 1 a complete response (3.8%), 6 stable disease (23.1%), 6 progressive disease (23.1) and 5 were not evaluable (19.2%). Patients that develop progressive disease had lower NAD (p = 0.0328) and BF (p = 0.0487) on pre-treatment CT. Higher basal NAD (median PFS in months: NA vs 6.8), p = 0.0154) and BF (17.23 vs 6.43, p = 0.0154) correlated with a longer progression-free survival (PFS). Baseline size did not present correlation with PFS. A high correlation between basal NAD and BF were found (R = 0.737, p Conclusions: Normalized arterial density and blood flow are potential biomarkers of response to sunitinib in mRCC patients. Disclosure: All authors have declared no conflicts of interest.