Abstract 1538: Vimentin expression as a potential immunomarker of predicting aggressive disease in clear cell renal cell carcinoma

Abstract Vimentin is a type III intermediate filament protein that is expressed in mesenchymal cells. Overexpression of vimentin has been detected in prostate cancer, lung cancer, gastrointestinal cancer, and melanoma. Although vimentin has been used for diagnosing and classifying renal neoplasms, little is known regarding its prognostic value. This study examines the prognostic significance of vimentin expression in clear cell renal cell carcinoma (ccRCC), chromophobe renal cell carcinoma (chRCC) and oncocytoma. Our patient group (n = 88) consisted of 63 men and 25 women with a mean age of 59 years at the time of diagnosis. Paraffin embedded specimens from these patients’ renal tumors were selected for this study which included ccRCC (n = 66), chRCC (n = 11) and oncocytoma (n = 11). Vimentin expression was determined by a tissue microarray technique (TMA) performed by a single pathologist (HL). Tumor staining results were classified as negative (<5%), weak positive (5-25%), intermediate positive (25-50%), moderate positive (50-75%), or strong positive (>75%). Clinicopathologic data was also included tumor histology, tumor size, T stage, grade, presence of sarcomatoid differentiation, presence of metastasis, and survival outcome following diagnosis were determined for each patient. Chi square statistical test analysis was performed in order to test the association of clinical parameters with vimentin immunoreactivity. Our results show that positive (>5%) vimentin expression was present in 100% of ccRCC cases, 9% of oncocytoma, and 0% of chRCC cases. In addition, vimentin expression in ccRCC was associated with metastasis (p<0.047) but was not significantly associated with pathologic T stage (P<0.185), Fuhrman grade (P<0.636), or the presence of sarcomatoid differentiation (P<0.855). With a median follow up of 7.2 years, there were 26 deaths in the ccRCC and none in the chRCC or oncocytoma groups. Positive vimentin staining was not associated with overall survival in the ccRCC group. Our results suggest that vimentin may be valuable predictor of metastatic disease in ccRCC patients. Citation Format: Mahmoud Mohamed, Lulin Hu, Haiyan Liu, Fan Lin, Heinric Williams. Vimentin expression as a potential immunomarker of predicting aggressive disease in clear cell renal cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1538.