Abstract 4378: Pericyte coverage of differentiated vessels inside tumor vasculature is an independent unfavorable prognostic factor for patients with clear cell renal cell carcinoma

Background: The clinical significance of pericyte coverage (PC) surrounding differentiated vessels in clear cell renal cell carcinoma (CCRCC) is unclear. Objective: To evaluate the effect of PC on the prognosis of patients with CCRCC. Methods: Samples from two cohorts of CCRCC patients (Asian, 101 cases; U.S., 542 cases) were immunohistochemically doubled-stained for a pericyte marker (α-SMA) and a differentiated vessel marker (CD34), followed by multispectral image capturing and computerized image analyses to quantify the microvessel density (MVD) and pericyte coverage of differentiated vessels. The correlations of PC or MVD with clinicopathological characteristics were analyzed. Univariate and multivariate survival analyses were performed. Results: Uneven distributions of differentiated MVD and PC were found, with higher MVD in the peripheral portion of the tumor and higher PC in the inner portion. There was an inverse correlation between differentiated MVD and PC. Higher PC correlated with more aggressive clinicopathological characteristics of CCRCC in both cohorts, including more advanced T-stage, higher pathological grades, and occurrence of tumor necrosis. The MVD:PC ratio was an independent favorable prognostic factor for overall survival in the Asian cohort and for recurrence-free survival in the U.S. cohort. PC and MVD were also independent prognostic factors, with higher PC or lower MVD predicting a poorer outcome. The combination of PC and MVD could better distinguish the outcome of CCRCC patients. PC combined with differentiated MVD, or MVD:PC ratio provided additional independent prognostic information to the Leibovich risk model, and using that information we generated improved risk models. Conclusions: The distributions of MVD and PC were uneven in CCRCC. Higher PC correlated with more aggressive clinicopathological characteristics. PC was an independent unfavorable prognostic factor. Targeting pericytes should be taken into consideration in anti-angiogenic therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4378. doi:1538-7445.AM2012-4378