Abstract 2260: CD151 immunoreactivity at diagnosis predicts early biochemical failure and metastasis in prostate cancer
Authors: Vasquez Catalina , Martinez Carlos , Chan Susanne , Chalasani Venu , Gomez-Lemus Jose , Williams Andrew , Chin Joseph , Zijlstra Andries , Lewis John 
Published: June 2012

Abstract
Background: One in seven men will be diagnosed with prostate cancer (PCa) during their lifetime and nearly 25% of those will die as a result of metastatic disease. Current diagnostic methods for PCa fail to predict which patients harbor occult metastases and although Epstein's criteria are useful in establishing relative risk, a significant number of patients diagnosed with “low risk” PCa develop metastasis. Clearly, there is a need for more accurate prognostic tools to determine which patients are at higher risk of suffering metastasis. We have previously demonstrated that tetraspanin CD151 plays a role in tumor cell motility and metastasis that is dependent upon an extracellular epitope recognized by the monoclonal antibody 1A5 (mAb 1A5). We surmised that this antibody might specifically recognize a pool of CD151 that is relevant for clinical metastasis. In this study, we evaluate the role of CD151 as detected by mAb 1A5 as a molecular prognostic factor for PCa disease progression and metastasis. Methods: Specimens from 99 patients who underwent radical prostatectomy (RP) between 1994-1998 with pathological pT2 and pT3 were assessed by immunohistochemistry using mAb 1A5 with a mean follow up of 12.1 years ± 1.6 SD. After deparaffinization, immunohistochemical analysis was carried out and protein expression was categorized as negative (score=0); or positive in weak (1), moderate (2) and strong (3). CD151 analysis was also performed in benign tissue around and away from the tumor as internal negative control. Additionally, 36 diagnostic biopsy specimens of patients who had documented metastasis during their follow up were assessed for CD151 immunoreactivity. A database of patient demographic factors, disease factors and relevant survival information was generated and correlated with disease-free progression and survival. Results: CD151 immunoreactivity was higher in malignant tissue than in either benign tissue around (p=0.01) or away from the tumor (p&lt;0.01) in RP specimens. There was a strong correlation between CD151 expression in the prostatic luminal epithelium and time to biochemical recurrence (p=0.022) following RP. Importantly, there was a significant correlation between CD151 expression and metastasis (p&lt;0.01) in these patients. In biopsies obtained at diagnosis, CD151 immunoreactivity was associated with overall metastasis (p&lt;0.01), bone metastasis (p=0.01), and hormone resistance (p&lt;0.01). Conclusions: Patients who were CD151 positive as assessed with mAb 1A5 had earlier biochemical failure and a significantly higher incidence of metastasis. In the RP group, these early failures likely represented a subset of patients that harbored unrecognized micrometastatic disease. The detection of CD151 adds significant prognostic value to the prediction of biochemical failure and shows considerable promise at initial biopsy to discriminate patients with higher risk of metastasis.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2260. doi:10.1158/1538-7445.AM2011-2260