463 Background: Previous studies have demonstrated that a considerable proportion of BCs express androgen receptor (AR), and that AR might drive tumor growth. The RNA-based AR activity score is a novel analytic tool that may better quantify the functional role of AR. Methods: Samples were obtained from patients (pts) with MIBC who had cystectomy or transurethral resection of bladder tumor (TURBT). AR expression was quantified by pathologist scoring of immunohistochemistry (IHC). The AR activity score was quantified using RNA isolates from benign and cancerous sections of slides adjacent to those used for IHC. RT-qPCR of a panel of AR-regulated genes was performed with comparison of transcript levels to those in LNCaP prostate cancer cells. Clinical results were validated in the RT-112 cell line. Results: A total of 37 pts (81.8% male) were analyzed with a median of age of 67. The majority were diagnosed as cT3 (54.5%) and 62.2% underwent neoadjuvant chemotherapy (86.9% with cisplatin/gemcitabine). IHC demonstrated a range of AR positivity from 0.0% to 90.0%, with most samples (46.0%) having no staining. In contrast, the AR activity score was between 2.1% and 178.9% (relative to LNCaP cells) with a median activity of 32.2% in cancerous tissues and 44.0% in benign regions. AR expression and score showed no direct correlation. A strong association was seen between AR activity score in cancerous tissue and DFS (P = 0.005). Interestingly, AR score in benign tissue was inversely correlated with DFS (P = 0.04). Pts who received neoadjuvant chemotherapy were noted to less likely develop metastases (P = 0.05). A more marginal correlation was noted between AR activity score and pathologic downstaging. Treatment of cells transfected with an AR expression plasmid along with an AR-responsive luciferase reporter demonstrated a dose-dependent effect of cisplatin in this assay. Conclusions: IHC and AR activity scores represent independent measures in this MIBC cohort. Our study suggests that pts with higher AR activity may be more susceptible to chemotherapy, and may have prolonged DFS. Additional studies in larger cohorts are warranted.
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