MP45-05 TO DISEASE: THE POTENTIAL OF AVOIDING CYSTECTOMIES THROUGH MIRNA PROFILES IN CELL-FREE URINE

Abstract

INTRODUCTION AND OBJECTIVES: Neoadjuvant chemotherapy prior to radical cystectomy has been shown to confer a survival advantage in patients with muscle-invasive bladder cancer. When combined with maximal endoscopic resection of visible tumor, 38% of patients can be rendered pathologic stage 0 (pT0) at the time of cystectomy. Previous studies have shown differential expression of microRNA (miRNA) in the cell-free urine of patients with muscle invasive and non-muscle invasive bladder cancer. We aimed to identify miRNA in the urine of patients with a history of invasive bladder cancer and differentiating patients with a complete response to therapy from those with persistent disease. METHODS: Total RNA was isolated from cell-free urine of patients undergoing cystectomy for muscle-invasive cancer (pT0, pT1, and >pT2), cT0 patients on active surveillance with a history of muscle invasive disease, as well as healthy control samples (HC) from patients with no history of cancer. Patient samples were divided into four groups: HC (n1⁄413), pT0/cT0 (n1⁄417), pT1 (n1⁄49) and pT2 (n1⁄423), consistent with the pathologic tumor stage of the specimen at the time of TURBT or surgery. Pooled RNA isolates from each group were profiled via PCR array of 751 miRNA (Exiqon). MiRNA expression levels were validated on individual samples by qRT-PCR. RESULTS: The number of miRNA detected within each group correlated with the severity of disease where 391 miRNAs were detected in the pT2 group, 137 in the pT1 group, 124 in the pT0/cT0 group, and 73 among the HCs. Hierarchical cluster analysis revealed two main branches; one consisting of the HC and pT0/cT0 pools and the other comprised of the pT1 and pT2 pools. Additionally, 32 miRNA were expressed in the pT1 and pT2 pools, and not detected in the pT0/ cT0 and HC pools. qRT-PCR confirmed differential expression of several miRNA distinguishing the two clustered groups (p<0.05). CONCLUSIONS: This study identified miRNA in cell-free urine differentiating patients with evidence of bladder cancer from those without evidence of disease (pT0/cT0). This miRNA profile may aid in the development of a noninvasive method of confirming response to neoadjuvant therapies, and may provide an adjunct to expectant management and surveillance strategies for the treatment of bladder cancer.