Subtyping Muscle-Invasive Bladder Cancer to Assess Clinical Response to Trimodality Therapy

287Background: Trimodality therapy with TURBT followed by chemoradiation is an acceptable alternative to cystectomy for muscle invasive bladder cancer (MIBC). Recently, genomic profiling has demonstrated MIBC can be divided into three or more subtypes with differing responses to chemotherapy, suggesting genomic subtype may impact therapeutic response. Here, we explore the utility of genomic information to better select patients for bladder-sparing trimodality therapy. Methods: Transcriptome-wide gene expression profiles were generated for 189 MIBC TURBT samples from patients undergoing trimodality therapy at the Massachusetts General Hospital. Of these, 108 passed microarray QC and 100 had complete clinical information. The patient tumors were classified as basal, basal claudin-low, infilrated luminal or luminal subtype. The subtype and the expression of a number of bladder cancer genes were assessed for their association with need for salvage cystectomy and for overall survival. Finally, transcriptome-wi...