The Impact Of Mre11 In Nuclear To Cytoplasmic Ratio On Outcomes In Muscle Invasive Bladder Cancer: An Analysis Of Nrg/Rtog 8802, 8903, 9506, 9706, 9906, And 0233.

343Background: Biomarkers are needed to help select patients (pts) with muscle invading bladder cancer (MIBC) for bladder sparing chemotherapy and radiation treatment (CRT). Higher MRE11 expression has been identified as a potential RT response marker in MIBC. MRE11 protein is involved in the DNA double strand break repair mechanism. This analysis evaluates associations between MRE11 expression and outcome in pts from 6 NRG/RTOG bladder-sparing RT protocols. Methods: Archival tissue via TMA or unstained slides was used. Cases were stained with anti MRE11 antibody Rabbit mAb, clone EPR3471 (Epitomics at 1:1500 dilution). Slides were scanned on an Aperio FL instrument and analyzed via Automated Quantitative Image analysis (AQUA). MRE11 scores were determined within the nucleus and cytoplasm of urothelial cells and a ratio of nuclear to cytoplasmic (N/C) score calculated. A ratio was used to normalize scores and overcome pre-analytical variation. MRE11 N/C was analyzed by quartile cut points. Cumulative inci...