Research ProposalBackgroundPatients with metastatic bladder cancer limited to the pelvic lymph nodes have improved rates of response to chemotherapy and better outcomes compared to those with widely metastatic disease. Research identifying biomarkers or subtypes to predict sensitivity to chemotherapy exclude node positive patients or only make up only a small subset. Additionally, these studies use bladder tumor tissue for analysis and have not analyzed lymph node positive tissue. This assumes that bladder tumors are surrogate predictors for response of micrometastatic or metastatic disease to the nodes, which is unknown. This is an important distinction as there may be unique signatures within the lymph node positive tissue not present in bladder tumor that can better predict response to chemotherapy. Interestingly, molecular subtype classification of bladder tumor tissue can be distinct from synchronous lymph node tissue. HypothesisDistinct mutational signatures, gene expression patterns and immune landscapes in node positive tissue more accurately predicts nodal response to chemotherapy and outcomes compared to matched bladder tumors. MethodsData was retrospectively collected from patients with cTanyN1-3M0 bladder cancer who underwent radical cystectomy at the University of Texas MD Anderson Cancer Center. A subset of these patients underwent lymph node biopsy prior to chemotherapy to determine true nodal status. Nodal and bladder response to chemotherapy was based on final pathology at cystectomy. Recurrence free and overall survival were determined. Next Generation Sequencing and mass spectrometry based methods (cytometry by time of flight, i.e. CyTOF) will be used to identify unique markers in bladder tumor and matched node tissue from biopsy prior to chemotherapy to identify novel immune signatures and molecular markers of predictors of response to chemotherapy.