Rapid organoid development, drug screening, and neoadjuvant chemotherapy response prediction for patients with locally advanced bladder cancer

543 Background: Neoadjuvant chemotherapy prior to radical cystectomy (RC) for muscle-invasive urothelial carcinoma (UCCx) is the standard of care though the absolute survival benefit is small, and some patients progress during chemotherapy. While progress has been made in the prediction of sensitivity to platinum-based chemotherapies, providing more accurate, personalized, and clinically-relevant chemotherapy response prediction is an unmet need. We present our early and ongoing experience with rapid, organoid-based drug-screening. Methods: one gram of tumor was procured from patients undergoing TURBT or RC and divided between DNA/RNA sequencing, organoid drug-screening, and patient-derived xenografts. Tissue was dissociated, filtered, and resuspended in organoid media for serial passage and drug screening. Drugs were tested at “Cmax” concentration, which is the maximum plasma concentration in human trials so as to provide physiologic relevance. Results were normalized to control such that a value of 100 indicated no drug effect compared to control, and a value of 0 indicated complete response. Number of drugs screened was dependent upon tissue available, but was often 20-30. Results: 25 patients have undergone rapid organoid development and drug testing to date. Clinical correlations with chemotherapy response are ongoing. Drug response analyses were available 5-10 days following procedure. Select drug response data from the 9 most recent patient organoid samples are presented in the Table. DNA and RNA sequencing and PDX models are in progress. Conclusions: This platform allows for the rapid determination of neoadjuvant chemotherapy response and may further guide selection of therapeutic agents in patients with locally advanced bladder cancer.[Table: see text]