Repurposing ethacrynic acid for the treatment of bladder cancer.

521Background: Bladder cancer is a common cancer in the US. Approximately seventy-five percent of new cases present as non-muscle invasive bladder cancer (NMIBC) with a high recurrence rate. Our group has demonstrated in well-characterized human NMIBC cell lines that ethacrynic acid (EA) suppresses growth by inhibiting proliferation, clonogenicity, spheroid formation and inducing apoptosis. Additionally, EA affects markers of stemness and may work through the NOTCH signaling pathway. We present a clinical trial characterizing the safety and urinary tract exposure to EA and metabolites following oral administration in patients undergoing transurethral resection of bladder tumor (TURBT). Methods: Institutional review board approval (#3674) was obtained for a Pilot trial in patients with presumed non-muscle invasive bladder cancer undergoing TURBT. All participants were given a single, 50 mg oral dose of EA in the pre-operative bay. Urine was collected at baseline, upon insertion of cystoscope (30-60 minutes...