A Study of Tazemetostat (Tazverik) Before Prostatectomy in Men With Prostate Cancer

This study is an open-label, single-arm, pilot, perioperative study of EZH2 inhibition in patients undergoing Radical Prostatectomy (RP). The EZH2 inhibition is intended to increase the sensitivity of the underlying tumor to the patient's immune system. Given the absence of data in this setting, we propose to pilot this experience with 4 weeks of tazemetostat at doses known to be clinically safe and effective at inducing clinical effects via inhibition of EZH2 as established for follicular lymphoma and epithelioid sarcoma: 800 mg twice daily with or without food. Prior to tazemetostat, blood will be collected (4 tubes) for immune cells, Circulating Tumor Cells, and plasma. This will be repeated at the time of RP. RP tissues will be collected. Additionally, patients will have a week lead-in to wear a FitBit Charge 5TM device (or similar model) to continuously monitor physical activity from baseline up until end of study. The start of the week lead-in will be considered the baseline visit. Subjects will also be asked to continue wearing the device until end of study and option to continue for up to 2 years after end of study in follow-up.