For the phase 1 dose escalation phase, the starting dose of enzalutamide will be 80 mg orally once a day (Level 1). The dosing regimen of cisplatin and gemcitabine will be at standard doses of Gemcitabine at 1000 mg/m^2 IV on days 1, 8 and cisplatin at 70 mg/m2 IV on day 1, repeated every 21 days for total of 6 cycles.~Three patients will be treated dose level 1 (enzalutamide 80 mg daily). If 0 patients experience dose limiting toxicity (DLT), dose escalation will be done to level 2 of enzalutamide 160 mg daily. If 1 patient experiences DLT, 3 more patients will be treated at the same dose level; if 1 of 6 experiences DLT, escalate the dose to next level, and if 2 or more of 6 experiences DLT, the dose level 1 (80 mg enzalutamide) will be the recommended dose for dose expansion cohort.~The cohort expansion will then be done by enrolling 12 patients with stage IV bladder cancer, who express androgen receptor (AR) staining of 1+ and above by immunohistochemistry (IHC), to determine the safety and tolerability of cisplatin and gemcitabine with the recommended dose level of enzalutamide (80 mg or 160 mg, depending upon the safety results from dose escalation part) in this expanded cohort of patients with AR + bladder cancer.~Enzalutamide would be continued after completion of 6 cycles of gemcitabine-cisplatin for patients exhibiting a response or stable disease, until they experience disease progression.
The main purpose of this study is to find out the dose of enzalutamide that can be safely given with gemcitabine and cisplatin in patients with advanced bladder cancer. Researchers also want to find out the side effects of these drugs when given together. This study will also help in finding out the effect on tumor of the combination of enzalutamide, gemcitabine and cisplatin.