Prednisone Not Yet Recruiting Phase 2 Trials for Stage IVB Prostate Cancer AJCC v8 / Prostate Carcinoma Metastatic in the Bone / Stage IV Prostate Cancer AJCC v8 / Stage IVA Prostate Cancer AJCC v8 / Adenocarcinoma, Prostate / Metastatic Hormone Refractory Prostate Cancer Treatment