Patients receive azacitidine subcutaneously (SC) on days 1-5 and 8-10, and entinostat orally (PO) on days 3 and 10. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients with progressive disease may continue azacitidine and entinostat in combination with hormonal therapy, at treating physician discretion, or undergo event monitoring.