Medroxyprogesterone Acetate With or Without Entinostat Before Surgery in Treating Patients With Endometrioid Endometrial Cancer

PRIMARY OBJECTIVES: I. To determine whether the addition of the histone deacetylase inhibitor, entinostat, in combination with medroxyprogesterone acetate in the pre-operative setting results in up-regulation of activated progesterone receptors (PR) compared to medroxyprogesterone acetate alone. SECONDARY OBJECTIVES: I. To assess the response rate (as measured by cellular morphology and proliferation) and change in activated receptor levels with the addition of entinostat at the time of hysterectomy. OUTLINE: Two arms were randomly allocated to eligible patients with equal probability. ARM I: Patients receive medroxyprogesterone acetate intramuscularly (IM) on day 1 and undergo hysterectomy between days 21-24. ARM II: Patients receive medroxyprogesterone acetate IM on day 1 and entinostat orally (PO) on days 1, 8, and 15. Patients undergo hysterectomy between days 21-24.