Onapristone and Anastrozole for the Treatment of Refractory Hormone Receptor Positive Endometrial Cancer

Inclusion Criteria: * Age greater than or equal to 18 years old * Histologically confirmed diagnosis of endometrial cancer with ER and/or PR expression \>= 1% by IHC on archival tissue taken within the prior 3 years or new biopsy if no archival tissue is available. IHC results do not have to be from Thomas Jefferson University * Patients who have failed one prior treatment with a platinum/taxane chemotherapy regimen for management of disease \* Patients cannot have treatment with more than 2 prior lines of therapy (one line must be platinum/taxane regimen) * Measurable disease as defined by Response Evaluation Criteria in Solid Tumors (RECIST) version (v.)1.1. Measurable disease is defined as at least one lesion that can be accurately measured in at least one dimension. Each lesion must be \>= 10 mm when measured by computed tomography (CT) or magnetic resonance imaging (MRI). Lymph nodes must be \>= 15 mm in short axis when measured by CT or MRI * Patients with the following histologic epithelial cell types are eligible: * Endometrioid adenocarcinoma * Serous adenocarcinoma * Undifferentiated carcinoma * Clear cell adenocarcinoma * Mixed epithelial carcinoma * Adenocarcinoma not otherwise specified (NOS) * Please note: patients with carcinosarcoma are ineligible for this trial * Patients must have had one prior treatment with a platinum/taxane chemotherapy regimen for management of disease * Eastern Cooperative Oncology Group (ECOG) performance status 0-1 …