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

PRIMARY OBJECTIVE: I. To evaluate the activity and safety of a pure progesterone receptor (PR) antagonist, extended-release onapristone (onapristone), with anastrozole to treat women with recurrent metastatic estrogen receptor positive (ER+)/progesterone receptor positive (PR+) endometrial carcinoma. SECONDARY OBJECTIVES: I. To estimate the disease control rate (DCR). II. To describe duration of response (DOR). III. To evaluate the safety and tolerability. IV. To evaluate quality of life using the Edmonton Symptom Assessment questionnaire. EXPLORATORY OBJECTIVES: I. To characterize the ER and PR expression by immunohistochemistry (IHC) pre- and post-treatment. OUTLINE: Patients receive onapristone orally (PO) twice daily (BID) and anastrozole PO once daily (QD) on days 1-28. Treatment repeats every 28 days for up to 24 cycles (24 months) in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 3 months for up to 1 year after last treatment administration.