Megestrol Acetate Compared With Megestrol Acetate and Metformin to Prevent Endometrial Cancer

PRIMARY OBJECTIVE: I. To compare the change in endometrial cell proliferation, as measured by the percentage (%) of Ki-67 positive cells, in participants with endometrial intraepithelial neoplasia who undergo 4 weeks of treatment with megestrol acetate + metformin or megestrol acetate alone prior to planned procedure (hysterectomy) or progestin intrauterine device \[IUD\] placement). SECONDARY OBJECTIVE: I. To measure the changes in protein expression in the endometrial intraepithelial neoplasia lesion, using immunohistochemistry (i-vi) in subjects treated with megestrol acetate + metformin compared to those treated with megestrol acetate alone. i. Estrogen receptor (ER) and progesterone receptor (PR) ii. PTEN/PAX2 expression iii. Markers of the PI3K-Akt-mTOR pathway (phosphor-acetyl-CoA carboxylase (ACC), p(Ser473)-Akt, phosphor-S6K, p4EBP1) iv. Markers of cell death (TUNEL, cleaved caspase-3) v. Markers of intratumoral insulin signaling (Phosphorylated insulin receptor (pIR) and insulin-like growth factor-1 receptor (total and phosphorylated IGF1R), vi. Mismatch repair (MMR) deficiency (baseline only). EXPLORATORY OBJECTIVE: I. To explore whether baseline Ki-67 expression and other clinical characteristics are associated with treatment response. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Prior to standard of care planned procedure, patients receive megestrol acetate orally (PO) twice daily (BID) for 21-35 days (up to and including the night before planned procedure) in the absence of disease progression or unacceptable toxicity. Patients also undergo biopsy on the day of planned procedure. ARM II: Prior to standard of care planned procedure, patients receive megestrol acetate PO BID and metformin hydrochloride extended-release PO BID for 21-35 days (up to and including the night before planned procedure) in the absence of disease progression or unacceptable toxicity. Patients also undergo biopsy on the day of planned procedure. After completion of study treatment, patients are followed for up to 42 days.