A Phase II, Two-Arm Study of Everolimus and Letrozole, +/- Ribociclib (Lee011) in Patients With Advanced or Recurrent Endometrial Carcinoma

Inclusion Criteria: * Patient has signed the informed consent (ICF) prior to any screening procedures being performed and is able to comply with protocol requirements. * Patients must have histologically-confirmed endometrial carcinoma (endometrioid and mixed endometrioid tumors, any grade). * Patients must have advanced or recurrent disease that is refractory to curative treatment based on imaging or clinical exam. * Patient must consent to allow for a baseline tumor biopsy. Tumor material from biopsies done before the screening period are acceptable if the biopsy was performed within 3 months prior to the planned treatment start and no other systemic cancer therapy was administered in the interim. If a biopsy is performed and the specimen is considered non-diagnostic, does not have enough tissue, or the biopsy is deemed infeasible to perform, this does not prevent the patient from proceeding with the treatment * Patients must have had no more than two prior chemotherapeutic regimens for recurrent endometrial carcinoma. Chemotherapy administered in conjunction with primary radiation as a radio-sensitizer is not counted as a prior treatment for recurrent or advanced disease. * Prior radiation therapy of any kind is allowed. * Prior treatment with letrozole is allowed if the patient meets the washout period of 10 days. * All patients must have measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 defined as at least one "target lesion" that …