• At least 18 years of age at the time of signing informed consent.
• Written informed consent signed in accordance with federal, local, and institutional
  guidelines prior to the first screening procedure.
• Histologically confirmed EC including: endometrioid, serous, undifferentiated, and
  carcinosarcoma.
• Must be able to initiate study drug 3 to 8 weeks after completion of their final dose of
  chemotherapy.

• Has any uterine sarcomas (carcinosarcomas – not excluded), clear cell or small cell
  carcinoma with neuroendocrine differentiation
• Received a blood or platelet transfusion during the 2 weeks prior to first cycle
• Major injuries or surgery within 14 days prior to C1D1 and/or planned major surgery
  during the on-treatment study period
• Females who are pregnant

Compliance to oral Sponsor-supplied study drug taken at home will be assessed by the
Investigator and/or study personnel at each visit and recorded in source documents after
discussion with the patient and after performing Sponsor-supplied study drug accountability.

• Patients will be provided a travel stipend
• Research Medications and treatment are provided at no charge.
• Medication, treatment, and testing considered standard of care will be billed to the patient’s insurance carrier

The objective of this study is to evaluate the efficacy of selinexor compared to placebo as maintenance therapy.