Study Overview: This study tests a drug called selinexor as a maintenance treatment for patients with a specific type of endometrial cancer (EC) that is advanced or has returned. This type of cancer is described as p53 wild-type (wt), meaning it doesn't have a certain genetic mutation. The goal is to see how safe and effective selinexor is for patients who have already responded well to a previous treatment using platinum-based therapy for at least 12 weeks. Participants will be randomly assigned to receive either selinexor or a placebo, which is a harmless pill with no active drug.

• The study will include 220 participants who meet specific medical criteria.
• Participants should be able to start taking the study drug within 3 to 8 weeks after their last chemotherapy session.
• Selinexor and placebo treatment will be compared to understand their effects.

Important Considerations: The study involves regular visits and monitoring. Participants must have a minimum life expectancy of 12 weeks and meet health criteria related to liver, kidney, and bone marrow function. It's important to consider potential risks and benefits before participating. Additionally, premenopausal women need a negative pregnancy test and must use contraception during the study. Participants must not have other serious health conditions or be pregnant or breastfeeding.