This study is testing a treatment called **lifileucel** for adults with advanced **endometrial cancer** (cancer of the lining of the uterus). It examines how effective and safe this treatment is for those who have already tried other treatments like **platinum-based chemotherapy** and medications that help the immune system fight cancer, known as **PD-1/PD-L1 agents**. **Key Points:** - **Participation Requirements:** You need to have a specific type of cancer diagnosis, have tried certain treatments, and meet health criteria. If you are over 70 years old, special permission is needed. - **Study Activities:** You'll need to have at least two tumors, one for removal and study, and one that can be measured for treatment response. - **Exclusions:** You cannot participate if you have untreated brain cancer, recent organ transplants, or other severe health issues. This study seeks individuals who can undergo this new treatment, and it provides a chance to try a potential new therapy for those with limited options. Participants should discuss their eligibility and potential risks with their healthcare provider.