Neo-adjuvant Pembrolizumab as an Alternative Treatment for MMRd Uterine Cancer

This study tests whether giving pembrolizumab — an immunotherapy drug that helps the immune system fight cancer — before surgery can shrink or eliminate uterine cancer, potentially making surgery less extensive. The study focuses on a specific type: Grade 3 or clear-cell uterine cancer with a defect in the DNA mismatch repair system (MMRd), which makes tumors more likely to respond to immunotherapy. **You may be eligible if...** - You are a woman 18 or older with a confirmed diagnosis of Grade 3 or clear-cell uterine cancer - Your tumor has been tested and found to have mismatch repair deficiency (MMRd) - You are planned for surgical removal of the uterus (hysterectomy) - You are not currently pregnant **You may NOT be eligible if...** - Your uterine cancer does not have mismatch repair deficiency - Your cancer is a different grade or type not covered by this study - You have autoimmune disease or have had prior immunotherapy - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.