Capecitabine Plus Pembrolizumab in Patients With Triple Negative Breast Cancer After Chemo-immunotherapy and Surgery

This study is testing whether adding pembrolizumab (an immunotherapy drug) to capecitabine (a chemotherapy pill) helps prevent triple-negative breast cancer from coming back after patients have already completed chemotherapy plus immunotherapy and surgery. **You may be eligible if...** - You are 18 or older - You have triple-negative breast cancer (a type that lacks hormone and HER2 receptors) - You previously received at least 6 cycles of standard chemotherapy before surgery - You still had cancer remaining in the breast or lymph nodes after surgery (residual disease) - You have recovered well enough from surgery **You may NOT be eligible if...** - You have already received pembrolizumab or other PD-1/PD-L1 immunotherapy drugs - You have had a prior different type of breast cancer treated with similar drugs - You have active autoimmune disease - You have serious heart, liver, or kidney problems Talk to your doctor to see if this trial is right for you.