This study investigates if the combination of two drugs, **sacituzumab govitecan-hziy (SG)** and **pembrolizumab**, is safe and effective for treating **triple negative breast cancer (TNBC)**. TNBC is a type of breast cancer that does not have certain receptors like estrogen, progesterone, or HER2. Participants in the study must be over 18, have had surgery to remove visible cancer, and still have some cancer remaining. The study compares this combination treatment with the treatment chosen by a doctor, which may include pembrolizumab alone or with another drug called **capecitabine**. Participants must have good organ function, have recovered from surgery, and not have stage IV cancer or specific heart problems.

• This study requires participants to have a history of surgery and certain pre-study treatments.
• Participants will need to provide tissue samples for analysis.
• There are specific medical conditions and past treatments that may disqualify participation.