This study looks at using two experimental medicines, *sacituzumab govitecan-hziy (SG)* and *pembrolizumab*, for treating people with **Triple Negative Breast Cancer (TNBC)** after surgery. TNBC is a type of breast cancer that does not have certain receptors (like estrogen, progesterone, and HER2). The study compares if these medicines work better than the usual treatments doctors choose, which might include *pembrolizumab* or *pembrolizumab* plus another medicine called *capecitabine*.

Eligibility: Participants must be over 18, have had surgery, and still have some cancer left. They also need to have had proper radiation treatment and be in good health otherwise. People with stage IV breast cancer or previous breast cancer will not be included.

• Length of Study: The time commitment for participation is not specified.
• Visits Needed: Participants may need to visit the study site regularly for treatments and check-ups.
• Possible Risks: Risks include side effects from the experimental drugs, which will be monitored closely by the study team.

Participants should discuss with their doctor if this study is suitable for them.