Sacituzumab Tirumotecan (MK-2870) Plus Pembrolizumab Versus TPC in TNBC Who Did Not Achieve pCR (MK-2870-012)

Inclusion Criteria: * Has centrally confirmed TNBC, as defined by the most recent American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines * Has no evidence of locoregional or distant relapse, as assessed by the treating physician * Had neoadjuvant treatment based on the KEYNOTE-522 regimen (pembrolizumab with carboplatin/taxanes and pembrolizumab with anthracycline-based chemotherapy) followed by surgery according to National Comprehensive Cancer Network (NCCN) treatment guidelines for TNBC * Had adequate excision and surgical removal of all clinically evident disease in the breast and/or lymph nodes and have adequately recovered from surgery * Has non-pathologic complete response at surgery * Is able to continue on adjuvant pembrolizumab * Randomization must be conducted within 16 weeks from surgical resection * Completed adjuvant radiation therapy (if indicated) and recovered before randomization * Has provided tissue from the surgical resection for central laboratory determination of trophoblast cell surface antigen 2 (TROP2) status * If capable of producing sperm, the participant agrees to the following during the intervention period and for at least the time needed to eliminate each study intervention after the last dose of study intervention (120 days for sacituzumab tirumotecan and 95 days for capecitabine \[no restriction for pembrolizumab\]): agrees to refrain from donating sperm AND is either abstinent and agrees to remain absti…