This study is testing a new medicine called **Sacituzumab Tirumotecan (Sac-TMT or MK-2870)** to treat certain types of breast cancer: **triple-negative breast cancer (TNBC)** and **hormone receptor (HR)-low positive/human epidermal growth factor receptor-2 (HER2) negative breast cancer**. These are cancers that have little or no amounts of proteins that help cancer cells grow. Sac-TMT is a targeted therapy, which means it specifically targets cancer cells to stop them from growing and spreading.
The study aims to find out if adding Sac-TMT to the usual treatment of **pembrolizumab** (an immune therapy) and chemotherapy helps reduce cancer in the breast and lymph nodes, and helps patients live longer without the cancer coming back.
- **Duration**: Participation involves multiple visits, including surgery.
- **Eligibility**: Must have early-stage, high-risk breast cancer and meet specific health criteria.
- **Risks**: Previous cancer treatments or specific health conditions may exclude participation.