Atezolizumab + Sacituzumab Govitecan to Prevent Recurrence in TNBC (ASPRIA)

This is an open label single-arm phase II study to evaluate the combination therapy of the antibody drug conjugate, sacituzumab govitecan, and the anti-PD-L1 antibody, atezolizumab, in patients with triple negative breast cancer. The research study procedures include screening for eligibility and study treatment including laboratory evaluations, stool collection and follow up visits. This research study involves the following investigational drugs: * Sacituzumab govitecan * Atezolizumab Participants will receive study treatment for 18 weeks and will be followed for every 6 months for 3 years. It is expected that about 40 people will take part in this research study. This research study is a Phase II clinical trial. Phase II clinical trials test the safety and effectiveness of an investigational drug to learn whether the drug or drug combination works in treating a specific disease. "Investigational" means that the drug combination is being studied. The U.S. Food and Drug Administration (FDA) has not approved atezolizumab (Tecentriq) for residual triple negative breast cancer but it has been approved for advanced triple negative breast cancer and other cancers. Atezolizumab is a protein that affects your immune system by blocking the PD-L1 pathway. The PD-L1 pathway controls your body's natural immune response, but for some types of cancer the immune system does not work as it should and is prevented from attacking tumors. Atezolizumab works by blocking the PD-L1 pathway, which may help your immune system identify and catch tumor cells. The U.S. Food and Drug Administration (FDA) has not approved sacituzumab govitecan (Trodelvy) for your specific disease, but it has been approved for patients with metastatic triple-negative breast cancer who have been treated with 2 or more prior treatment regimens for their cancer. Sacituzumab govitecan is composed of a chemotherapy drug, called Irinotecan, which is attached to an antibody. Antibodies are proteins normally made by the immune system that bind to substances that don't belong in the body to prevent harm. The antibody in this study binds to certain types of cancer tumors.