Trial Category: Breast

This randomized phase III trial studies how well paclitaxel, trastuzumab, and pertuzumab with or without atezolizumab works in treating patients with breast cancer that has spread to other parts of the body. Drugs used in chemotherapy, such as paclitaxel, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Immunotherapy with trastuzumab, pertuzumab, and atezolizumab, may induce changes in body’s immune system and may interfere with the ability of tumor cells to grow and spread. It is not yet known whether giving paclitaxel, trastuzumab, and pertuzumab with or without atezolizumab may kill more tumor cells.