Ribociclib, Tucatinib, and Trastuzumab for the Treatment of HER2 Positive Breast Cancer

This phase Ib/II trial studies the side effects and best dose of ribociclib, tucatinib, and trastuzumab for the treatment of HER2 positive breast cancer that has spread to other parts of the body (metastatic), and then compares the effect of ribociclib, tucatinib, trastuzumab with or without fulvestrant to docetaxel, carboplatin, trastuzumab, and pertuzumab (standard of care) for the treatment of early stage breast cancer before surgery (neoadjuvant therapy). Ribociclib and tucatinib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Trastuzumab is a form of targeted therapy because it attaches itself to specific molecules (receptors) on the surface of tumor cells, known as HER2 receptors. When trastuzumab attaches to HER2 receptors, the signals that tell the cells to grow are blocked and the tumor cell may be marked for destruction by the body's immune system. Pertuzumab is a monoclonal antibody that may interfere with the ability of tumor cells to grow and spread. Estrogen can cause the growth of breast tumor cells. Fulvestrant blocks the use of estrogen by the tumor cells. Chemotherapy drugs, such as docetaxel and carboplatin, 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. Giving ribociclib, tucatinib, and trastuzumab with or without fulvestrant before surgery may make the tumor smaller and may reduce the amount of normal tissue that needs to be removed.