The AVIATOR Study: Trastuzumab and Vinorelbine With Avelumab OR Avelumab & Utomilumab in Advanced HER2+ Breast Cancer

This research study is a Phase II clinical trial. Phase II clinical trials test the safety and effectiveness of an investigational drug combination to learn whether the drug combination works in treating a specific disease. "Investigational" means that drug combination is being studied. The FDA (the U.S. Food and Drug Administration) has not approved Utomilumab as a treatment for any disease. The FDA (the U.S. Food and Drug Administration) has approved Avelumab as a treatment for other diseases. The FDA (the U.S. Food and Drug Administration) has approved trastuzumab as a treatment option for this disease. The FDA (the U.S. Food and Drug Administration) has approved vinorelbine as a treatment for other diseases and is commonly used as a treatment option for this disease. The immune system is the body's natural defense against disease. The immune system sends a type of cells called T cells throughout the body to detect and fight infections and diseases-including cancers. One way the immune system controls the activity of T cells is through the PD-1 (programmed cell death protein-1) pathway. However, some cancer cells hide from T-cell attack by taking control of the PD-1 pathway and this stops T cells from attacking cancer cells. Avelumab is a type of drug, known as an antibody which is designed to block the PD-1 pathway and helps the immune system in detecting and fighting cancer cells. An antibody is a protein produced by the body's immune system when it detects harmful substances. Previous studies show that the administration of antibodies which block the PD-1 pathway can lead to tumor destruction. Utomilumab is an antibody designed to stimulate the body's immune system to fight cancer cells. Previous studies have shown that the administration of this type of antibody may help to prevent tumors from growing. In the laboratory, adding avelumab and Utomilumab to trastuzumab appears to improve effectiveness. It is not known whether this is true in humans. In this research study, the investigators are evaluating the activity of 3 different combinations: (a)trastuzumab and vinorelbine combined, (b) trastuzumab, vinorelbine and avelumab combined, and (c) trastuzumab, vinorelbine, avelumab and utomilumab combined in participants with metastatic HER2- positive breast cancer.