Brief summary

This phase III trial compares the addition of an immunotherapy drug (durvalumab) to usual chemotherapy versus usual chemotherapy alone in treating patients with MammaPrint High 2 Risk (MP2) stage II-III hormone receptor positive, HER2 negative breast cancer. Immunotherapy with monoclonal antibodies, such as durvalumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Chemotherapy drugs, such as paclitaxel, doxorubicin, and cyclophosphamide 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. There is some evidence from previous clinical trials that people who have a MammaPrint High 2 Risk result may be more likely to respond to chemotherapy and immunotherapy. Adding durvalumab to usual chemotherapy may be able to prevent the cancer from returning for patients with MP2 stage II-III hormone receptor positive, HER2 negative breast cancer.