Imlunestrant with or without abemaciclib for treating ER-positive, HER2-negative locally advanced or metastatic breast cancer after endocrine therapy

Imlunestrant with or without abemaciclib is in development for the treatment of patients with locally advanced or metastatic oestrogen receptor positive (ER+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer. Breast cancer is when abnormal cells in the breast begin to grow in an uncontrolled way and eventually form a tumour. Locally advanced breast cancer is where cancer has spread from the breast to areas close to the breast or to the chest wall. Metastatic breast cancer is where the cancer has spread to other parts of the body. ER+ breast cancer is a type of breast cancer that expresses the oestrogen hormone receptors. HER2- breast cancers have low or no expression of the HER2 protein in cancer cells. Targeted therapies remain an unmet need in the treatment of ER+/HER2- metastatic breast cancer due to the development of resistance to existing hormonal treatment.