ERBB2 and breast cancer: Neratinib, a tyrosine kinase inhibitor, has recently been approved for the extended adjuvant treatment of patients with HER2-positive early BC, due to its significant improvement of five-year disease-free survival (DFS) [22]; it was approved in the United States for the treatment of metastastic breast cancer as well, based on an improvement of PFS and time to intervention for the involvement of the central nervous system [23].