The aim of this review is, therefore, to also highlight three of the most helpful and/or promising recent molecules in BC treatments to date (one for each main BC subtype: one for HER2+ patients, one for triple-negative breast cancer (TNBC) patients, and one for HR+/HER2− patients, with neratinib, atezolizumab, and palbociclib, respectively). The gene discussed is HR; the disease is breast cancer.