 Triple negative breast cancer, TNBC, is a challenging form of breast cancer as it lacks estrogen receptor, ER, progesterone receptor, PR, and human epidermal growth factor receptor 2, HER2, expression, making it difficult to treat with traditional hormonal therapies. Recent research has focused on identifying biomarkers in TNBC, such as tumor infiltrating lymphocytes, TILS, and mismatch repair deficiency, DM, to guide patient selection for immunotherapy. Additionally, microsatellite instability, MSI, is also associated with DMMR and can be used as a predictive marker for immunotherapeutic responses. These biomarkers have the potential to identify patients who may benefit from immunotherapy, allowing for more targeted treatment and improved outcomes. This article was authored by Francesca Maria Porta, Elam Sejati, Konstantinos Venetus, and others.