The quantity of tumor-infiltrating lymphocytes (TILs) in breast cancer is a robust prognostic factor for improved patient survival, particularly in triple-negative and HER2- overexpressing breast cancer subtypes. In the last year, pembrolizumab, a T checkpoint based therapy has been approved for the treatment of patients with early stage and late stage triple negative breast cancer. In this talk I will discuss the latest clinical updates, upcoming potential trials as well as the complexities in patient management.