**8. Tumor infiltrating lymphocytes as biomarkers (TILs)**

Tumor infiltrating lymphocytes (TILs) have a predominant role in breast cancer as predictive and prognostic biomarker. It is present intratumorally and in adjacent stromal tissues. The increased presence of TILs in Breast cancer is associated with improved prognosis and overall survival in response to neoadjuvant chemotherapy [52, 53]. In a recent study higher number of TILs was in TNBC as compared to other breast cancer subtypes, therefore is associated with the possibility to show better responses to neoadjuvant and adjuvant chemotherapy with relapse free survival [54, 55]. The connection of TILs with anti-tumor immune response in TNBC patients also serves as a predictive biomarker, thereby making examination of immunotherapy in TNBC more interesting [14]. Furthermore, clinical trial KEYNOTE-173 trial investigating pembrolizumab in combination with chemotherapy has shown

promising results in the neoadjuvant setting of TNBC, as this trial demonstrated the presence of higher levels of TILs and higher PD-L1 expression resulting in a high combination score with increased overall response rates in TNBC patients [56].
