CD8-Positive T-Cells Are Key Immune Cells for Predicting the Therapeutic Effect of Neoadjuvant Chemotherapy in Triple-negative Breast Cancer

Background/Aim: Patients with triple-negative breast cancer (TNBC) who obtain a pathological complete response (pCR) after neoadjuvant chemotherapy have an improved prognosis. Lymphocyte-predominant breast cancer is more likely to respond to neoadjuvant chemotherapy. Here, we investigated the correlation between tumor-infiltrating lymphocytes (TILs) in pre-treatment biopsy specimens from patients with TNBC in relation to response to NAC. Patients and Methods: The level of infiltration by immune cells expressing immune cell lineage surface markers (CD8, CD4, CD19, CD14, CD11c, and CD11b) in biopsy specimens from 52 patients with TNBC was examined using multispectral immunofluorescent labelling. Results: The level of CD8-positive TILs was significantly higher in patients with a pCR (p=0.045). The Cox proportional hazard model confirmed that lymph node involvement was associated with poorer disease-free survival (p=0.008). A high level of CD8-positive TILs was related to significantly prolonged disease-free survival in patients with node-positive TNBC (p=0.018). Conclusion: Assessing infiltration by CD8-positive TILs in the primary tumor is a useful biomarker to predict pCR and improved outcome in patients with node-positive TNBC.