Introduction Anticancer immune responses contribute to the success of chemotherapy. We aimed to elucidate the value of tumor-infiltrating lymphocytes (TILs) as a prognostic marker for distant relapse-free survival (DRFS) in patients with HR positive/HER2 negative breast cancer in the taxane/anthracycline-based neoadjuvant chemotherapy (NACT).

Methods The cell type enrichment analysis for 64 immune and stromal cell types was performed with the web-based tool xCell based on RNA expression profiles of breast cancer from National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO). Kaplan-Meier analysis and LASSO-Cox PH regression model were used to assess the correlation of TILs and stromal cells infiltration with breast cancer distant relapse-free survival.

Results In this study, 123 HR positive/HER2 negative breast cancer patients derived from the dataset GSE25055 were eventually enrolled in the present study. LASSO-Cox PH regression analysis demonstrated that pre-NACT plasma cells and Th2 cells infiltration exhibited an independent prognostic value for DRFS (HR = 11.26, P = 0.036; HR = 15.13, P <0.001; respectively). A risk scoring model based on the TILs was conducted to divide patients into different risk groups with significantly different DRFS rates (P=0.0028). Compared with low risk group, high-risk group was comparatively associated with worse DRFS rates (3-year DRFS rate, 72.3% vs. 93.2%, P=0.0028).

Conclusion/Implications These results suggested that pre-NACT immunological plasma cells and Th2 cells infiltration is an independent predictive factor of DRFS for the patients with HR positive/HER2 negative breast cancer, which provides valuable and profound perspective of immune microenvironment and NACT prognosis.