Quantitative and Qualitative Variations in TILs in Risk Stratification and Patient Selection for Neoadjuvant Chemotherapy of the Luminal B and Triple-Negative Breast Cancer Immunophenotype

Luminal B breast cancer (LBBC) represents an aggressive, high-grade ER+ disease, associated with a high proliferation rate, higher mutation burden, and higher probability of eliciting the immune response. Clinical and pathological data from 89 patients of stage II-III, triple-negative (TN), and luminal B-like BC (LB-like BC) were included in the analysis. All patients were submitted to neoadjuvant chemotherapy (NACT). Quantitative and qualitative evaluations of TILs (Tumor-Infiltrating Lymphocytes) were performed on tissue microarrays constructed from pretreatment core-needle biopsy tumor specimens. The proportion of stromal TILs, CD8, CD4, and PD-L1 positive (+) immune cells (IC), as well as the number of FOXP3, CTLA4, and HSP-70+ IC, was observed concerning tumor immunophenotype, traditional clinicopathological prognostic factors, and tumor response to NACT. There was no statistically significant difference in the proportion of stromal TILs between the LB-like and TNBC (p = 0.344) cohorts. However, a higher CD4/CD8 ratio was associated with the TNBC biology (p = 0.018) and within the LB-like BC cohort with a high proliferation index and metastatic nodal involvement (p = 0.045, p = 0.015). Within the LB-like BC cohort, a higher expression of PD-L1 and HSP70+ IC was associated with a high proliferation index of tumor cells (p = 0.018, p = 0.040), massive metastatic nodal involvement (p = 0.002, p = 0.026), and higher stages of disease (p = 0.004, p = 0.042). Better response to NACT was associated with higher numbers of HSP70+ IC and higher proportions of CD8+ cells within the LB-like BC cohort (p = 0.045, p = 0.012). Routine evaluation of immune markers and HSP70 may help identify high-risk patients of LB-like breast cancer who would have a better response to NACT.