By multivariate analysis (represented by the forest plot in Figure 2D), we observed that this biomarker can predict BC patients’ response to NACT (p = 0.01, OR = 1.856 (95% CI 1.161–2.968)), even when the patients’ age, the BC subtype, and other immunological parameters of the tumor, such as HLA-DR expression level in Tregs, PD-L1 expression in tumor cells, and percentage of infiltrating CD4+ and CD8+ T cells, are taken into account. The gene discussed is CD8A; the disease is neoplasm.