Takada K, et al. - Researchers evaluated the how chemotherapy with a trastuzumab, pertuzumab, and docetaxel (TPD) regimen effected immune microenvironments in human epidermal growth factor receptor (HER)2-positive breast cancer using immune-related proteins as indicators. Due to the use of TPD regimen, high CD8/FOXP3 ratio (CFR) gave rise to a high objective response rate (ORR) and long progression-free survival (PFS) in HER2-positive breast cancer. Thus, it was deduced that CFR could serve as one of the vital prognostic factors for this disease. Findings underscored the significance of cancer microenvironment in tumor immunology in anti-tumor treatment.