Cytotoxic T lymphocyte associated antigen 4 expression predicts poor prognosis in luminal B HER2-negative breast cancer

Cytotoxic T lymphocyte associated antigen 4 (CTLA-4) serves an important role in inhibiting anti-tumor immune response in the majority of solid tumors. However, a limited number of studies reported the function of CTLA-4 in luminal B HER2-negative breast cancer. Immunohistochemistry was performed to evaluate the expression of tumor and interstitial CTLA-4 in luminal B HER2-negative breast cancer tissues. The percentage of patients with tumor and interstitial CTLA-4 + was 41.2% (42/102) and 46.1% (47/102), respectively. There was a positive association between tumor CTLA-4 expression and interstitial CTLA-4 expression (P<0.05). The disease-free survival (DFS) of the tumor CTLA-4 + group was significantly shorter compared with patients with tumor CTLA-4 - (mean, 89.070 vs. 39.022 months; P<0.0001). Additionally, the DFS of interstitial CTLA-4 + group was shorter compared with the interstitial CTLA-4 - group (mean, 85.526 vs. 46.574 months; P<0.0001). Tumor and interstitial CTLA-4 expression may have prognostic predicting value in luminal B HER2-negative breast cancer. The present study may provide the basis for the use of a CTLA-4 blocker in patients with luminal B HER2-negative breast cancer.