The role of peripheral T lymphocyte subsets and PD-1 expression as a biomarker for neoadjuvant treatment response in breast cancer

Background: The prognostic and predictive role of the interaction of the immune system with the tumor during the disease process has become increasingly important in recent years. T lymphocyte subgroups in peripheral blood can be used to monitor this dynamic interaction. We evaluated the relationship between baseline peripheral T lymphocyte subsets and treatment response (best objective response) in 47 breast cancer patients receiving neoadjuvant chemotherapy. Methods: This study investigated the impact of initial peripheral T lymphocyte subsets on neoadjuvant chemotherapy response in patients with invasive ductal breast. A total of 47 consecutive patients whose peripheral blood samples were able was included in the study group. The patients’ T lymphocyte subsets were measured before treatment. The patients were then followed up to assess their treatment response. Results: In our study, we found a significant negative relationship between baseline CD3, CD4, and CD8 absolute counts and pathologic complete response. We also found that high CD4/programmed cell death protein 1 expression (OR: 0.212, 95% CI: 0.061–0.735, P = .015) and high CD8/programmed cell death protein 1 expression (OR: 0.250, 95% CI: 0.073–0.858, P = .028) from baseline peripheral T lymphocyte were correlated with poor pathologic complete response. Conclusions: These results suggest that T lymphocyte subsets may be a predictive biomarker for treatment response in patients with breast cancer undergoing neoadjuvant chemotherapy. Further studies are needed to confirm these findings and to identify the optimal T lymphocyte subset for predicting treatment response.