PD-L1 acts as a promising immune marker to predict the response to neoadjuvant chemotherapy in breast cancer patients

Abstract Aims Programmed death-ligand 1 (PD-L1) is a negative immune stimulatory molecule that plays a key role in the tumor immune escape. Here in this study, we have tried to analyze the clinical value of PD-L1 positive expression (PD-L1+) in predicting the outcome of breast cancer patients and to establish its role as new biomarker to guide precise treatment. Method The PubMed and EMBASE were searched for all original English language articles published before 30 January 2019, all articles reported the predictive and prognostic implications of PD-L1+ in breast cancer. The data was analyzed using Stata version 12.0. Results Our analysis showed that PD-L1+ rate varied from 19.7% to 77.6% in breast cancer patients. Specifically, the patients from ER+, PR+, luminal A, luminal B, and HER2+ subtypes displayed lower PD-L1 expression, while the PD-L1+ percentages did not follow any trend in patients with ki67+, normal-like, HER2 overexpression and basal-like subtype. In addition, PD-L1+ was observed to be associated with significantly improved pathological complete response to neoadjuvant chemotherapy (ORs = 2.01, 95%CI: 1.35-3.01, p Conclusion Our study concluded that PD-L1+ was a promising immune parameter with a potential to predict neoadjuvant chemotherapy response, but cannot indicate the higher death or recurrence / metastasis risk.