Serum sPD-1 and sPD-L1 as Biomarkers for Evaluating the Efficacy of Neoadjuvant Chemotherapy in Triple-Negative Breast Cancer Patients

Background Neoadjuvant chemotherapy (NAC) is widely administered in the primary treatment of triple-negative breast cancer (TNBC). However, serum biomarkers for evaluating or monitoring the curative efficacy of NAC have not been established. Accumulating data have shown that soluble programmed death 1 (sPD-1) and its ligand (sPD-L1) might be potential biomarkers for evaluating the curative efficacy of chemotherapy and patient prognosis in several cancers but not yet in breast cancer. Patients and Methods Blood specimens were obtained from 66 TNBC patients who received NAC and 59 healthy women. The serum concentrations of sPD-1 and sPD-L1 were measured by enzyme-linked immunosorbent assay. Results Compared to healthy women, the serum concentration of sPD-1 was significantly elevated in TNBC patients before NAC (549.3 ± 58.76 pg/mL vs. 379.2 ± 17.30 pg/mL, P = .007), but there was only an increase tendency for sPD-L1 (227.7 ± 23.99 pg/mL vs. 195.0 ± 8.49 pg/mL, P = .22). The serum levels of sPD-1 and sPD-L1 before NAC in TNBC patients increased with tumor stage (P = .038 and .030, respectively). Patients who experienced complete or partial remission after NAC had significantly decreased serum levels of sPD-1 and sPD-L1 compared to patients with a poor response to NAC (P = .019 and .021, respectively). Conclusion Serum levels of sPD-1 and sPD-L1 could be used as noninvasive biomarkers for evaluating the malignancy of TNBC before NAC and for predicting the NAC response in TNBC patients.