Soluble programmed death-ligand 1 are highly expressed in peripheral T-cell lymphoma: a biomarker for prognosis

Purpose: To investigate the role of soluble programmed cell death ligand 1 (sPD-L1) protein in plasma of patients with Peripheral T-cell lymphoma (PTCL). Methods: In total, 80 patients with newly diagnosed PTCL and 75 healthy controls were enrolled. Levels of sPD-L1 were measured by ELISA at diagnosis and after 3-8 courses of chemotherapy. The expression of PD-L1 in tumor tissues from nine PTCL patients was also detected. Results: sPD-L1 was higher in PTCL patients at diagnosis compared to healthy subjects (P < 0.0001). Patients in the intermediate/high-risk disease group had a higher level of sPD-L1 than patients in the low-risk group (P = 0.0003). Elevated sPD-L1 (>= 176.30 pg/ml) was the only biomarker for PTCL that retain statistical significance in multivariate analysis. Patients in the low-risk group with sPD-L1 >= 176.30 pg/ml had an adverse prognosis. Histological analysis showed that the expression of PD-L1 in tissues was positively correlated with sPD-L1 levels in plasma (Spearman = 0.9177, P = 0.0013). Conclusions: sPD-L1 is a sensitive biomarker predicting clinical outcomes in PTCL.