Impact of serum soluble programed death ligand 1 on end of treatment metabolic response of diffuse large B cell lymphoma patients

Programmed death ligand-1 (PD-L1) plays an important role in the immune evasion of cancer cells and, in turn, can influence the outcome of many malignancies. The serum soluble PD-L1 (sPD-L1) levels were measured in diffuse large B cell lymphoma (DLBCL) patients at diagnosis and at end of treatment. Their impact on end of treatment metabolic response was analyzed. Serum sPD-L1 level was significantly elevated in DLBCL patients at diagnosis than in controls (P<0.001). Also, serum sPD-L1 level at diagnosis was significantly higher than that at end of treatment (P<0.001). Patients who achieved partial response (PR) had significantly higher serum sPD-L1 level at end of treatment than controls (P<0.001). In contrast, all patients especially those who achieved complete response (CR) had insignificantly different serum sPD-L1 level at end of treatment than controls (P=0.354 and P=0.090, respectively). There was a significant difference between serum sPD-L1 level at diagnosis and that at end of treatment in patients who achieved PR and CR (P=0.023 and P<0.001, respectively). On univariate analysis, presence of comorbidities, Ann Arbor stage IV, high serum sPD-L1 level at diagnosis and high serum sPD-L1 level at end of treatment were significantly associated with achievement of PR (P=0.018 and P=0.043, P=0.045 and P<0.001, respectively). On multivariate analysis, serum sPD-L1 levels at diagnosis and at end of treatment were still influencing metabolic response significantly (P=0.014 and P=0.007, respectively). Serum sPD-L1 is a predictor for metabolic response to immunochemotherapy in DLBCL patients.