SPDL1 and neoplasm: In the present study, we found that the serum sPD‐L1 concentration was weakly correlated in a linear manner with PD‐L1 expression on tumor cells and that a high serum sPD‐L1 level was a negative predictor of disease control using anti‐PD‐1 antibody (pembrolizumab or nivolumab) and an independent negative predictor of prognosis in advanced NSCLC patients receiving anti‐PD‐1 antibody (pembrolizumab or nivolumab).