SPDL1 and central nervous system cancer: For PFS, patients with sPD-L1 concentrations above 14.35 pg/ml had worse PFS than those with low sPD-L1 levels (20.4 vs. 26.7 months, P = 0.027; Figure 3A), but an sPD-L1 concentration >14.35 pg/ml was not proven to be an independent prognostic factor for glioma patients in the multivariate analysis.