SPDL1 and neoplasm: Strongly positive PD‐L1 expression on tumor cells (HR, 0.486 [95% CI: 0.277–0.852]; P = 0.001) and an sPD‐L1 concentration ≥90 pg/mL (HR, 1.910 [95% CI: 0.972–3.753]; P = 0.061) were independent predictors for PFS.