SPDL1 and Pleural effusion: Taken together, these findings suggest that the presence of sPD-L1 splicing variants or the level of soluble PD-L1 in plasma or pleural effusion may work as a biomarker to predict a patient’s response to PD-L1 blockade therapy and that aPD-1 antibody treatment could be a therapeutic option to overcome sPD-L1 variant-induced resistance.