In recent years, soluble PD-1/PD-L1 (sPD-1/sPD-L1) and exosomal PD-L1 (exoPD-L1) have been detected in the blood of tumor patients (17, 27), with many studies investigating the exact roles of these soluble molecules in cancer (28, 29). Here, SPDL1 is linked to neoplasm.