SPDL1 and lung carcinoma: The level of soluble PD-L1 (sPD-L1) in serum/plasma has been detected from patients with some malignancies including pancreatic cancer, renal cell carcinoma, esophageal cancer, hepatocellular carcinoma, soft tissue sarcomas, metastatic gastrointestinal stromal tumors, and lung cancer (8–16).