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). The gene discussed is PDCD1; the disease is cancer.