The median expression levels of sera exosomal miR-15a, -16, and -193a-3p were significantly down regulated (all p < 0.05) in BE PD-L1(+) patients when compared to BE PD-L1(-) patients (Figure 4); further sera exosomal miR-15a, -15b, -16, and -193a-3p expression levels in EAC PD-L1(+) patients were significantly lower (all p < 0.01) when compared to EAC PD-L1(-) patients (Figure 4). Here, CD274 is linked to Barrett esophagus.