Existing randomized studies that evaluate PD-(L)1 blockade in the second-line treatment of ESCC patients demonstrate a significant OS improvement in anti-PD-(L)1 compared with chemotherapy (Kato et al., 2019; Shah et al., 2019; Huang et al., 2020; Kojima et al., 2020; Luo et al., 2021). Here, CD274 is linked to esophageal squamous cell carcinoma.