CD274 and esophageal squamous cell carcinoma: Similarly, PFS was also higher for chemo-IO irrespective of histology or PD-L1 expression (overall pooled HR = 0.72, 95% CI = 0.64 to 0.81, P < .001; for adenocarcinoma only, HR = 0.76, 95% CI = 0.70 to 0.83, P < .001; and for ESCC, HR = 0.69, 95% CI = 0.65 to 0.79, P < .00001) (Table  2, Supplementary Figure 3, A-F, available online).