CD274 and gallbladder cancer: Next, we examined the expression levels of gallbladder cancer-related markers (ERBB2, CA19-9, CEA, EGFR, Ki67, PD-L1) using immunohistochemistry; all markers were detected in the PDX, PDO, and PT samples with the exception of PD-L1, which is a negative prognosticator for gallbladder cancer (Figure 1D).