Besides, the expression of BTLA was found to be up‐regulated in various tumors.31, 32 For instance, Oguro et al31 showed that the elevated expression of BTLA was closely correlated with a lower density of CD8+ T cells, and further indicated that the higher expression of BTLA was associated with a worse prognosis in gallbladder cancer patients. This evidence concerns the gene CD8A and gallbladder cancer.