We performed a correlation analysis of high-level microsatellite instability status with the quantity and quality of tumour-infiltrating immune cells, Major histocompatibility Complex class I (MHC I), and Programmed Death-Ligand 1 (PD-L1) expression in the same cholangiocarcinoma cohort.8,9 This revealed a significant higher number of tumour-infiltrating immune cells (particularly intratumoural CD8 + T cells, FOXP3 + regulatory T cells (Tregs), and CD20 + B cells) compared to all other microsatellite-stable cases of the cohort (n = 308, Table 2). The gene discussed is CD8A; the disease is cholangiocarcinoma.