CD8A and neoplasm: Studies have reported that MMRD/MSI-high status is a promising biomarker for predicting the sensitivity to ICIs27, with tumours exhibiting high PD-L1/high CD8+ CTLs designated as “immune-inflamed tumours” or “hot tumours” displaying positive responses compared with ICI-resistant uninflamed tumours or ‘cold tumours’ without PD-L1 expression/CD8+ CTLs28.