TMB is a genomic biomarker calculated by the total number of somatic alterations detected using exome sequencing of the coding region.51 Highly mutated tumours can express neoantigens, which cause T-cell activation, suggesting that TMB may be a useful predictive biomarker for ICI response.52 Studies have demonstrated that tumours with high TMB showed positive treatment outcomes with PD-1/PDL-1 or CTLA-4 blockade.53, –55 A pan-tumour analysis of 12 trials using pembrolizumab treatment highlighted that patients with high TMB displayed significant improvement in pembrolizumab efficacy.56,57. This evidence concerns the gene CTLA4 and neoplasm.