Genomic aberrations previously linked to resistance in dMMR/MSI-H tumours treated with anti-PD-1/PD-L1 monotherapy were detected in more than half of the study population12–15,30 but their presence did not influence response to therapy suggesting that combined anti-PD-1/CTLA-4 blockade may overcome these resistance mechanisms. This evidence concerns the gene CTLA4 and neoplasm.