KRAS and lung adenocarcinoma: First of all, KRAS-mutant tumours are characterised by the presence of CD8 + lymphocyte infiltrates in the tumour microenvironment (TME),20 while a significant association between KRAS mutations and PD-L1 expression has been observed in lung adenocarcinoma.21,22 Coelho et al.23 have recently demonstrated that oncogenic RAS signalling upregulated tumour PD-L1 expression stabilising the PD-L1 transcript in KRAS-mutant adenocarcinoma, thus providing an additional mechanism whereby KRAS-positive tumours respond to PD-1/PD-L1 inhibitors.