Since CD8+ T cells showed an exhausted phenotype in the 4NQO-L tumors, and given that MAPK-pathway mutated HNCs are considered to be ‘hot’ tumors (enriched with CD8+ cells) and are thus susceptible to αPD-1 therapy,4 we predicted that blocking PD-1 would suppress tumor progression of KRAS-mutated 4NQO-T and 4NQO-L tumors. This evidence concerns the gene KRAS and neoplasm.