In vivo experiments confirmed a synergistic therapeutic efficacy of the trametinib and anti-PD-1 combo, reducing tumor growth (p<0.05) and increasing mice survival (p<0.05), compared with either trametinib or immunotherapy alone...PD-L1 upregulation induced by Id1 blockade after trametinib treatment sensitized NSCLC cells to anti-PD-1 immunotherapy, blocking tumor growth and improving overall survival.