CD274 and neoplasm: This is in agreement with a study in mice by Ebert et al., where MEK inhibition with cobimetinib profoundly blocked naïve CD8+ T cell priming, but led to a greater proportion of antigen-specific CD8+ T effector cells within the tumour by abating chronic T cell receptor (TCR) stimulation (Fig. 1), and ultimately resulted in a synergistic effect with PD-L1 ICB [33].