PDCD1 and lung adenocarcinoma: Li et al. [73] conducted an in vivo CRISPR screening using a sgRNA library targeting epigenetic factors in the KrasG12D/p53−/−(KP) mouse model of lung adenocarcinoma and found that the absence of the histone chaperone antisilencing function 1A (ASF1A) sensitizes the tumor to anti-PD-1 treatment, providing the basis for a novel combination treatment of ASF1A inhibition and anti-PD-1 immunotherapy.