Gettinger et al. functionally demonstrated that loss of HLA class I expression by CRISPR-mediated knock-out of β2-m in an immunocompetent cancer mouse model (A/J mice transplanted with murine lung cancer cell line UN-SCC680AJ) confers resistance to PD-1 blockade and tumour progression [220]. This evidence concerns the gene PDCD1 and neoplasm.