CD274 and lung carcinoma: HLA-A is usually downregulated on the cell surface, unlike HLA-B, but HLA-A02 might escape this downregulation mechanism because its expression has a statistically significant association with improved survival in lung cancer patients, driving MHC-I gene expression along with the effect of homozygosity at the HLA-I loci, which is more pronounced in patients with strong PDL1 expression (≥50%), as this is a key factor determining increased immune cell infiltration into tumor tissue [208].