CD274 and lung adenocarcinoma: Previous research has shown that EGFR mutations can lead to reduced PD-L1 expression, diminished T-cell infiltration, and a shrinking proportion of PD-L1+/CD8+ TILs [49]. A lack of CD8+ tissue-resident memory (TRM) cells in EGFR-mutated lung adenocarcinoma might be a key factor contributing to a suppressive TME [50].