CD274 and neoplasm: Regarding the immune checkpoint protein PD-L1, a significant association was found between BRCA1 promoter hypermethylation and PD-L1 expression by tumor cells, using a 1% threshold (52.8% of hypermethylated tumors for tumors with < 1% cells expressing PD-L1 vs. 70% for tumors with ≥ 1% cells expressing PD-L1; p = 0.03), or by immune cells using a 50% threshold (34.7% of hypermethylated tumors in score three tumors vs. 17.9% in tumors with PD-L1 expression score 0–2; p = 0.011) (Table 2).