CD274 and neoplasm: Correspondingly, a recent study on children reported PD-1 expression in 19.4% of HL cases and in 18.2% of r/r HL cases, while PD-L1 expression in more than 50% of tumor cells was documented in 67.7% of HL cases and in 72.7% of r/r HL cases, suggesting that comparable responses to PD-1/PD-L1 blockade would be expected in patients undergoing first-, second-, or third-line therapy [156].