CD274 and neuroblastoma: Previous immunotherapy studies advocated the blockade of immunosuppressive targets as an effective strategy (e.g., inhibition of PD-L1 (Okla et al., 2020) or CTLA4 (Ascierto et al., 2011)); thus, our focus was directed toward immunosuppressive markers highly expressed on NB cells (EZH2, SMC3 and DNMT1).