IDO1 and neuroblastoma: Interestingly, 11q‐deleted NB showed significantly higher levels of the immune checkpoint PD‐L1 (Fig. 4A), as well as the immunosuppressive molecules IL‐10 (Fig. 4B), TGF‐β1 (Fig. 4C), and IDO1 (Fig. 4D), compared to MYCN‐amplified NB.