Trial 201 is a phase 2, single‐arm, open‐label, international clinical trial designed to evaluate the efficacy and safety of naxitamab plus GM‐CSF in patients with HR neuroblastoma and primary refractory disease (refractory) or incomplete response to salvage therapy for relapsed or progressive disease (relapsed) limited to bone and/or BM (see Figure 1 for study definitions). Here, CSF2 is linked to neuroblastoma.