Children and adults diagnosed with high-risk neuroblastoma patients with primary refractory disease or incomplete response to salvage treatment in bone and/or bone marrow will be treated for up to 101 weeks with naxitamab and granulocyte-macrophage colony stimulating factor (GM-CSF). Patients will be followed for up to five years after first dose. Naxitamab, also known as hu3F8 is a humanised monoclonal antibody targeting GD2