MYCN and neuroblastoma: In a prospective study, high-dose combined chemotherapy did not improve the prognosis of stage IV patients with MYCN amplification.[12] The efficacy of anti-GD2 antibody in relapsed or refractory patients remains under investigation.[13] Although immunotherapy with maintenance therapy was found to increase 2-year survival in patients with recurrent or refractory NB,[14] it was not analyzed in patients with MYCN amplification, and the 5-year and longer survival values are still unknown.