Four European clinical trials with different treatment schedules of ch14.18/CHO are being conducted to investigate the influence of a combined immunotherapy of ch14.18/CHO, interleukin-2 (IL-2) and 13-cis-retinoid acid on the outcome of patients with high-risk NB in the absence or presence of haploidentical blood stem cell transplantation. Here, IL2 is linked to neuroblastoma.