-  Established diagnosis of neuroblastoma according to the international criteria (INSS)<br/><br/>          -  High risk (HR): stage 4 over 18 months of age and oncogen MYCN (MYCN) amplified<br/>             neuroblastoma of any stage and any age until 25 years (recurrent disease (Germany and<br/>             The Netherlands) after re-induction chemotherapy (+/- other modalities) or newly<br/>             diagnosed disease (only The Netherlands):<br/><br/>          -  Complete front-line treatment including induction chemotherapy, radioisotope (mIBG)<br/>             treatment, appropriate local therapy such as surgical removal and/ or local<br/>             irradiation of the primary tumor and myeloablative chemotherapy with autologous stem<br/>             cell reinfusion according to the actual guidelines of the GPOH/DCOG<br/><br/>          -  achieved response status: stable disease or better (CR, VGPR, PR, SD).<br/><br/>          -  Written informed consent of parents or guardian and - if appropriate - of the<br/>             patient.<br/><br/>          -  For at least two weeks prior to start of trial medication off any standard or<br/>             experimental treatment no tumour surgery no immediate requirements for palliative<br/>             chemotherapy, radiotherapy or surgery<br/><br/>          -  The patient may have had prior central nervous system (CNS) metastases provided the<br/>             following criteria are all met:<br/><br/>        The patient's CNS disease has been previously treated The patient's CNS disease has been<br/>        clinically stable for four weeks prior to starting this study (assessed clinically and by<br/>        MRI or CT) The patient is off steroids for four weeks prior to starting the study and will<br/>        not require them during the course of the study A patient with seizure disorders may be<br/>        enrolled if well controlled on anticonvulsants and if no seizures have occurred within a 6<br/>        week period prior to starting trial treatment<br/><br/>          -  HIV sero-negative and neither active nor chronic-replicative hepatitis B infection<br/><br/>          -  Laboratory testing: The patients should have adequate functions of the cor, lung,<br/>             bone marrow, liver, kidney<br/>