International Randomised Phase III Clinical Trial in Children With Acute Myeloid Leukaemia

Inclusion Criteria: Inclusion criteria for trial entry * Diagnosis of acute myeloid leukaemia (AML) /high risk Myelodysplastic syndrome (MDS) (\>10% blasts in the bone marrow)/isolated myeloid sarcoma (MS) (either de novo or secondary). * Age \<18 years at trial entry. * No prior chemotherapy or biological therapy for AML/high risk MDS/isolated MS other than that permitted in the protocol. * Normal cardiac function defined as fractional shortening ≥28% or ejection fraction ≥55%. * Fit for protocol chemotherapy. * Documented negative pregnancy test for female patients of childbearing potential. * Patient agrees to use effective contraception (patients of child bearing potential). * Written informed consent from the patient and/or parent/legal guardian. Inclusion criteria for participation in the gemtuzumab ozogamicin dose finding study: Centres must be formally activated in order to be take part in the embedded dose escalation study. Please contact the trial office for further information. * Patient meets the inclusion criteria for trial entry. * Age: * ≥12 months for the major dose finding study * ≥ 12 weeks and \<12 months for the minor dose finding study * Normal renal function defined as calculated creatinine clearance ≥90ml/min/1.73m2. * Normal hepatic function defined as total bilirubin ≤2.5 upper limit of normal (ULN) for age unless it is caused by leukaemic involvement or Gilbert's syndrome or similar disorder. * Alanine transaminase (ALT) or aspartate transa…