A Treatment Study Protocol for Participants 0-45 Years With Acute Lymphoblastic Leukaemia

Inclusion Criteria: * Patients newly diagnosed with T-lymphoblastic (T-cell) or B-lymphoblastic precursor (BCP) leukaemia (ALL) according to the WHO-classification of Tumours of Haematopoetic and Lymphoid Tissues (Revised 4th edition 2017) and with a diagnosis confirmed by an accredited laboratory at a participating paediatric oncology or adult haematology centre. * Age 0 - \< 46 years (one day before 46th birthday) at the time of diagnosis with the exception of infants with KMT2A-rearranged (KMT2A-r) BCP ALL. * Patients with surface immunoglobulin negative (sIG-) BCP-ALL and an IG::MYC rearrangement, unless they have a concurrent BCL2/6 rearrangement. T-ALL patients with MYC translocations. * Informed consent signed by the patient and/or parents/legal guardians according to country-specific age-related guidelines. * The ALL diagnosis should be confirmed by an accredited laboratory at a participating paediatric oncology or adult haematology centre. * The patient should be diagnosed and treated at a participating paediatric oncology or adult haematology centre in the participating countries. * The patient should be a resident in one of the participating countries on a permanent basis or should intend to settle in a participating country, for instance by an application for asylum. Patients who are visiting the country as tourists should not be included. However, returning expatriots with primary diagnosis abroad may be included if no treatment has been administered and the diagnostic procedures are repeated at a participating centre. * All women of childbearing potential (WOCBP) have to have a negative pregnancy test within 2 weeks prior to the start of treatment. * For each intervention/randomisation an additional set of inclusion-criteria is provided. Exclusion Criteria: * Age \< 365 days and KMT2A-rearranged (KMT2A-r) BCP-ALL (documented presence of a KMT2A-split by FISH and/or a KMT2A fusion transcript). * Age \>45 years at diagnosis. * Patients with a previous malignant diagnosis (ALL as a second malignant neoplasm - SMN). * Relapse of ALL. * Patients with mature B-ALL (as defined by surface IG positivity) or any patients with IG::MYC and a concurrent BCL2/6 rearrangement. * Patients with Ph-positive ALL (documented presence of t(9;22)(q34;q11) and/or of the BCR::ABL fusion transcript). These patients will be transferred to an appropriate trial for t(9;22) if available. * Previously known ALL prone syndromes (e.g. Li-Fraumeni syndrome, germline ETV6 mutation), except for Down syndrome. Exploration for such ALL prone syndromes is not mandatory and patients in whom genetic work-up reveals a new germ-line mutation (index-cases) will remain in the study. * Treatment with systemic corticosteroids corresponding to (\>10mg prednisolone/m2/day) for more than one week and/or other chemotherapeutic agents in a 4-week interval prior to diagnosis (pre-treatment). * Pre-existing contraindications to any treatment according to the ALLTogether protocol (constitutional or acquired disease prior to the diagnosis of ALL preventing adequate treatment). * Any other disease or condition, as determined by the investigator, which could interfere with the participation in the study according to the study protocol, or with the ability of the patients to cooperate and comply with the study procedures. * Women of childbearing potential who are pregnant at the time of diagnosis. * Women of childbearing potential and fertile men who are sexually active and are unwilling to use adequate contraception during therapy. Efficient birth control is required. * Female patients, who are breast-feeding. * Essential data missing from the registration of characteristics at diagnosis (in consultation with the protocol chair). * For each intervention/randomisation an additional set of exclusion-criteria is provided.