['acute lymphoblastic leukaemias (all)', 'acute myeloid leukaemias (aml)', 'myelodysplastic syndromes (mds)', 'juvenile myelomonocytic leukaemias (jmml)']
['treosulfan']

        Inclusion Criteria:

          1. Haematological malignant disease i.e. ALL, AML, MDS or JMML, indicated for allo-HSCT.

          2. Indication for first allo-HSCT or second allo-HSCT due to disease relapse, graft
             failure, or secondary malignancy after previous HSCT.

          3. Available matched sibling donor (MSD), matched family donor (MFD) or matched unrelated
             donor (MUD). For bone marrow (BM) and peripheral blood (PB) match is defined as 9/10
             or 10/10 allele match after four digit typing in human leucocyte antigens (HLA)-A, B,
             C, DRB1 and DQB1.

          4. Patients with ALL or AML in complete morphologic remission (blast counts <5 % in BM)
             and patients with MDS or JMML with blast counts < 20 % in BM at study entry.

          5. Age at time of registration from 28 days to less than 18 years of age.

          6. Lansky (patients aged <16 years) or Karnofsky (patients aged ≥ 16 years) performance
             score of at least 70 %.

          7. Written informed consent of the parents/ legal guardians and patient's assent/consent
             according to national regulations.

          8. Females of child-bearing potential or male patients' partners with child-bearing
             potential must use a highly effective method of contraception (pearl index < 1 %) such
             as complete sexual abstinence, combined oral contraceptive, hormone intrauterine
             contraceptive device (IUCD), vaginal hormone ring, transdermal contraceptive patch,
             contraceptive implant or depot contraceptive injection in combination with a second
             method of contraception like a condom or a cervical cap / diaphragm with spermicide or
             surgical sterilisation (vasectomy) in male patients or male partners during the study
             and at least 6 months thereafter.

          9. Negative pregnancy test for females of child-bearing potential.

        Exclusion Criteria:

          1. Third or later allo-HSCT.

          2. HSCT from haploidentical or umbilical cord blood donor.

          3. Symptomatic involvement of central nervous system (CNS) at study entry.

          4. Treatment with cytotoxic drugs within 10 days prior to day 7.

          5. Obese paediatric patients with body mass index: weight (kg)/[height (m)]² > 30 kg/m².

          6. Solid tumours (e.g. neuroblastoma, peripheral neuroectodermal tumour [PNET], Ewing
             sarcoma).

          7. Fanconi anaemia and other deoxyribonucleic acid (DNA) breakage repair disorders.

          8. Impaired liver function indicated by Bilirubin > three times the upper limit of normal
             (ULN) or aspartate aminotransferase/alanine aminotransferase (AST/ALT) > five times
             ULN, or active infectious hepatitis.

          9. Impaired renal function indicated by estimated glomerular filtration rate ([GFR],
             according to the Schwartz formula) < 60 mL/min/1,73m2.

         10. Impaired cardiac function: severe cardiac insufficiency indicated by left ventricle
             ejection fraction (LVEF) < 35 %.

         11. Requirement for supplementary continuous oxygen.

         12. Severe active infection requiring deferral of conditioning.

         13. Human immunodeficiency virus (HIV) positivity.

         14. Known pregnancy, breast feeding.

         15. Known hypersensitivity to Treosulfan and/or Fludarabine.
      