Treosulfan-based Versus Busulfan-based Conditioning in Paediatric Patients With Non-malignant Diseases

The prospective clinical phase II protocol MC-FludT.16/NM is to be conducted to verify safety and efficacy of Treosulfan-based conditioning compared to Busulfan-based conditioning in paediatric patients. Based on the given clinical experience with either Treosulfan-based or Busulfan-based conditioning in combination with Fludarabine no increased risk for graft failure is expected in paediatric patients. A potential benefit for study patients is expected with respect to a probably low non-haematological toxicity of treatment compared to myeloablative TBI-based conditioning or high-dose Busulfan-based conditioning in combination with Cyclophosphamide.

However, the allogeneic HSCT procedure itself potentially involves serious risks with regard to severe or life-threatening conditions like graft versus host disease (GvHD) and/or infectious complications as well as graft failure.

In summary, the primary goal of this study is to evaluate the Treosulfan-based myeloablative conditioning regimen as an alternative in children and to contribute to the current PK model for Treosulfan to be able to finally give age (or body surface area [BSA]) dependent dose recommendations. The treatment regimens given in the protocol MC-FludT.16/NM are based on sufficient clinical safety and efficacy data. Considering the vital indication for allogeneic HSCT of the selected patient population, the risk-benefit assessment seems to be in favour of the study conduct.

Moreover, planned interim analyses will ensure the early identification of unexpected risks. Therefore, the conduct of the protocol MC-FludT.16/NM is considered reasonably justified.

Inclusion criteria

• Non-malignant disease indicated for first myeloablative allogeneic HSCT, including inborn errors of metabolism, primary immunodeficiencies, haemoglobinopathies and bone marrow failure syndromes.
• First allogeneic HSCT.
• 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 at least 9/10 allele matches after four digit typing in human leucocyte antigen (HLA)-A, -B, -C, -DRB1 and DQB1 antigens. For umbilical cord blood (UCB) match is defined as at least 5/6 matches after two digit typing in HLA-A and -B and four digit typing in DRB1 antigens.

Exclusion criteria

• Second or later HSCT.
• HSCT from mismatched donor (less than 9/10 BM/peripheral blood stem cells (PBSC) or less than 5/6 matched cord donor).
• Preterm newborn infants (<37 weeks gestational age) and term newborn infants aged 0 - 27 days at time of registration.
• Obese paediatric patients with body mass index weight (kg)/[height (m)]² > 30 kg/m².
• Diagnosis of Fanconi anaemia and other chromosomal breakage disorders, radiosensitivity disorders (deoxyribonucleic acid (DNA) Ligase 4, Cernunnos- X-ray repair cross-complementing protein 4 (XRCC4) like factor (XLF), Nijmegen Breakage Syndrome (NBS)) and Dyskeratosis Congenita.