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Aims: Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is a vital treatment for various paediatric malignant and nonmalignant diseases. The conditioning treatment before allo-HSCT is crucial for successful engraftment. Treosulfan, a cytotoxic prodrug, has gained popularity due to its lower toxicity compared to traditional alkylating agents used for conditioning treatment., Methods: We investigated the relationship between pharmacokinetics and pharmacodynamics of treosulfan in paediatric patients, in a substudy pooling from 2 multicentre phase 2 clinical trials. A total of 83 children with malignant and nonmalignant diseases received treosulfan-based conditioning. Treosulfan exposure and its relationship with clinical outcomes, including survival, graft failure and graft-vs.-host disease, were investigated., Results: Our findings reveal no significant association between treosulfan exposure and the key clinical outcomes or toxicity (P-values between .22 and .99), if the dosing is based on the approved product information., Conclusion: These findings suggest that treosulfan exposure after standardized body surface area-based dosing is appropriate in paediatric allo-HSCT., (© 2024 British Pharmacological Society.)

We retrospectively analysed outcomes among 395 patients with haematologic malignancies who underwent non-myeloablative haematopoietic cell transplantation (HCT) from human leucocyte antigen (HLA)-matched related (n = 297) or unrelated donors (n = 98) in order to identify a possible correlation between the time of onset of graft-versus-host disease (GVHD) and survival. The non-myeloablative regimen consisted of 2 Gy total body irradiation with or without fludarabine, followed by postgrafting immunosuppression with mycophenolate mofetil and cyclosporine. The cumulative incidences of grades II-IV acute GVHD and extensive chronic GVHD were 45% and 47%, respectively, with related donors, and 68% and 68%, respectively, with unrelated donors. High-dose corticosteroid treatment for acute or chronic GVHD was started at a median of 79 (range, 8-799) days and 30 (range, 5-333) days after transplantation from related and unrelated donors respectively. With related donors, the cumulative incidence of non-relapse mortality among patients with GVHD was 55% at 4 years when prednisone was started before day 50 (n = 72), compared with 29% when treatment was started after day 50 (n = 115) (P < 0.001). With unrelated donors, time to onset of treatment for GVHD was not associated with survival. Patients with early-onset GVHD after non-myeloablative HCT from HLA-identical related donors might benefit from intensified primary immunosuppressive treatment.

We hypothesized that patients undergoing major ABO-incompatible non-myeloablative haematopoietic stem cell transplantation (nm-HSCT) might experience prolonged haemolysis after transplant due to the delayed disappearance of host plasma cells producing anti-donor isohaemagglutinins (HAs). To address this question, we analysed data from 107 consecutive patients transplanted with allogeneic peripheral blood stem cells from human leucocyte antigen-matched (related, n = 84; unrelated, n = 23) donors after non-myeloablative conditioning (200 cGy total body irradiation +/- fludarabine). In total, 23 out of the 107 patients received major or major/minor ABO-incompatible transplants. Red blood cell (RBC) transfusion requirements during the first 120 d post transplant were higher in major ABO-mismatched than in ABO-matched recipients (0.12 vs 0.03 median units RBC concentrate/d, P = 0.04). Two patients developed transient pure red cell aplasia, which had resolved spontaneously by 9 months after transplant. Major ABO incompatibility did not influence rates of engraftment. Patients with sustained engraftment experienced gradual declines of anti-donor HAs, and the estimated median time to reaching IgM and IgG titres of < 1:1 was at least 133 d in evaluable patients, approximately twice longer than reported after myeloablative conditioning. There was a strong correlation between degrees of donor chimaerism in erythroid burst-forming units, granulocyte macrophage colony-forming units and granulocytes, indicating that donor erythroid engraftment, defined by early erythroid progenitors, was as prompt as myeloid engraftment. In conclusion, our data suggest that major ABO-incompatibility is not a barrier to successful non-myeloablative HSCT.

A 50-year-old woman who was retrospectively diagnosed with an early asymptomatic myelodysplastic syndrome (MDS) served as a haemopoietic stem cell donor for her HLA-identical sister who had chemotherapy-refractory non-Hodgkin's lymphoma. The MDS of the donor was classified as refractory anaemia (RA) and cytogenetically characterized by deletion of the long arm of chromosome 20 [del(20q)]. Donor cell engraftment in marrow and peripheral blood was analysed over a period of 5 months after transplant using conventional cytogenetics, fluorescence in situ hybridization, and variable number of tandem repeats. Neutrophil counts >0.5 x 109/l and platelet counts >20 x 109/l were reached promptly on days 12 and 24, respectively. Throughout the period of observation the percentage of cells with the del(20q) abnormality in the recipient's marrow and peripheral blood was comparable to the proportion of these cells in the donor. These data indicate that the abnormal clone was capable of homing to the marrow, proliferating, differentiating, and therefore contributing to haemopoiesis in a relatively efficient manner. This implies that MDS progenitor cells may not have homing and growth deficiencies, a finding that has particular relevance for autologous transplantation in MDS patients where tumour cells potentially contaminate the graft.

To investigate whether expression of intercellular adhesion molecule 1 (ICAM-1, CD54) in childhood acute lymphoblastic leukaemia (ALL) has an impact on the biological behaviour of the disease, we evaluated 751 children of the ALL-BFM 90 trial with B-cell precursor- (n = 677) or T-cell-ALL (n = 74) for CD54 expression within immunological subgroups, its correlation to certain clinical features, and therapy outcome. The highest percentage of patients expressing CD54 was found in common- and pre-B-ALL (76.1% and 61.4%, respectively). There was intermediate expression in pre-pre-B-ALL (47.8%), and the lowest expression was detected in T-ALL (12.2%). A significant positive correlation could be demonstrated between low CD54 expression (< 20% stained blasts) and high peripheral leucocyte counts, central nervous system (CNS) involvement, and splenomegaly at the time of diagnosis (P < 0.01). In addition, CD54 expression was a favourable but not independent prognostic factor. Event-free survival estimate at 4.5 years was 86% for CD54+ patients (n = 463), compared with 78% for CD54- patients (n = 241) (P < 0.01). These findings demonstrate that CD54 expression has an impact on dissemination patterns and outcome of childhood ALL, and emphasizes the potential relevance of adhesion mechanisms in influencing clinical characteristics and prognosis of haematological malignancies.