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Treosulfan-based conditioning regimen for allogeneic HSCT in children with AML: study of the Polish Pediatric Study
Agnieszka Sobkowiak-Sobierajska1, Olga Zając-Spychała1, Monika Mielcarek-Siedziuk2
1Department of Paediatric Oncology, Hematology and Transplantology, University of Medical Sciences, Poznań, Poland.
Insights
Treosulfan-based conditioning is a safe and effective alternative for pediatric acute myeloid leukemia patients undergoing allogeneic hematopoietic stem cell transplant (allo-HSCT). This regimen shows promising long-term survival rates and reduced toxicity compared to busulfan-based treatments.
Area of Science:
- Hematology
- Pediatric Oncology
- Transplantation Medicine
Background:
- Allogeneic hematopoietic stem cell transplant (allo-HSCT) is crucial for high-risk pediatric acute myeloid leukemia (AML) patients.
- Busulfan-based conditioning, while standard, presents significant short- and long-term toxicities.
- Treosulfan emerged as an alternative conditioning agent in pediatric HSCT since 2000, offering a better toxicity profile with retained efficacy.
Purpose of the Study:
- To evaluate the long-term outcomes of pediatric AML patients receiving their first allo-HSCT.
- To assess the safety and efficacy of treosulfan-based conditioning regimens in this population.
- To compare outcomes in patients conditioned with treosulfan in CR1 versus CR2 remission status and with different donor types.
Main Methods:
- Retrospective analysis of 85 pediatric AML patients (0.8-18.3 years) undergoing first allo-HSCT between 2000-2022.
- Patients received treosulfan-based conditioning from matched sibling (MSD) or unrelated (MUD) donors.
- Outcomes assessed included regimen-related toxicity, engraftment, chimerism, GvHD, non-relapse mortality (NRM), and survival probabilities.
Main Results:
- No early deaths from regimen-related toxicity; common toxicities included mucositis.
- High rates of granulocyte/platelet engraftment (91.8%) and complete donor chimerism (93.5%) were observed.
- Five-year survival probabilities: Relapse-Free Survival (76.9%), Event-Free Survival (71.3%), Overall Survival (75.4%), with no significant difference based on remission status or donor type. Low incidence of secondary malignancy (1.2%).
Conclusions:
- Treosulfan-based conditioning is a safe and effective option for pediatric AML patients undergoing allo-HSCT.
- It provides a viable alternative to busulfan-based regimens, particularly for patients at risk of severe toxicities.
- The regimen supports favorable long-term survival outcomes in pediatric AML patients.
Background:
Allogeneic HSCT (allo-HSCT) is indicated in high risk pediatric AML patients in CR1 and in all patients in CR2. The myeloablative busulfan-based conditioning for HSCT has been accepted commonly as the standard in them, but its short- and long-term complications forced the development of alternative regimens. Treosulfan started to be used in pediatric HSCT patients in the year 2000 due to its better toxicity profile along with sufficient myeloablative, antileukemic and immunosuppressive effects.
Objective:
The objective of the study was to evaluate the long-term results of the first allo-HSCT after treosulfan-based regimens in children with AML in CR1 or CR2.
Study Design:
This retrospective analysis evaluated 85 children (0.8-18.3 years; median 6.5) with AML in CR1 or CR2, who between 2000 and 2022 underwent the first allo-HSCT from a matched sibling (MSD) (n = 23) or matched unrelated (MUD) (n = 62) donor after a treosulfan-based conditioning regimen.
Results:
No patients died due to early regimen-related toxicity (RRT), and the most frequent early RRT grade ≥ 3 (acc. CTCAE) was oral (15.3%) and gastrointestinal (2.4%) mucositis. Granulocyte and platelet engraftment was achieved by 78/85 (91,8%) patients. All patients who survived beyond day +30 achieved granulocyte engraftment. The rate of complete donor chimerism was 93.5%. Acute GvHD II-IV occurred in 31.8%, extensive chronic GvHD in 8.2% of patients. The rate of acute GvHD after MSD- and MUD-HSCT was comparable, while the incidence of chronic GvHD tended to be higher after MSD-HSCT. The overall rate of non-relapse mortality (NRM) was 5.9% and was related to infection or GvHD; in all children in this group, pre-HSCT risk factors of NRM were identified. The five-year probability of relapse-free survival (76.9%), event-free survival (71.3%), and overall survival (75.4%) did not correlate with remission status (CR1 or CR2) or donor type. One patient (1.2%) developed secondary malignancy.
Conclusions:
Overall, the treosulfan-based regimen seems to be safe and effective in pediatric AML patients and provides an alternative to the busulfan-based one, especially in patients with pretransplant risk factors of severe regimen-related toxicities.
