# Treosulfan

Source: https://onco.cc/drugs/treosulfan/  
OnCo record `treosulfan` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A conditioning chemotherapy given before donor stem-cell transplant in AML and MDS; it was long used in Europe and reached the US in 2025.

## Summary

Treosulfan is a busulfan analogue that converts non-enzymatically to epoxides that alkylate DNA. It is myeloablative but carries lower hepatic and neurological toxicity than busulfan, which makes it suitable for conditioning older or comorbid patients before allogeneic stem-cell transplant. In the MC-FludT.14/L trial (Lancet Haematology 2020), treosulfan-fludarabine improved event-free and overall survival versus reduced-intensity busulfan-fludarabine in older or comorbid patients with AML or MDS. It was approved in the EU in 2019 for conditioning in adults and children and reached the US in 2025 as a preparative regimen for allogeneic transplant in AML and MDS with fludarabine. It has also been used in paediatric transplant and historically in ovarian cancer in Europe. The core idea is a gentler way to clear the marrow so a donor graft can take hold.

## Fields

- Kind: Treatment
- Status: approved
- Last checked: 2026-09-08
- Tags: gap-fill; supportive
- Brand: Grafapex
- Modality: Alkylating conditioning agent (busulfan analogue)
- Mechanism: Prodrug converting non-enzymatically to epoxides that alkylate DNA; myeloablative with lower hepatic and neurotoxicity than busulfan.
- Approvals: EU 2019: Conditioning before allogeneic HSCT (with fludarabine) in adults and children; US 2025: Preparative regimen for allogeneic HSCT in AML/MDS with fludarabine

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Treosulfan
- FDA novel approvals 2025: https://www.fda.gov/drugs/novel-drug-approvals-fda/novel-drug-approvals-2025

## Connected records

- cancers: [Acute myeloid leukaemia](https://onco.cc/cancers/aml/), [Myelodysplastic syndromes / neoplasms (MDS)](https://onco.cc/cancers/mds/)
- technologies: [Allogeneic stem cell transplantation](https://onco.cc/technologies/allogeneic-hsct/), [Cytotoxic chemotherapy](https://onco.cc/technologies/cytotoxic-chemotherapy/)
- companies: [medac](https://onco.cc/companies/medac/)
- trials: [ALL-SCT BFM International- HSCT in Children and Adolescents With ALL](https://onco.cc/trials/nct01423500/), [Clinical Phase III Trial Treosulfan-based Conditioning Versus Reduced-intensity Conditioning (RIC)](https://onco.cc/trials/nct00822393/), [Euro Ewing 2012](https://onco.cc/trials/euro-ewing-2012/)
- terms: [Conditioning regimen (myeloablative, reduced-intensity)](https://onco.cc/terms/conditioning-regimen/)

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