FDA Approval of Treosulfan for AML and MDS

The FDA has started 2025 with a significant approval: treosulfan (Grafapex, Medexus Pharmaceuticals) is now approved for conditioning before allogeneic stem cell transplantation (alloHCT) in patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), including pediatric patients over one-year-old.

This article breaks down the details of the approval and the key clinical trial that made it possible.

Key Trial Results That Led to FDA Approval

The approval was based on data from a Phase 3 trial (NCT00822393), which demonstrated:

• A 33% reduction in mortality risk with treosulfan-fludarabine compared to busulfan-fludarabine as a conditioning regimen.

• A higher 2-year event-free survival rate, the trial’s primary endpoint, as in the time that patients lived without relapsing after the allogeneic transplant:

• 64.0% in the treosulfan group

• 50.4% in the busulfan group

These findings highlight treosulfan's potential to improve transplant outcomes in AML and MDS patients.

How is Treosulfan Administered?

Treosulfan is given intravenously as part of a conditioning regimen before alloHCT:

• Treosulfan: 10 g/m² per day (2-4 days before alloHCT)
• Fludarabine: 30 mg/m² per day (2-6 days before alloHCT)

What are the Common Side Effects of Treosulfan? 

Treosulfan is an alkylating agent. It binds to one of the cancer cell's DNA and impedes these cells from growing and dividing.  Although this mechanism is straightforward, all medications come with possible side effects. The most common are:

• Musculoskeletal pain
• Mouth sores
• Fever 
• Nausea and vomiting
• Swelling
• Infections

Final Thoughts

The approval of treosulfan as a conditioning agent for stem cell transplantation offers a crucial alternative for patients with AML and MDS. Having a second option enhances personalized treatment plans, allowing physicians to choose the most suitable conditioning regimen based on individual patient needs and risk profiles. This advancement not only broadens therapeutic choices but also holds the potential to improve survival outcomes and reduce complications, providing new hope for patients and their families as they navigate their treatment journeys.

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Sources: 

• Treosulfan or busulfan plus fludarabine as conditioning treatment before allogeneic haemopoietic stem cell transplantation for older patients with acute myeloid leukaemia or myelodysplastic syndrome (MC-FludT.14/L): a randomised, non-inferiority, phase 3 trial

• Medexus Announces FDA Approval of GRAFAPEX (treosulfan) for Injection and Provides Business Update