Busulfan
| Evidence Level: L1 | Predicted Indications: 10 |
Table of Contents
- Busulfan
- Pharmacist Assessment Report
- Busulfan: From an Unspecified Original Indication to Myelodysplastic Syndrome
- One-Sentence Summary
- Quick Overview
- Why is This Prediction Reasonable?
- Clinical Trial Evidence
- Literature Evidence
- Australia Market Information
- Cytotoxicity
- Safety Considerations
- Conclusion and Next Steps
- Other Predicted Indications (Brief Notes)
- Disclaimer
Busulfan: From an Unspecified Original Indication to Myelodysplastic Syndrome
One-Sentence Summary
Busulfan is an oral alkylating agent marketed in Australia as Myleran 2 mg tablets. The approved indication text was not available in the data compiled for this report. The TxGNN model predicts it may be useful for myelodysplastic syndrome (MDS), where it is already used as a conditioning agent before allogeneic stem cell transplant. The data compiled for this report include 36 clinical trials and 20 publications linked to this prediction, including a completed Phase 3 randomised trial.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not available in the data compiled for this report |
| Predicted New Indication | Myelodysplastic syndrome |
| TxGNN Prediction Score | 0.9962 |
| Evidence Level | L1 |
| Australia Market Status | Listed on the PBS Schedule (1 of 1 items) – TGA (ARTG) registration status is not included in this data |
| Number of PBS Items | 1 (valid: 1) |
| Recommended Decision | Proceed with Guardrails |
Why is This Prediction Reasonable?
Detailed mechanism of action data are not available in the data compiled for this report. Busulfan is a bifunctional alkylating agent: it forms DNA crosslinks and is myeloablative, meaning it destroys the bone marrow. In MDS it is used as a backbone of conditioning (with fludarabine, cyclophosphamide, clofarabine or cladribine) before allogeneic haematopoietic stem cell transplantation (HSCT). The aim is to eradicate the malignant clone and make marrow space for donor cells to engraft.
This is an established transplant-conditioning practice, not a disease-modifying monotherapy. Allogeneic HSCT remains the only potentially curative option for eligible patients with higher-risk MDS, which is why the prediction is credible. The evidence supports busulfan as a component of a conditioning regimen, not as a stand-alone treatment for MDS.
Clinical Trial Evidence
The data include 36 trials for this prediction. The most relevant are shown below, prioritising busulfan-specific, MDS-focused designs.
| Trial Number | Phase | Status | Enrolment | Key Findings |
|---|---|---|---|---|
| NCT00005866 | Phase 3 | Completed | 240 | Randomised comparison of busulfan-TBI vs cyclophosphamide-TBI conditioning in advanced MDS or MDS-related AML |
| NCT00822393 | Phase 3 | Completed | 570 | Treosulfan-based vs reduced-intensity busulfan-based conditioning in AML/MDS patients ineligible for standard conditioning |
| NCT04708054 | Phase 2/3 | Recruiting | 324 | Venetoclax added to a fractionated busulfan regimen in high-risk AML and MDS |
| NCT05453552 | Phase 2/3 | Unknown | 242 | G-CSF + decitabine + BuCy vs G-CSF + decitabine + BuFlu in high-risk MDS undergoing allo-HSCT; results need verification |
| NCT04713956 | Phase 2/3 | Unknown | 242 | Same comparison in RAEB-1, RAEB-2 and AML secondary to MDS |
| NCT00502905 | Phase 2 | Completed | 200 | High-dose IV busulfan with fludarabine before allogeneic transplant in AML and MDS |
| NCT02250937 | Phase 2 | Active, not recruiting | 116 | Venetoclax plus timed-sequential busulfan, cladribine and fludarabine; busulfan’s contribution is confounded |
| NCT01168219 | Phase 2 | Completed | 68 | Busulfan, fludarabine and ATG followed by transplant and azacitidine in high-risk MDS and older AML |
| NCT01643668 | Phase 2 | Completed | 34 | Reduced-intensity busulfan/clofarabine conditioning; small but busulfan-specific |
| NCT07183878 | N/A | Recruiting | 138 | Randomised trial of venetoclax-enhanced BuCy vs standard BuCy in high-risk AML and MDS |
Most trials test busulfan as part of multi-drug regimens, so busulfan’s individual contribution is often hard to separate. No ANZCTR identifiers were included in the data compiled for this report.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 31606445 | 2020 | RCT (Phase 3) | Lancet Haematol | Treosulfan/fludarabine vs reduced-intensity busulfan/fludarabine conditioning in older AML/MDS patients; non-inferiority design |
| 35617104 | 2022 | RCT (Phase 3) | Am J Hematol | Final analysis: treosulfan compared with reduced-intensity busulfan in older AML/MDS patients (476 patients at interim analysis) |
| 42285355 | 2026 | RCT (Phase 2) | Transplant Cell Ther | Two fractionation schedules of myeloablative busulfan with fludarabine and cladribine in AML or MDS |
| 36702138 | 2023 | Phase 3 randomised trial | Lancet Haematol | G-CSF, decitabine and BuCy vs BuCy conditioning for relapse in MDS or secondary AML after allo-HSCT |
| 40079242 | 2025 | Review | Am J Hematol | Contemporary review of allogeneic HSCT for myelofibrosis and MDS |
| 34692485 | 2021 | Meta-analysis | Front Oncol | Reduced-intensity conditioning followed by allo-HSCT in AML and MDS |
| 33425740 | 2020 | Systematic review/meta-analysis | Front Oncol | Long-term outcomes of treosulfan- vs busulfan-based conditioning in MDS and AML |
| 34489555 | 2021 | Registry analysis | Bone Marrow Transplant | Flu/Bu4 vs Bu4/Cy as myeloablative conditioning for MDS (propensity score-matched) |
| 37856098 | 2024 | Risk assessment | Pediatr Blood Cancer | Evidence-based assessment of the risk of subsequent malignancy after busulfan |
| 38176654 | 2024 | Cohort | Transplant Cell Ther | Long-term complications after treosulfan- or busulfan-based conditioning in children with acute leukaemia or MDS |
The two Phase 3 randomised trials in the literature compared treosulfan with reduced-intensity busulfan, so busulfan served as the reference arm rather than the investigational drug.
Australia Market Information
| ARTG Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| ARTG 1128J | Myleran | Tablet 2 mg (oral) | Not available in the data compiled for this report |
The data list one valid single-ingredient licence and no cancelled licences. The intravenous formulation used in most of the conditioning trials above is not listed in the data compiled for this report.
Cytotoxicity
| Item | Content |
|---|---|
| Cytotoxicity Classification | Conventional cytotoxic (bifunctional alkylating agent) |
| Myelosuppression Risk | High (myeloablative at conditioning doses; neutropenia, thrombocytopenia and anaemia are expected) |
| Emetogenicity Classification | Please refer to the Product Information (PI) |
| Monitoring Items | FBC with differential, liver function (including signs of hepatic sinusoidal obstruction syndrome), seizure monitoring, and exposure-guided dosing for IV busulfan |
| Handling Protection | Handle according to local cytotoxic drug handling requirements |
Safety Considerations
- Key warnings and contraindications from the label: these were not available in the data compiled for this report. Please refer to the TGA-approved Product Information (PI).
- Knowledge-graph contraindication signals (from drug-disease links in the TxGNN knowledge graph, not label text): epilepsy, thrombocytopenia, neutropenia, agranulocytosis, anaemia (including macrocytic anaemia and Fanconi anaemia), pulmonary fibrosis, hyperglycaemia, infectious disease (including fungal infection and dermatophytosis), and potassium deficiency. These should be treated as signals to verify against the PI, not as confirmed contraindications.
- Drug interactions: the interaction screen returned 100 entries. Of those shown, the graded ones are:
- Major: metronidazole
- Moderate: aprepitant, miconazole
- Minor: levofloxacin
- Many others are listed with an unknown severity grade, including corticosteroids (prednisone, prednisolone, hydrocortisone, dexamethasone), proton pump inhibitors (omeprazole, pantoprazole, lansoprazole), antiemetics (ondansetron, granisetron, metoclopramide), vancomycin, amphotericin B, morphine, mannitol, ranitidine and famotidine.
- Guardrails from the evidence: monitor for hepatic sinusoidal obstruction syndrome, seizures and long-term complications. A 2024 review also notes a low but poorly characterised risk of subsequent malignancy.
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: Busulfan-based conditioning for MDS is supported by completed Phase 2 and Phase 3 randomised trials and several randomised publications, which supports an L1 evidence level. The benefit applies to transplant conditioning in specialist centres, not to busulfan as a stand-alone therapy for MDS. The label safety data are also missing from the data compiled for this report.
To proceed, the following is needed:
- The TGA-approved Product Information (warnings, contraindications and approved indications), since label data were missing from the data compiled for this report
- Confirmation of the intravenous busulfan products and indications available in Australia, as the oral Myleran tablet is the only ARTG entry listed
- Pharmacokinetic-guided dosing, with intensity matched to age and comorbidity
- A monitoring plan for hepatic sinusoidal obstruction syndrome, seizures and late effects
- Detailed mechanism of action data
Other Predicted Indications (Brief Notes)
| Predicted Indication | Evidence Level | Recommendation | Comment |
|---|---|---|---|
| Refractory cytopenia of childhood | L2 | Proceed with Guardrails | Paediatric MDS subtype; supported by Phase 2 transplant protocols in mixed haematologic populations and one single-centre paediatric series. Needs paediatric PK-guided dosing |
| Aregenerative anaemia | L1 | Proceed with Guardrails | Evidence is partly indirect: the Phase 3 trial (NCT00005866) is in an MDS transplant population. Confirm applicability to the specific marrow failure diagnosis |
| Unclassified myelodysplastic syndrome | L3 | Research Question | Only a 1994 allogeneic transplant report; extrapolated from the broader MDS evidence |
| HIV infectious disease | L3 | Research Question | Busulfan is not an antiviral; it is used only to condition for gene-modified cell therapy or HIV-associated lymphoma, in very small early-phase studies |
| Partial deletion of the long arm of chromosome 5 | L5 | Hold | No direct evidence; model prediction only |
| Severe congenital hypochromic anaemia with ringed sideroblasts | L5 | Hold | No trials or literature |
| Neurodevelopmental disorder with ataxic gait, absent speech, and decreased cortical white matter | L5 | Hold | No evidence or plausible mechanism |
| Seborrhoeic keratosis | L5 | Hold | No evidence; a systemic myelotoxic agent is not justified for a benign lesion |
| Simian immunodeficiency virus infection | L5 | Hold | No evidence in the compiled data |
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.