Busulfan
| Evidence Level: L1 | Predicted Indications: 10 |
Table of Contents
- Busulfan
- Busulfan: From Hematologic Conditioning (Original Indication Not Recorded) to Myelodysplastic Syndrome
Busulfan: From Hematologic Conditioning (Original Indication Not Recorded) to Myelodysplastic Syndrome
One-Sentence Summary
Busulfan is a myeloablative alkylating agent registered in Singapore as an injection (Busulfex) and an oral tablet (Myran). It is predicted by the TxGNN model to be useful for myelodysplastic syndrome (MDS), where it is already used as a conditioning agent before stem cell transplantation. The data compiled for this report include 40 clinical trials (including a completed Phase 3 RCT) and 20 publications for this indication.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not recorded (the approved indication text in the Singapore licences is empty) |
| Predicted New Indication | Myelodysplastic syndrome |
| TxGNN Prediction Score | 99.62% |
| Evidence Level | L1 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 2 |
| Recommended Decision | Proceed with Guardrails |
Why is This Prediction Reasonable?
Detailed mechanism of action data is not available in the compiled data. Based on known pharmacology, busulfan is a bifunctional alkylating agent that cross-links DNA and is myeloablative. In MDS it forms the backbone of conditioning regimens given before allogeneic hematopoietic stem cell transplantation (HSCT). It eradicates the malignant clone and creates marrow space for donor engraftment.
This is established transplant practice rather than a new mechanism. Busulfan is a conditioning component, not a standalone disease-modifying therapy for MDS. The "new indication" is therefore best understood as a transplant-conditioning use.
Other predicted indications (lower in the ranking) are mostly extensions of the same conditioning concept:
| Predicted Indication | TxGNN Score | Evidence Level | Suggested Stance |
|---|---|---|---|
| Refractory cytopenia of childhood | 99.54% | L2 | Proceed with Guardrails |
| Unclassified MDS | 99.53% | L3 | Research question |
| Aregenerative anemia (marrow failure, including aplastic anemia) | 99.49% | L1 | Proceed with Guardrails |
| HIV infectious disease | 99.44% | L3 | Research question (conditioning for gene therapy only; busulfan is not antiviral) |
| Partial deletion of chromosome 5q, severe congenital hypochromic anemia with ringed sideroblasts, a rare neurodevelopmental disorder, seborrheic keratosis, feline AIDS | 99.0–99.5% | L5 | Hold (prediction only, no supporting studies) |
Clinical Trial Evidence
Top trials for myelodysplastic syndrome (selected by relevance grade and design):
| Trial Number | Phase | Status | Enrollment | Key Findings |
|---|---|---|---|---|
| NCT00005866 | Phase 3 | Completed | 240 | Randomized comparison of busulfan-TBI vs cyclophosphamide-TBI 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 |
| NCT00502905 | Phase 2 | Completed | 200 | IV busulfan + fludarabine with allogeneic transplant for AML and MDS |
| NCT04708054 | Phase 2/3 | Recruiting | 324 | Venetoclax added to fractionated busulfan regimen in high-risk AML/MDS |
| NCT05453552 | Phase 2/3 | Unknown | 242 | G-CSF + decitabine + Bu/Cy vs Bu/Flu-based conditioning in high-risk MDS |
| NCT04713956 | Phase 2/3 | Unknown | 242 | Same regimens in RAEB-1, RAEB-2 and AML secondary to MDS |
| NCT02250937 | Phase 2 | Active, not recruiting | 116 | Venetoclax with timed sequential busulfan, cladribine and fludarabine conditioning in AML/MDS |
| NCT01168219 | Phase 2 | Completed | 68 | Busulfan/fludarabine/ATG reduced-intensity transplant plus azacitidine in MDS and older AML |
| NCT01643668 | Phase 2 | Completed | 34 | Reduced-intensity busulfan/clofarabine conditioning before allogeneic transplant |
| NCT06247917 | Phase 2 | Unknown | 59 | Single-arm FLU-BU-MEL conditioning for MDS |
Several additional trials were identified (a withdrawn Phase 2 with no enrolment, and many mixed-population transplant studies), but they add little direct evidence.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 31606445 | 2020 | RCT (Phase 3) | Lancet Haematol | Treosulfan/fludarabine vs reduced-intensity busulfan/fludarabine in older AML/MDS patients |
| 35617104 | 2022 | RCT (Phase 3) | Am J Hematol | Final analysis: treosulfan improved outcomes versus reduced-intensity busulfan |
| 42285355 | 2026 | RCT (Phase 2) | Transplant Cell Ther | Two fractionation schedules of myeloablative busulfan with fludarabine and cladribine in AML/MDS |
| 36702138 | 2023 | Randomized Phase 3 | Lancet Haematol | G-CSF + decitabine + Bu/Cy vs Bu/Cy on relapse in MDS or secondary AML |
| 40079242 | 2025 | Review | Am J Hematol | Allogeneic HSCT is the only potentially curative therapy for MDS and myelofibrosis |
| 34692485 | 2021 | Meta-analysis | Front Oncol | Reduced-intensity vs myeloablative conditioning in AML/MDS |
| 33425740 | 2020 | Meta-analysis | Front Oncol | Treosulfan- vs busulfan-based conditioning in MDS/AML |
| 34489555 | 2021 | Registry study | Bone Marrow Transplant | Flu/Bu4 vs Bu4/Cy in MDS (propensity-matched) |
| 37856098 | 2024 | Risk assessment | Pediatr Blood Cancer | Evidence-based assessment of subsequent malignancy risk after busulfan |
| 38176654 | 2024 | Cohort | Transplant Cell Ther | Long-term complications with treosulfan vs busulfan conditioning in children |
Notably, the two Phase 3 RCTs in older patients favoured treosulfan over reduced-intensity busulfan. This supports busulfan as an established comparator and standard conditioning backbone rather than as the clearly superior option.
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN13260P | BUSULFEX® INJECTION 60 mg/vial (Baxter Oncology GmbH) | Injection, solution, concentrate | Not recorded in the data compiled |
| SIN11001P | MYRAN TABLETS 2 mg (Korea United Pharmaceutical Inc) | Tablet | Not recorded in the data compiled |
Both licences are valid single-ingredient products. The injectable form is the one used for transplant conditioning.
Cytotoxicity
| Item | Content |
|---|---|
| Cytotoxicity Classification | Conventional cytotoxic (bifunctional alkylating agent) |
| Myelosuppression Risk | High (myeloablative at conditioning doses; the knowledge graph lists neutropenia, thrombocytopenia, agranulocytosis and anemia as contraindication-linked conditions) |
| Emetogenicity Classification | Please refer to the package insert warnings and precautions |
| Monitoring Items | CBC with differential, liver function (including signs of hepatic veno-occlusive disease), renal function, and drug exposure monitoring where targeted dosing is used |
| Handling Protection | Must follow cytotoxic drug handling regulations |
Safety Considerations
- Key Warnings and Contraindications (label): Package insert warnings and contraindications were not available in the data compiled. Please refer to the package insert for safety information.
- Knowledge-graph contraindication signals (from drug–disease relationships, not label text): epilepsy, thrombocytopenia, neutropenia, agranulocytosis, anemia (including macrocytic anemia and Fanconi anemia), pulmonary fibrosis, hyperglycemia, infectious disease (including fungal infections and dermatophytosis), potassium deficiency, and hyperuricemia.
- Drug Interactions: 100 interactions were identified. The main ones are:
- Major: metronidazole
- Moderate: aprepitant, miconazole
- Minor: levofloxacin
- Others with unknown severity include amphotericin B, vancomycin, corticosteroids (prednisone, hydrocortisone, prednisolone, dexamethasone), proton pump inhibitors, H2 blockers, antiemetics (ondansetron, granisetron, metoclopramide), morphine, and mannitol.
- Long-term risk: Literature notes a risk of secondary malignancy and long-term complications after busulfan-based conditioning, particularly in children.
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: Multiple Phase 2 trials, completed Phase 3 randomized trials and published RCTs support busulfan-based conditioning in MDS. However, this reflects established transplant practice, not a new standalone therapy, and the label-level safety data are missing. The lower-ranked predictions (L5 candidates such as seborrheic keratosis and feline AIDS) have no supporting evidence and should be held.
To proceed, the following is needed:
- Singapore package insert (warnings, contraindications and approved indications), as the current licence records have no indication text
- Detailed mechanism of action data
- Confirmation that the use is limited to the injectable formulation within specialist transplant centres, with a defined dosing and exposure-monitoring plan
- A safety monitoring plan for high-risk groups (older or comorbid patients, children, and patients with pre-existing cytopenias, lung disease or seizure history)
- Review of the major interaction with metronidazole and the antifungal and antiemetic co-medications commonly used in transplant
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.