Eflornithine
| Evidence Level: L5 | Predicted Indications: 10 |
Table of Contents
- Eflornithine
- Eflornithine: From Human African Trypanosomiasis to Bovine Trypanosomiasis (and Monoclonal Gammopathy as a Secondary Hypothesis)
Eflornithine: From Human African Trypanosomiasis to Bovine Trypanosomiasis (and Monoclonal Gammopathy as a Secondary Hypothesis)
One-Sentence Summary
Eflornithine (DB06243) is an ornithine decarboxylase (ODC) inhibitor already approved for human African trypanosomiasis (Gambian sleeping sickness). TxGNN’s top-ranked prediction (esotropia, 99.85%) has no supporting evidence and is assessed by the model’s own rationale as a likely false positive; among the ten candidates screened, only two — bovine trypanosomiasis and monoclonal gammopathy — advanced past initial screening (S1), each supported by preclinical/mechanistic literature only (2 and 9 publications respectively, no clinical trials).
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Human African Trypanosomiasis (per repurposing rationale; not separately recorded in structured original_indications) |
| Predicted New Indication | Trypanosomiasis, Bovine (primary candidate); Monoclonal Gammopathy (secondary candidate — see below) |
| TxGNN Prediction Score | 98.42% (bovine trypanosomiasis, rank 13,875 of model output) |
| Evidence Level | L4 (preclinical/mechanistic literature only, no clinical trials) |
| Taiwan Market Status | Not marketed (Not marketed) |
| Number of Authorizations | 0 |
| Recommended Decision | Hold |
Note: the model’s #1-ranked prediction by raw score, esotropia (99.85%), is not used as the headline indication here because it has zero clinical trials, zero literature, and the evidence pack’s own mechanistic rationale flags it as “an KG-embedding-similarity false positive.” The two candidates below are the only ones that reached decision stage S1 (“Research Question”).
Why is This Prediction Reasonable?
Detailed mechanism-of-action data is not available in this evidence pack (original_moa: [Data Gap]). Based on the literature captured here, eflornithine (DFMO, α-difluoromethylornithine) is an irreversible inhibitor of ornithine decarboxylase, the rate-limiting enzyme in polyamine biosynthesis. It is clinically established for late-stage human African trypanosomiasis (Trypanosoma brucei gambiense), where blocking parasite polyamine synthesis halts proliferation.
Bovine trypanosomiasis is caused by closely related trypanosome species (e.g., T. congolense, T. vivax) that share highly conserved polyamine metabolism pathways with T. brucei. This is the most mechanistically direct extension of the drug’s approved use across host species rather than across disease categories, and is supported by in vitro evidence (PMID 32053698) showing eflornithine activity against blood parasites including trypanosomes, and mechanistic work on the trypanosomatid polyamine pathway (PMID 23525104).
Monoclonal gammopathy (a plasma-cell disorder and myeloma precursor) has a different rationale: multiple 1985–1995 studies show that human myeloma cell lines develop resistance to DFMO via ODC gene amplification/overexpression, demonstrating that the drug-target axis is pharmacologically active in plasma cells. This is evidence of target engagement, not of therapeutic efficacy — no study tested DFMO as a treatment for gammopathy itself, and the evidence base is three decades old with no contemporary follow-up.
Clinical Trial Evidence
Currently no related clinical trials registered for either candidate indication (bovine trypanosomiasis or monoclonal gammopathy).
Literature Evidence
Candidate 1: Trypanosomiasis, Bovine
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 32053698 | 2020 | Preclinical/In vitro | PLoS One | Eflornithine shows antitrypanosomal activity against blood parasites (Babesia, Theileria, related trypanosomatids); positioned as best-choice therapy for late-stage human African trypanosomiasis |
| 23525104 | 2013 | Preclinical/Mechanistic | J Biol Chem | Characterizes polyamine biosynthesis as a key drug target in African trypanosomes; eflornithine inhibits the first step (spermidine synthesis) via ODC inhibition |
Candidate 2: Monoclonal Gammopathy
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 7646459 | 1995 | In vitro/Mechanistic | Biochem J | DFMO-resistant human myeloma cells show long-term reduction of amplified ODC gene sequences after drug withdrawal |
| 3934157 | 1985 | In vitro/Mechanistic | J Biol Chem | ODC is translationally regulated by polyamines in DFMO-resistant mouse myeloma cells |
| 3015379 | 1986 | In vitro/Mechanistic | Cancer Research | Polyamines modulate etoposide cytotoxicity and DNA strand scission in myeloma (8226) and leukemia (L1210) cell lines |
| 3141118 | 1988 | Cohort (biomarker) | Chemotherapy | Polyamine levels increase in blood/marrow mononuclear cells of leukemia/myeloma patients treated with MGBG despite DFMO co-administration |
| 3139580 | 1988 | Cohort (biomarker) | Investigational New Drugs | IV DFMO alters circulating and marrow polyamine levels in refractory leukemia/myeloma patients (9 patients) |
| 1898373 | 1991 | In vitro/Mechanistic | Biochem J | Quantifies ODC gene dosage and mRNA in DFMO-resistant human myeloma cells |
| 2501085 | 1989 | In vitro/Mechanistic | EMBO J | DFMO-resistant mouse myeloma cells show ODC gene rearrangement with the immunoglobulin gamma-1 switch region |
| 3109382 | 1987 | In vitro/Mechanistic | Biochem J | Human myeloma cells acquire DFMO resistance via ODC gene amplification (10-fold activity increase) |
| 3107550 | 1987 | In vitro/Mechanistic | Biochem Biophys Res Commun | Human myeloma cells acquire DFMO resistance without ODC overproduction, via an alternative mechanism |
Taiwan Market Information
Eflornithine is not marketed in Taiwan (0 authorizations on file). No TFDA license records are available in this evidence pack; TFDA package-insert warnings/contraindications remain an unresolved blocking data gap (see below).
Safety Considerations
Please refer to the SmPC for safety information. No structured warnings, contraindications, or drug-interaction data were retrievable for eflornithine in this evidence pack (TFDA label lookup is flagged as a blocking data gap: DG001).
Other Screened Candidates (Not Advanced)
Eight additional TxGNN-predicted indications (esotropia, neurotrophic keratopathy, congenital analbuminemia, hyperamylasemia, polyclonal hyperviscosity syndrome, blood group incompatibility, premalignant hematological system disease, congenital prothrombin deficiency) scored highly (98–99.9%) but returned zero clinical trials and zero literature on targeted search, and each rationale explicitly notes no known mechanistic link to ODC/polyamine biology. These remain at decision stage S0 (Hold) and are not pursued further.
Conclusion and Next Steps
Decision: Hold
Rationale: Both viable candidates (bovine trypanosomiasis, monoclonal gammopathy) are supported only by decades-old preclinical/mechanistic literature with no clinical trials — sufficient to frame a research question, but not to justify clinical development or a guardrailed pilot. The model’s top-scored prediction (esotropia) has no evidentiary support and is assessed as a probable false positive.
To proceed, the following is needed:
- TFDA package-insert data (warnings, contraindications) — currently a blocking gap (DG001)
- DrugBank-sourced mechanism of action detail (DG002)
- Contemporary (post-1995) validation of the ODC/polyamine-myeloma link, ideally in patient-derived samples
- Assessment of regulatory pathway feasibility for bovine trypanosomiasis (veterinary use of a human-approved drug is a distinct approval track from clinical repurposing)
- Any available DDI/toxicity data, since the current DDI query returned no results
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.