Defibrotide

證據等級: L5

預測適應症: 10 個

Defibrotide: From Hepatic Veno-Occlusive Disease to Thrombotic Thrombocytopenic Purpura

One-Sentence Summary

Defibrotide's established clinical use — evident from trial context (NCT02851407, Phase 3) — is prevention of hepatic veno-occlusive disease (VOD) in patients undergoing hematopoietic stem cell transplantation (HSCT). TxGNN's top-ranked prediction (pseudo-von Willebrand disease) has zero supporting evidence and is explicitly flagged by the evidence review as a likely knowledge-graph artifact. The most credible predicted new indication is Thrombotic Thrombocytopenic Purpura (TTP) / transplant-associated thrombotic microangiopathy (TA-TMA), supported by 11 publications spanning 1984–2023, though with no dedicated clinical trials and no market presence in Norway.

Note on candidate selection: This evidence pack contains 10 TxGNN-predicted indications. Eight of them (ranks 1–3, 5–9) have no clinical trial or literature evidence at all and are scored L5/Hold — several rationales explicitly state the mechanistic direction is opposite to defibrotide's antithrombotic profile (e.g., Glanzmann thrombasthenia, factor V deficiency, collagen receptor defects are bleeding disorders, not thrombotic ones). Only rank 4 (TTP) and rank 10 (thrombocytopenic purpura, near-duplicate evidence set) reach L3/S2. This report focuses on TTP as the scientifically defensible candidate rather than mechanically reporting the highest raw TxGNN score.

Quick Overview

Item	Content
Original Indication	Not formally recorded in this evidence pack (0 licenses; unmarketed in Norway). Trial context (NCT02851407) indicates established use in prevention of hepatic veno-occlusive disease (VOD) in HSCT patients
Predicted New Indication	Thrombotic Thrombocytopenic Purpura (TTP)
TxGNN Prediction Score	99.71% (rank 3665 overall)
Evidence Level	L3 (observational studies / case series, no RCTs)
Norway Market Status	✗ Not marketed (未上市)
Number of Authorizations	0
Recommended Decision	Proceed with Guardrails

Why is This Prediction Reasonable?

Currently, detailed mechanism of action data is not available in structured form (Data Gap). Based on the available trial and literature context, defibrotide is a polydeoxyribonucleotide with antithrombotic, profibrinolytic, and endothelial-protective properties, and its established use is prevention/treatment of hepatic VOD in HSCT patients — a condition driven by sinusoidal endothelial injury and microvascular thrombosis.

TTP and transplant-associated thrombotic microangiopathy (TA-TMA) share substantial pathophysiological overlap with VOD: both occur predominantly in the HSCT setting and are driven by endothelial injury with consumptive microthrombus formation. This overlap is reflected directly in the literature — several papers on defibrotide-and-TTP are framed specifically in transplant patients (e.g., Uderzo 2000, Corti 2002), and reviews of TA-TMA (Ikezoe 2018, Choi 2009, Batts & Lazarus 2007) describe essentially the same endothelial-injury mechanism defibrotide is designed to address in VOD.

However, this mechanistic plausibility is tempered by evidence quality: no RCTs exist, most literature is older case series/case reports (1984–2002), and — importantly — one publication (Perotti 1994) reports TTP occurring as an adverse event following defibrotide therapy, rather than as a treatment response. This creates a safety signal that must be resolved before clinical application (see Safety Considerations below).

Clinical Trial Evidence

Currently no related clinical trials registered.

(Note: NCT02851407, a completed Phase 3 VOD-prevention trial, appears elsewhere in this evidence pack but was graded "C" / not relevant by the evidence reviewer for platelet-disorder indications — it is not counted as TTP evidence.)

Literature Evidence

PMID	Year	Type	Journal	Key Findings
11100281	2000	Cohort	Bone Marrow Transplant	TTP incidence and risk factors in 131 pediatric leukemia patients undergoing HSCT
11960280	2002	Case series	Bone Marrow Transplant	Defibrotide described as a promising treatment for TTP in HSCT patients
8317470	1993	Case series	Am J Hematol	Treatment of TTP with defibrotide
6547211	1984	Case series	Nephron	Defibrotide as a new antithrombotic agent in HUS/TTP-related acute renal failure
30305540	2018	Review	Rinsho Ketsueki	Management of transplant-associated thrombotic microangiopathy (TA-TMA)
17603513	2007	Review	Bone Marrow Transplant	Diagnosis and treatment progress in TA-TMA
19228075	2009	Review	Drugs	TMA in HSCT: diagnosis and treatment overview
10775024	2000	Case report	Clin Appl Thromb Hemost	Defibrotide used in recurrent TTP
37001283	2023	In-vitro/mechanistic	Thrombosis Research	Defibrotide mitigates endothelial cell injury from COVID-19/TMA patient plasmas
7896218	1994	Case report (Adverse Event)	Haematologica	TTP reported as an adverse event after defibrotide therapy — safety signal, not efficacy evidence

Norway Market Information

Defibrotide is currently not marketed in Norway — 0 marketing authorizations are on record in this evidence pack. No product/dosage-form data is available.

Safety Considerations

Data gap flagged as Blocking: No TFDA/label warnings or contraindications are available in this evidence pack (DG001, severity: Blocking) — this prevents any preliminary safety assessment.
Safety signal from literature: One case report (Perotti et al., 1994, Haematologica) describes TTP occurring after defibrotide therapy, i.e., as a possible adverse event rather than a therapeutic benefit. This directly conflicts with the repurposing hypothesis and must be reconciled before proceeding.
No structured drug-drug interaction data is available (query returned no results).

Please refer to the package insert for complete safety information once available.

Conclusion and Next Steps

Decision: Proceed with Guardrails (conditional — see rationale)

Rationale: Among 10 TxGNN-predicted indications, TTP/TA-TMA is the only one with a mechanistically coherent rationale (shared endothelial-injury pathophysiology with defibrotide's known VOD use) and multi-decade literature support (11 publications, L3 evidence). However, the absence of RCTs, the presence of a conflicting adverse-event report, and a Blocking-severity safety data gap mean this cannot advance to formal evaluation (S1) without additional data.

To proceed, the following is needed:

TFDA/manufacturer label warnings and contraindications (DG001, Blocking — required before any S1 safety evaluation)
Structured mechanism of action data (DG002, High)
Resolution of the conflicting signal between defibrotide-as-treatment (case series) vs. defibrotide-as-cause (Perotti 1994 AE report) for TTP
Confirmation of the drug's actual approved original indication(s), since original_indications is currently empty in this pack
If pursued further, a targeted literature/registry search specifically for TA-TMA (rather than idiopathic TTP) given the stronger mechanistic and clinical-context overlap with defibrotide's known VOD indication
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.