Bosentan

證據等級: L5

預測適應症: 10 個

Bosentan: From Pulmonary Arterial Hypertension to Rheumatoid Arthritis

One-Sentence Summary

Bosentan (Tracleer) is a dual endothelin receptor antagonist (ETA/ETB) with established use internationally for pulmonary arterial hypertension (PAH) and, in European markets, for the prevention of digital ulcers in systemic sclerosis. The TxGNN model predicts it may be effective for Rheumatoid Arthritis (RA), with 1 clinical trial (in giant cell arteritis, a mechanistically related autoimmune vasculitis) and 16 publications currently providing supporting context. Evidence at this stage is primarily preclinical, placing this prediction at Level 4 — a biologically plausible research question that warrants targeted investigation before clinical translation.

Quick Overview

Item	Content
Original Indication	Pulmonary Arterial Hypertension (WHO Group I); digital ulcer prevention in systemic sclerosis (EMA-approved internationally)
Predicted New Indication	Rheumatoid Arthritis
TxGNN Prediction Score	99.80%
Evidence Level	L4 (preclinical animal models; no human RA trial data)
Australia Market Status	Not Marketed
Number of ARTG Entries	0
Recommended Decision	Hold (Research Question)

Why is This Prediction Reasonable?

Bosentan is a potent dual antagonist of endothelin receptor subtypes A and B (ETA/ETB). Endothelin-1 (ET-1) is a vasoactive peptide produced by endothelial cells that drives vascular constriction, smooth muscle proliferation, and — crucially — inflammation and tissue remodelling. Its established efficacy in pulmonary arterial hypertension is based on reversing ET-1-driven pathological changes in the pulmonary vasculature.

The mechanistic rationale for rheumatoid arthritis rests on growing evidence that ET-1 is elevated in the synovial fluid and plasma of RA patients. Acting through downstream mediators including TNF-α and leukotriene B4 (LTB4), ET-1 appears to promote neutrophil recruitment, joint oedema, and pain hypersensitisation in inflamed joints. Preclinical work is directly supportive: bosentan significantly reduced joint pathology, swelling, and inflammatory mediator production in both collagen-induced arthritis (CIA) and zymosan-induced arthritis mouse models. Separately, IL-15 and IL-17 — cytokines central to RA pathophysiology — have been shown to trigger hypernociception via the endothelin axis, which dual ET receptor blockade can suppress.

Currently, the only human trial involving bosentan in the autoimmune vasculitis space is NCT06957002, a Phase 2 study in giant cell arteritis (GCA). While GCA is not RA, both conditions share TNF-α and ET-1 mediated vascular inflammation mechanisms, and this trial will generate important human safety and pharmacodynamic data. No dedicated RA clinical trial has been conducted. The evidence supports mechanistic plausibility, but a purpose-designed human study is required before this indication can be progressed.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrolment	Key Findings
NCT06957002	Phase 2	Not Yet Recruiting	40	Bosentan + glucocorticoids vs glucocorticoids alone in giant cell arteritis (GCA); primary endpoint is failure-free survival at 12 months. GCA shares ET-1/TNF-α vascular inflammation pathways with RA, providing indirect mechanistic and safety context — but is not a direct RA efficacy study.

Literature Evidence

PMID	Year	Type	Journal	Key Findings
22249931	2012	Animal Study	Inflammation Research	Bosentan (dual ETA/ETB antagonist) significantly ameliorates collagen-induced arthritis in mice; TNF-α shown to upregulate endothelin system genes in arthritic joints — the most directly relevant preclinical study
18515326	2008	Animal Study	Journal of Leukocyte Biology	ET-1 drives neutrophil accumulation and joint oedema via LTB4, TNF-α, and CXCL-1 in zymosan-induced arthritis; ETA/ETB receptor blockade reduces joint inflammation
16766656	2006	Animal Study	PNAS	IL-15-induced joint hypernociception suppressed by dual ET receptor blockade; endothelin pathway identified as a downstream mediator of inflammatory pain in experimental arthritis
19969421	2010	Animal Study	Pain	IL-17 mediates articular hypernociception in antigen-induced arthritis in mice; implicates ET system in RA-associated pain, suggesting ET blockade may have analgesic benefit
20054770	2009	Case Report	Kardiologia Polska	Paediatric patient receiving bosentan for Eisenmenger syndrome subsequently diagnosed with juvenile rheumatoid arthritis; no adverse pharmacodynamic interaction with naproxen observed
24268012	2014	Review	Rheumatic Diseases Clinics of North America	PAH associated with connective tissue diseases including RA; establishes ET-1 dysregulation as shared mechanism across rheumatic conditions
16218473	2005	Review	Lupus	PAH as complication of CTDs including RA, SLE, and Sjögren’s; ET-1 dysregulation common to autoimmune vascular disease
19487226	2009	Review	Rheumatology (Oxford)	Vasculopathy and PAH in CTDs; contextualises bosentan’s role in managing ET-1 driven vascular complications across rheumatic diseases
18238768	2008	Review	American Journal of Health-System Pharmacy	Drug therapy for systemic sclerosis complications; reviews bosentan efficacy in ET-1 driven rheumatic vascular disease
19851110	2010	Review	Current Opinion in Rheumatology	Pathophysiology and therapy of rheumatic skin diseases; broader context for ET-1 involvement in inflammatory rheumatic conditions

Australia Market Information

Bosentan is not currently registered on the Australian Register of Therapeutic Goods (ARTG). There are no TGA-approved products available in Australia as at the data cutoff date (April 2026).

Healthcare professionals in Australia wishing to access bosentan for any indication — including its internationally approved PAH indication — would need to do so via the TGA Special Access Scheme (SAS Category B) or similar regulatory pathway.

Internationally, bosentan is marketed as Tracleer® and is approved by the FDA and EMA for pulmonary arterial hypertension (WHO Group I) in adults and paediatric patients. The EMA additionally approves its use for reducing the number of new digital ulcers in systemic sclerosis patients.

Safety Considerations

Bosentan is not TGA-registered in Australia and no local Product Information is available. Based on internationally approved prescribing information (EMA SmPC / FDA label for Tracleer®), prescribers should be aware of the following:

Detailed safety data was not available in the Evidence Pack for this evaluation. Please refer to the internationally approved Product Information for Tracleer® (EMA SmPC or FDA Prescribing Information) for comprehensive safety guidance.

Key internationally documented concerns include:

Hepatotoxicity: Dose-dependent elevation of liver enzymes (≥3× ULN) observed in approximately 10% of patients; mandatory monthly liver function monitoring required
Teratogenicity: Bosentan is contraindicated in pregnancy (Category X equivalent); mandatory pregnancy prevention programme required for all women of childbearing potential
Drug interactions: Bosentan is a potent inducer of CYP3A4 and CYP2C9 — significant interactions expected with many DMARDs, immunosuppressants, and other rheumatology medications

Conclusion and Next Steps

Decision: Hold (Research Question)

Rationale: The ET-1/ETA/ETB axis is mechanistically implicated in RA joint inflammation and pain, with consistent supportive data from multiple preclinical animal models; however, no human clinical trial has assessed bosentan directly in RA patients, and the single related trial (NCT06957002) targets GCA rather than RA. L4 evidence is insufficient to support clinical use or formal repurposing development at this stage.

To proceed, the following is needed:

A dedicated pilot clinical study (Phase 1/2) assessing bosentan in active RA patients, ideally with biomarker-stratified patient selection based on elevated baseline ET-1 levels
Biomarker validation studies measuring synovial ET-1, ETA/ETB receptor expression, and endothelin pathway activity in RA patient samples
Safety assessment specifically in the RA population context, including interactions with standard DMARDs (methotrexate, leflunomide) that share hepatotoxic potential with bosentan
Review of the NCT06957002 GCA trial results (completion expected September 2029) for indirect safety and mechanistic insights
TGA Special Access Scheme pathway assessment if an investigator-initiated trial is planned in Australia
Important note: Bosentan’s evidence base is substantially more mature for limited systemic sclerosis (Rank 3 TxGNN prediction, L1 evidence, multiple Phase 3 RCTs, EMA-approved indication). This indication represents a more immediate clinical opportunity and warrants a separate priority evaluation report.
Disclaimer

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