Bosentan

證據等級: L5

預測適應症: 9 個

Bosentan: From Pulmonary Arterial Hypertension to Rheumatoid Arthritis

One-Sentence Summary

Bosentan is a dual endothelin receptor antagonist (ERA) approved for pulmonary arterial hypertension (PAH) and prevention of digital ulcers in systemic sclerosis (SSc). The TxGNN model predicts it may be effective for Rheumatoid Arthritis (RA), with 1 related clinical trial (conducted in giant cell arteritis, a related vasculitic condition) and 16 publications providing indirect and preclinical mechanistic support for this direction. Evidence is currently limited to animal models and observational data, with no dedicated RA clinical trials yet completed.

Quick Overview

Item	Content
Original Indication	Pulmonary arterial hypertension (WHO Group 1); prevention of new digital ulcers in systemic sclerosis
Predicted New Indication	Rheumatoid Arthritis
TxGNN Prediction Score	99.80%
Evidence Level	L4
UK Market Status	Not marketed (data gap — Tracleer holds EMA approval for PAH and SSc digital ulcers; current MHRA authorisation status should be verified independently)
Number of Marketing Authorisations	0 (data gap)
Recommended Decision	Hold

Why is This Prediction Reasonable?

Bosentan is a dual endothelin receptor antagonist that blocks both ETA and ETB receptors, suppressing the downstream effects of endothelin-1 (ET-1). ET-1 is a potent vasoconstrictor and pro-fibrotic mediator. In its established indications — pulmonary arterial hypertension and systemic sclerosis — ET-1 overexpression is a central pathological driver, making receptor blockade a rational and proven therapeutic strategy.

The mechanistic rationale for rheumatoid arthritis rests on the observed elevation of ET-1 in RA synovial fluid. ET-1 stimulates synoviocytes to secrete TNF-α, promotes angiogenesis and pannus formation, and participates in articular hypernociception through a sequential IL-15 → IFN-γ → ET-1 → prostaglandin cascade. Notably, a murine collagen-induced arthritis (CIA) model demonstrated that bosentan significantly reduced joint inflammation and TNF-α production by blocking ET-A/ET-B receptors (Donate et al., 2012). Multiple animal studies further confirm that endothelin signalling modulates neutrophil trafficking and pain sensitisation in experimental arthritis models.

However, the ET-1 pathway is considered a secondary mechanism in RA. The primary drivers of disease — adaptive immune dysregulation mediated by TNF-α, IL-6, and JAK-STAT signalling — are already targeted by established DMARDs and biologics. The extent to which ET-receptor blockade could meaningfully alter RA disease activity in human patients, beyond its indirect anti-inflammatory contribution, remains scientifically uncertain and clinically undemonstrated.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrolment	Key Findings
NCT06957002	Phase 2	Not Yet Recruiting	40	Multicentre RCT comparing bosentan + glucocorticoids vs glucocorticoids alone in giant cell arteritis (GCA); primary endpoint is failure-free survival at 12 months (completion expected September 2029). GCA shares vascular endothelial inflammation and elevated ET-1 with RA, providing indirect mechanistic support. Results cannot be extrapolated directly to RA, but a positive outcome would provide proof-of-concept for ERA in inflammatory vasculitic/rheumatic disease.

Literature Evidence

PMID	Year	Type	Journal	Key Findings
22249931	2012	Animal Study	Inflammation Research	Bosentan ameliorated collagen-induced arthritis in mice; TNF-α was found to upregulate endothelin system gene expression, establishing a mechanistic feedback loop; the most directly relevant preclinical evidence for RA repurposing
18515326	2008	Animal Study	Journal of Leukocyte Biology	ET-1 promotes neutrophil accumulation, oedema formation, and release of LTB4, TNF-α, and CXCL-1 in zymosan-induced murine arthritis; selective ETA/ETB blockade attenuated joint inflammation
16766656	2006	Animal Study	PNAS	IL-15–induced articular hypernociception mediated through a sequential IFN-γ → endothelin → prostaglandin cascade; dual ERA prevented hypernociception in mice, highlighting ET-1’s role in RA pain pathways
19969421	2010	Animal Study	Pain	IL-17 drives articular hypernociception in antigen-induced arthritis via mechanisms that intersect with the endothelin pathway; provides broader context for ET-1’s role in RA nociception
24268012	2014	Review	Rheumatic Disease Clinics of North America	Comprehensive review of PAH in connective tissue diseases; discusses ET-1’s central role across the rheumatic disease spectrum and the evidence base for ERA therapy
19487226	2009	Review	Rheumatology (Oxford)	Reviews vascular disease and PAH in SLE, Sjögren’s syndrome, and primary vasculitides; establishes ET-1 as a shared mediator of vasculopathy across rheumatic diseases including RA
16218473	2005	Review	Lupus	PAH as a complication of CTDs including RA, dermatomyositis, and Sjögren’s; endothelin pathway implicated in vascular complications across the rheumatic spectrum
19851110	2010	Review	Current Opinion in Rheumatology	Overview of rheumatic skin disease and overlapping therapeutic considerations; contextualises evolving treatment approaches in immune-mediated rheumatic conditions
18238768	2008	Review	AJHP	Reviews pharmacological options for SSc complications; provides context for bosentan’s role across ET-1–driven rheumatic conditions
20054770	2009	Case Report	Kardiologia Polska	Paediatric case of Eisenmenger syndrome co-occurring with juvenile RA managed with bosentan and naproxen; clinical co-management context demonstrating safety of bosentan alongside anti-inflammatory therapy in a patient with concurrent RA

Safety Considerations

Please refer to the Summary of Product Characteristics (SmPC) and the British National Formulary (BNF) for complete safety information. Report suspected adverse reactions via the Yellow Card Scheme at https://yellowcard.mhra.gov.uk.

Formal safety data — including key warnings, contraindications, and drug interaction profiles — were not available in this Evidence Pack. Clinicians and researchers should consult the current Tracleer SmPC before considering any off-label use. Of particular note from published literature: bosentan is associated with hepatotoxicity requiring regular liver function monitoring, teratogenicity (Pregnancy Category X — absolutely contraindicated in pregnancy), potential anaemia, and fluid retention. It is also a potent inducer of CYP3A4 and CYP2C9, with multiple clinically significant drug interactions (e.g., ciclosporin, glyburide, hormonal contraceptives).

Conclusion and Next Steps

Decision: Hold

Rationale: The current body of evidence is limited to preclinical animal models and mechanistic studies demonstrating a modulatory role for ET-1 in RA pathophysiology. No clinical trials have directly evaluated bosentan in RA patients, and the ET pathway is a secondary contributor to RA pathogenesis compared with the well-validated TNF-α/IL-6/JAK axes already addressed by licensed biologics and targeted synthetic DMARDs. The mechanistic link, whilst biologically plausible, is insufficiently supported to justify clinical translation at this stage.

To proceed, the following is needed:

A dedicated Phase 1/2 proof-of-concept clinical trial evaluating bosentan in active RA, ideally enriched for patients with elevated synovial ET-1 levels, concurrent Raynaud’s phenomenon, or PAH comorbidity
Mechanistic human studies clarifying the relative contribution of ET-1 signalling to RA disease activity and its interaction with dominant cytokine pathways
Biomarker identification to define RA subpopulations most likely to respond to ET-receptor blockade (e.g., those with vasculopathic or fibrotic RA phenotypes)
Results from NCT06957002 (GCA trial, expected 2029) to determine whether ERA is effective in a related inflammatory vasculitic condition, which could provide proof-of-concept to justify a dedicated RA study
Formal verification of the current MHRA marketing authorisation status for bosentan (Tracleer) in the UK, and review of the SmPC for any updated safety information before any off-label use is contemplated
A full Drug Interaction Assessment given bosentan’s significant CYP enzyme induction potential and the frequent co-prescription of DMARDs and biologics in RA management

Disclaimer: This report is produced for research purposes only and does not constitute medical advice. All drug repurposing candidates require prospective clinical validation before clinical application. The information contained herein should not be used to guide individual patient treatment decisions.

Disclaimer

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