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) internationally approved for pulmonary arterial hypertension (PAH) and prevention of digital ulcers in systemic sclerosis, though no local regulatory approval is currently on record in this market. The TxGNN model predicts it may be effective for Rheumatoid Arthritis (RA), with 1 clinical trial (indirectly related, targeting Giant Cell Arteritis) and 16 publications currently supporting this direction — predominantly preclinical mechanistic studies without direct human RA trial data.

Quick Overview

Item	Content
Original Indication	Pulmonary arterial hypertension (based on known pharmacology; no local regulatory approvals on file)
Predicted New Indication	Rheumatoid Arthritis
TxGNN Prediction Score	99.80%
Evidence Level	L4
Italy Market Status	Not Marketed
Number of Authorizations	0
Recommended Decision	Hold

Why is This Prediction Reasonable?

Currently, detailed mechanism of action data is not available in this evidence pack. Based on known information, bosentan is a dual ETA/ETB endothelin receptor antagonist, and its efficacy in pulmonary arterial hypertension and systemic sclerosis has been well established internationally. The predicted bridge to RA rests on a shared biological pathway: endothelin-1 (ET-1) is both a potent vasoconstrictor and a pro-inflammatory mediator whose levels are significantly elevated in the synovial fluid and pannus tissue of RA patients. Acting through the ETA receptor, ET-1 promotes TNF-α release, amplifying synovial inflammation and driving the progressive joint destruction that characterises RA.

The key mechanistic argument is that blocking ETA and ETB receptors with bosentan could interrupt this ET-1 → TNF-α inflammatory loop while simultaneously improving synovial microcirculation. This hypothesis has direct preclinical support: in a collagen-induced arthritis (CIA) mouse model — the gold-standard animal model for RA — bosentan significantly ameliorated arthritis (PMID 22249931). Multiple additional animal studies confirm that endothelins modulate neutrophil accumulation, oedema formation, and articular pain sensitisation in models of inflammatory arthritis, and that IL-15 triggers a sequential endothelin-dependent hypernociception cascade relevant to RA pain pathophysiology.

Despite this mechanistic plausibility, direct clinical evidence in RA patients is entirely absent. The only clinical trial identified (NCT06957002) targets Giant Cell Arteritis (GCA), a large-vessel granulomatous vasculitis with a pathological mechanism distinct from RA's autoimmune synovial inflammation; results from this trial cannot be extrapolated to RA. The evidence therefore remains at Level L4, warranting further mechanistic investigation before clinical translation can be considered.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrollment	Key Findings
NCT06957002	Phase 2	Not Yet Recruiting	40	Bosentan + glucocorticoids vs. glucocorticoids alone in Giant Cell Arteritis; primary endpoint is failure-free survival at 12 months. ⚠️ Indication is GCA (large-vessel vasculitis), not RA — results cannot be directly extrapolated to rheumatoid arthritis.

Literature Evidence

PMID	Year	Type	Journal	Key Findings
22249931	2012	Preclinical (CIA Mouse Model)	Inflammation Research	Bosentan directly ameliorates collagen-induced arthritis in mice; TNF-α drives ET system gene upregulation in joints, and bosentan suppresses this cascade — the most directly relevant evidence for RA repurposing
18515326	2008	Preclinical (Animal Model)	Journal of Leukocyte Biology	Endothelins mediate neutrophil accumulation and oedema in zymosan-induced arthritis; ET-1 elevated in RA synovial membrane; ETA/ETB blockade reduces joint inflammation
16766656	2006	Preclinical (Animal Model)	PNAS	IL-15 triggers sequential IFN-γ → endothelin → prostaglandin release causing articular hypernociception; dual ERA blockade inhibits this RA-relevant pain pathway
19969421	2010	Preclinical (Animal Model)	Pain	IL-17 drives articular hypernociception in antigen-induced arthritis with confirmed ET-1 pathway involvement; supports endothelin's role in RA pain generation
20054770	2009	Case Report	Kardiologia Polska	Juvenile RA co-occurring with Eisenmenger syndrome; bosentan initiated for Eisenmenger with clinical improvement noted — incidental observation, not a controlled RA study
24268012	2014	Review	Rheumatic Disease Clinics of North America	PAH complicating CTDs including RA; bosentan role in CTD-PAH management; provides disease-overlap context for endothelin pathway relevance in RA
19487226	2009	Review	Rheumatology (Oxford)	Vasculopathy and PAH in rheumatic CTDs; endothelin pathway central to vascular pathology in autoimmune diseases; contextual support for ERA use in rheumatic conditions
16218473	2005	Review	Lupus	PAH as complication of CTDs including RA, dermatomyositis and Sjögren's syndrome; supports broad ET pathway relevance across the rheumatic disease spectrum
21165350	2010	Review	Canadian Respiratory Journal	Targeted PH therapies including bosentan in CTD patients with concomitant ILD; real-world clinical use of ERA across rheumatic disease contexts
19851110	2010	Review	Current Opinion in Rheumatology	Overview of rheumatic skin disease pathophysiology and emerging therapies; contextual background for endothelin antagonism in the broader rheumatic disease landscape

Italy Market Information

No regulatory authorizations for Bosentan are currently on record in this market.

Note: Bosentan (Tracleer®) holds EMA approval for pulmonary arterial hypertension and prevention of new digital ulcers in systemic sclerosis. If the absence of local records reflects a data retrieval gap rather than a true lack of local approval, further verification with the relevant regulatory authority (AIFA) is recommended.

Safety Considerations

Please refer to the package insert for safety information.

Conclusion and Next Steps

Decision: Hold

Rationale: Bosentan has a mechanistically plausible and preclinically supported rationale for RA repurposing, with ET-1/ERA pathway involvement confirmed in collagen-induced and other animal arthritis models. However, no human clinical trials in RA patients have been conducted, placing this squarely at Evidence Level L4 — insufficient to support clinical translation without further dedicated investigation.

To proceed, the following is needed:

Retrieve full MOA and safety profile data from DrugBank (currently unavailable in this evidence pack)
Obtain the local package insert to assess TFDA/AIFA-specific warnings, contraindications, and approved dosing
Conduct a dedicated systematic review of ET receptor antagonism in RA, focusing on human biomarker and translational data
Evaluate bosentan's drug interaction profile with common RA therapies — particularly methotrexate and biologics — given bosentan's known CYP3A4/CYP2C9 induction capacity
Design a Phase 1/2 proof-of-concept clinical study; a pragmatic entry point would be RA patients with comorbid PAH or systemic sclerosis overlap, where ERA therapy is already clinically justified
Investigate hepatotoxicity risk in the context of concurrent DMARD use, as both bosentan and methotrexate carry hepatotoxic potential
Disclaimer

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