Infliximab versus alpha interferon in the treatment of Behçet’s disease: the BIO BEHÇET’S RCT
Authors: Moots Robert J , Fortune Farida , Jackson Richard , Thornburn Tony , Morgan Ann W , Carr Dan , Murray Philip Ian , Wallace Graham Robert , Situnayake Deva 
Published: November 2023

Background
While biologic therapy, typically with infliximab or Roferon, was used for Behçet syndrome after first-line immunosuppressants, no high-quality randomised trials or predictive biomarkers were available.

Objective
To undertake a randomised controlled clinical trial of infliximab versus Roferon in Behçet syndrome and identify potential biomarkers for response.

Design
Pragmatic, standard of care, single-masked, randomised, two-arm, parallel head-to-head trial, with exploratory study on potential role of interferon lambda 3 and interferon lambda 4 single nucleotide polymorphisms and urinary metabolomics biomarkers.

Setting
Three national UK Behçet syndrome centres and allied clinics.

Participants
Patients with active Behçet syndrome, fulfilling International Study Group 1990 criteria, with inadequate response to or intolerance of first-line treatment.

Intervention
Randomisation to infliximab (5 mg/kg intravenous infusion) or Roferon (subcutaneous injection), utilising the UK Behçet syndrome drug pathway protocol.

Outcomes
Primary outcome: modified Behçet’s disease activity index at 12 weeks of therapy. Secondary outcomes: (1) modified Behçet’s disease activity index score at 24 weeks and (2) significant improvement at 12 and 24 weeks from baseline in vitreous haze and best corrected visual acuity change, oral ulcer severity score, number of genital ulcers, arthritis pain, adverse events, reduction in dose of glucocorticoid, quality-of-life scores and Physician’s Global Assessment of disease activity.

Sample size
Utilising a Bayesian analysis of covariance model (80% credible interval), initial sample size was 45/arm (Bayesian power 90%). With an anticipated 10% dropout rate, 100 patients were to be recruited. Following recommendations to reduce the overall length of the trial, this was revised down to 80 patients (36 in each arm, allowing for 10% dropout): 80% equi-tailed credibility interval, Bayesian power 88%. In total, 79 patients were eventually recruited for the study.

Methods
Patients with refractory active Behçet syndrome underwent stratified block randomisation, based on randomly permuted blocks with random block sizes of two and four, allocating treatment to either infliximab or Roferon. Follow up with symptom-directed examination at weeks 12 and 24 according to standard of care. Analysis of the primary end point was undertaken using a Bayesian analysis of covariance approach. Informative priors for the anticipated treatment effect were derived from a cohort of six international experts prior to the start of the study.

Results
In this first prospective head-to-head randomised controlled clinical trial of two biologic drugs in Behçet syndrome, both infliximab and Roferon were equally effective [mean difference (80% credibility interval) = 0.13 (–0.19 to 0.46)], with a trend for minor benefit in favour of infliximab in terms of tolerability and treatment persistence. Genetic data suggested a potential association between patient outcome and carriage of either rs4803221 or rs7248668 variants in the interferon lambda 3 (interleukin 28B) gene locus in the Roferon-treated arm. However, with the relatively small sample size, statistical significance of the association was lost when correcting for multiple tests. Metabolomic analysis identified potential markers of a metabolic response to treatment with infliximab.

Limitations
Single-masked design. Slow recruitment with fewer patients recruited in total, limiting the strength of analysis for secondary outcomes and mechanistic studies.

Conclusion
We report clinical efficacy in both infliximab and Roferon in refractory active Behçet syndrome, together with the potential for a novel metabolomic biomarker identifying response to infliximab.

Future work
Further work will characterise the appropriate metabolite(s) from existing samples to inform future prospective trials to study this in more detail clinically. The efficacy of Roferon in Behçet syndrome may support future manufacture of this drug.

Trial registration
This trial is registered as EudraCT Number: 2014-005390-36; ISRCTN49793874.

Funding
This award was funded by the National Institute for Health and Care Research (NIHR) Efficacy and Mechanism Evaluation (EME) programme (NIHR award ref: 12/205/46) and is published in full in Efficacy and Mechanism Evaluation; Vol. 11, No. 17. See the NIHR Funding and Awards website for further award information.