Rozanolixizumab fails to show broad efficacy in severe fibromyalgia trial
Primary endpointBPI-SF interference score mean change from baseline after 12 weeks
Where these numbers come from
“The primary endpoint met the pre-specified one-sided 10% α level, with greater improvement from baseline observed for rozanolixizumab versus placebo (least squares mean difference -0.5, 80% CI -1.0 to -0.1; p=0.065), but without significance at a two-sided 5% α level (95% CI -1.2 to 0.2; p=0.13).”
The publication
In a phase 2A trial of 63 adults with severe fibromyalgia, weekly subcutaneous rozanolixizumab did not demonstrate broad efficacy. The primary endpoint showed a least squares mean difference of -0.5 in the Brief Pain Inventory-Short Form interference score versus placebo, which was not statistically significant at the two-sided 5% alpha level.
Who the findings apply to
The trial included adults aged 18 to 70 years with severe fibromyalgia, defined by a Brief Pain Inventory-Short Form interference score of 6 or higher and a 10-day mean daily Pain Numeric Rating Scale score of 6 or higher but less than 10.
Participants were recruited at seven sites in north west England between December 21, 2022, and July 9, 2024, with 63 individuals randomly assigned to treatment groups.
Why this matters
The study aimed to evaluate whether reducing IgG concentration via the neonatal Fc receptor could alleviate symptoms in patients with severe fibromyalgia, a condition characterized by widespread pain and fatigue. The authors concluded that while there was an improvement in the Brief Pain Inventory-Short Form score, it was not meaningful at a group level, suggesting that the inability to select for patients with pathogenic autoantibodies may have contributed to heterogeneity in the results.
What the study found
The primary endpoint, the mean change from baseline in the Brief Pain Inventory-Short Form interference score after 12 weeks, met the pre-specified one-sided 10% alpha level with a least squares mean difference of -0.5 (80% CI -1.0 to -0.1; p=0.065) for rozanolixizumab versus placebo.
However, the result was not significant at a two-sided 5% alpha level, with a 95% CI of -1.2 to 0.2 and a p-value of 0.13.
No serious treatment-emergent adverse events were reported by participants receiving rozanolixizumab during the treatment period.
What the result does not establish
The authors noted that the inability to select for patients with pathogenic autoantibodies might have contributed to between-patient heterogeneity, limiting the ability to detect a benefit in the overall group.
The study was a phase 2A trial, and the authors stated that response-predictors are required to determine whether IgG reduction benefits subsets of patients with severe fibromyalgia.
Authors’ conclusion
“Rozanolixizumab did not demonstrate broad efficacy in this severe fibromyalgia population. While there was an improvement in BPI-SF, this was not meaningful at a group level. Inability to select for patients with pathogenic autoantibodies might have contributed to between-patient heterogeneity. Response-predictors are required to determine whether IgG reduction benefits subsets of patients with severe fibromyalgia.”
Trial registration
| Registered title | A Proof-of-concept Study to Evaluate the Efficacy and Safety of Rozanolixizumab to Treat Adult Study Participants With Severe Fibromyalgia Syndrome |
|---|---|
| Registry status | Phase 2, interventional, completed |
| Lead sponsor | UCB Biopharma SRL |
| Registered size | 63 participants — actual enrolment |
| Where | 7 sites in 1 country (United Kingdom) |
| Registered primary outcome |
Primary endpoint named in the abstract: BPI-SF interference score mean change from baseline after 12 weeks. Compare the two: a change of primary endpoint after registration matters. |
| Results on the registry | Posted Jul 2025 |
- Start: Dec 2022
- Primary completion: May 2024
- Completion: Jul 2024
- Results posted: Jul 2025
- Paper published: Sep 2026
ClinicalTrials.gov record as held by ENCLAI, last updated Jun 2025. The registry status may have changed since; the link shows the current record.
Study and sources
Efficacy and safety of rozanolixizumab in severe fibromyalgia: a phase 2A randomised, double-blind, placebo-controlled, multicentre trial
Randomised trial · Lancet Rheumatology · 2026-09-16
Sources and limitations
- PubMed record PMID 42748952 (PubMed / NLM · 2026-09-28)
- Trial registry NCT05643794 (ClinicalTrials.gov · 2026-09-28)
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