Minimal residual disease flow cytometry of peripheral blood B-cell subsets in patients with idiopathic inflammatory myopathies following rituximab therapy: a single-centre, retrospective cohort study
Authors' conclusion
Complete early B-cell depletion, measured using an early HSFC-based strategy, but not conventional flow cytometry, was associated with rituximab response in patients with idiopathic inflammatory myopathies
Study context
- Population
- Adults (≥18 years) with IIM (American College of Rheumatology (ACR)/EULAR criteria) treated with rituximab, Leeds Teaching Hospitals NHS Trust, UK, 2015–2025
- Participants
- 44 complete datasets
- Exposure
- Complete highly sensitive flow cytometry (HSFC) depletion (<0.1 cells per μL) of naive B cells, memory B cells and plasmablasts vs conventional flow cytometry cutoff (<5 total B cells per μL), in relation to clinical response
- Respondersn = 31
- Non-respondersn = 13reference
- Outcome
- Clinical response (at least moderate improvement on the 2016 ACR-EULAR total improvement score)
- Follow-up
- First 4-6 months after infusion
Methodological detailssingle-centre, multivariable Firth penalised logistic regression
- Single-centre
- Multivariable Firth penalised logistic regression
Main finding
As reported in the abstract
Rituximab response · 4-6 months
Rituximab response
31
70%
Observational data: associations, not effects.
Further findings
Complete plasmablast depletion at 2 weeks
P < 0.0001
Association with response (multivariable models) · 2 weeks
| OR (95% CI) | ||
|---|---|---|
| Higher 2-week plasmablast counts | 0.03 (0.00–0.23) | |
| Memory B-cell depletion | 8.68 (1.13–82.80) | |
| Plasmablast depletion | 25.20 (4.61–214.54) | |
| 0.050.21520Odds ratio (log scale) |
Median
| Outcome | Responders | Non-responders | P value |
|---|---|---|---|
| Total improvement score | 50.0 (IQR 45.0–55.0) | 17.5 (IQR 10.0–30.0) | P < 0.0001 |
Complete plasmablast depletion at 2 weeks
- Memory B-cell and plasmablast counts at 2 weeks lower in responders than non-responders
Association with response (multivariable models) · 2 weeks
- Conventional flow cytometry cutoff showed no association with response
Original publication
Minimal residual disease flow cytometry of peripheral blood B-cell subsets in patients with idiopathic inflammatory myopathies following rituximab therapy: a single-centre, retrospective cohort study. Lancet Rheumatol. Published 27 August 2026. doi:10.
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