Anticitrullinated peptide antibody epitope expansion and the HLA DRB1 ‘shared epitope’ are less common in seropositive checkpoint inhibitor-induced inflammatory arthritis than in longstanding rheumatoid arthritis
Authors' conclusion
Patients with ICI-IA had lower ACPA titres and targeted fewer ACPA epitopes than longstanding patients with RA, and there were no significant differences in the presence of the shared epitope between those that developed ICI-IA and ICI controls.
Study context
- Population
- Patients with CCP+ ICI-IA and patients with rheumatoid arthritis (RA) (early and longstanding disease)
- Exposure
- CCP+ ICI-IA vs CCP+ RA (early and longstanding); ICI-IA vs immune checkpoint inhibitors (ICI) controls for HLA DRB1 shared epitope
- Outcome
- Degree of anticitrullinated peptide antibodies (ACPA) epitope expansion (IgG ACPA reactivities to 18 putative RA-associated citrullinated proteins)
Methodological detailsbead-based antigen array, HLA DRB1 typing
- Bead-based antigen array
- HLA DRB1 typing
Main finding
As reported in the abstract
ACPA levels and number of distinct ACPA epitopes
- ICI-IA vs RA: P < 0.001
Observational data: associations, not effects.
Further findings
| Outcome | P value |
|---|---|
| Clinical characteristics, CCP+ ICI-IA vs CCP+ RAICI-IA vs RA · older | P < 0.001 |
| Clinical characteristics, CCP+ ICI-IA vs CCP+ RAICI-IA vs RA · less likely to have positive RF | P < 0.001 |
| Clinical characteristics, CCP+ ICI-IA vs CCP+ RAICI-IA vs RA · shorter duration of symptoms | P < 0.001 |
Frequency of HLA DRB1 shared epitope
- No differences between ICI-IA and ICI controls
Original publication
Anticitrullinated peptide antibody epitope expansion and the HLA DRB1 ‘shared epitope’ are less common in seropositive checkpoint inhibitor-induced inflammatory arthritis than in longstanding rheumatoid arthritis. RMD Open. Published 23 June 2023. doi:10.
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