Table 1.
Clinical characteristics and CD5+ B cell repopulation of patients with AAV after B cell depletion therapy
| Characteristic | Repopulation with >30% CD5+ B cells n=42 | Repopulation with ≤30% CD5+ B cells n=8 | p Value* |
|---|---|---|---|
| Age at time of rituximab infusion, median (IQR) | 54 (41–62) | 56 (52–60) | 0.572 |
| Female gender, n (%) | 23 (55) | 4 (50) | 0.999 |
| Caucasian (non-Hispanic), n (%) | 31 (74) | 7 (88) | 0.661 |
| MPO-ANCA serotype, n (%) | 18 (43) | 3 (38) | 0.999 |
| Disease, n (%) | 0.999 | ||
| GPA | 23 (55) | 4 (50) | |
| MPA | 15 (36) | 3 (38) | |
| ANCA GN (renal-limited) | 4 (10) | 1 (12) | |
| Organ involvement (past and/or present), n (%) | |||
| Upper Respiratory | 31 (74) | 2 (25) | 0.013 |
| Pulmonary | 28 (67) | 7 (88) | 0.407 |
| Renal | 38 (90) | 8 (100) | 0.999 |
| Time to B cell repopulation (months), median (IQR) | 9 (8–13) | 12 (10–13) | 0.549 |
| Percentage of total B cells at time of B cell repopulation, median (IQR) | 5 (2–8) | 2 (1–6) | 0.036 |
| Percentage of CD5+ B cells at time of B cell repopulation, median (IQR) | 74 (57–86) | 24 (21–28) | <0.001 |
| ANCA titre† (U/mL) at time of B cell repopulation, median (IQR) | 34 (21–61) | 31 (16–79) | 0.833 |
| ANCA titre† (U/mL) at time of relapse, median (IQR) | 64 (35–84) | 74 (56–86) | 0.901 |
| Previous rituximab, n (patients) (%) | 16 (38) | 3 (38) | 0.999 |
| Medications following rituximab therapy, n (patients) (%) | |||
| Mycophenolate mofetil | 18 (43) | 1 (13) | 0.112 |
| Azathioprine | 3 (7) | 0 (0) | 0.999 |
| Cyclophosphamide | 1 (2) | 0 (0) | 0.999 |
| Ciclosporin | 1 (2) | 1 (13) | 0.302 |
| Prednisone | 14 (33) | 4 (50) | 0.427 |
| Methylprednisolone | 1 (2) | 0 (0) | 0.999 |
| None | 11 (26) | 2 (25) | 1.000 |
| Time to relapse from rituximab (months), median (IQR) | 23 (18–30) | 16 (12–19) | 0.005‡ |
| Time to relapse from B cell repopulation (months), median (IQR) | 12 (6–21) | 3 (1–9) | 0.001§ |
p Values were calculated by Fisher’s exact test for categorical variables, Wilcoxon rank test for continuous variables and log-rank for time-to-event measures. A Bonferroni correction was applied and p values <0.025 were considered significant.
ANCA titres were determined by the McLendon Clinical Laboratories at the University of North Carolina using ELISA kits specific for either MPO or proteinase 3 (PR3, Inova Diagnostics, San Diego, California, USA). Negative titres are ≤20 U/mL.
After adjusting for differences in upper respiratory involvement by time-to-event proportional hazards modelling, p=0.002.
After adjusting for differences in upper respiratory involvement by time-to-event proportional hazards modelling, p=0.001.
ANCA GN, antineutrophil cytoplasmic autoantibody glomerulonephritis; AAV, antineutrophil cytoplasmic autoantibody-associated vasculitis; GPA, granulomatosis with polyangiitis; MPA, microscopic polyangiitis; MPO, myeloperoxidase; n, number.