Background Rituximab (Mabthera; RTX) has not been approved for use in SLE, but uncontrolled observations have suggested efficacy in some patients and the medication can be used off-label in many European countries. We previously reported that based on data from the International Registry for Biologics in SLE (IRBIS), and additional data from investigators, between 0.5 and 1.3% of European patients with SLE have been treated, off-label, with RTX.

Objectives To compare characteristics of SLE patients treated off-label with RTX to those of SLE patients treated with conventional, non-biologic immunosuppressives (ISs) at the same specialty centers.

Methods Investigators participating in IRBIS, initiated by the SLICC group, provided the data for this study. Data previously submitted to the IRBIS registry by 28 centers in 11 European countries were complemented with additional clinical information from the participating sites. Comparator patients were those started on any conventional IS; not necessarily naïve for previous ISs.

Results In this European study, 175 patients were analyzed; 103 were treated off-label with RTX and 72 with conventional ISs. The most frequently used ISs were mycophenolate mofetil (43%) and azathioprine (33%). For both groups, about 90% were female, 90% were Caucasians and 85% were non-smokers. Organ manifestations leading to treatment with RTX were lupus nephritis in 58%, hematological lupus in 16%, musculoskeletal in 11%, skin disease in 6%, CNS in 7%, and other manifestations in 7%. For patients started on ISs, the corresponding percentages were 53%, 11%, 22%, 6%, 7%, and 6%. These distributions were not statistically different. Reason for treatment initiation with RTX was mainly disease control while steroid sparing was frequently the main reason for conventional ISs. At treatment initiation mean disease duration (±SD) was 9.1±7.0 for RTX-treated patients and 4.1±6.6 for patients on ISs (p<0.0001); mean ages were 41.2±12.5 and 36.1±11.3, respectively (p=0.007). There were significant differences between the groups for SLEDAI scores (12.2±7.0 vs. 9.4±7.0, p=001) and SLICC damage index (1.6±3.4 vs. 0.57±1.0, p=0.014).

Conclusions Both RTX and conventional ISs are used mostly in lupus nephritis. No organ manifestion was more likely to be treated with RTX, however, patients started on RTX were somewhat older, had significantly longer disease duration, higher disease activity and more damage compared to patients started on conventional ISs. These data support the view that RTX is used for selected patients with later-stage, more severe SLE.

Acknowledgements Supported by a research grant from Roche

Disclosure of Interest None Declared