Background The effectiveness and safety of sirolimus for the treatment of systemic lupus erythematosus (SLE) and lupus nephritis (LN) have been shown in some studies. However, a comparison of sirolimus with standard of care (SoC) for LN patients has not been reported. We conducted the study to compare the efficiency and safety of sirolimus versus mycophenolate mofetil (MMF) for LN treatment.

Methods A real-world cohort study based on the Chinese SLE Treatment and Research (CSTAR) registry was conducted. LN patients who were prescribed sirolimus or MMF were enrolled. Patients who achieved LLDAS (lupus low disease activity state) or remission at baseline were excluded. Propensity score matching was used to ensure equivalent disease conditions and background medications. SLE disease activity indices, serological parameters, steroid doses, renal efficacy, and adverse events were compared between the two groups at 3-month, 6-month, and 12-month follow-up visits.

Results Data from 53 patients in each group were analyzed. The clinical effectiveness of sirolimus, including the proportion of patients with LLDAS/remission, or clinical response (SLEDAI-2K reduction≥4 and PhGA increase <0.3), the change of Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) scores, physician’s global assessment (PhGA) scores, the remission of lupus nephritis, the change of 24 hours urine protein level, and the steroid tapering effect, were equivalent to those of MMF at all follow-up timepoints (all P≥0.05). Greater improvements in complement levels were observed in the sirolimus group than the MMF group at 3, 6, and 12 months. Ten adverse events in the sirolimus group and one in the MMF group were recorded. None was severe or led to drug discontinuation.

Conclusions Sirolimus was as effective as MMF in the treatment of LN and glucocorticoid tapering. Sirolimus had better effects on serological improvement. Sirolimus was well tolerated in LN patients.