Belimumab was recently approved for treatment of lupus glomerulonephritis (LN).
To evaluate renal response and its predictors in LN patients receiving belimumab in real-life.
We considered all patients fulfilling the SLEDAI-2K renal items and/or having estimated glomerular filtration rate (eGFR)≤60 ml/min/1.73 m, with positive anti-dsDNA and/or low C3/C4 enrolled in the multicentre Italian lupus cohort BeRLiSS (BElimumab in Real LIfe Setting Study), treated with monthly IV Belimumab 10 mg/kg over standard treatment. Primary efficacy renal response (PERR), defined as proteinuria ≤0.7 g/24 h, eGFR≥60 ml/min/1.73 m without rescue therapy, was considered as primary outcome. Complete renal response (CRR; proteinuria <0.5 g/24 h, eGFR≥90 ml/min/1.73 m) was considered as secondary outcome. Prevalence and predictors of PERR were evaluated at 6, 12, 24 months by multivariate logistic regression.
Among the 466 SLE patients of BeRLiSS, 91 fulfilled the inclusion criteria, 79 females, median age 41.0 (33.0-47.0) years, median follow-up 22.0 (12.0-36.0) months. Sixty-four (70.3%) achieved PERR, of whom 38.4% reached CRR. Among patients achieving PERR at 6 months, 86.7% maintained response throughout the follow-up. At multivariable analysis, hypertension (OR [95%CI]: 0.28 [0.09-0.89], p = 0.032), high baseline serum creatinine (0.97 [0.95-0.99], p = 0.01) and high baseline proteinuria (0.37, [0.19-0.74], p = 0.005) negatively predicted PERR. Positive predictors of PERR at 12 and 24 months were baseline anti-Sm positivity (OR [95%CI]: 6.2 [1.21-31.7], p = 0.029; 19.8 [2.01-186.7], p = 0.009, respectively) and having achieved PERR at 6 months (14.4 [3.28-63.6]; 11.7 [2.7-48.7], p = 0.001 for both).
Add-on therapy with belimumab led to durable renal response in patients with LN in a real-life setting.

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