Belimumab efficacy in mucocutaneous lupus erythematosus: a large post-hoc analysis from five phase III clinical trials

To determine the efficacy of belimumab on mucocutaneous manifestations of systemic lupus erythematosus (SLE) in a large integrative analysis. Using data from five phase III clinical trials (BLISS-52; BLISS-76; BLISS-NEA; EMBRACE; BLISS-SC; N = 3086), we investigated the effect of belimumab vs placebo on top of standard therapy on inducing improvement in mucocutaneous British Isles Lupus Assessment Group (mcBILAG) and mucocutaneous SLE Disease Activity Index 2000 (mcSLEDAI-2K), and on preventing mcBILAG flares. We employed logistic and Cox regression analysis, adjusting for trial variance. Belimumab was superior to placebo in inducing mcBILAG (week-52 OR: 1.29; 95% CI: 1.07-1.57; p = 0.008) and mcSLEDAI-2K (week-52 OR: 1.37; 95% CI: 1.16-1.62; p < 0.001) improvement, as well as in inducing sustained (≥2 visits, maintained through week 52) mcBILAG (HR: 1.23; 95% CI: 1.07-1.41; p = 0.003) and mcSLEDAI-2K (HR: 1.24; 95% CI: 1.17-1.31; p < 0.001) improvement. These associations held true for patients with SLEDAI-2K ≥10 and positive anti-dsDNA levels at baseline, but not their counter groups. Belimumab prevented mcBILAG flares to a greater extent than placebo in patients with positive anti-dsDNA levels (HR: 0.70; 95% CI: 0.50-0.98; p = 0.035) and with a near-significant separation in patients with baseline SLEDAI-2K ≥10 (HR: 0.71; 95% CI: 0.51-1.00; p = 0.050), whereas no difference was seen in their counter groups. Belimumab is superior to placebo in inducing improvement and in preventing flares in the mucocutaneous domain of SLE, especially in patients with high disease activity and in serologically active patients.