Smoking reduces the efficacy of belimumab in mucocutaneous lupus.

Objectives: Recently, we demonstrated a negative impact of smoking on belimumab efficacy in patients with systemic lupus erythematosus (SLE). Here, we particularly investigated clinical effects of belimumab and a potential impact of smoking in mucocutaneous and articular SLE.

Methods: We surveyed 62 SLE patients treated between 2011 and 2017. Evaluation included the mucocutaneous descriptors of SLEDAI-2K (rash, alopecia, mucosal ulcers; mcSLEDAI-2K), CLASI, the arthritis SLEDAI-2K descriptor (arSLEDAI-2K) and the 28-joint count.

Results: mcSLEDAI-2K and CLASI activity decreased from baseline to month 6 and 12 (P < 0.001 for all). No worsening in CLASI damage was observed. Current or previous smokers displayed a higher probability of unchanged/worsened mcSLEDAI-2K compared to never smokers (OR: 6.4; 95% CI: 1.5-27.4; P = 0.012), also after adjustment for antimalarial agents. arSLEDAI-2K scores had decreased at month 6 (P < 0.001) and 12 (P < 0.001). Likewise, tender and swollen 28-joint counts had improved at month 6 (P = 0.010 and P < 0.001, respectively) and 12 (P = 0.001 for both). We observed no impact of smoking on belimumab efficacy in articular SLE.

Conclusion: We observed a negative impact of smoking on the efficacy of belimumab in mucocutaneous SLE. In contrast, no impact of smoking on belimumab efficacy was seen in patients with articular manifestations.