Safety profile of baricitinib in patients with systemic lupus erythematosus: an integrated analysis.

Objectives: To assess the safety of the oral Janus kinase inhibitor baricitinib in adult patients with systemic lupus erythematosus (SLE) receiving stable background therapy. Topics of special interest included infections and cardiovascular and thromboembolic events.

Methods: This analysis included integrated safety data from three randomised, placebo-controlled studies (one phase 2 and two phase 3) and one long-term extension study. Data are reported in three data sets: placebo-controlled, extended exposure and all-baricitinib. Outcomes include treatment-emergent adverse events (AEs), AEs of special interest and abnormal laboratory changes. Proportions of patients with events and incidence rates (IRs) were calculated.

Results: A total of 1655 patients received baricitinib for up to 3.5 years (median duration 473 days). With baricitinib 4 mg, baricitinib 2 mg and placebo, respectively, 50.8%, 50.7% and 49.0% of patients reported at least one infection and 4.4%, 3.4% and 1.9% of patients had a serious infection. The most common treatment-emergent infections included urinary tract infection, COVID-19, upper respiratory tract infection and nasopharyngitis. Herpes zoster was more common with baricitinib 4 mg (4.7%) vs baricitinib 2 mg (2.7%) and placebo (2.8%). Among baricitinib-4 mg, 2 mg and placebo-treated patients, respectively, 4 (IR=0.9), 1 (IR=0.2) and 0 experienced at least one positively adjudicated major adverse cardiovascular event, and 0, 3 (IR=0.6) and 2 (IR=0.4) reported at least one positively adjudicated venous thromboembolism.

Conclusions: The results of this integrated safety analysis in patients with SLE are not substantially different to the established safety profile of baricitinib. No increased venous thromboembolism was found.