Baricitinib inhibits radiographic progression of structural joint damage at 1 year in patients with rheumatoid arthritis (RA) and an inadequate response to CSDMARDS

Background: Baricitinib (bari), a JAK1 and JAK2 inhibitor, was efficacious in a 24-week (wk) Ph 3 study in patients (pts) with active RA and an inadequate response (IR) to conventional synthetic DMARDs (csDMARDs) (RA-BUILD)1. Objectives: To evaluate radiographic progression of structural joint damage in RA-BUILD pts with IR or intolerance to ≥1 csDMARD over 48 wks of bari treatment in the long-term extension study, RA-BEYOND. Methods: In the 24-wk RA-BUILD study, pts were randomized to placebo (PBO; N=228), bari 2mg (N=229) or bari 4mg (N=227) once daily (QD), with rescue possible from Wk16. Pts completing RA-BUILD and entering RA-BEYOND continued to receive the bari dose received at the end of RA-BUILD. Pts receiving PBO at the end of RA-BUILD were switched to bari 4mg in RA-BEYOND. Pt and investigator blinding was maintained in RA-BEYOND. Joint damage was measured using the van der Heijde modified total Sharp score (mTSS). To account for missing scores and scores obtained after rescue or discontinuation of study drug, data were analyzed using 1) linear extrapolation (LE), and 2) last observation carried forward (LOCF). The observed/LOCF method used all available observed data, including after rescue or switch, with pts analyzed according to original treatment assignment. Results: Using LE, progression of mTSS, bone erosion, and joint space narrowing (JSN) at 24 and 48 wks was statistically significantly lower for both bari 2 or 4mg compared to PBO (Table). Only bari 4mg demonstrated statistically significant inhibition of progressive radiographic joint damage compared to PBO using observed/LOCF at Wk 48 or based on categorical measures. Conclusions: Once daily oral bari inhibited radiographic progression of structural joint damage in pts with an IR or intolerance to csDMARDs over 48 wks of treatment. The most robust benefit across measures of radiographic progression was seen for the 4mg dose. (Table Presented).