Baricitinib, an oral Janus kinase 1 (JAK1) and Janus kinase 2 (JAK2) inhibitor was associated with significant clinical improvements vs. placebo and adalimumab in patients with rheumatoid arthritis with inadequate response to methotrexate.

• Phase 3, 52-week, double-blind, placebo- and active-controlled trial
• 1,307 patients with active rheumatoid arthritis receiving therapy with methotrexate enrolled
• Patients were randomized (3:3:2) to placebo (switched to baricitinib after 24 weeks), baricitinib 4mg once daily or adalimumab 40mg every other week
• Primary endpoint was a 20% improvement according to the American College of Rheumatology (ACR20 response)
• Secondary endpoints included the Disease Activity Score for 28 joints (DAS28), the Health Assessment Questionnaire-Disability Index, and the Simplified Disease Activity Index at Week 12, and radiographic progression of joint damage at Week 24

• Primary endpoint was achieved in more baricitinib-treated patients vs. placebo (70% vs. 40%; P<0.001) at Week 12
• Less structural joint damage at Week 24 with baricitinib vs. placebo as seen by inhibition of radiographic progression of joint damage (mean change from baseline 0.41 vs. 0.90; P<0.001)
• Increased ACR20 response rate at Week 12 was seen with baricitinib vs. adalimumab (70% vs. 61%; P=0.014)
• Adverse events were more frequent through Week 24 with baricitinib and adalimumab vs. placebo
• Cancers reported in 2 baricitinib-treated patients and 3 placebo-treated patients