Efficacy and Safety of Baricitinib in Japanese Patients with Active Rheumatoid Arthritis Receiving Background Methotrexate Therapy: A 12-week, Double-blind, Randomized Placebo-controlled Study
Clinical trials have shown baricitinib once daily to be effective in patients with RA. However, this Janus kinase (JAK) 1/JAK2 inhibitor has not been evaluated in a Japanese population. In this 12-week, placebo-controlled study, 145 Japanese patients were enrolled and received placebo, 1 mg, 2 mg, 4 mg or 8 mg oral baricitinib daily.
Efficacy results were encouraging and consistent with earlier trials. Significantly more baricitinib patients achieved ACR20 response at Week 12 of treatment compared with the placebo group [primary endpoint] ((37/48, 77%) vs 15/49, 31%, p<0.001). Efficacy was further demonstrated by the observation that the higher doses resulted in a greater percentage of patients achieving an improvement in most efficacy measures, including HAQ-DI (but not DAS28-ESR), when compared with the lower doses or placebo. 4mg and 8 mg led to similar improvements. Improvements in disease activity were seen as early as 2 weeks after commencing treatment.
Baricitinib was well tolerated over the study period, however the 8 mg baricitinib dose was associated with a higher incidence of AEs and a greater decline in hemoglobin concentration than the lower doses or placebo.
Since this was a dose-ranging study, balanced consideration of the efficacy and safety results would suggest that the 4 mg dose, and potentially the 2 mg dose, would be optimal for further evaluation.