OBJECTIVES: To evaluate efficacy/safety of baricitinib for rheumatoid arthritis 
(RA) in Japanese subpopulations from four phase 3 studies, and assess whether 
results in these subpopulations are consistent with the overall study 
populations.
METHODS: Subgroup analyses (394 patients) of four phase 3 randomized controlled 
trials: RA-BEGIN [no or limited treatment with disease-modifying antirheumatic 
drugs (DMARDs)], RA-BEAM [inadequate response (IR) to methotrexate], RA-BUILD 
[IR to conventional synthetic DMARDs (csDMARDs)], and RA-BEACON (IR to tumor 
necrosis factor inhibitors receiving csDMARDs).
RESULTS: For American College of Rheumatology 20% improvement (ACR20) response 
rate, Japanese patients receiving baricitinib 4-mg showed similar improvement 
compared to methotrexate at Week 24 (72 versus 69%; RA-BEGIN), and greater 
improvement compared with placebo at Week 12 (67 versus 34%; RA-BEAM). Japanese 
patients receiving baricitinib 4-mg also showed greater improvement compared 
with placebo at Week 12 in RA-BUILD and RA-BEACON. Across all studies, 
baricitinib was well-tolerated, with no deaths and one malignancy. In RA-BEGIN 
and RA-BEAM, herpes zoster rates were higher for Japanese patients than for 
overall populations; all events were mild/moderate.
CONCLUSION: Data for baricitinib, with/without methotrexate, in Japanese 
subpopulations across all stages of the RA treatment continuum accord with the 
efficacy/safety profile in overall study populations. Baricitinib appears to be 
similarly effective in Japanese patients.