Efficacy of Long-Term Treatment with Once-Daily Baricitinib 2 mg in Patients with Active Rheumatoid Arthritis: Post Hoc Analysis of Two 24-Week, Phase III, Randomized, Controlled Studies and One Long-Term Extension Study

Introduction: To evaluate long-term efficacy of once-daily baricitinib 2 mg in patients with active rheumatoid arthritis who had an inadequate response (IR) to conventional synthetic disease-modifying antirheumatic drugs (csDMARD) or biologic DMARDs (bDMARD).

Methods: Data from patients treated with baricitinib 2 mg daily in two 24-week, phase III studies, RA-BUILD (csDMARD-IR; NCT01721057) and RA-BEACON (bDMARD-IR; NCT01721044), and one long-term extension study (RA-BEYOND; NCT01885078), were analyzed (120 weeks). The main outcomes were achievement of low-disease activity (LDA; Simple Disease Activity Index [SDAI] ≤ 11), clinical remission (SDAI ≤ 3.3), Health Assessment Questionnaire Disability Index (HAQ-DI) ≤ 0.5 and improvement from baseline of ≥ 0.22, and safety. Analysis populations included (1) all patients and (2) never-rescued patients. Completer and non-responder imputation (NRI) analyses were conducted on each population.

Results: In RA-BUILD, 684 were randomized (229 to baricitinib 2 mg, 180 of whom completed RA-BUILD and entered RA-BEYOND). In RA-BEACON, 527 were randomized (174 to baricitinib 2 mg, 117 of whom completed RA-BEACON and entered RA-BEYOND). In RA-BUILD-BEYOND, 85.1% (63/74, completer) and 27.5% (63/229, NRI) of csDMARD-IR patients treated with baricitinib 2 mg achieved SDAI LDA; 40.5% (30/74, completer) and 13.1% (30/229, NRI) were in SDAI remission; 62.2% (46/74, completer) and 20.1% (46/229, NRI) had HAQ-DI ≤ 0.5 and 81.1% (60/74, completer); and 26.2% (60/229, NRI) achieved ≥ 0.22 change from baseline at week 120. In RA-BEACON-BEYOND, 86.5% (32/37, completer) and 18.4% (32/174, NRI) of bDMARD-IR patients treated with baricitinib 2 mg achieved SDAI LDA; 24.3% (9/37, completer) and 5.2% (9/174, NRI) were in SDAI remission; 50.0% (19/38, completer) and 10.9% (19/174, NRI) had HAQ-DI ≤ 0.5; and 73.7% (28/38, completer) and 16.1% (28/174, NRI) achieved ≥ 0.22 change from baseline at week 120. Rates of adverse events of special interest were consistent with previous reports.

Conclusions: Long-term treatment with baricitinib 2 mg demonstrated efficacy for up to 120 weeks and was well tolerated.

Trial registration: ClinicalTrials.gov identifier, NCT01721057NCT01721044, and NCT01885078.

Keywords: Arthritis; Baricitinib; Rheumatoid.