Superior RA Outcomes for JAK1/JAK2 Inhibitor Baricitinib

Active rheumatoid arthritis signs and symptoms, physical function and patient-reported outcomes were improved significantly compared to methotrexate monotherapy with 4mg QD of oral baricitinib with or without methotrexate in the Phase 3 RA-BEGIN Study. Patients had received limited or no prior treatment with DMARDs, according to Roy Fleischmann, MD, Metroplex Clinica Research Center, in an oral presentation on Nov. 9, at the 2015 ACR/ARHP annual meeting in San Francisco, Calif.

Baricitinib, an oral, reversible inhibitor of JAK1 and JAK2, mediates signal transduction for a variety of cytokines involved in inflammatory conditions. In other recently completed Phase 3 studies among patients with moderately-to-severely active rheumatoid arthritis whose response to conventional synthetic or biologic DMARDS was inadequate, baricitinib satisfactorily and safely improved disease activity.

In RA-BEGIN, 210 patients received methotrexate monotherapy, 159 received baricitinib 4 mg QD and 215 received baricitinib 4 mg QD + methotrexate QW. The primary endpoint was an ACR20 response at 24 weeks with a noninferiority margin of ≤12% for baricitinib 4 mg versus methotrexate. Patients had early rheumatoid arthritis; median duration of disease was 0.2 years. Most patients were ACPA and RF positive with at least one erosion. Almost 80% completed a year of treatment and entered long-term extension.

After 24 weeks, both baricitinib groups were superior to methotrexate monotherapy (ACR20: 78% baricitinib + methotrexate [p≤.001]; 77% baricitinib [≤.01]; methotrexate 62%), and similar to each other. The same pattern persisted for ACR50 (63%;60%;43%) and ACR70 (40%;42%; 40%). A significantly higher percentage of patients receiving the combination (80.8% vs. 75.7% for baricitinib alone, vs. 68.1% for methotrexate), however, had no radiographic progression.

“So in combination or as monotherapy, baricitinib is superior to methotrexate clinically, and methotrexate performed the way that you would expect it to perform in this population with a response rate of about 60%/40%/20%,” Dr. Fleischmann said. The effect persisted through 1 year. Also, analysis of components of ACR showed effects for baricitinib within the first week.

Discontinuations were more common in the baricitinib combination group than in the baricitinib and methotrexate monotherapy groups (7% vs 4% vs 2%).

Dr. Fleischmann’s conclusion was that baricitinib monotherapy was as good as the combination therapy clinically and functionally. Radiographically, the combination was superior; monotherapy was safer and both were better than methotrexate.

References:

 Abstract 1045 - "

Baricitinib, Methotrexate, or Baricitinib Plus Methotrexate in Patients with Early Rheumatoid Arthritis Who Had Received Limited or No Treatment with Disease-Modifying Anti-Rheumatic Drugs (DMARDs): Phase 3 Trial Results

," Roy Fleischmann MD. ACR/ARHP 2015.