Background Baricitinib (bari), a JAK1 and JAK2 inhibitor, showed significant improvements across multiple measures of disease activity as early as week (wk) 1 that were maintained through wk 52 in ph 3 studies of patients (pts) with active RA.^1,2

Objectives To determine if, in bari-treated pts, early changes in disease activity predicted later achievement of low disease activity (LDA) or remission.

Methods 1305 pts with inadequate response to methotrexate (MTX) were randomized in RA-BEAM (3:3:2, oral PBO/4 mg bari QD/SC injection adalimumab [ADA] Q2W, 52 wks); 584 MTX-naïve pts were randomized in RA-BEGIN (4:3:4, oral MTX QW/4 mg bari QD/4 mg bari QD+MTX QW, 52 wks). Improvement from baseline (BL) to wk 4 was used to predict LDA or remission defined by Disease Activity Score (DAS28) and Simplified Disease Activity Index (SDAI) at wks 12/24 (bari 4 mg arm, both studies). Early responder and early nonresponder were predefined as Clinical Disease Activity Index (CDAI) improvement ≥6 and <6, respectively, at wk 4.

Results Compared to PBO or ADA (RA-BEAM) or MTX (RA-BEGIN), treatment with bari was associated with rapid decrease in DAS28 and CDAI from wk 1.^1,2 By wk 4, 86% (RA-BEAM) and 85% (RA-BEGIN) of bari pts had a CDAI decrease ≥6. In both studies, LDA/remission rates at wks 12/24 were higher in pts with CDAI improvement ≥6 compared to pts with CDAI improvement <6 from BL to wk 4 (Table). Negative predictive values (NPV) for remission at wks 12/24 associated with CDAI improvement <6 from BL to wk 4 exceeded 90%, indicating that pts with CDAI improvement <6 were highly unlikely to achieve remission; NPV for LDA exceeded 80%.

Conclusions In RA-BEAM/RA-BEGIN, lack of early clinical response to bari 4 mg (failure to achieve CDAI improvement ≥6 at 4 wks) was associated with low rates of LDA/remission at wks 12/24. These results are consistent with similar analyses from previous ph 3 studies of bari.³ The majority of bari pts had improvement in CDAI ≥6 at wk 4; these decreases were associated with improved clinical responses at wks 12/24. Early identification of pts (4 wks) who are not likely to achieve LDA/remission may be useful in tailoring therapy to individual pts.

1. Taylor PC et al. Arthritis Rheumatol. 2015; 67 (suppl 10).

2. Fleischmann R et al. Arthritis Rheumatol. 2015; 67 (suppl 10).

3. Kremer J et al. Arthritis Rheumatol. 2015; 67 (suppl 10).

Disclosure of Interest M. Weinblatt Grant/research support from: Crescendo Bioscience, Consultant for: Eli Lilly and Company, Pfizer, AbbVie, Crescendo Bioscience, P. Taylor Grant/research support from: UCB, GlaxoSmithKline, Celgene, Consultant for: AbbVie, Bristol-Myers Squibb, Eli Lilly and Company, Galapagos, GlaxoSmithKline, Merck, Pfizer, Takeda, USB, Y. Tanaka Grant/research support from: Mistubishi-Tanabe, Takeda, Chugai, Astellas, Eisai, Taisho-Toyama, Kyowa-Kirin, Abbvie, Bristol-Myers, Speakers bureau: Abbvie, Daiichi-Sankyo, Chugai, Takeda, Mitsubishi-Tanabe, Bristol-Myers, Astellas, Eisai, Janssen, Pfizer, Asahi-kasei, Eli Lilly, GlaxoSmithKline, UCB, Teijin, MSD, Santen, E. Keystone Grant/research support from: Abbott Laboratories, Amgen Inc., AstraZeneca Pharmaceuticals LP, Bristol-Myers Squibb, Eli Lilly and Company, F. Hoffmann-La Roche Inc, Janssen Inc, Novartis Pharmaceuticals, Pfizer Pharmaceuticals, Sanofi-Aventis, UCB, Consultant for: Abbott Laboratories, AstraZeneca Pharma, Biotest, Bristol-Myers Squibb Company, Eli Lilly and Company, F. Hoffmann-La Roche Inc, Genentech Inc, Janssen Inc, Merck, Pfizer Pharmaceuticals, UCB, Speakers bureau: Abbott Laboratories, Astrazeneca LP, Bristol-Myers Squibb Canada, F. Hoffmann-La Roche Inc., Janssen Inc., Pfizer Pharmaceuticals, UCB, Amgen, M. Schiff Grant/research support from: Eli Lilly and Company, Consultant for: Eli Lilly and Company, R. Fleischmann Grant/research support from: Eli Lilly and Company, Pfizer, Consultant for: Eli Lilly and Company, Pfizer, L. Yang Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, V. Arora Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, S. de Bono Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, T. Holzkaemper Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, D. Schlichting Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, T. Takeuchi Grant/research support from: Eli Lilly and Company, Chugai Pharmaceutical Co,. Ltd, Consultant for: Eli Lilly and Company