Baricitinib Versus Placebo or Adalimumab in Patients with Active Rheumatoid Arthritis (RA) and an Inadequate Response to Background Methotrexate Therapy: Results of a Phase 3 Study

BACKGROUND/PURPOSE:

In phase 3 studies, baricitinib (bari) improved disease activity in patients (pts) with active RA and an inadequate response (IR) to conventional synthetic DMARDs1 or biologic DMARDs2. This abstract reports the 24-wk results from a 52-wk, global, phase 3, double-blind, placebo (PBO) and active-controlled study of bari in MTX-IR RA pts.

METHODS:

Pts with active RA (TJC≥6 & SJC≥6 & hsCRP≥6 mg/L) despite stable background MTX were randomized 3:3:2 to PBO, bari 4 mg once daily (QD), or adalimumab (ADA) 40 mg biweekly (Q2W), stratified by region and baseline joint erosion status. Non-responders were rescued from Wk 16. At Wk 24, pts on PBO switched to bari 4 mg QD. The primary endpoint was ACR20 response at Wk 12 for bari vs. PBO. Major secondary endpoints included comparisons of bari vs. ADA for ACR20 and change in DAS28-CRP at Wk 12.

RESULTS:

Of 1305 randomized pts, 89%, 94% and 93% completed Wk 24 in PBO, bari and ADA groups, respectively. Rescue rates were 26%, 7% and 12% for PBO, bari and ADA, respectively. ACR20 response at Wk 12 was higher for bari vs. PBO (70% vs. 40%, p≤.001 – Table 1). At Wks 12 and 24, statistically significant improvements in ACR 20/50/70 & HAQ-DI response rates, and DAS28, CDAI, and SDAI low disease activity and remission rates were seen for bari vs. PBO, many as early as Wk 1. Compared to ADA, bari was superior with respect to measures including ACR20 response and improvement in DAS28-CRP at Wk 12. Compared to PBO, daily diary measures of morning joint stiffness (MJS) duration and severity, worst tiredness, and worst joint pain were significantly improved in pts receiving bari, from as early as Wk 1. Rates of treatment-emergent adverse events (TEAEs), including infections, were higher for bari and ADA compared to PBO (Table 2). Compared to PBO, serious adverse events (SAE) rates were similar for bari and lower for ADA; serious infection rates were similar across groups. Two deaths occurred (bari), 1 pneumonia and 1 duodenal ulcer haemorrhage. Five malignancies were reported, 2 bari and 3 PBO. Three potential opportunistic infections occurred, 2 bari and 1 PBO; none were SAEs. One case of tuberculosis occurred (ADA). There were no GI perforations. Lab abnormalities were consistent with other phase 3 studies1,2; few led to discontinuation.

CONCLUSION:

In pts with active RA despite background MTX, once-daily oral bari was associated with significant clinical improvements compared to PBO and to ADA, with an acceptable safety and tolerability profile.