Baricitinib Safely and Effectively Reduces Symptoms of Rheumatoid Arthritis

Treatment with baricitinib, a once-daily, oral, selective JAK1 and JAK2 inhibitor, is associated with significant improvements in morning joint stiffness duration and severity, tiredness, and joint pain compared to placebo in patients with moderate to severe rheumatoid arthritis.

In results to be presented at the 2015 ACR/ARHP Annual Meeting in San Francisco, CA, researchers reported that a phase 3 study that compared baricitinib to placebo and adalimumab in patients with active rheumatoid arthritis (who were also receiving treatment with methotrexate) met its primary endpoint of ACR20 response at week 12 compared to placebo.

For the study, 1,305 patients were randomized in a 3:3:2 ratio to receive once-daily oral 4 mg baricitinib, every-other-week 40 mg adalimumab injection, or placebo. Patients who did not respond to treatment by week 16 were rescued. At week 24, patients on placebo were switched to once-daily 4 mg baricitinib.

Secondary endpoints for the study included comparison of baricitinib to adalimumab at week 12 for ACR20 response and change in DAS28-hsCRP score.

A large percentage of patients in all 3 arms completed the study through week 24 (89% for placebo, 94% for baricitinib, and 93% for adalimumab). The rescue rate at week 16 was higher for the placebo group (26%) than the baricitinib (7%) and adalimumab (12%) groups.

At week 12, ACR20 response was 70% for the baricitinib group compared to 40% in the placebo group (p≤.001). By week 24, ACR20 response had risen to 74% for the baricitinib group and dropped slightly to 37% for placebo.

The authors reported statistically significant improvements across a range of measures (ACR20/50/70 response; HAQ-DI response rates; and DAS28, CDAI, and SDAI low disease activity and remission rates) at weeks 12 and 24 for baricitinib compared to placebo. Many of the benefits were observed as early as week 1.

Compared to treatment with adalimumab, at week 12, treatment with baricitinib “was superior with respect to measures including ACR20 response and improvement in DAS28-CRP.”

Rates of treatment-emergent adverse events (including infections) were higher for barictinib and adalimumab compared to placebo. Rates of serious adverse events were similar for baricitinib and lower for adalimumab compared to placebo. Serious infection rates were similar across groups.

There was one case of tuberculosis in each of the baricitinib and adalimumab groups. The most common adverse events in the baricitinib group were nasopharyngitis and bronchitis.