Oral Add-On Drug to Methotrexate Shows Promise in Rheumatoid Arthritis

When used as an add-on treatment to methotrexate (MTX), the oral Janus kinase 1 selective inhibitor filgotinib improved outcomes in patients with active rheumatoid arthritis (RA) who had an inadequate response to MTX.

For the phase 2b DARWIN1 study, published in the Annals of the Rheumatic Disease, investigators sought to evaluate the safety and efficacy of various doses and regiments of filgotinib as an add-on to MTX in patients with RA and inadequate response to standard treatment.

The 24-week trial included 594 patients with moderate-to-severe active RA who were receiving a stable dose of MTX. The participants were randomized to receive a placebo or 50 mg, 100 mg, or 200 mg of filgotinib administered once or twice daily.

The primary endpoint was the percentage of patients who achieved a week 12 American College of Rheumatology (ACR) 20 response.

At week 12, the results of the study showed that significantly more patients in the 100-mg daily dose group and 200-mg daily dose group achieved an ACR20 response compared with the placebo group.

Differences were also observed between all filgotinib groups and the placebo group in secondary endpoints including ACR50, disease activity score based on 28 joints and C reactive protein value, and clinical disease activity index.

No significant differences between once-daily and twice-daily filgotinib regimens were observed, according to the study.

The most notable findings, however, were that the positive responses to treatment were maintained or improved through to week 24.

The rate of treatment-emergent adverse events (AEs) were similar among the placebo and filgotinib groups. Serious AEs occurred in 1 patient in the placebo arm and 5 patients in the filgotinib groups. There were no reported of tuberculosis or opportunistic infections.

“Filgotinib as add-on to MTX improved the signs and symptoms of active RA over 24 weeks and was associated with a rapid onset of action,” the authors concluded. “Filgotinib was generally well tolerated.”