Adalimumab combined with methotrexate versus adalimumab monotherapy in psoriasis: Three-year follow-up data of a single-blind randomized controlled trial.

Background: Anti-drug antibodies (ADA) are formed in patients treated with adalimumab (ADL). This might increase clearance of ADL, potentially causing a (secondary) non-response. Combination therapy of ADL and methotrexate (MTX) reduces ADA levels and has a clinical benefit in rheumatologic diseases. In psoriasis however, the long-term effectiveness and safety have not been studied.

Objectives: To investigate the three-year follow-up data of ADL combined with MTX compared to ADL monotherapy in ADL-naive patients with moderate to severe plaque type psoriasis.

Methods: We conducted a multicentre RCT in the Netherlands and Belgium. Randomization was performed by a centralized online randomization service. Patients were seen every 12 weeks until week 145. Outcome assessors were blinded. We collected data on drug survival, effectiveness, safety, pharmacokinetics and immunogenicity of patients that started ADL combined with MTX compared to ADL monotherapy. We present descriptive analysis and patients were analysed according to the group initially randomized to. Patients becoming non-adherent to the biologic were excluded from analyses.

Results: Sixty-one patients were included and 37 patients (ADL group n = 17, ADL + MTX group n = 20) continued in the follow-up study after 1 year. After 109 weeks and 145 weeks, there was a trend towards longer drug survival in the ADL + MTX group compared to the ADL group (week 109: 54.8% vs. 41.4%; p = 0.326, week 145: 51.6% vs. 41.4%; p = 0.464). At week 145, 7/13 patients were treated with MTX. In the ADL group, 4/12 patients that completed the study developed ADA, and 3/13 in the ADL + MTX group.

Conclusions: In this small study, there was no significant difference in ADL overall drug survival when it was initially combined with MTX, compared to ADL alone. Discontinuation due to adverse events was common in the combination group. To secure accessible healthcare, combination treatment of ADL and MTX can be considered in individual patients.