Maintenance treatment using abatacept with dose reduction after achievement of low disease activity in patients with rheumatoid arthritis (MATADOR) - A prospective, multicenter, single arm pilot clinical trial.

Objectives: To preliminarily evaluate the feasibility of maintenance therapy with reduced dose of intravenous abatacept (ABT) to 250 mg/body/month after achieving remission or low disease activity (LDA).
Patients and Methods: RA patients treated with ABT at 13 sites were enrolled in this prospective interventional pilot study during the period between March 2013 and March 2015. Inclusion criteria were (1) age at 20 years or older, (2) under treatment with monthly intravenous ABT at approved doses, (3) DAS28-CRP lower than 2.7 at least for 6 months, (4) agreed to join this trial with written informed consent and (5) body weight under 125 kg. Enrolled patients were maintained with intravenous monthly ABT at a reduced dose of 250 mg/body (MATADOR protocol). The primary end point was the proportion of the patients continued with MATADOR protocol at week 48. MATADOR protocol was discontinued upon disease flare or other reasons such as patients' request or severe adverse event (AE). Disease activities and structural changes were also evaluated.
Results: Fifty-three patients fulfilled the entry criteria and were followed for 1-year. MATADOR protocol was continued for 1-year in 43 (81%) of the evaluated patients. Three patients experienced severe AEs. Mean DAS28-CRP and remission rate were 1.56 and 88% when ABT reduced and 1.80 and 81% at 1-year, respectively. Structural remission was achieved in 34 out of 42 evaluated patients.
Conclusions: Reduced dose of intravenous ABT was proposed as a feasible choice for maintenance therapy for RA after achievement of remission/LDA, although further randomized trials would be awaited.