Background There has been increased interest in understanding whether biologics can be safely withdrawn from patients (pts) receiving combination therapy with MTX once a clinical target has been achieved. The ability of the biologic to maintain the target as monotherapy has received less consideration.

Objectives To evaluate long-term clinical and radiographic outcomes in pts treated with open-label (OL) adalimumab (ADA) as monotherapy following attainment of low-disease activity (LDA).

Methods PREMIER was a 2-year (yr), phase 3, randomized, controlled trial (RCT) in MTX-naïve pts with early RA who were randomized to MTX, ADA (40 mg every other week), or ADA+MTX.¹ Pts completing the RCT were eligible to receive OL ADA for up to an additional 8 yrs (this trial is ongoing); MTX could be added at the investigator’s discretion. This post hoc analysis included data from pts who were in an LDA state [defined as DAS28(CRP) <3.2] at Yr 2 (ie, the end of the RCT) and received OL ADA as monotherapy between Yrs 2 and 8. The percentages of pts remaining in LDA at Yr 8 were summarized using non-responder imputation (NRI) based on the population entering the OL period and as observed for pts with clinical and radiographic data available at Yrs 2 and 8. The mean ΔmTSS from Yr 2 to Yr 8 and the percentage of pts without radiographic progression (ΔmTSS ≤0.5) from Yr 2 to Yr 8 were summarized.

Results Of the 497 pts who enrolled in the OL extension, 313 were in an LDA state at the end of the RCT (ie, Yr 2). Among the LDA responders, 173 (55%) received ADA as monotherapy during the OL period. One-half (n/N=87/173, 50%) of the pts who entered the OL period with LDA maintained this disease activity state at Yr 8 with ADA monotherapy (Table). More than half (n/N=99/173, 57%) completed 6 yrs of OL ADA monotherapy and had DAS28(CRP) values at Yr 8, with 88% (n/N=87/99) maintaining LDA at the Yr 8 assessment. Further, OL ADA monotherapy was associated with clinically insignificant radiographic progression for pts completing Yr 8 (annual progression rate between Yrs 2 and 8, ΔmTSS =0.4 units/yr).

Conclusions OL ADA effectively maintained pts in a state of LDA and with minimal radiographic progression following 6 yrs of treatment. These data suggest that ADA monotherapy can be effective in some pts whose disease activity does not necessitate supplemental MTX therapy.

1. Breedveld FC, et al. Arthritis Rheum 2006;54:26-37.

Disclosure of Interest E. Keystone Grant/Research support from: Abbott, AstraZeneca, Biotest, BMS, Centocor, Genentech, Merck, Nycomed, Pfizer, Roche, UCB, Consultant for: Abbott, Amgen, AstraZeneca, BMS, Centocor, Genzyme, Merck, Novartis, Pfizer, UCB, F. Breedveld Consultant for: Centocor, Schering-Plough, Amgen/Wyeth, Abbott, H. Kupper Shareholder of: Abbott, Employee of: Abbott, S. Liu Shareholder of: Abbott, Employee of: Abbott, S. Florentinus Shareholder of: Abbott, Employee of: Abbott