Background Efficacy of anti–tumor necrosis factor (TNF) therapy in patients with axial spondyloarthritis (SpA) has been tested only in patients who are refractory to NSAID therapy.

Objectives To determine whether combination infliximab (IFX)+NSAID therapy is superior to NSAID monotherapy for reaching clinical and MRI remission in patients with early, active axial SpA who were naïve to NSAIDs or had a submaximal dose of NSAIDs.

Methods INFAST was a double-blind, randomized controlled trial of IFX in biologic-naïve patients 18–48 years of age with early, active axial SpA (Assessment in Ankylosing Spondylitis [ASAS] criteria, disease duration ≤3 years with chronic back pain and active inflammatory lesions of the sacroiliac [SI] joints on MRI). Patients naïve to NSAIDs or treated with a submaximal dose of NSAIDs were randomized (2:1) to receive 28 weeks of treatment with either IV IFX 5 mg/kg (weeks 0, 2, 6, 12, 18, and 24)+naproxen (NPX) 1000 mg/d or IV placebo (PBO)+NPX 1000 mg/d. The primary endpoint was the proportion of subjects meeting ASAS partial remission criteria at week 28. ASAS-20 and ASAS-40 responses were also assessed. Treatment group differences were analyzed using Fisher exact tests. MRI lesions of spine and SI joints were also evaluated.

Results In preliminary results, 106 patients were randomized to IFX+NPX and 52 to PBO+NPX. At baseline, mean BASDAI scores (100 mm VAS) were 64.4 (SD=15.37) mm and 63.0 (SD=15.43) mm and HLA-B27–positive statuses were 82.1% and 90.4% in the IFX+NPX and PBO+NPX groups, respectively. At week 28, ASAS partial remission, ASAS-40, and complete absence of MRI lesions (spine+SI joints [MRI remission] and SI joints alone) were achieved by significantly greater percentages of patients in the IFX+NPX group than in the PBO+NPX group (Table 1).

Serious adverse events were reported in 5 (4.8%) patients in the IFX+NPX group (possibly related to study medication in 3 [2.9%] patients) and 3 (5.8%) patients the PBO+NPX group (possibly related in 2 [3.8%] patients). No deaths occurred.

Conclusions 62% of patients with early, active axial SpA reached clinical remission with IFX+NPX vs 35% with NPX alone; clear superiority of combination therapy over NPX monotherapy was also evident for ASAS-40, but not ASAS-20, response. MRI remission was achieved with combination treatment but not NPX alone. The safety profile was consistent with that of other anti-TNF biologics.

Disclosure of Interest J. Sieper Grant/Research support from: Merck, Abbott, Pfizer, Consultant for: Merck, Abbott, Pfizer, UCB, Roche, Lilly, Speakers Bureau: Merck, Abbott, Pfizer, J. Lenaerts Consultant for: Abbott, BMS, MSD, Pfizer, Roche, Astra Zeneca, J. Wollenhaupt: None Declared, V. Mazurov: None Declared, L. Myasoutova: None Declared, S.-H. Park: None Declared, Y.-W. Song: None Declared, R. Yao Employee of: Merck, D. Chitkara Employee of: Merck, N. Vastesaeger Employee of: Merck