Objective To evaluate radiographic progression in patients with ankylosing spondylitis (AS) receiving two different doses of the tumour necrosis factor antagonist golimumab.

Methods 356 patients with AS were randomly assigned to placebo, or golimumab 50 mg or 100 mg every 4 weeks (wks). At wk16, patients with inadequate response early escaped with blinded dose adjustments (placebo→golimumab 50 mg, 50 mg→100 mg). At wk24, patients still receiving placebo crossed over to golimumab 50 mg. Lateral view radiographs of the cervical/lumbar spine were obtained at wk0, wk104 and wk208, and scored (two blinded readers, modified Stoke AS Spine Score (mSASSS)). Observed data were used for wk104 analyses; missing wk208 scores were linearly extrapolated.

Results Wk104 changes from baseline in mSASSS averaged 1.6±4.6 for placebo crossover, 0.9±2.7 for 50 mg and 0.9±3.9 for 100 mg. By wk208, following golimumab therapy for 3.5–4 years, mean changes in mSASSS were 2.1±5.2 for placebo crossover, 1.3±4.1 for 50 mg and 2.0±5.6 for 100 mg. Less than a third of patients (placebo crossover, 19/66 (28.8%); 50 mg, 29/111 (26.1%); 100 mg, 35/122 (28.7%)) had a definitive change from baseline mSASSS (>2). Less radiographic progression was observed through wk208 in patients without baseline syndesmophytes (0.2 vs 2.8 in patients with ≥1 syndesmophyte; p<0.0001) and with baseline C-reactive protein (CRP) levels ≤1.5 mg/dl (0.9 vs 2.9 with CRP >1.5 mg/dl; p=0.0004).

Conclusions No difference in mSASSS change was observed between golimumab 50 mg and 100 mg. The radiographic progression rate remained stable at years 2 and 4, suggesting no acceleration of new bone formation over time. Golimumab-treated AS patients with no syndesmophytes and less systemic inflammation at baseline had considerably less radiographic progression.