Magnetic resonance imaging examinations of the spine in patients with ankylosing spondylitis before and after therapy with the tumor necrosis factor alpha receptor fusion protein etanercept

Objective

To assess spinal inflammation by magnetic resonance imaging (MRI) before and after treatment with the tumor necrosis factor (TNF) receptor fusion protein etanercept compared with placebo.

Methods

MRI examinations of the lower thoracic and lumbar spine of 40 patients with active ankylosing spondylitis (AS) were performed as part of the recently published randomized controlled trial at four different timepoints: baseline (BL), after 12 weeks (FU1), 24 weeks (FU2) and 48 weeks (FU3). Nineteen patients received etanercept twice weekly, 2 × 25 mg subcutaneously, for 1 year and 21 patients received placebo for 6 months (until FU2) before switching to etanercept. The patients' (mean age 39.7 years, 75% male, 89% HLA-B27-positive) mean disease duration was 13 years. MRI examinations included T1-weighted sequences before (T1) and after application of gadolinium-diethylenetriamine-pentaacetic-acid (T1/Gd-DTPA) and T2-weighted fat-saturated (T2-FS) sequences. MRI examinations were scored by a modified ASspiMRI score using predefined vertebral units as a basis.

Results

After 12 weeks, spinal inflammation (T2-FS) regressed by 54% (1.33 mean scoring points per vertebral units at BL and 0.61 at FU1, P = 0.002) in the etanercept group, but worsened by 13% in the placebo group (0.94 at BL and 1.06 at TP1, respectively; P < 0.05). After switching to etanercept, placebo patients improved similarly. T1/Gd-DTPA MRI sequences performed equally well. About 60% of all active lesions at BL were detected in the thoracic spine. There were no significant changes in the chronicity score.

Conclusions

Treatment with etanercept of patients with active AS results in regression of spinal inflammation as assessed by spinal MRI. Inclusion of the thoracic spine in MRI examinations of AS patients may be of particular importance.