To examine the therapeutic effect of the interleukin 1 (IL1) receptor antagonist anakinra in ankylosing spondylitis in an open label trial.
Anakinra (100 mg) was given subcutaneously daily over 24 weeks to 20 NSAID refractory patients with ankylosing spondylitis. Thirteen completed the study. Clinical outcome assessments included disease activity, function, metrology, patients' and physicians' global assessment, peripheral joint assessment, quality of life, and C reactive protein. Dynamic magnetic resonance imaging (MRI) of sacroiliac joints or spine, using gadolinium DTPA as contrast agent, was done before treatment in 15/20 patients, and in 10 patients at study end. The primary end point was the Bath ankylosing spondylitis disease activity index (BASDAI) and ASAS (assessments in ankylosing spondylitis) short term response after six months.
Using an intention to treat analysis, an ASAS 20% response (ASAS 20) was achieved in five patients, ASAS 40 in four, and ASAS 70 in two after 24 weeks. There was no change in mean C reactive protein (22.3 v 33.1 mg/l) or in MRI score. The drug was well tolerated. Injection site reaction was the commonest adverse event.
In this open study, anakinra improved spinal symptoms in only a small subgroup of patients with active ankylosing spondylitis.