Efficacy of infliximab in refractory ankylosing spondylitis: results of a six‐month open‐label study

Objective. To evaluate the efficacy and safety of a loading regimen of the anti‐tumour necrosis factor α (TNF‐α) antibody infliximab in predominantly axial severe ankylosing spondylitis (AS). Methods. We enrolled in this study 50 patients (76% males, 87% HLA‐B27+, median age 35 yr, median disease duration 13 yr) with active AS [Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) ≥30/100 and serum C‐reactive protein concentration ≥15 mg/l) despite treatment with a non‐steroidal anti‐inflammatory drug, and without peripheral arthritis, uveitis or active inflammatory bowel disease. Other disease‐modifying anti‐rheumatic drugs were discontinued ≥3 months before inclusion and were not allowed during the study. Patients received three infusions of infliximab (5 mg/kg) at weeks 0, 2 and 6 and were monitored clinically and biologically until week 24. Results. Forty‐eight patients completed the treatment. In intention‐to‐treat analysis, all parameters were significantly improved at week 2 and generally reached maximal improvement at week 8. The proportion of responders, defined by a reduction of ≥20% in the global assessment of pain (GAP) or by the AS Assessment Study Group (ASAS 20%) criteria, and the proportion of patients reaching partial remission were 98, 94 and 70% respectively. Relapse, defined as ≥50% loss of maximal GAP improvement, occurred in 73% of completers, with a median delay of 14 weeks after the third infusion. No serious adverse event related to the treatment was observed. Conclusions. This study confirms, in a large group of severely affected AS patients, the remarkable efficacy of infliximab. Relapse usually occurred after discontinuation of the drug, but almost one‐third of completers were still free of relapse 4 months after the last infusion.