Novel approaches in the treatment of ankylosing spondylitis and other spondyloarthritides

The therapeutic options for patients suffering from severe forms of spondyloarthritis (SpA) have been rather limited in recent decades. There is now accumulating evidence that anti-TNF therapy is highly effective in SpA, especially in ankylosing spondylitis (AS) and psoriatic arthritis (PsA). Based on the data recently published on what is now several hundred AS and PsA patients, this treatment seems to be even more effective than the same therapy in rheumatoid arthritis (RA). The anti-TNF-alpha agents currently available, infliximab (Remicade(R); Centocor), etanercept (Enbrel(R); Amgen) and adalimumab (Humira(TM); Abbott), are approved for the treatment of RA in the US; infliximab and etanercept are approved in Europe. The situation in SpA is different to RA because there is an unmet medical need, especially in AS, since no therapies with disease-controlling antirheumatic drugs are available for severely affected patients, especially with spinal disease. Thus, TNF blockers might even be considered as first-line immunosuppressive agents in patients with active AS and PsA who are not sufficiently treated by non-steroidal anti-inflammatory drugs and sulfasalazine, if peripheral arthritis is present. For infliximab, a dosage of 5 mg/kg at intervals between 6 and 12 weeks was necessary to constantly suppress disease activity; this is also a major aim of long-term treatment. No dose-finding studies have yet been performed. The standard dose of etanercept is 25 mg s.c. twice-weekly. No studies on adalimumab (standard RA dose 20-40 mg s.c. every 2 weeks) have yet been conducted in SpA. The efficacy of etanercept was first demonstrated in PSA and etanercept is now approved for this indication. A double-blind study has also been performed in AS, with similarly clearcut efficacy. There is preliminary evidence that both agents do also work in other SpA such as undifferentiated SpA. Infliximab has recently been approved for short-term treatment of severe uncontrolled AS; the approval for etanercept is pending. Studies should be performed to document the long-term efficacy of this treatment. There is hope that ankylosis might be preventable but it remains to be shown whether patients benefit from long-term anti-TNF therapy and whether radiological progression and ankylosis can be stopped. Severe adverse events have remained rare. Complicated infections including tuberculosis have been reported. Tuberculosis can be mostly prevented if patients are checked for previous contact with tuberculosis. Currently, the benefits of anti-TNF therapy in AS seem to outweigh these shortcomings.