What is the recommended dose and duration of anti-Tumor Necrosis Factor (anti-TNF) therapy in patients with ankylosing spondylitis?

Dose and Duration of Anti-TNF Therapy in Ankylosing Spondylitis

For patients with ankylosing spondylitis requiring anti-TNF therapy, the standard dosing regimen should be initiated with loading doses followed by maintenance therapy, with treatment generally continued long-term rather than discontinued or tapered. 1

Initial Treatment Approach

• NSAIDs are strongly recommended as first-line therapy for patients with ankylosing spondylitis experiencing pain and stiffness 1, 2
• For patients with persistent high disease activity despite NSAID treatment, anti-TNF therapy is strongly recommended 1
• No particular TNF inhibitor is recommended as the preferred choice for axial disease 1

Anti-TNF Dosing Regimens

Infliximab

• Dosing: 5 mg/kg at weeks 0,2, and 6, then every 6 weeks for maintenance 3
• Administered by intravenous infusion over a period of not less than 2 hours 3

Etanercept

• Dosing: Either 25 mg twice weekly or 50 mg once weekly subcutaneously 4, 5
• Meta-analysis shows no significant efficacy difference between the two dosing regimens 6

Other TNF Inhibitors

• Adalimumab, golimumab, and certolizumab are also approved options 1, 2
• TNF monoclonal antibodies (infliximab, adalimumab, certolizumab, golimumab) are preferred over etanercept for patients with concomitant inflammatory bowel disease 2

Duration of Therapy

• The American College of Rheumatology conditionally recommends against discontinuation of biologic therapy in patients with ankylosing spondylitis 1
• Long-term treatment is generally recommended as discontinuation results in relapses in 60-74% of patients, often within weeks to months 1
• Discontinuation might only be considered in patients with sustained remission for several years, with the understanding that approximately two-thirds of patients will relapse 1

Dose Tapering Considerations

• The American College of Rheumatology conditionally recommends against tapering of the biologic dose as a standard approach 1
• Some studies suggest that a subset of patients who achieve remission may maintain their response with reduced dosing:
  • In one study, 47% of patients maintained remission with reduced etanercept dosing (either weekly or every other week) 7
  • Another study found 86.3% of patients maintained remission with etanercept 50 mg every other week compared to 90.4% with weekly dosing 8

Monitoring and Continuation

• Regular monitoring of disease activity using validated measures is conditionally recommended 1
• Regular monitoring of CRP or ESR is conditionally recommended over usual care without regular monitoring 1
• For patients with unclear disease activity while on a biologic, spinal or pelvic MRI may be helpful to assess inflammation 1

Switching Between Biologics

• For patients with primary non-response to the first TNF inhibitor, switching to secukinumab or ixekizumab is conditionally recommended over switching to a different TNF inhibitor 1
• For patients with secondary non-response (initial response followed by loss of efficacy), switching to a different TNF inhibitor is conditionally recommended over switching to a non-TNF biologic 1

Combination Therapy

• In patients receiving TNF inhibitors, continuing TNF inhibitor alone is conditionally recommended over continuing both TNF inhibitor and NSAIDs 1
• For patients on TNF inhibitors and conventional synthetic DMARDs, continuing TNF inhibitor alone is conditionally recommended 1
• Co-treatment with low-dose methotrexate is conditionally not recommended for patients on TNF inhibitors 1

Remember that treatment decisions should be guided by regular assessment of disease activity, and patients should be maintained on anti-TNF therapy long-term unless there are contraindications or adverse effects.