Infliximab (Remicade) is Medically Indicated for This Patient
Infliximab is medically indicated for this patient with ankylosing spondylitis who has failed at least two NSAIDs and a prior biologic, as switching to a different TNF inhibitor is the recommended approach for patients with inadequate response to their first biologic. 1
Treatment Algorithm for Biologic-Experienced AS Patients
Primary Recommendation: Switch to Alternative TNF Inhibitor
The 2019 ACR/SAA/SPARTAN guidelines conditionally recommend switching to a different TNF inhibitor (such as infliximab) over adding conventional synthetic antirheumatic drugs or using non-TNF biologics in patients with active AS despite treatment with their first TNF inhibitor. 1
This recommendation applies to both primary nonresponse (lack of clinically meaningful improvement over 3-6 months) and secondary nonresponse (recurrence of AS activity after initial sustained improvement). 1
Observational data demonstrate that 25-40% of patients who fail their first TNF inhibitor achieve meaningful clinical response when switched to a second TNF inhibitor. 2
Infliximab-Specific Evidence
Infliximab 5 mg/kg demonstrated 61.2% ASAS20 response rates at 24 weeks in the pivotal ASSERT trial, compared to 19.2% with placebo (P < 0.001). 3
Clinical benefit occurs as early as week 2 and is maintained long-term with infusions at weeks 0,2,6, and every 6-8 weeks thereafter. 4, 3
Infliximab is effective even in patients with established spinal ankylosis and high disease activity, with majority achieving PBS continuation criteria and international consensus response measures at 54 weeks. 5
Rationale for Continued Biologic Therapy
Long-Term Treatment Necessity
The ACR strongly recommends against discontinuation of biologics in patients with axial spondyloarthritis, as discontinuation leads to relapse rates of 60-74%, often within weeks to months. 1, 2
Biologic therapy should be planned as long-term treatment, barring toxicities, as this represents one of the few remaining effective treatment options for patients who have failed multiple therapies. 1, 2
Why Not Alternative Approaches
Adding conventional synthetic antirheumatic drugs (sulfasalazine, methotrexate) to failed TNF inhibitor therapy is not recommended, as these agents show limited benefit for axial manifestations. 1
Non-TNF biologics (abatacept, tocilizumab, rituximab) have very low-quality evidence in AS, with most studies failing to demonstrate benefit for important patient outcomes. 1
Critical Clinical Considerations
Prescriber Qualification
- The prescription by a rheumatology specialist is appropriate, as these guidelines emphasize that treatment decisions should be made by clinicians with expertise in managing inflammatory arthritis. 1
Monitoring Requirements
Response should be assessed at 3-6 months using validated measures (BASDAI, ASAS criteria, patient global assessment, functional indices). 1, 4, 3
Lack of clinically meaningful improvement over this timeframe would constitute primary nonresponse and warrant consideration of switching to yet another biologic agent. 1
Common Pitfall to Avoid
- Do not add methotrexate routinely to infliximab for AS, as the 2019 ACR guidelines recommend against co-treatment with low-dose methotrexate in AS patients on TNF inhibitors, unlike in rheumatoid arthritis. 1 While methotrexate co-administration may prolong TNF inhibitor treatment duration (primarily studied with infliximab), clinical responses are not greater, and the added burden outweighs uncertain benefits. 1
Expected Outcomes
Infliximab treatment results in significant improvements in disease activity (BASDAI), functional capacity (BASFI), spinal mobility (BASMI), acute phase reactants (CRP), and quality of life (SF-36 physical component). 4, 3
The majority of responders achieve ASAS50 (44%) and ASAS70 (28%) responses, with 22% achieving low disease activity state. 4