In an adult patient with psoriatic arthritis and active axial disease who has not responded adequately to NSAIDs, how do the tumor necrosis factor‑α inhibitors (etanercept, infliximab, adalimumab, golimumab, certolizumab pegol) compare regarding efficacy, dosing convenience, and safety?

TNF Inhibitors for Axial Disease in Psoriatic Arthritis

For adult patients with psoriatic arthritis and active axial disease who have failed NSAIDs, TNF inhibitors should be the first-line biologic therapy, with all five agents (infliximab, adalimumab, etanercept, golimumab, certolizumab pegol) demonstrating comparable efficacy for axial manifestations. 1, 2

Treatment Selection Algorithm

First-Line Biologic Choice

Switch to a TNF inhibitor over IL-17 or IL-12/23 inhibitors for axial disease specifically. 1, 2 The 2018 ACR/NPF guidelines provide conditional recommendations based on very-low-quality evidence that TNF inhibitors are preferred over IL-17 inhibitors (PICO 46) and IL-12/23 inhibitors (PICO 45) for psoriatic spondylitis/axial disease. 2 Notably, an IL-12/23 inhibitor trial in axial spondyloarthritis was stopped, making this class not recommended for predominant axial involvement. 1, 2

The 2024 EULAR recommendations state that in patients with clinically relevant axial disease with insufficient response to NSAIDs, therapy with an IL-17A inhibitor, TNF inhibitor, IL-17 A/F inhibitor, or JAK inhibitor should be considered. 3 However, TNF inhibitors remain the most established option with the longest track record for axial disease. 4

Comparative Efficacy Among TNF Inhibitors

All five TNF inhibitors demonstrate similar efficacy for axial manifestations when used at standard doses. 5, 6, 7 A 2019 Swiss cohort study of 966 patients with axial spondyloarthritis found no significant differences in drug survival (time to discontinuation or dose escalation) between adalimumab, etanercept, golimumab, and infliximab in multiple adjusted analyses. 5 The hazard ratios comparing each agent to etanercept were all non-significant: infliximab 1.16 (95% CI 0.80-1.67), golimumab 0.80 (95% CI 0.58-1.10), and adalimumab 0.93 (95% CI 0.69-1.26). 5

A 2025 Cochrane systematic review confirmed that TNF inhibitors as a class result in large clinical improvements in csDMARD-inadequate responders with PsA, with moderate-certainty evidence. 7 The ACR50 response rate was 37% with TNF inhibitors versus 8% with placebo (RR 5.63,95% CI 3.98-7.96). 7

Dosing Convenience Considerations

Dosing frequency varies significantly and should influence selection:

• Infliximab (IV): 5 mg/kg at weeks 0,2,6, then every 8 weeks 8, 9

  • Requires infusion center visits
  • May need dose escalation to every 4 weeks or up to 10 mg/kg for better control 10
  • More frequent dose escalation observed compared to subcutaneous agents 5

• Adalimumab (SC): 40 mg every 2 weeks 8, 11

  • Self-administered subcutaneous injection
  • Initial loading: 80 mg week 1,40 mg week 2, then every 2 weeks 8

• Etanercept (SC): 50 mg weekly (or 50 mg twice weekly for first 12 weeks) 10

  • Self-administered subcutaneous injection
  • Most frequent self-injection schedule

• Golimumab (SC): 50 mg every 4 weeks 12

  • Self-administered subcutaneous injection
  • Least frequent subcutaneous dosing

• Certolizumab pegol (SC): 400 mg at weeks 0,2,4, then 200 mg every 2 weeks (or 400 mg every 4 weeks) 13

  • Self-administered subcutaneous injection
  • Flexible dosing options

Golimumab offers the most convenient subcutaneous dosing at once monthly, while infliximab requires the least frequent administration overall but necessitates infusion center visits. 12

Safety Profile

All TNF inhibitors share a class-wide safety profile with comparable serious adverse event rates. 7 Low-certainty evidence from the Cochrane review showed serious adverse events occurred in 4% of TNF inhibitor-treated patients versus 3% with placebo (RR 1.00,95% CI 0.70-1.42). 7 Withdrawals due to adverse events were slightly higher with TNF inhibitors at 3% versus 2% with placebo (RR 1.53,95% CI 1.01-2.33). 7

Key safety considerations apply to all TNF inhibitors: 8

• Contraindicated in active serious infections
• Tuberculosis screening (PPD) mandatory before initiation - reports of TB reactivation exist across the class
• Avoid in multiple sclerosis or demyelinating diseases and use caution in first-degree relatives of MS patients (sibling relative risk 18-36)
• Congestive heart failure: Avoid in NYHA class III-IV; use caution in class I-II with ejection fraction monitoring (avoid if <50%)
• Hepatitis B screening required - reactivation reported with TNF inhibitors
• Do not use with live vaccines; inactivated vaccines may be considered

Injection site reactions are more common with subcutaneous agents, particularly etanercept and infliximab (when given subcutaneously in other formulations). 8 Certolizumab pegol showed higher adverse event risk in one analysis. 14

Special Considerations for Concomitant Manifestations

If significant skin involvement (≥3% BSA or critical areas): Consider that infliximab and adalimumab may provide superior skin responses compared to etanercept. 10, 11, 9 Infliximab achieved PASI75 in 60% versus 1% with placebo at 6 months in PsA patients. 9 However, for axial disease specifically, this should not override the comparable efficacy of all TNF inhibitors for musculoskeletal manifestations.

If inflammatory bowel disease is present: Avoid etanercept, as it is ineffective for IBD. 15 Infliximab, adalimumab, golimumab, and certolizumab pegol all have demonstrated efficacy in IBD. 15

If enthesitis is prominent: All TNF inhibitors demonstrate efficacy for enthesitis, with no clear superiority among agents. 4, 13

Cost-Effectiveness

A 2016 analysis of non-radiographic axial spondyloarthritis found adalimumab had the lowest cost per responder (number needed to treat), followed by certolizumab pegol 400 mg every 4 weeks, with etanercept having the highest cost per responder. 14 However, actual costs vary by insurance coverage and patient assistance programs.

Common Pitfalls

1. Do not use IL-12/23 inhibitors (ustekinumab) for predominant axial disease - a recent trial in axial SpA was stopped due to lack of efficacy. 1, 2

2. Do not assume within-class differences in axial disease efficacy - drug survival studies show comparable outcomes when used at standard doses. 5

3. Do not forget tuberculosis and hepatitis B screening before initiating any TNF inhibitor - this is mandatory across all agents. 8

4. Do not use in patients with NYHA class III-IV heart failure - all TNF inhibitors are contraindicated. 8

5. Recognize that infliximab may require dose escalation more frequently than subcutaneous agents, potentially affecting long-term convenience and cost. 5