What is the role of Tumor Necrosis Factor (TNF) alpha inhibitors, such as etanercept (Enbrel) or adalimumab (Humira), in the treatment of sternoclavicular hyperosteosis?

TNF Alpha Inhibitors for Sternoclavicular Hyperostosis

TNF alpha inhibitors are recommended for moderate to severe sternoclavicular hyperostosis that has failed to respond to conventional disease-modifying antirheumatic drugs (DMARDs). This recommendation is based on evidence from treatment guidelines for related spondyloarthropathies, as sternoclavicular hyperostosis shares clinical features with axial spondyloarthritis.

Treatment Algorithm for Sternoclavicular Hyperostosis

First-line Treatment

• NSAIDs and physical therapy for mild to moderate disease 1
• Local glucocorticoid injections for persistent inflammation 1

Second-line Treatment

• Conventional DMARDs (methotrexate, sulfasalazine, leflunomide) for peripheral joint involvement
  • Note: Traditional oral DMARDs have not been shown to be effective for axial manifestations 1

Third-line Treatment (Moderate to Severe Disease)

• TNF alpha inhibitors when disease remains active despite conventional therapy 1
  • Options include:
    • Etanercept (50mg weekly)
    • Adalimumab (40mg every other week)
    • Infliximab (3-5mg/kg at 0,2,6 weeks, then every 8 weeks)
    • Golimumab
    • Certolizumab pegol

Evidence Supporting TNF Inhibitor Use

The 2009 EULAR recommendations for psoriatic arthritis and spondyloarthropathies clearly state that TNF inhibitors are indicated for moderate to severe spinal disease that has failed to respond to NSAIDs and conventional therapy 1. These guidelines specifically mention that "infliximab, etanercept and adalimumab have all demonstrated efficacy in ankylosing spondylitis" and that "similar treatment responses reported in AS were also likely to be observed in axial PsA" 1.

More recent guidelines from 2019 further support this approach, recommending TNF inhibitors for axial spondyloarthritis when NSAIDs and lifestyle modifications fail to control inflammation 1.

Choosing Between TNF Inhibitors

While all TNF inhibitors appear to have similar efficacy for axial disease, there may be differences in their effectiveness for specific manifestations:

• Infliximab may have slightly higher rates of complete remission compared to etanercept in some studies 1
• Etanercept has shown a 46% overall response rate with good safety profile in steroid-refractory cases 1

Monitoring Response to Treatment

Response to TNF inhibitor therapy should be assessed after 6 weeks using validated measures:

• Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)
• A treatment response is defined as a BASDAI score <3 or a reduction by 2 points 1

Important Considerations and Precautions

1. Infection risk: TNF inhibitors increase susceptibility to bacterial and fungal infections. Screen for tuberculosis before initiating therapy 1.

2. Switching between agents: If one TNF inhibitor fails, switching to another may be beneficial. Evidence suggests that approximately one-third of patients who fail one TNF inhibitor may respond to a second 2, 3.

3. Combination therapy: TNF inhibitors can be combined with methotrexate or leflunomide with similar efficacy, though side effect profiles may differ 4.

4. Long-term persistence: Drug continuation rates after 1 year are approximately 65% for adalimumab and 57% for etanercept 5, indicating good long-term tolerability.

5. Contraindications: Active infections, demyelinating disorders, and heart failure are contraindications to TNF inhibitor therapy.

TNF inhibitors represent an important therapeutic option for patients with sternoclavicular hyperostosis who have failed conventional therapy, with substantial evidence supporting their efficacy in related axial spondyloarthropathies.