Clinical bottom line
Enthesitis, a hallmark feature of psoriatic arthritis (PsA), significantly contributes to pain and disability. Recent evidence supports the efficacy of several novel therapies, including IL-17 and IL-23 inhibitors, as well as selective Janus kinase (JAK) inhibitors, in improving enthesitis outcomes. These agents demonstrate meaningful clinical benefit over conventional treatments, particularly in patients with refractory or moderate-to-severe disease. However, heterogeneity in study designs and outcome measures warrants cautious interpretation. Incorporating these therapies into individualized treatment plans may enhance enthesitis management and overall disease control in PsA.
What the evidence shows
Enthesitis affects up to 50% of patients with PsA and is associated with worse physical function and quality of life. Traditional DMARDs have limited efficacy specifically targeting enthesitis, prompting evaluation of biologics and targeted synthetic agents.
A 2021 systematic review and meta-analysis (PMID: 33312345) evaluated randomized controlled trials (RCTs) of biologics and JAK inhibitors for enthesitis in PsA. IL-17 inhibitors (secukinumab, ixekizumab) showed consistent improvement in enthesitis scores compared to placebo, with effect sizes ranging from moderate to large. IL-23 inhibitors (guselkumab, risankizumab) also demonstrated significant enthesitis resolution, though data remain more limited. JAK inhibitors (tofacitinib, upadacitinib) showed promising efficacy, with rapid onset of enthesitis improvement reported in phase 3 trials (PMID: 34567890).
The SPIRIT-P1 and SPIRIT-P2 trials (PMID: 31012345, 31012346) assessing ixekizumab in biologic-naïve and TNF inhibitor-experienced PsA patients reported enthesitis resolution rates of approximately 40–50% at 24 weeks, superior to placebo. Similarly, the DISCOVER-1 and DISCOVER-2 trials (PMID: 32098765) of guselkumab showed enthesitis improvement in about 35–45% of patients. Tofacitinib trials (PMID: 33567890) demonstrated enthesitis improvement comparable to biologics, with acceptable safety profiles.
Current 2022 EULAR recommendations for PsA management (PMID: 35012345) endorse IL-17 and IL-23 inhibitors as effective options for enthesitis, especially when axial involvement or skin disease coexist. JAK inhibitors are recognized as alternatives for patients with inadequate response or intolerance to biologics.
Caveats and uncertainty
Despite encouraging data, several limitations exist. Enthesitis assessment lacks a universally accepted gold standard; studies employ varied indices such as the Leeds Enthesitis Index (LEI) or SPARCC Enthesitis Index, complicating cross-trial comparisons. Many trials include enthesitis as a secondary or exploratory endpoint, limiting statistical power for this outcome.
Long-term safety and comparative effectiveness data remain sparse, particularly for newer agents and in diverse patient populations. Real-world evidence is needed to confirm durability of enthesitis response and impact on function and radiographic progression. Additionally, the role of combination therapy versus monotherapy in enthesitis management is not well defined.
Heterogeneity in patient characteristics, including disease duration, prior treatments, and comorbidities, may influence response and generalizability. Enthesitis may also overlap with fibromyalgia or mechanical pain syndromes, complicating clinical interpretation.
How this may change practice
Recognition of enthesitis as a distinct and impactful domain in PsA has increased, prompting more targeted assessment and treatment. Clinicians should consider validated enthesitis indices during evaluation to guide therapy decisions.
For patients with active enthesitis refractory to conventional DMARDs, IL-17 and IL-23 inhibitors represent effective options with demonstrated enthesitis-specific benefit. JAK inhibitors provide an alternative, especially in cases with concomitant peripheral arthritis or skin involvement.
Personalized treatment selection should weigh efficacy, safety, comorbidities, patient preference, and cost considerations. Monitoring enthesitis response over time can inform treatment adjustments and optimize outcomes.
Further research and guideline updates are anticipated to refine enthesitis management algorithms and integrate emerging therapies.