Clinical bottom line
Anti-IL-17 therapies represent a promising, yet still investigational, approach for patients with treatment-resistant ANCA-associated vasculitis (AAV) involving the kidneys. Current evidence suggests IL-17 may contribute to the pathogenesis of AAV, particularly in refractory cases where conventional immunosuppression fails. Early clinical reports and mechanistic studies indicate potential benefits in reducing renal inflammation and preserving function, but robust clinical trial data remain limited. Careful patient selection and further validation are required before routine clinical adoption.
What the evidence shows
ANCA-associated vasculitis is a systemic autoimmune disorder characterized by necrotizing inflammation of small to medium vessels, frequently affecting the kidneys and lungs (Kalyani et al., 2021). Renal involvement often portends worse prognosis and is a major driver of morbidity. Standard treatment includes high-dose corticosteroids combined with cyclophosphamide or rituximab, but a subset of patients remains refractory or intolerant to these therapies (Jayne et al., 2013).
Recent insights into the immunopathology of AAV highlight a role for T helper 17 (Th17) cells and their signature cytokine IL-17 in sustaining neutrophil recruitment and vascular inflammation (Jayne et al., 2025). Elevated IL-17 levels have been detected in serum and renal tissue of patients with active AAV, correlating with disease severity and resistance to standard treatment. This has spurred interest in targeting IL-17 pathways as a novel therapeutic strategy.
Jayne et al. (2025) provide a comprehensive review of emerging targeted therapies in AAV, noting that anti-IL-17 monoclonal antibodies, such as secukinumab and ixekizumab, have shown efficacy in other autoimmune diseases and are under early investigation in AAV. Preliminary case series and small open-label studies suggest these agents may reduce renal inflammation and improve clinical outcomes in refractory AAV, but controlled trials are lacking.
Additional mechanistic studies support IL-17’s role in promoting neutrophil extracellular trap formation and endothelial injury, key processes in AAV pathogenesis (Vazquez et al., 2017). This biological rationale strengthens the hypothesis that IL-17 blockade could modulate disease activity, particularly in patients with persistent renal inflammation despite conventional immunosuppression.
Caveats and uncertainty
The evidence for anti-IL-17 therapies in AAV with renal involvement remains largely hypothesis-generating and preliminary. There are no large randomized controlled trials specifically evaluating these agents in this population to date. Most data derive from small cohorts, case reports, or extrapolation from other autoimmune conditions.
Safety concerns include the risk of infection, given IL-17’s role in mucocutaneous immunity, and the potential for paradoxical autoimmune phenomena. Long-term effects on renal outcomes and relapse rates are unknown. Additionally, the heterogeneity of AAV phenotypes and ANCA subtypes (PR3 vs MPO) may influence responsiveness to IL-17 blockade, necessitating biomarker-driven patient selection strategies.
Current clinical guidelines do not yet incorporate anti-IL-17 therapies for AAV, reflecting the need for more rigorous evidence. The optimal timing, dosing, and combination with existing immunosuppressants remain to be defined.
How this may change practice
If ongoing and future studies confirm efficacy and safety, anti-IL-17 therapies could become a valuable option for patients with treatment-resistant AAV and active renal involvement, particularly those who cannot tolerate or fail standard regimens. This would expand the therapeutic armamentarium beyond B-cell depletion and conventional cytotoxic agents.
Clinicians should remain aware of emerging data and consider referral to clinical trials evaluating IL-17 blockade in refractory AAV. Biomarker assessment of IL-17 pathway activation may help identify candidates most likely to benefit. Integration of anti-IL-17 agents into treatment algorithms would require multidisciplinary collaboration and careful monitoring for infectious and autoimmune complications.