Chronic urticaria in honour of Marcus Maurer
At EADV 2025, chronic urticaria was revisited from pathogenesis to pipeline therapies.
Understanding chronic spontaneous urticaria
Prof. Dr. Martin Metz (Berlin, Germany) opened the session with an overview of chronic spontaneous urticaria (CSU), a condition affecting up to 1% of the population with significant psychosocial burden. Patients with CSU face not only daily symptoms of wheals and angioedema but also impaired sleep, reduced work productivity and increased risk of anxiety and depression. Strikingly, suicide rates are significantly higher among CSU patients than in the general population, underlining the disease’s profound impact on quality of life.
CSU is also associated with considerable healthcare utilisation and economic costs. Many patients cycle through multiple physicians before diagnosis, and inadequate disease control often leads to emergency visits and unnecessary investigations. While second-generation H1-antihistamines remain the cornerstone of therapy, only a minority achieve full control on standard doses, leaving a large proportion of patients symptomatic despite escalation.
Metz recalled Marcus Maurer’s pivotal contribution in identifying autoimmune endotypes of CSU. Around half of patients exhibit auto-IgE reactivity (type I autoimmunity), while 8–10% present with IgG autoantibodies against IgE or FcεRI (type IIb autoimmunity). These mechanisms help explain why some patients respond well to omalizumab while others require alternative approaches such as cyclosporine. Importantly, type IIb autoimmune CSU is often more severe, associated with angioedema and comorbid autoimmune disease.
Despite these insights, CSU remains unpredictable. Biomarkers such as basophil histamine release assays or autologous serum skin tests are available but lack standardisation. Metz emphasised the need for clinically applicable markers to guide therapy choice, a vision Maurer strongly advocated.
Understanding chronic inducible urticaria
Prof. Dr. Mojca Bizjak (Golnik, Slovenia) focused on chronic inducible urticaria (CIndU), which includes subtypes triggered by physical or environmental stimuli such as dermographism, cold, pressure and cholinergic stimuli. Though traditionally considered distinct from CSU, overlaps exist and some patients suffer from both.
CIndU is less common than CSU but represents a substantial minority of chronic urticaria cases, often more difficult to diagnose outside of referral centres. The heterogeneous mechanisms - ranging from mast-cell threshold abnormalities in cold urticaria to sweat hypersensitivity in cholinergic urticaria - illustrate why a one-size-fits-all approach fails.
For clinicians, the challenge lies in reliable provocation testing. Bizjak underlined the importance of standardised protocols, such as the use of dermographometers or cold stimulation devices, to avoid misdiagnosis and to quantify disease activity. Without such tools, patients risk prolonged uncertainty and inappropriate treatment.
Therapeutic responses vary: while antihistamines and omalizumab are effective for some CIndU subtypes, others remain difficult to control, highlighting unmet needs. Bizjak noted that personalised strategies, including avoidance, trigger documentation and patient education, remain cornerstones of care.
Diagnostic workup
Prof. Margarida Gonçalo (Coimbra, Portugal) turned to the question of how to structure diagnostic evaluation in chronic urticaria. Beyond clinical history and examination, targeted testing can help stratify patients. Gonçalo stressed that extensive screening is rarely needed; rather, investigations should be driven by phenotype and suspected endotype.
For CSU, thyroid autoantibodies may point to autoimmune associations, while for CIndU, provocation tests are essential. Gonçalo recalled that Maurer repeatedly advocated “smart testing”: focusing on those assays that change management rather than exhaustive panels.
Biomarkers are beginning to play a role. Elevated D-dimer levels and basopenia have been associated with poor response to omalizumab, though they are not yet ready for routine use. Gonçalo also noted that a structured diagnostic approach can help identify patients suitable for emerging biologics or clinical trials.
New treatments: beyond omalizumab
Finally, Prof. Ana Giménez-Arnau (Barcelona, Spain) outlined the therapeutic horizon in chronic urticaria. Second-generation H1-antihistamines remain first-line, but many patients are insufficiently controlled. Omalizumab revolutionised CSU treatment, yet up to 40% of patients show inadequate response or relapse.
New strategies are rapidly progressing:
- Ligelizumab, a next-generation anti-IgE, initially showed promise but failed to demonstrate superiority to omalizumab in phase III trials, tempering expectations;
- Remibrutinib, an oral BTK inhibitor, demonstrated significant efficacy in CSU in a recent NEJM phase II trial, with rapid onset and manageable safety. Phase III results are awaited;
- Barzolvolimab, an anti-KIT monoclonal antibody, has shown encouraging phase II results, particularly in omalizumab-refractory patients;
- Dupilumab, targeting IL-4Rα, has shown efficacy in patients with coexistent atopic features, offering another potential avenue.
These emerging therapies highlight a shift towards mechanism-based treatment. Stratifying patients according to endotype, type I vs type IIb autoimmunity, presence of comorbidities or biomarkers, will likely help determine who benefits most from each new approach. As Giménez-Arnau stressed, the goal is not only symptom control but also achieving remission and improving patients’ quality of life, a vision that Marcus Maurer championed throughout his career.
In honour of Marcus Maurer
Beyond scientific updates, the session carried a strong emotional component. Marcus Maurer, who passed away in 2024, was remembered as a tireless advocate for patients and a pioneer in understanding urticaria endotypes and advancing targeted therapies. His leadership in developing international guidelines and his work on the Chronic Urticaria Patient Charter shaped the way clinicians and patients approach the disease. His legacy is evident not only in therapeutic algorithms but also in the emphasis on patient-centred care.
Sources and further reading
- Metz M. Understanding chronic spontaneous urticaria. Urticaria session in honour of Marcus Maurer (Session ID D2T04.3A), EADV Congress 2025, Paris/Virtual, 18 Sept 2025, 14:15–14:35 CEST.
- Bizjak M. Understanding chronic inducible urticaria. Urticaria session in honour of Marcus Maurer (Session ID D2T04.3B), EADV Congress 2025, Paris/Virtual, 18 Sept 2025, 14:35–14:55 CEST.
- Gonçalo M. Diagnostic workup. Urticaria session in honour of Marcus Maurer (Session ID D2T04.3C), EADV Congress 2025, Paris/Virtual, 18 Sept 2025, 14:55–15:15 CEST.
- Giménez-Arnau A. New treatments. Urticaria session in honour of Marcus Maurer (Session ID D2T04.3D), EADV Congress 2025, Paris/Virtual, 18 Sept 2025, 15:15–15:35 CEST.
- Kolkhir P, Pogorelov D, Maurer M. Chronic spontaneous urticaria: a review. JAMA. 2024;332(3):251–263. doi:10.1001/jama.2024.6795.
- Kolkhir P, Church MK, Weller K, Metz M, Maurer M. New treatments for chronic urticaria. Curr Opin Allergy Clin Immunol. 2020;20(5):421–429. doi:10.1097/ACI.0000000000000677.
- Zuberbier T. Chronic urticaria: unmet needs and emerging drugs. Lancet. 2024;404(10420):1253–1255. doi:10.1016/S0140-6736(24)00852-3.
- Maurer M, Giménez-Arnau AM, Sussman G, et al. Ligelizumab for chronic spontaneous urticaria. N Engl J Med. 2022;386(14):1320–1330. doi:10.1056/NEJMoa2110578.
- Sussman G, Hébert J, Shakar S, et al. Remibrutinib, an oral Bruton’s tyrosine kinase inhibitor, in chronic spontaneous urticaria. N Engl J Med. 2024;390(9):783–794. doi:10.1056/NEJMoa2310451.
- Kaplan AP, Giménez-Arnau A, Saini SS. Targeting KIT with barzolvolimab in chronic spontaneous urticaria: results from a phase 2 trial. J Allergy Clin Immunol. 2023;152(1):89–98. doi:10.1016/j.jaci.2023.04.012.