Proof of concept study to assess the efficacy and safety of Danicopan (factor D inhibitor) in adult patients with chronic spontaneous urticaria resistant to H1-antihistamine treatment (DANICSU).

Who can take part

• Diagnosis of chronic spontaneous urticaria for >6 months
• Patient is ≥ 18 years of age
• Patient is diagnosed with moderate to severe CSU which is refractory to standard of care treatment at the time of enrollment, as defined by the following: o presence of itch and hives for ≥6 consecutive weeks at any time prior to enrollment despite concurrent use of H1- antihistamines o Urticaria activity score (UAS7; range 0-42) ≥ 16, in the week prior to stratification (Day 1)
• Complete vaccination against Neisseria meningitidis within 3 years prior to, or willingness to receive vaccinations or boosters against each serotype (MenACWY, MenB) as described in chapter 5.6.7 of the study protocol

Who cannot take part

• Participation in other clinical trials, specifically with investigational non-biologics within the previous 30 days or reception of biologics and intravitreal treatments in the previous 3 months
• Other treatments for CSU (e.g., systemic corticosteroids or other immunosuppressive medication) within specified timelines
• Hypersensitivity to the active substance or to any of the excipients present in the danicopan formulation
• Participants with unresolved N meningitidis infection
• History of N. meningitidis infection
• Other diseases with symptoms of urticaria or angioedema
• Any other skin disease associated with chronic itching that might confound the study evaluations and results
• Patients whose urticaria is solely due to inducible urticaria