A total of approximately 340 patients with H1 antihistamines (H1AH) refractory CSU will be randomized into two treatments arms (SYN008 300 mg s.c., and omalizumab 300 mg s.c.) at a 1:1 ratio. Both SYN008 and omalizumab will be injected every 4 weeks as an add-on therapy on top of H1AH treatment.~The study will consist of three distinct epochs over 27 weeks, as follows:~Screening epoch: Day -21 to Day -1~Randomized-treatment epoch: Day 1 to Week 12~Post-treatment follow-up epoch: Week 1
• This study is a multicenter, randomized, double-blind, parallel-group, positive-controlled phase III study to evaluate the therapeutic equivalence of SYN008 versus omalizumab for injection (Xolair®) in the treatment of CSU patients who remain symptomatic despite antihistamine treatment.