CT-P39 Compared With Reference Omalizumab in Chronic Spontaneous Urticaria: Results From a Double-Blind, Randomized, Active-Controlled, Phase 3 Study.

Background: This study compared the therapeutic equivalence of CT-P39 (an omalizumab biosimilar) and EU-approved reference omalizumab (ref-OMA) in patients with chronic spontaneous urticaria.

Methods: This double-blind, randomized, active-controlled Phase 3 study (NCT04426890) included two 12-week treatment periods (TPs). In TP1, patients received CT-P39 300 mg, ref-OMA 300 mg, CT-P39 150 mg, or ref-OMA 150 mg. In TP2, patients treated with ref-OMA 300 mg were rerandomized to CT-P39 300 mg or ref-OMA 300 mg; patients initially randomized to CT-P39 300 mg continued this regimen; and patients initially randomized to CT-P39 or ref-OMA 150 mg received 300 mg dosing with the same drug. The primary endpoint for the assessment of therapeutic equivalence of CT-P39 300 mg and ref-OMA 300 mg was change from baseline in weekly itch severity score (ISS7) at week 12.

Results: In TP1, 619 patients were randomized (CT-P39 300 mg, n = 204; ref-OMA 300 mg, n = 205; CT-P39 150 mg, n = 107; ref-OMA 150 mg, n = 103). Equivalence was demonstrated between CT-P39 300 mg and ref-OMA 300 mg for mean change from baseline in ISS7 at week 12; confidence intervals (CIs) were within predefined equivalence margins: global analysis: treatment difference 0.77, 95% CI -0.37 to 1.90; US analysis: treatment difference 0.70, 90% CI -0.22 to 1.63. The proportion of patients experiencing ≥ 1 treatment-related adverse event was comparable across groups. Secondary efficacy, quality of life, pharmacokinetic, safety, and immunogenicity outcomes were comparable between groups at a given dose level, with no evident impact of switching.

Conclusions: Equivalent efficacy was observed between CT-P39 and ref-OMA, with comparable safety also evident.