CT-P39 is Just as Effective as Omalizumab for Chronic Spontaneous Urticaria Treatment

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A phase 3 trial compared the efficacy of CT-P39 to omalizumab for the treatment of chronic spontaneous urticaria (CSU).¹ Both were equally effective and had similar safety profiles when added on to second-generation H₁-antihistamine therapy. CT-P39 is an omalizumab biosimilar approved by the European Commission.²

The phase 3, double-blind, randomized, active-controlled study (NCT04426890) took place in 64 centers across 6 countries. It included male and female patients between the ages of 12 and 75. Each had a CSU diagnosis of ≥ 6 months with active hives and itching for 6 weeks, despite the use of H₁-antihistamines. They also had a weekly itch severity score (ISS7) of ≥ 8 points and a weekly urticaria activity score (UAS7) of ≥ 16 points. The mean ISS7 and UAS7 at baseline ranged from 15.27 to 15.77 and 31.04 to 32.46, respectively.

The study consisted of a 4-week screening period, 2 12-week treatment periods, and a 16-week follow-up. In the first treatment period, 619 patients received 150 mg or 300 mg of either CT-P39 or the reference omalizumab (ref-OMA). With a ratio of 2:2:1:1, the breakdown is as follows:

• CT-P39 300 mg: n = 204
• ref-OMA 300 mg: n = 205
• CT-P39 150 mg: n = 107
• ref-OMA 150 mg: n = 103

In the second period, these 4 patient groups were randomized 1:1. Participants taking ref-OMA 300 mg were rerandomized to take CT-P39 300 mg or ref-OMA 300 mg while those who were originally taking CT-P39 300 mg continued the dosage. Additionally, patients taking 150 mg of either drug were upped to the 300 mg dosing.

Participants received the drug subcutaneously at weeks 0, 4, 8, 12, 16, and 20. They also completed eDiaries in the morning and evening for the entirety of the study. Investigators assessed the changes in ISS7 and UAS7 at week 12 as the primary endpoint. The Dermatology Life Quality Index (DLQI) and Chronic Urticaria Quality of Life Questionnaire (CU-Q2oL) were used to evaluate quality of life.

The average ISS7 and HSS7 decreased in all groups, representing equivalent efficacy. There were also improvements in quality of life, angioedema-free days, and rescue medication use for all dosages. Additionally, switching from ref-OMA 300 mg to CT-P39 300 mg at week 12 did not impact overall efficacy.

At the end of the first treatment period, responses were comparable in the ref-OMA 300 mg group (40.5% and 30.7%, respectively) to the CT-P39 300 mg group (37.9% and 23.6%, respectively). This continued in the second period with the CT-P39 300 mg cohort at 54.5% and 40.1% versus the ref-OMA 300 mg cohort at 47.9% and 37.5%.

Adverse events were also comparable in all groups during both treatment periods, making CT-P39 well-tolerated. The most frequently reported were COVID-19 infections and nasopharyngitis. Most adverse effects were not new or unexpected based on previous trials and remained at Grade 1 or 2 in intensity. Drug discontinuation occurred in 6 participants: 4 in the CT-P39 cohort and 2 in the ref-OMA 300 mg group.

The short study duration and lack of racial diversity may impact the generalizability of the results. Nonetheless, this trial suggests that CT-P39 is a promising omalizumab biosimilar for a disease that affects approximately 1% of the population.³

“These are the first reported results for a biosimilar in CSU,” the authors wrote. “Further long-term studies are warranted in larger cohorts, to validate our findings and identify potential factors affected with treatment response.”

References

1. Saini SS, Maurer M, Dytyatkovska Y, et al. CT-P39 Compared With Reference Omalizumab in Chronic Spontaneous Urticaria: Results From a Double-Blind, Randomized, Active-Controlled, Phase 3 Study. Allergy. Published online January 9, 2025. doi:10.1111/all.16446

2. Celltrion Inc, “Celltrion Receives European Commission Approval of Omlyclo® (CT-P39), the First and Only Omalizumab Biosimilar Approved in Europe [Press Release],” 2024, https://celltrion.com/en-us/company/media-center/press-release/3246.

3. Kolkhir P, Muñoz M, Asero R, et al. Autoimmune chronic spontaneous urticaria. J Allergy Clin Immunol. 2022;149(6):1819-1831. doi:10.1016/j.jaci.2022.04.010