Celldex has announced that two Phase III trials of its anti-KIT antibody in chronic spontaneous urticaria (CSU) met their primary and key secondary endpoints.
In two Phase III trials, EMBARQ-CSU1 and EMBARQ-CSU2, barzolvolimab was pitted against placebo in CSU patients whose symptoms are inadequately controlled by H1-antihistamines. The studies were both investigating two doses of Celldex’s drug.
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Celldex said that both Phase III trials met the primary endpoint of mean change from baseline in weekly urticaria activity score (UAS7) at week 12, with a 20.2-point reduction in the 150mg cohort and 20.5 points in the 300mg cohort in the CSU1 trial. The placebo cohort saw a 10.7-point reduction.
In the CSU2 study, the 150mg cohort saw a 29.7-point reduction and the 300mg cohort saw a 29.6-point reduction. The placebo cohort saw an 11.4-point reduction.
Key secondary endpoints were also met, including the proportion of patients with complete response, a UAS7 score of 0. In the EMBARQ-CSU1 study, after 12 weeks, this was achieved by 42.4% of patients in the 150mg cohort, 42.1% in the 300mg cohort and 9.3% in the placebo cohort after 12 weeks. At 24 weeks, it was achieved by 49.0% and 45.1% of patients in the 150mg and 300mg cohorts, respectively, compared to 15.4% in the placebo group.
In the EMBARQ-CSU2 study, the same endpoint was achieved at 12 weeks in 45.7% and 44% of patients in the 150mg and 300mg cohorts and 12.6% in the placebo group. After 24 weeks, the endpoint was reached by 54% of patients in the 150mg cohort, 48.4% of patients in the 300mg cohort, and 17.6% in the placebo arm.
There was also significant improvement in treated patients in other key secondary endpoints, including the proportion of patients with complete response at week 12 in omalizumab-refractory CSU and the proportion of patients with a seven-day angioedema activity score (AAS7) of zero at week 12 in patients with a baseline score of over zero.
Barzolvolimab was well-tolerated through the 24-week placebo-controlled treatment period. Both EMBARQ-CSU trials are ongoing, with treatment continuing through 52 weeks.
Based on the data, Celldex plans to submit a Biologics License Application (BLA) to the US Food and Drug Administration (FDA) for barzolvolimab in CSU in 2027.
Barzolvolimab recently failed to show benefit in a Phase II prurigo nodularis (PN) study, raising concerns about an upcoming atopic dermatitis (AD) readout. Celldex has terminated development of the drug in PN.
CSU is a skin condition characterised by red, itchy, and painful hives lasting six weeks or longer. Unlike allergen-induced conditions, CSU is driven by immune system responses and is typically managed symptomatically with antihistamines, antipruritics, and anti-inflammatory treatments. Barzolvolimab inhibits a part of the KIT receptor, a protein critical for mast cell function that drives inflammatory responses.
