Celldex Therapeutics (NASDAQ: CLDX) presented long-term results from its Phase 2 study of barzolvolimab at the European Academy of Allergy and Clinical Immunology Annual Meeting in Istanbul. The data showed that up to 64% of patients with chronic spontaneous urticaria (CSU) who had angioedema at baseline remained angioedema-free seven months after completing treatment.

The study involved 208 patients with CSU refractory to antihistamines who received various doses of barzolvolimab or placebo over a 52-week treatment period, followed by a 24-week follow-up period. Angioedema improvements began as early as Week 1 and were sustained at Week 76, seven months after the last dose.

"Barzolvolimab has consistently shown profound, lasting results including high rates of complete response, defined as complete absence of itch and hives, and dramatic improvements in quality of life and angioedema control through 52 weeks of therapy and now seven months after the last dose," said Diane C. Young, Celldex's Chief Medical Officer.

Angioedema affects 55% of people with CSU, with patients reporting an average of 7.7 episodes annually. The condition causes painful swelling and significantly impacts quality of life, leading to increased emergency room visits and hospitalizations compared to CSU patients without angioedema.

Celldex has completed enrollment in two Phase 3 trials of barzolvolimab in CSU, with 1,939 patients enrolled across 500 sites in 43 countries. The company expects topline data in the fourth quarter of 2026 and plans to submit a biologics license application in 2027.

Barzolvolimab is a monoclonal antibody that targets mast cells by binding to the KIT receptor and inhibiting its activity. The company is also studying the drug in Phase 3 trials for cold urticaria and symptomatic dermographism, and Phase 2 studies for prurigo nodularis and atopic dermatitis.