Celldex Therapeutics Barzolvolimab (Anti-KIT Monoclonal Antibody) Meets Primary and All Key Secondary Endpoints in Phase 3 EMBARQ-CSU1 and EMBARQ-CSU2 Trials in Chronic Spontaneous Urticaria
Celldex Therapeutics reported on Tuesday, September 22, 2026 that both Phase 3 trials of barzolvolimab, a humanized monoclonal antibody that binds the KIT receptor on mast cells, met their primary endpoint of mean change in weekly urticaria activity score (UAS7) at week 12 in adults with chronic spontaneous urticaria who remained symptomatic on H1 antihistamines. EMBARQ-CSU1 randomized 963 patients and EMBARQ-CSU2 randomized 976, for 1,939 in total. UAS7 fell by 19.7 to 20.5 points on the two barzolvolimab regimens (150 mg every 4 weeks or 300 mg every 8 weeks) versus 10.7 and 11.4 points on placebo, and complete response (UAS7 of 0) rates were 42.1% to 45.7% versus 9.3% and 12.6% on placebo. All key secondary endpoints were met, benefit was reported in omalizumab-refractory patients, and the drug was well tolerated through 24 weeks. Treatment continues to 52 weeks, and Celldex plans to file a Biologics License Application in 2027.