Celldex says barzolvolimab hit all primary and secondary goals in two Phase 3 CSU trials

Celldex Therapeutics announced on September 22, 2026 that its Phase 3 trials EMBARQ-CSU1 and EMBARQ-CSU2 both hit the primary endpoint of mean change from baseline in weekly urticaria activity score at Week 12, along with every key secondary endpoint, with improvements the company called clinically meaningful and statistically significant.¹ The two studies enrolled patients with chronic spontaneous urticaria (CSU) who were not adequately controlled on H1-antihistamines.

Trial design put 1,939 patients into randomized groups (963 in EMBARQ-CSU1 and 976 in EMBARQ-CSU2), split evenly among barzolvolimab 150 mg dosed every 4 weeks after a 300 mg loading dose, barzolvolimab 300 mg dosed every 8 weeks after a 450 mg loading dose, or placebo for 24 weeks, with active dosing continuing to 52 weeks.¹ Patients on placebo were switched to active treatment once they reached 24 weeks.¹

On the primary measure, baseline UAS7 scores were similar across arms (around 30 points), and by Week 12 the LS mean change was -10.7 for placebo versus -20.2 for the 150 mg arm and -20.5 for the 300 mg arm in EMBARQ-CSU1 (p<.00001 for both doses versus placebo), with comparable separation in EMBARQ-CSU2 (-11.4 for placebo versus -20.2 and -19.7 for the two doses, also p<.00001).¹

The company also highlighted complete response data: a higher share of patients reached complete symptom absence (UAS7=0) at Week 12 compared with placebo among those whose CSU had not responded to omalizumab.¹ Safety was reported as well-tolerated with a favorable profile consistent with prior experience through the placebo-controlled period ending at Week 24.¹

Both Phase 3 studies remain ongoing, and Celldex said it plans to submit a Biologics License Application to the FDA in 2027.¹ A separate global Phase 3b long-term extension study is also underway for patients completing the EMBARQ-CSU trials.¹