A Phase 3 interventional study of barzolvolimab and Standard of Care in Chronic Spontaneous Urticaria, sponsored by Celldex Therapeutics. Enrolling by invitation at 201 sites in 30 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-02.
Sponsored by Celldex Therapeutics · Phase 3, Interventional, and Treatment
Colombia, Czechia, Georgia, Hungary, Netherlands, Slovakia, Tunisia
The purpose of this extension study is to collect long-term efficacy and safety data on barzolvolimab in adult participants with Chronic Spontaneous Urticaria (CSU) who completed the treatment and follow-up periods of the Phase 3 clinical trials.
This study will also fulfill the Celldex commitment to provide post-trial access to participants who have completed the phase 3 studies, where applicable.
This is a global, multicenter, long-term extension phase 3b study to determine the time to disease worsening or treatment failure in adult participants with Chronic Spontaneous Urticaria (CSU) who completed the treatment and follow-up periods the phase 3 clinical trials.
The study will consist of 2 Groups: Group 1 (Observation Group), comprising participants whose UAS7 score is less than 16 at entry and Group 2 (Barzolvolimab Retreatment Group) comprising participants whose UAS7 score is 16 or greater.
Participation in this trial will last for approximately 52 weeks for participants assigned to Group 1 (Observation Group) and who do not receive barzolvolimab during the trial. Participants assigned to Group 1 who require barzolvolimab rescue during the trial will be in the trial for up to 68 weeks. Participants assigned to Group 2 (Barzolvolimab Retreatment Group), trial participation will last for approximately 68 weeks from the start of treatment (Day 1).
194 studies on the registry are indexed under Chronic Urticaria; 46 are open to participants now.
This study's planned enrollment of 1,370 is above the median of 80 across 145 interventional studies indexed under Chronic Urticaria.
Browse Chronic Urticaria studies →Celldex Therapeutics is the lead sponsor of 45 studies on the registry; 3 are open to participants now.
Of its 14 completed or terminated interventional studies of FDA-regulated products, 1 (7%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Key Exclusion Criteria:
There are additional criteria that your study doctor will review with you to confirm you are eligible for the study.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Standard of care treatment (at least 2nd generation Type 1 antihistamines \[H1AH\] with or without other permitted background medications) for 52 weeks. For participants with worsening disease (UAS7 score of 16 or greater at any time between Weeks 0-24), barzolvolimab will be administered once as a 300 mg subcutaneous injection followed by 150 mg every 4 weeks for up to 52 weeks.
Biological: barzolvolimab · Other: Standard of Care
Barzolvolimab given once as a 300 mg subcutaneous injection followed by 150 mg administered every 4 weeks for 52 weeks
Biological: barzolvolimab
Subcutaneous Administration
Observational/Standard of Care
Time to disease worsening or treatment failure through Week 52 based on the occurrence of UAS7 (Urticaria Activity Score) of 16 or greater.
The UAS7 is a simple scoring system to evaluate urticaria signs and symptoms. It is based on scoring wheals (hive severity score) and itch (itch severity score) separately on a scale of 0 (no signs/symptoms) to 3 (intense signs/symptoms) over 7 days. The final score is calculated by adding together the daily scores, which can range from 0 to 6, for 7 days. This results in a maximum total score of 42, and a minimum possible score of 0.
Time frame: From Day 1 (baseline) to Week 52.
Time to disease worsening or treatment failure through Week 52 based on the occurrence of the discontinuation of barzolvolimab in Group 2 due to lack of efficacy or to a treatment related adverse event.
Evaluate duration of efficacy of barzolvolimab on urticaria activity or to a treatment related adverse event.
Time frame: From Day 1 (baseline) to Week 52.
Time to disease worsening or treatment failure through Week 52 based on the occurrence of first use of strongly confounding prohibited medication (Group 1 or 2) or use of barzolvolimab in Group 1.
Evaluate duration of efficacy of barzolvolimab on urticaria activity leading to initiation of either a confounding prohibited medication (Group 1 or 2) or barzolvolimab in Group 1.
Time frame: From Day 1 (baseline) to Week 52.
Group 1: Change from baseline in Urticaria Activity Score (UAS7) at Week 26.
Evaluate efficacy of barzolvolimab on urticaria activity as measured by urticaria activity score (UAS7). The UAS7 is a simple scoring system to evaluate urticaria signs and symptoms. It is based on scoring wheals (hive severity score) and itch (itch severity score) separately on a scale of 0 (no signs/symptoms) to 3 (intense signs/symptoms) over 7 days. The final score is calculated by adding together the daily scores, which can range from 0 to 6, for 7 days. This results in a maximum total score of 42, and a minimum possible score of 0.
Time frame: From Day 1 (baseline) in phase 3 trial to Week 26.
Group 1: Change from baseline in UAS7 at Week 52/End of Study.
Evaluate efficacy of barzolvolimab on urticaria activity as measured by urticaria activity score (UAS) The UAS7 is a simple scoring system to evaluate urticaria signs and symptoms. It is based on scoring wheals (hive severity score) and itch (itch severity score) separately on a scale of 0 (no signs/symptoms) to 3 (intense signs/symptoms) over 7 days. The final score is calculated by adding together the daily scores, which can range from 0 to 6, for 7 days. This results in a maximum total score of 42, and a minimum possible score of 0.
Time frame: From Day 1 (baseline) in phase 3 trial to Week 52/End of Study.
Percentage of Group 1 participants with UAS7 ≤ 6 at week 26.
Group 1: Proportion of participants who maintained at least well-controlled disease (UAS7 ≤ 6) at Week 26.
Time frame: From Day 1 (baseline) to Week 26.
Percentage of Group 1 participants with UAS7 ≤ 6 at week 52.
Group 1: Proportion of participants who maintained at least well-controlled disease (UAS7 ≤ 6) at Week 52.
Time frame: From Day 1 (baseline) to Week 52/End of Study.
Percentage of Group 1 participants with UAS7 = 0 at Day 1 who have UAS7 ≤ 6 at Week 26.
Group 1: Proportion of participants with complete absence of hives and itch (UAS7 = 0) at Day 1 who have well controlled CSU (UAS7 ≤ 6) at Week 26.
Time frame: From Day 1 (baseline) to Week 26.
Percentage of Group 1 participants with UAS7 = 0 at Day 1 who have UAS7 ≤ 6 at Week 52.
Group 1: Proportion of participants with complete absence of hives and itch (UAS7 = 0) at Day 1 who have well-controlled disease (UAS7 ≤ 6) at Week 52.
Time frame: From Day 1 (baseline) to Week 52/End of Treatment.
Group 1: Proportion of participants with complete absence of hives and itch (UAS7 = 0 AAS7 = 0) at Day 1 who maintained complete control at Week 26.
Angioedema Activity Score over 7 days \[AAS7\] describes the effect of angioedema on five categories with 0 being none and 3 being most severe. The final score is calculated by adding together daily scores which can range from 0-15 for 7 days. The resulting maximum score is then 105.
Time frame: From Day 1 (baseline) to Week 26.
Group 1: Proportion of participants with complete absence of hives and itch (UAS7 = 0 AAS7 = 0) at Day 1 who maintained complete control at Week 52.
Angioedema Activity Score over 7 days \[AAS7\] describes the effect of angioedema on five categories with 0 being none and 3 being most severe. The final score is calculated by adding together daily scores which can range from 0-15 for 7 days. The resulting maximum score is then 105.
Time frame: From Day 1 (baseline) to Week 52/End of Study.
Group 1: Participants with UAS7 ≤ 6 at Day 1, time to loss of well-controlled disease through Week 52.
Group 1: Participants with at least well-controlled disease (UAS7 ≤ 6) at Day 1, time to loss of well-controlled disease through Week 52.
Time frame: From Day 1 (baseline) to Week 52/End of Study.
Group 1: Participants with UAS7 = 0 at Day 1, time to loss of complete controlled disease through Week 52.
Group 1: Participants with complete absence of hives and itch (UAS7 = 0) at Day 1, time to loss of complete controlled disease through Week 52.
Time frame: From Day 1 (baseline) to Week 52/End of Study.
Group 1: Participants with UAS7 = 0 and AAS7 = 0 at Day 1, time to loss of CSU completely controlled through Week 52.
Group 1: Participants with complete controlled CSU (UAS7 = 0 and AAS7 = 0) at Day 1, time to loss of CSU completely controlled through Week 52.
Time frame: From Day 1 (baseline) to Week 52/End of Study.
Group 2: Change from baseline in UAS7 at Week 12.
Evaluate efficacy of barzolvolimab on urticaria activity as measured by urticaria activity score (UAS7).
Time frame: From Day 1 (baseline) to Week 12.
Group 2: Change from baseline in UAS7 at Week 24.
Evaluate efficacy of barzolvolimab on urticaria activity as measured by urticaria activity score (UAS7).
Time frame: From Day 1 (baseline) to Week 24.
Group 2: Change from baseline in UAS7 at Week 52.
Evaluate efficacy of barzolvolimab on urticaria activity as measured by urticaria activity score (UAS7).
Time frame: From Day 1 (baseline) to Week 52.
Group 2: Change from baseline in UAS7 at Week 68.
Evaluate efficacy of barzolvolimab on urticaria activity as measured by urticaria activity score (UAS7).
Time frame: From Day 1 (baseline) to Week 68.
Group 2: Percentage of participants with UAS7 ≤ 6 at Week 12.
Group 2: Proportion of participants with at least well-controlled disease (UAS7 ≤ 6) at Week 12.
Time frame: From Day 1 (baseline) to Week 12.
Group 2: Percentage of participants with UAS7 ≤ 6 at Week 24.
Group 2: Proportion of participants with at least well-controlled disease (UAS7 ≤ 6) at Week 24.
Time frame: From Day 1 (baseline) to Week 24.
Group 2: Percentage of participants with UAS7 ≤ 6 at Week 52.
Group 2: Proportion of participants with at least well-controlled disease (UAS7 ≤ 6) at Week 52.
Time frame: From Day 1 (baseline) to Week 52.
Group 2: Percentage of participants with UAS7 ≤ 6 at Week 68.
Group 2: Proportion of participants with at least well-controlled disease (UAS7 ≤ 6) at Week 68.
Time frame: From Day 1 (baseline) to Week 68.
From Day 1 (baseline) to Week 68.
Group 2: Proportion of participants who achieve complete absence of hives and itch (UAS7 = 0) at Week 12.
Time frame: From Day 1 (baseline) to Week 12.
Group 2: Percentage of participants with UAS7 = 0 at Week 24.
Group 2: Proportion of participants who achieve complete absence of hives and itch (UAS7 = 0) at Week 24.
Time frame: From Day 1 (baseline) to Week 24.
Group 2: Percentage of participants with UAS7 = 0 at Week 52.
Group 2: Proportion of participants who achieve complete absence of hives and itch (UAS7 = 0) at Week 52.
Time frame: From Day 1 (baseline) to Week 52.
Group 2: Percentage of participants with UAS7 = 0 at Week 68.
Group 2: Proportion of participants who achieve complete absence of hives and itch (UAS7 = 0) at Week 68.
Time frame: From Day 1 (baseline) to Week 68.
Group 1 Incidence of adverse events.
Group 1: Proportion of participants experiencing adverse events during the study.
Time frame: From Day 1 to Week 52.
Group 1 Incidence of non-treatment emergent adverse events.
Group 1: Proportion of participants who never receive barzolvolimab retreatment experiencing non-treatment emergent adverse events.
Time frame: From Day 1 to Week 52.
Group 1 Incidence of treatment emergent adverse events in participants receiving barzolvolimab retreatment.
Group 1: Proportion of participants who receive barzolvolimab retreatment experiencing treatment emergent adverse events.
Time frame: From Day 1 to Week 68.
Group 1 Incidence of treatment emergent adverse events leading to treatment discontinuation.
Group 1: Proportion of participants who receive barzolvolimab retreatment experiencing treatment emergent adverse events leading to treatment discontinuation during the study.
Time frame: From Day 1 to Week 68.
Group 2 Incidence of treatment emergent adverse events.
Group 2: Proportion of participants experiencing treatment emergent adverse events during the study.
Time frame: Time Frame: From Day 1 to Week 68.
Group 2 Incidence of treatment emergent adverse events leading to treatment discontinuation.
Group 2: Proportion of participants experiencing treatment emergent adverse events leading to treatment discontinuation during the study.
Time frame: From Day 1 to Week 68.
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Started Nov 2025 (actual). Primary completion is estimated for Sep 2028, 34 months after the start.
Of 27 industry-sponsored phase 3 interventional studies under Chronic Urticaria, half reached primary completion within 24 months of starting (the median), counting those still running; a quarter within 19 and three quarters within 32. This study's planned 34 months is above that.
Counting every sponsor, half of 29 studies reached it within 24 months; a quarter within 19 and three quarters within 32.
How these figures are worked out, and which studies are left out of them.
Colombia, Czechia, Georgia, Hungary, Netherlands, Slovakia, Tunisia
Colombia, Czechia, Georgia, Hungary, Netherlands, Slovakia, Tunisia
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Barzolvolimab