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Long-term barzolvolimab extension for chronic spontaneous urticaria

A Phase 3b Long-term Efficacy and Safety Extension Study of Barzolvolimab in Participants With Chronic Spontaneous Urticaria Who Have Completed CDX0159-12 or CDX0159-13

Phase 3 Interventional Celldex Therapeutics · NCT07256392

This extension will test whether continued or retreatment with barzolvolimab keeps symptoms controlled and is safe for adults with chronic spontaneous urticaria who completed the earlier phase 3 studies.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment1370 (estimated)
Ages18 Years and up
SexAll
SponsorCelldex Therapeutics Industry-sponsored
Drugs / interventionsbarzolvolimab
Locations20 sites (Birmingham, Alabama and 19 other locations)
Trial IDNCT07256392 on ClinicalTrials.gov

What this trial studies

This global, multicenter long-term extension enrolls adults with chronic spontaneous urticaria who completed the parent phase 3 trials to track time to disease worsening or treatment failure. Participants are assigned to either an Observation Group (UAS7 <16) or a Barzolvolimab Retreatment Group (UAS7 ≥16), with monitoring or treatment over approximately 52–68 weeks depending on group and need for rescue. The protocol includes scheduled clinic visits, daily electronic symptom diaries, standard-of-care treatments, and barzolvolimab dosing for those in the retreatment group or requiring rescue. The study is designed to collect extended safety data and measure durability of response after prior exposure in the phase 3 program.

Who should consider this trial

Good fit: Adults with chronic spontaneous urticaria who completed the CDX0159-12 or CDX0159-13 phase 3 trials, have a documented UAS7 from Weeks 64–68, can comply with daily electronic symptom diaries, and agree to required contraceptive measures when applicable are ideal candidates.

Not a fit: Patients with additional active pruritic skin conditions, significant medical comorbidities that increase risk, or those who did not complete the parent phase 3 trials are unlikely to be eligible or to receive benefit from this extension.

Why it matters

Potential benefit: If successful, continued or retreatment with barzolvolimab could prolong symptom control and reduce flares in people with CSU who responded in the parent trials.

How similar studies have performed: Earlier phase 3 trials of barzolvolimab produced results that led to this extension to study longer-term control and safety.

Eligibility criteria

Show full inclusion / exclusion criteria 
Key Inclusion Criteria:

1. Written informed consent
2. Must have successfully completed the preceding phase 3 clinical trials (CDX0159-12 or CDX0159-13).
3. Both males and females of child-bearing potential must agree to use highly effective contraceptives when receiving barzolvolimab treatment and for 150 days after treatment.
4. Willing and able to comply with all study requirements and procedures, including completion of a daily symptom electronic diary.

Key Exclusion Criteria:

1. Active pruritic skin condition in addition to CSU.
2. Medical condition that would cause additional risk or interfere with study procedures.
3. Participants without at least one documented UAS7 score from Weeks 64-68 of the CDX0159-12 or CDX0159-13 trials.

There are additional criteria that your study doctor will review with you to confirm you are eligible for the study.

Where this trial is running

Birmingham, Alabama and 19 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Chronic Spontaneous UrticariaCDX-0159barzolvolimabchronic spontaneous urticariaCSUurticaria activity scoreitch severity score
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.