Long-term Efficacy and Safety Extension (LTE) Study of Barzolvolimab in Participants With Chronic Spontaneous Urticaria

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).

Primary Outcome Measures

1. 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.
2. 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.
3. 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.

Secondary Outcome Measures

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
6. 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.
7. 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.
8. 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.
9. 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.
10. 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.
11. 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.
12. Group 2: Change from baseline in UAS7 at Week 12.
    Evaluate efficacy of barzolvolimab on urticaria activity as measured by urticaria activity score (UAS7).
13. Group 2: Change from baseline in UAS7 at Week 24.
    Evaluate efficacy of barzolvolimab on urticaria activity as measured by urticaria activity score (UAS7).
14. Group 2: Change from baseline in UAS7 at Week 52.
    Evaluate efficacy of barzolvolimab on urticaria activity as measured by urticaria activity score (UAS7).
15. Group 2: Change from baseline in UAS7 at Week 68.
    Evaluate efficacy of barzolvolimab on urticaria activity as measured by urticaria activity score (UAS7).
16. 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.
17. 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.
18. 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.
19. 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.
20. 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.
21. 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.
22. 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.
23. 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.
24. Group 1 Incidence of adverse events.
    Group 1: Proportion of participants experiencing adverse events during the study.
25. 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.
26. 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.
27. 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.
28. Group 2 Incidence of treatment emergent adverse events.
    Group 2: Proportion of participants experiencing treatment emergent adverse events during the study.
29. 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.