A Study to Evaluate the Long-term Safety and Efficacy of Fenebrutinib in Participants Previously Enrolled in a Fenebrutinib Chronic Spontaneous Urticaria (CSU) Study

Study Overview
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Brief Summary
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This is a Phase II, multicenter, open-label extension (OLE) study to evaluate the long-term safety and efficacy of fenebrutinib in participants with Chronic Spontaneous Urticaria (CSU) who have completed the treatment period in a fenebrutinib CSU parent study. Participants may enroll in this OLE study at any time after completing the treatment period of the parent study. Participants will receive open-label fenebrutinib at a dose of 200 milligram (mg) orally twice a day. Treatment may continue until the end of the study.

Official Title
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A Phase II Open-Label Extension Study To Evaluate The Long-Term Safety And Efficacy Of Fenebrutinib In Patients Previously Enrolled In A Fenebrutinib Chronic Spontaneous Urticaria Study

Conditions
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Urticaria

Intervention / Treatment
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* Drug: GDC-0853


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Ability to comply with the study protocol, in the investigator's judgment Completion of the treatment period as specified in the parent study Acceptable demonstration of tolerance to study drug during the parent study as determined by the investigator or Medical Monitor For participants receiving treatment with proton-pump inhibitors (PPIs) or H2-receptor antagonists (H2RAs), agreement to maintain treatment at a stable dose for the first 12 weeks of the study For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive measures, and agreement to refrain from donating eggs For men: agreement to remain abstinent (refrain from heterosexual intercourse) or use a condom, and agreement to refrain from donating sperm Exclusion Criteria Pregnant or breastfeeding, or intending to become pregnant during the study or within 4 weeks after the final dose of fenebrutinib Treatment with any investigational agent or live/attenuated vaccine in the preceding 6 weeks Any signs or symptoms of infection judged by the investigator to be clinically significant since completing the treatment period of the parent study Any significant changes (e.g., events, changes in medication) occurring after completion of participation in the parent study that, in the investigator's judgment, would increase the risk of adverse events in this OLE study

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Parent Study: GDC-0853<br>Participants (who had received 50, 150 and 200mg GDC-0853 in Cohort 2 of the Parent GS39684 Study) received open-label fenebrutinib/GDC-0853 at a dose of 200mg orally twice a day. | Drug: GDC-0853<br>* Participants were administered GDC-0853 200mg orally, as per the dosing schedules described above.<br>* Other names: fenebrutinib, RO7010939;|
| Placebo Comparator: Parent Study: Placebo<br>Participants (who had received Placebo in Cohort 2 of the Parent GS39684 Study) received open-label fenebrutinib/GDC-0853 at a dose of 200mg orally twice a day. | Drug: GDC-0853<br>* Participants were administered GDC-0853 200mg orally, as per the dosing schedules described above.<br>* Other names: fenebrutinib, RO7010939;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Participants With Adverse Events (AEs) | An Adverse Event (AE) is any untoward medical occurrence in a participant administered a pharmaceutical product and which does not necessarily have to have a causal relationship with the treatment. An Adverse Event can therefore be any unfavorable and unintended sign (including abnormal laboratory values or abnormal clinical test results), symptom, or disease temporally associated with the use of a pharmaceutical product, whether or not considered related to the pharmaceutical product. Preexisting conditions which worsen during a study are also considered as Adverse Events. | Baseline up until 4 weeks after the last dose of study drug (up to 10 months). | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Plasma Concentrations of Fenebrutinib (GDC-0853) at Specified Timepoints | Plasma Concentration Data for fenebrutinib (GDC-0853) will be tabulated and summarised by visits. Descriptive summary statistics for Arithmetic Mean and Standard Deviation will be presented. | Week 1 Day 1; Weeks 12 and 24; Study Completion/Early Discontinuation |