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

Phase 2

Terminated

Brief Summary: 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.

Recruitment & Eligibility

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

Exclusion Criteria

Not provided

Arm && Interventions

Group	Intervention	Description
Parent Study: GDC-0853	GDC-0853	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.
Parent Study: Placebo	GDC-0853	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.

Primary Outcome Measures

Name	Time	Method
Percentage of Participants With Adverse Events (AEs)	Baseline up until 4 weeks after the last dose of study drug (up to 10 months).	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.

Secondary Outcome Measures

Name	Time	Method
Plasma Concentrations of Fenebrutinib (GDC-0853) at Specified Timepoints	Week 1 Day 1; Weeks 12 and 24; Study Completion/Early Discontinuation	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.

Locations (10): Allergy & Asthma Immunology Associates
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Scottsdale, Arizona, United States
Kern Allergy Med Clinic, Inc.
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Bakersfield, California, United States
Integrated Research Group Inc
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Riverside, California, United States
Clinical Research Center of Alabama, LLC
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Birmingham, Alabama, United States
Allergy & Asthma Consultants
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Redwood City, California, United States
Southern California Research Center
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Mission Viejo, California, United States
Asthma, Nasal Disease, and Allergy Research Center of New England
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East Providence, Rhode Island, United States
Vital Prospects Clinical Research Institute PC - CRN
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Tulsa, Oklahoma, United States
Renstar Medical Research
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Ocala, Florida, United States
Timber Lane Allergy and Asthma Research, LLC
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Burlington, Vermont, United States