Development of MTPS9579A was terminated for strategic/business reasons.

This pilot and dose-ranging study will evaluate the efficacy, safety, and pharmacokinetics of MTPS9579A compared with placebo in participants with chronic spontaneous urticaria (CSU) refractory to antihistamines. This study comprises two parts. In Part 1, participants will be randomized to receive MTPS9579A or placebo. On the basis of positive results from Part 1, a dose-ranging Part 2 may be opened, where participants will be randomized to receive one of four MTPS9579A doses or placebo.

Inclusion Criteria:

• Diagnosis of CSU refractory to sgH1-AHs at the time of randomization
• Demonstrated ability to comply with the required use of the eDiary for the duration of the study
• For patients on H2 antihistamines or LTRAs for non-CSU indications, treatment at a stable dose for >=2 weeks prior to screening, with no anticipated changes throughout duration of study, including the screening period
• For women of childbearing potential: agreement to remain abstinent or use contraception
• For men: agreement to remain abstinent or use a condom, and agreement to refrain from donating sperm

Exclusion Criteria:

• Previous participation in a clinical trial of MTPS9579A
• Chronic urticaria with known cause or other disease with symptoms of urticaria or angioedema
• Other skin disease associated with chronic itching
• Uncontrolled disease where flares are commonly treated with systemic corticosteroids
• History or evidence of any clinically significant medical condition/disease or abnormalities in laboratory tests that, in the investigator's judgment, preclude the patient's safe participation and completion of the study, or interferes with the conduct and interpretation of the study
• History of anaphylaxis without clearly identifiable avoidable antigen
• History of anaphylaxis to any biologic therapy for any indication

Qualified researchers may request access to individual patient level data through the clinical study data request platform (www.clinicalstudydatarequest.com). Further details on Roche's criteria for eligible studies are available here (https://clinicalstudydatarequest.com/Study-Sponsors/Study-Sponsors-Roche.aspx). For further details on Roche's Global Policy on Sharing of Clinical Study Information and how to request access to related clinical study documents, see here (https://www.roche.com/research\_and\_development/who\_we\_are\_how\_we\_work/clinical\_trials/our\_commitment\_to\_data\_sharing.htm).