UBP Greater China (Shang Hai) Co., Ltd.

Primary Objective: To evaluate the efficacy of various UB-221SC doses compared to placebo in CSU patients. Secondary Objectives: To evaluate the efficacy of different dose cohorts in CSU patients; To evaluate the efficacy of the study drug in terms of time to complete remission (UAS7=0), UAS7≤6, and first relapse after the first dose; To evaluate the efficacy of UB-221 SC in terms of time to first rescue medication use after the first dose, number of rescue medication use days, and number of rescue medication tablets per week; To evaluate the safety and tolerability of different dose cohorts in CSU patients; Pharmacokinetics (PK) of UB-221 SC in CSU patients; Pharmacodynamics (PD) of different dose cohorts in CSU patients; Immunogenicity of different dose cohorts in CSU patients; To evaluate the Dermatology Life Quality Index (DLQI) of different dose groups in CSU patients. Exploratory Objectives: To explore the mechanism of action of UB-221 SC in CSU patients.