Phase Ib, Randomized, Double-blind, Placebo-Controlled, Dose-Escalation Study of Alpha-0261 Tablets to Assess Safety and Tolerability in Patients With Chronic Spontaneous Urcaria (Part 1) and Food Effect in Healthy Adults (Part 2).

Inclusion Criteria: * Written informed consent must be obtained before any assessment is performed.(Part 1 and Part 2) * Aged ≥ 18 and ≤ 75, male or female (Part 1). * Diagnosed with CSU prior to screening at least 6 months. (Part 1) * Received stable second-generation H1 antihistamine therapy for at least 2 weeks before randomization, and is willing to maintain the stable treatment regimen throughout the study treatment period. (Part 1) * Aged ≥ 18 and ≤ 55, male or female (Part 2). * Weight: ≥ 50 kg for males, ≥ 45 kg for females; 19 kg/m2 ≤ body mass index (BMI) ≤ 28 kg/m2. (Part 2) * In general good health. (Part 2) Exclusion Criteria: * Inducible urticaria with identifiable triggers, including dermographism, cold contact urticaria, heat contact urticaria, solar urticaria, pressure urticaria, delayed pressure urticaria, aquagenic urticaria, cholinergic urticaria, or contact urticaria. (Part 1) * Other chronic pruritic skin diseases that may affect the assessment of study outcomes, such as atopic dermatitis, bullous pemphigoid, dermatitis herpetiformis, senile pruritus, or psoriasis. (Part 1) * Other conditions that may cause urticaria or angioedema symptoms, including but not limited to urticarial vasculitis, urticaria pigmentosa, erythema multiforme, mastocytosis, hereditary urticaria, or acquired/drug-induced urticaria. (Part 1) * Have a history of any severe allergic reaction or anaphylaxis. (Part 2) * Any condition, which in the investigator's opinion might jeopardize articipant's safety or compliance with the protocol. (Part 2) * Have clinically significant abnormalities on clinical laboratory results. (Part 2)