QY-201

This study is a Phase Ib/II clinical study of the safety, efficacy and pharmacokinetic characteristics of QY201 tablets in patients with moderate to severe atopic dermatitis. The study is divided into two parts: the first part is a multicenter, randomized, double-blind, placebo-controlled, dose-escalating, 29-day continuous medication Phase Ib clinical study; the second part is a multicenter, randomized, double-blind, placebo-controlled, parallel-group, 12-week continuous medication Phase II clinical study. Part I (Phase Ib): Primary purpose: To evaluate the safety and tolerability characteristics of QY201 tablets in the treatment of patients with moderate to severe atopic dermatitis, and to provide a basis for the dose selection of Phase II clinical studies. Secondary purpose: To evaluate the preliminary efficacy and pharmacokinetic (PK) characteristics of QY201 tablets in the treatment of patients with moderate to severe atopic dermatitis. Exploratory purpose: To evaluate the pharmacodynamic (PD) characteristics of QY201 tablets in the treatment of patients with moderate to severe atopic dermatitis, and the relationship between PK and PD. Part II (Phase II): Main purpose: To evaluate the effectiveness of QY201 tablets in the treatment of patients with moderate to severe atopic dermatitis and provide a basis for the dose selection of the confirmatory Phase III clinical study. Secondary purpose: To evaluate the safety of QY201 tablets in the treatment of patients with moderate to severe atopic dermatitis; to evaluate the population pharmacokinetic characteristics of QY201 tablets in the indicated population.