Abstract. Background:. Atopic dermatitis (AD) affects approximately 10% of adults worldwide. CM310 is a humanized monoclonal antibody targeting interleukin-4 receptor alpha that blocks interleukin-4 and interleukin-13 signaling. This trial aimed to evaluate the efficacy and safety of CM310 in Chinese adults with moderate-to-severe AD. Methods:. This multicenter, randomized, double-blind, placebo-controlled, phase 2b trial was conducted in 21 medical institutions in China from February to November 2021. Totally 120 eligible patients were enrolled and randomized (1:1:1) to receive subcutaneous injections of 300 mg CM310, 150 mg CM310, or placebo every 2 weeks for 16 weeks, followed by an 8-week follow-up period. The primary endpoint was the proportion of patients achieving ≥75% improvement in the Eczema Area and Severity Index (EASI-75) score from baseline at week 16. Safety and pharmacodynamics were also studied. Results:. At week 16, the proportion of EASI-75 responders from baseline was significantly higher in the CM310 groups (70% [28/40] for high-dose and 65% [26/40] for low-dose) than that in the placebo group (20%[8/40]). The differences in EASI-75 response rate were 50% (high vs. placebo, 95% CI 31%-69%) and 45% (low vs. placebo, 95% CI 26%-64%), with both P values