This is a multi-center, randomized, double blind, placebo-controlled phase 2 study to evaluate the efficacy, safety, PK and PD ofLW402 in patients with moderate-to-severe atopic dermatitis.

The study consists of an up-to-4-week screening period, a 12-week double-blind treatment period and a 4-week safety follow-up period.

Inclusion Criteria:

• Diagnosed with AD for at least 12 months before Screening, with below requirements: 1) EASI score ≥16 at Screening and Baseline; 2) IGA score ≥3 at Screening and Baseline; 3) ≥10% BSA of AD involvement at Screening and Baseline

Exclusion Criteria:

• Not enough washing-out period for previous therapy. Concurrent disease/status which may potentially affect the efficacy/safety judgement.

pregnancy. Other.