This is a randomized, double-blind, placebo-controlled, multicenter phase Ib/II clinical study to evaluate the safety, pharmacokinetics and efficacy of AK120 in the treatment of subjects with moderate to severe atopic dermatitis.

This is a randomized, double-blind, placebo-controlled, multicenter phase Ib/II clinical study to evaluate the safety, pharmacokinetics and efficacy of AK120 in subjects with moderate to severe atopic dermatitis.

Inclusion Criteria:

1. Male or female with age 18 - 75 years (inclusive).
2. Atopic dermatitis (AD) diagnosed at least half an year before screening.
3. Subject with EASI score ≥16, IGA ≥ 3, BSA ≥ 10% at screening and baseline.
4. Subjects with a history of an inadequate response or medically inappropriate use of topical drug treatment within 6 months.

Exclusion Criteria:

1. Suffering from other inflammatory diseases that may affect efficacy outcomes (such as rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, scleroderma, inflammatory myopathy, mixed connective tissue disease, overlap syndrome, etc.).
2. History of exposure to active TB, and/or history or current evidence of TB infection.
3. Positive serology results at Screening for hepatitis B, hepatitis C or HIV.
4. Any history of vernal keratoconjunctivitis (VKC) or atopic keratoconjunctivitis (AKC) within 6 months before the baseline visit.
5. History of clinical parasite infection, recent or planned travel to an area with endemic parasite infection within 6 months before the Screening visit
6. Any medical or psychiatric condition, laboratory, or ECG parameter which, in the opinion of the Investigator or the Sponsor's medical monitor, would place the subject at risk, interfere with participation in the study, or interfere with the interpretation of study results.

Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)