This is a multicenter, open label phase II clinical study to evaluate the efficacy and safety of AK120 in the treatment of subjects with moderate to severe atopic dermatitis.

This is a multicenter, open label phase II clinical study to evaluate the efficacy and safety of AK120 in the treatment of subjects with moderate to severe atopic dermatitis. The total duration of the study (including screening period, treatment period and follow-up period) planned for each subject is approximately 25 weeks.

Inclusion Criteria:

1. Male or female subjects aged ≥18≤75 years old.
2. Atopic dermatitis (AD) diagnosed at least half a year before screening.
3. Subject with EASI score ≥16, IGA ≥ 3, BSA ≥ 10% at screening and baseline.
4. Subjects who are suitable for continue using biological treatment assessed by investigator

Exclusion Criteria:

1. Acute onset of AD within 4 weeks before drug administration.
2. The accompany disease have been assessed by the investigators during screening period as unsuitable for participation in this study.
3. Any history or symptoms of malignant tumors in any organ within 5 years prior to screening, regardless of whether treatment has been received and whether there are signs of recurrence or metastasis
4. Have a known or suspected history of immunosuppressive diseases, including a history of invasive infections.
5. Having undergone or planned major surgery within 4 weeks prior to drug administration, or unable to fully recover from surgery prior to drug administration.
6. any medical or psychological condition that puts subjects at risk or may affect the study results assessed by investigators.