Evaluation of 611(Recombinant Humanized Anti-interleukin-4 Receptor Alpha IgG4 Monoclonal Antibody) in Chinese Adults With Moderate to Severe Atopic Dermatitis

Inclusion Criteria:

1. Subject must be able to understand and comply with the requirements of the study. andmust participate voluntarily and sign the written informed consent.
2. Male or female adults ages 18 to 75 years old when signing the informed consent.
3. AD (according to Hanifin-Rajka Criteria) that had been present for at least 1 yearsbefore the screening visit.
4. Eczema Area and Severity Index (EASI) score greater than or equal to (>=) 16 at thescreening and baseline visits.
5. Investigator's Global Assessment (IGA) score >=3 (on the 0 to 4 IGA scale, in which 3was moderate and 4 was severe) at the screening and baseline visits.
6. Participants with >=10 percent (%) body surface area (BSA) of AD involvement at thescreening and baseline visits.
7. Baseline Pruritus Numerical Rating Scale (NRS) average score for maximum itchintensity >=4.
8. Recent history (within 12 months before the screening visit) of inadequate response totreatment with topical medications or for whom topical treatments were otherwisemedically inadvisable (e.g., because of important side effects or safety risks).
9. Have applied a stable dose of topical emollient (moisturizer) twice daily for at leastthe 7 consecutive days immediately before the baseline visit.
10. Female subjects of reproductive age (and their male partners) and male subjects (andtheir female partners) must use highly effective contraception throughout the studyperiod and for at least 3 months after the last dose. The subjects had no plans topregnancy, donate sperm or donate egg during the whole study period and for at least 3months after the last dose.

Exclusion Criteria:

1. Presence of skin comorbidities that may interfere with study assessments
2. Presence of active endoparasitic infections; or suspected endoparasitic.
3. Any history of vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC).
4. History of malignancy within 5 years before the baseline visit, except completelytreated in situ carcinoma of the cervix at least 1 year, completely treated andresolved non-metastatic squamous or basal cell carcinoma of the skin at least 1 year.
5. Active chronic or acute infection requiring treatment with systemic anti-infectivetherapy within 2 weeks before the baseline visit, or superficial skin infectionswithin 1 week before the baseline visit.
6. Known or suspected history of immunosuppression, including history of invasiveopportunistic infections (e.g., histoplasmosis, listeriosis, coccidioidomycosis,pneumocystosis, aspergillosis) despite infection resolution: or unusually frequentinfections, per investigator judgment.
7. Active TB, unless that was well documented that the participants had adequatelytreated.
8. Any medical condition that, in the opinion of the investigator, is serious or unstableand may affect the subject's safety and/or prevent the subject from completing thestudy
9. Treatment with topical drugs such as corticosteroids, topical calcineurin inhibitors,PDE inhibitors, or Janus kinase (JAK) inhibitors within 2 weeks before baseline;
10. The lab abnormalities at screening or baseline and not suitable for inclusion in thestudy judged by investigator;
11. Patients who have active Hepatitis B, Hepatitis C or HIV infections as determined bypositive results at Screening.
12. History of alcohol or drug abuse within 6 months before baseline.
13. History of hypersensitivity to 611 or their excipients.
14. Have been vaccinated with live (attenuated) vaccine within 2 months before baseline orplanned during the study period;
15. Have used any investigational drug/treatment within 12 weeks before baseline;
16. Planned or anticipated major surgical procedure during the patient's participation inthis study.
17. Pregnant or lactating women, or subjects with pregnancy or lactation plans during thestudy period.
18. Any reason which, in the opinion of investigator, would prevent the subject fromparticipating in the study.