Rationale (What is the reason for this study?) Atopic dermatitis (AD) is a condition that makes the skin dry and itchy and is the most common skin condition that causes redness and irritation.

The exact cause of AD is unclear but genetic and environmental factors are believed to play a role. Common treatment options for participants with AD include basic skin care, medicine that is applied to the skin, and medicine that works in more than one part of the body. Typically, these treatment options work for participants with AD but some have skin lesions (skin sores or damaged skin) over large areas of the body and do not see an improvement in their AD symptoms. MG-K10 has been shown to be effective in treating participants with moderate-to-severeatopic dermatitis in Phase 2 studies (Chaoying Gu et al.2025) and has already completed a Phase 3 clinical study for adults in China. This study aims to evaluate the efficacy and safety of MG-K10 in the adolenscents and adults with moderate-to-severeatopic dermatitis in global population.

Objectives (goals of the study) and Endpoints (how goals are measured) Check how MG-K10 treatment affects atopic dermatitis Study doctors will look at the safety of MG-K10 and if any side effects are reported by participants when they take it.

Check how the body processes MG-K10 Check how MG-K10 affects the biomarkers of effect Check how the body's immune system (the body's defense system) reacts to MG-K10

Inclusion Criteria:

1. Age: ≥12 years, both males and females.
2. Diagnosed with AD (according to the 2014 American Academy of Dermatology Consensus Criteria) that has been present for ≥1 year before the screening visit, and meeting the following conditions:
3. Within 6 months prior to the screening visit, the patient has shown an insufficient response to topical medication or is medically unsuitable for topical treatment (e.g., significant side effects or safety risks).
4. Participants should start a stable dose of moisturizer from the signing of ICF, apply a moisturizer twice daily for at least 7 consecutive days prior to randomization and continue using it throughout the study period.
5. Women of childbearing age have a negative blood pregnancy test result during the screening period.
6. Participants and their partners agree to use effective contraception from the time of signing the Informed Consent Form (ICF) until 6 months after the end of treatment ; no donation or freezing of germ cells is allowed from the time of signing the ICF until 6 months after the end of treatment.
7. The participant voluntarily signs the ICF and can comply with all required visits and study-related procedures outlined in the protocol.
8. For participants ≥ 12 and < 18 years of age at Screening Visit: Parent or legal guardian, as required, has voluntarily signed and dated an informed consent form, approved by an IEC, after the nature of the stud has been explained and the participant's parent or legal guardian has had the opportunity to ask questions.

Exclusion Criteria:

1. Body weight < 30 kilograms (kg).

2. The participant currently has a diagnosis of another active skin disease that may affect AD evaluation (e.g., psoriasis or lupus erythematosus).

3. Known allergies to any component of the investigational drug.

4. The participant cannot tolerate venipuncture or have a history of needle or blood phobia.

5. The participant has comorbidities that may require systemic steroid therapy, other intervention measures, or require active and frequent monitoring.

6. Those with significant cardiac, pulmonary, gastrointestinal, hepatic, renal, hematologic, neurologic, and psychiatric disorders that are unstable or not well controlled and are considered clinically significant by the investigator.

7. Participants with ocular diseases deemed unsuitable for study entry by the investigator, such as a history of atopic keratoconjunctivitis involving the cornea.

8. Participants are planning to undergo major surgery during the study period, including inpatient and outpatient surgeries.

9. Patients with malignant tumors within 5 years

10. Participants with any of the following conditions within the related timeline:

    • Use of biologics
    • Use of targeted inhibitors (e.g., JAK inhibitors), systemic corticosteroids, cyclosporine, or other immunosuppressants
    • Use of topical treatments for AD
    • Receipt of allergen-specific immunotherapy
    • Vaccination with live or attenuated live vaccines
    • Participation in another clinical drug study
    • Previous use of interleukin-4 receptor alpha (IL-4Rα) or interleukin-13 (IL-13) monoclonal antibody drugs

11. Received systemic (oral or intravenous) antibacterial, antiviral, or antifungal treatment within 4 weeks prior to randomization.

12. Evidence of active tuberculosis, or previous evidence of active tuberculosis without documented adequate treatment

13. Diagnosis of active parasitic infection; suspected parasitic infection or high risk of infection unless clinical and (if necessary) laboratory evaluations have ruled out active infection prior to randomization.

14. Laboratory results at screening showing any of the abnormalities

15. Abnormal 12-lead electrocardiogram (ECG) at screening

16. Active hepatitis at screening, or positive for hepatitis B surface antigen (HBsAg), or positive for hepatitis B core antibody (HBcAb) with hepatitis B virus DNA (HBV-DNA) positive, or positive for hepatitis C virus (HCV) antibodies with HCV RNA positive.

17. History of human immunodeficiency virus (HIV) infection, or positive for HIV antibodies at screening

18. Positive for Treponema pallidum antibodies (TP-Ab) at screening, except if rapid plasma reagin (RPR) or Toluidine Red Unheated Serum Test (TRUST) results are negative

19. History of illicit drug use, drug abuse, or excessive alcohol consumption

20. Women who are breastfeeding, pregnant, or planning to become pregnant or breastfeed during the study period.

21. Any other conditions that the investigator considers inappropriate for study participation.

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