The purpose of this trial is to evaluate the efficacy and safety of tralokinumab administered as subcutaneous (SC) injection by an autoinjector in adults and adolescents (age 12 to 17 years) with moderate-to-severe atopic dermatitis (AD).

This is a single-arm, phase 3 trial designed to evaluate the efficacy and safety of tralokinumab when administered by an autoinjector in adults and adolescent subjects with moderate-to-severe AD. At baseline, the subjects will receive an initial SC dose of 600 mg tralokinumab. For the rest of the treatment period, all subjects will self-administer a dose of 300 mg tralokinumab every other week for 14 weeks.

Inclusion Criteria:

• Age 12 years and above.
• Subject able and willing to self-administer tralokinumab with Device A.
• Diagnosis of AD as defined by the Hanifin and Rajka (1980) criteria for AD.
• History of AD for ≥1 year.
• A recent history (within 1 year before the screening visit) of inadequate response to treatment with topical medication or for whom topical treatments are otherwise medically inadvisable.
• AD involvement of ≥10% body surface area at screening and baseline.
• An EASI score of ≥12 at screening and ≥16 at baseline.
• An IGA score of ≥3 at screening and at baseline.
• Applied a stable dose of emollient twice daily (or more, as needed) for at least 14 days before baseline.

Exclusion Criteria:

• Active dermatologic conditions that may confound the diagnosis of AD or would interfere with assessment of treatment.
• Use of tanning beds or phototherapy within 4 weeks prior to baseline.
• Treatment with systemic immunosuppressive/immunomodulating drugs and/or systemic corticosteroids within 4 weeks prior to baseline.
• Treatment with topical corticosteroids, topical calcineurin inhibitors, topical phosphodiesterase 4 inhibitors, or topical Janus kinase inhibitors within 2 weeks prior to baseline.
• Receipt of any marketed biological therapy (i.e. immunoglobulin, anti immunoglobulin E) including dupilumab or investigational biologic agents 3 to 6 months prior to baseline.
• Active skin infections within 1 week prior to baseline.
• Clinically significant infection within 4 weeks prior to baseline.
• A helminth parasitic infection within 6 months prior to the date informed consent is obtained.
• Tuberculosis requiring treatment within 12 months prior to screening.
• Known primary immunodeficiency disorder.