A Study to Assess the Efficacy and Safety of CMK389 in Patients With Moderate to Severe Atopic Dermatitis.

Inclusion Criteria: * Adult male or female participants with chronic atopic dermatitis, aged 18 to 65 years, present for at least 1 year before screening. * Participants with Moderate to severe AD defined by IGA score of ≥ 3 (on a scale of 0 to 4, in which 3 is moderate and 4 is severe) at Baseline, EASI score of ≥ 12 at Baseline and Pruritus (NRS) of at least ≥ 3 at Baseline * Participants who are candidates for a systemic therapy, defined as e.g. inadequate response to treatment with topical medications, or for whom topical treatments are otherwise medically inadvisable (e.g. because of important side effects or safety risks, patients with large affected body surface areas) as assessed by the investigator. * Participants must have a body mass index (BMI) at screening within the range of 18 to ≤35 kg/m2. Exclusion Criteria: * Any skin disease that, in the opinion of the investigator, would confound the diagnosis or evaluation of AD disease activity. * Participants taking prohibited medication not completing the wash out period * Use of other investigational drugs at the time of enrolment, or within 5 half-lives of enrolment, or until the expected PD effect has returned to baseline, whichever is longer; or longer if required by local regulations. * Any active, recent or recurrent systemic or localized infection at screening or prior to first treatment which in the opinion of the investigator immunocompromises the participant and/or places the participant at unacceptable risk for immunomodulatory therapy, such as: * Any acute bacterial, fungal, or viral skin/mucosal infection that has not resolved within 2 weeks prior to first treatment or within 12 months in case of eczema herpeticum. * Clinically infected AD within 4 weeks prior to first treatment. * Any other infection requiring treatment with systemic antibiotics, antivirals, antiparasitics, antiprotozoals, or antifungals within 4 weeks prior to first treatment. * Tuberculosis (TB), Human Immunodeficiency Virus (HIV), Hepatitis B, Hepatitis C * Any other current or past clinically significant medical condition, including psychiatric condition, which in the Investigator's opinion may interfere with safety of the participant, study objectives or adherence to the protocol. * Participants with confirmed abnormal absolute neutrophil count (ANC) of \<1.5 x 10\^9/L or with thrombocytopenia of \< 75.0 x 10\^9/L at screening and baseline * History of malignancy of any organ system (other than localized basal cell carcinoma of the skin), treated or untreated, within the past 5 years, regardless of whether there is evidence of local recurrence or metastases. * History of hypersensitivity to any component of the study drug product, or to drugs of similar chemical classes. * History of severe or serious allergy or hypersensitivity reactions, such as anaphylactic shock, asthma, or uncontrolled urticaria. * Pregnant or nursing (lactating) women.