This is a randomized, double-blind, placebo-controlled, dose-escalation, phase I study for the assessment of safety, tolerability and pharmacokinetics of single ascending doses of MOR106 in healthy male subjects and multiple ascending doses in subjects with moderate to severe atopic dermatitis.

Inclusion Criteria:

- Able and willing to give voluntary written informed consent

Single ascending dose (SAD)

• Negative urine drug screen
• Male between 18-50 years of age
• A body mass index (BMI) between 18-30 kg/m², inclusive.
• Judged to be in good health

Multiple ascending dose (MAD)

• Male or female between 18-65 years of age
• A BMI between 18-30 kg/m²
• Diagnosis of Atopic Dermatitis (AD) for at least 6 months as per the Hanifin and Rajka Criteria
• EASI ≥ 16 at the screening and baseline visits
• IGA score ≥3 (on the 0 to 4 IGA scale, in which 3 is moderate and 4 is severe) at the screening and baseline visits
• Greater than or equal to 10% body surface area (BSA) of AD involvement at screening
• Willingness to continue stable use of an additive free, basic, bland emollient twice daily for at least 7 days before the baseline visit
• Subject is a candidate for systemic therapy and is not responding adequately or has a contraindication to topical corticosteroids and/or topical calcineurin inhibitors (per Investigator's judgement)
• Absence of current active, latent or history of tuberculosis (TB) infection based on medical history and as determined by a negative QuantiFERON TB Gold test at screening
• Female subjects must have a negative serum pregnancy test at screening and a negative urine pregnancy test at baseline
• Female subjects of childbearing potential must use a highly effective method contraception from 28 days prior to the first dose of study drug, during the study and for at least 24 weeks after the last dose

Exclusion Criteria:

• Known hypersensitivity to study drug ingredients.
• History of or a current immunosuppressive condition
• Symptoms of clinically significant illness in the 3 months before the initial study drug administration.
• Any concurrent illness, condition, disability, or clinically significant abnormality
• Treatment with any drug known to have a well-defined potential for toxicity to a major organ in the last 3 months preceding the initial study drug administration.
• A history of significant psychological, neurologic, hepatic, renal, endocrine, cardiovascular, gastrointestinal (GI), pulmonary, or metabolic disease.

MAD only

• Active (skin) infection requiring systemic antibiotics
• immunosuppressive/immunomodulating drugs or phototherapy 4 weeks prior to baseline
• Treatment with topical corticosteroids (TCS) or topical calcineurin inhibitors (TCI) within 2 weeks before the baseline
• Treatment with biologics within 5 half-lives (if known) or 12 weeks prior to baseline visit
• history of immunosuppression
• Regular use (more than 2 visits per week) of a tanning booth/ parlor within 4 weeks of the screening visit
• Regular daily use of oral nonsteroidal anti-inflammatory drugs (NSAIDs), except low-dose aspirin (≤200 mg/day) for cardioprotection, within 7 days prior to screening