This single- and multiple-ascending dose study is a Phase 1, first in human study of ARTS-011. The goal of the study is to assess the safety, tolerability, pharmacokinetics, pharmacodynamics and food effect of ARTS-011 after single and multiple oral doses of ARTS-011 in Chinese healthy volunteers.

ARTS-011 is an oral potent Tyrosine kinase 2 (TYK2) inhibitor with a good selectivity profile over other human kinase. TYK2 is required for signal transduction and cellular functions downstream of interferons (IFN), IL-23, and IL-12 which are involved in the initiation and pathogenesis of psoriatic diseases. ARTS-011 is being developed for treatment of moderate-severe psoriasis and other autoimmune diseases.

Inclusion Criteria:

• Healthy female and male subjects between the ages of 18 and 55 years.
• Body Mass Index (BMI) of 19.0 to 28.0 kg/m2; and a total body weight male ≥50.0 kg, female ≥45.0 kg.
• Evidence of a personally signed and dated informed consent document indicating that the subject has been informed of all pertinent aspects of the study.
• Subjects who are willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures.
• No evidence or history of clinically significant abnormalities of , vital signs (body temperature, pulse and blood pressure), laboratory tests (blood hematology and biochemistry, urine and coagulation function), 12-lead ECG and other examinations.
• Subjects has no fertility and sperm donation, egg donation plan and takes highly effective contraception during correctly for the duration of the active treatment period and for at least 90 days after the last dose of investigational drugs.

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal, endocrine pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at time of dosing).
• Any condition possibly affecting drug absorption (eg, gastrectomy).
• A positive urine drug screen.
• History of regular alcohol consumption exceeding 7 drinks/week for females or 14 drinks/week for males (1 drink = 150 mL) of wine or 360 mL of beer or 45 mL of hard liquor within 3 months of screening.
• History of tobacco/nicotine containing products in excess of >5 cigarettes/day within 3 months of screening.
• Treatment with an investigational drug within 30 days (or as determined by the local requirement) or 5 half-lives preceding the first dose of investigational product, whichever is longer.
• 12-lead ECG demonstrating QTc >450, or a QRS interval >120 msec at Screening. If QTc exceeds 450 msec, or QRS exceeds 120 msec, the ECG should be repeated two more times and the average of the three QTc (or QRS) values should be used to determine the subject's eligibility.
• Screening laboratory abnormalities as defined by the protocol.
• Unwilling or unable to comply with the Lifestyle Guidelines as defined by the protocol.
• Subjected is not appropriate to be enrolled in the study per investigator's assessment.