Study to Evaluate ASN008 Topical Gel (TG)

Inclusion Criteria: Part A - Healthy Volunteers: * Written informed consent obtained prior to any required study-related procedure * Healthy female or male subject aged 18 to 65 * Willing to use medically effective methods of birth control * Females of reproductive potential must have a negative serum pregnancy test at screening and negative serum or urine pregnancy test prior to first study drug application on Day 1 * Non-smoker (no nicotine products for at least 6 months prior to screening) * BMI ≥18.5 kg/m2 and ≤32.0 kg/m2 with minimum weight of 60 kg Part B- Subjects with AD: * Written informed consent obtained prior to any required study-related procedure * Confirmed diagnosis of active atopic dermatitis (AD) * History of AD for at least 6 months prior to Day 1 with an investigator global assessment ≥3 and body surface area covered with 1-10% AD * Pruritus score (NRS)≥ 5 at screening and NRS ≥7 on Day 1 Exclusion Criteria: Both Part A and Part B: * Pregnant or breast-feeding women * Skin disease that may interfere with study assessments * Febrile illness within 6 days prior to Day 1, history of cancer within 5 years of Day 1, major surgery within 8 weeks prior to Day1, known immunodeficiencies, positive for hepatitis B or C or HIV infection * Significant medical/surgical history or condition or current physical/laboratory/ECG/ vitals signs abnormality that might compromise the subject * Corrected QT duration ≥450 milliseconds or other significant ECG abnormality * Received marketed or investigational biological agent within 12 weeks prior to Day 1 or JAK inhibitor or nonbiological product or device within 4 weeks of Day 1 or within 8 weeks of Day 1 if investigational product used or any drug/ substance that is a strong inhibitor or inducer of CYP3A4 or CYP2D6 * Suspected hypersensitivity/allergy to lidocaine * Significant drug or alcohol abuse or mental illness in 2 years prior to Day 1 Part A Only- Healthy Volunteers: -Used medications or skin emollients within 2 weeks prior to Day 1 unless approved by investigator and sponsor Part B Only - Subjects with AD: * Has infected atopic dermatitis * Used dupilumab 12 weeks prior to Day 1 * Used doxepin, hydroxyzine or diphenhydramine, urea containing topical products within 1 week prior to Day 1 * Used systemic antibiotics or topical medicated treatment or other systemic treatments that could affect AD 2 weeks prior to Day 1 * Received any UV-B phototherapy, excimer laser treatment or psoralen-UV-A treatment within 4 weeks prior to Day 1