This is an open label, multicenter study designed to evaluate the safety and tolerability of ATI-502 Topical Solution in male and female subjects with moderate or severe atopic dermatitis (AD). Subjects will be required to apply ATI-502 study medication to their identified AD treatment areas. All subjects will be required to complete a safety follow up visit 4 weeks post last study medication application

Inclusion Criteria:

1. Male or non-pregnant, non-nursing female subjects ≥ 18 years old at the time of informed consent.
2. Subject must have diagnosis of AD.
3. Subject must have a diagnosis of moderate or severe AD for a period of ≥6 months prior to the first dose of study medication.
4. Body surface area involvement must be between 2-20%.
5. Subject must have an absolute neutrophil count and a platelet count within normal range.
6. Subject must be willing to refrain from excess of sun exposure.
7. Subjects must refrain from participating in strenuous exercise that would cause profuse sweating for a period of 6 hours after each treatment application with ATI-502.
8. Be in good general health and free of any known disease state or physical condition which, in the investigator's opinion, might impair evaluation of the subject or which might expose the subject to an unacceptable risk by study participation.
9. If a woman of childbearing potential (WOCBP), must have a negative serum pregnancy test at Screening and a negative urine pregnancy test at Baseline and agree to: use a highly effective method of birth control for the duration of the study; not be planning a pregnancy during the study duration and use contraception for 30 days after last application of study medication.
10. Sexually active male subjects must agree to use a barrier method of contraception from the first application of study medication to at least 30 days after the last application of study medication.

Exclusion Criteria:

1. Subject has any signs or symptoms associated with AD therapy which, in the investigator's opinion, might impair evaluation of the AD or which exposes the subject to unacceptable risk by study participation.

2. Subjects unable to complete the required washout periods. Use of prescription moisturizers within 7 days of Visit 1.

3. Subject has used any emollients/moisturizers on the planned treatment area (s) within 4 hours of Visit 1.

4. Subject has clinically infected AD.

5. Subject is currently using an oral H1 antihistamines (e.g. diphenhydramine, terfenadine) UNLESS the subject is on a stable dose for at least 14 days prior to Visit 1.

6. Clinically significant laboratory abnormalities at Visit 1 that, in the opinion of the Investigator, would make the subject a poor candidate for the study.

7. History of, or current, severe, progressive or uncontrolled renal, hepatic, gastrointestinal, pulmonary, cardiovascular, genitourinary (renal disease) or hematological disease, neurologic or cerebral disorders, infectious disease or coagulation disorders that, as determined by the Investigator, would preclude participation in and completion of study assessments.

8. History of, current or suspected systemic or cutaneous malignancy and /or lymphoproliferative disease, other than subjects with: a history of adequately treated and well healed and completely cleared non-melanoma skin cancers (basal or squamous cell carcinoma) treated successfully at least 1 year prior to study entry with no evidence of disease.

9. Evidence of active or latent bacterial (including tuberculosis) or viral infections at the time of enrollment or history of incompletely treated or untreated tuberculosis. Subjects who have completed therapy for latent tuberculosis may participate.

10. History of a serious local infection (e.g., cellulitis, abscess) or systemic infection including but not limited to a history of treated infection (e.g., pneumonia, septicemia) within 3 months prior to Visit 2. Subjects on an antibiotic for a non-serious, acute local infection must complete the course prior to enrollment into the study.

11. Positive serological test for HIV(antibody), HCV (antibody), or HepB (HBsAg). Subjects with herpes zoster or cytomegalovirus (CMV) that resolved less than 2 months before study enrollment. Subjects with a history of frequent outbreaks of Herpes Simplex Virus (defined as 4 or more outbreaks a year).

12. Screening ECG findings of:

    1. QTcF >450msec for males or >470msec for females.
    2. Heart rate < 45 or > 100 beats/minutes (inclusive).
    3. Rhythm disturbance other than sinus arrhythmia or ectopic supraventricular rhythm (ectopic atrial rhythm).
    4. Conduction disturbance including PR >240msec, pre-excitation (delta wave and PR <120msec), second degree or higher AV block.
    5. Acute or chronic signs of ischemia.
    6. Left Bundle Branch Block.
    7. Prior myocardial infarction.

56 days

An AE is the development of an undesirable medical condition or the deterioration of a pre-existing medical condition following or during exposure to a pharmaceutical product, whether or not considered casually related to the product. In clinical studies, an AE can include an undesirable medical condition occurring at any time, including baseline or washout periods, even if no study treatment has been administered.