Screening Inclusion Criteria:

1. Males or females between 18 and 65 years of age at the time of obtaining the written Informed Consent.
2. Patient understands the study procedures and agrees to participate in the study by giving written Informed Consent.
3. Patient agrees to allow digital photography of AD-affected target area during the study.
4. Patient satisfies the diagnostic criteria for AD as determined by the criteria of Hanifin and Rajka.
5. Patient has a negative laboratory results for hepatitis B surface antigen (HBsAg) and IgG anti- Hepatitis B core (anti-HBc), hepatitis C virus antibodies, and Human Immunodeficiency Virus (HIV) antibody tests at Screening.
6. Serum creatinine and blood urea nitrogen (BUN) are in the normal range at Screening.
7. Female patients of child bearing potential have a negative pregnancy test at Screening.
8. Patient has a negative screen for drugs of abuse at Screening.
9. Patient does not have a history or clinical manifestations of significant metabolic, hepatic, renal, hematological, pulmonary, cardiovascular, gastrointestinal or urological disease.
10. Patient does not have liver function test results (AST, ALT) >1.25 the upper limit of normal.
11. Patient does not have QTc > 450 ms (males) or 470 ms (females) at screening.

Randomization Inclusion Criteria:

1. Patient satisfies all of the following at the end of the Single-blind Period (just before randomization to study drug):

   • Physician's Global Assessment (PGA) = or > 2 but < or = 4.
   • Average Baseline Numerical Rating Scale (NRS) = or > 4
   • Average Baseline Behavioral Rating Score (BRS) = or > 2
2. Patient has a negative laboratory results for hepatitis B surface antigen (HBsAg) and IgG anti-Hepatitis B core (anti-HBc), hepatitis C virus antibodies, and Human Immunodeficiency Virus (HIV) antibody tests, based on Screening results.
3. Female patients of childbearing potential ,must have a negative pregnancy test at Screening , Placebo Run-in (Day-14) and Baseline (Day 1).
4. Serum creatinine and blood urea nitrogen (BUN) are in the normal range at Screening.
5. Patient has a negative test for drugs of abuse at Screening and Placebo Run-In (Day -14) and Baseline (Day 1).

6. Use of adequate birth control, if of reproductive potential and sexually active. Adequate birth control is defined as agreement to consistently practice an effective and accepted method of contraception throughout the duration of the study and for 2 weeks after last administration/dose of study drug

   • For females, adequate birth control methods will be defined as: hormonal contraceptives, intrauterine device, or double barrier contraception, i.e., condom + diaphragm, condom or diaphragm + spermicidal gel or foam.
   • For males adequate birth control methods will be defined as double barrier contraception, i.e., condom + diaphragm, condom or diaphragm + spermicidal gel or foam.
   • For females, menopause is defined as one year without menses; if in question, a follicle-stimulating hormone (FSH) of >40 U/mL must be documented. Hysterectomy, bilateral oophorectomy, or bilateral tubal ligation must be documented, as applicable.

7. Patient has NOT used any treatments for AD prior to Day 1, using the following time periods:

   • Systemic (inhaled, oral, suppository or immediate release injectable, depot or sustained-release injectable) corticosteroids, cytostatic drugs, or other immunosuppressant drugs: 5 weeks prior to Day 1
   • Topical immunosuppressant drugs: 4 weeks prior to Day 1
   • Phototherapy, specific desensitization therapy, nonspecific disease-modulating therapy and elimination diet therapy: 4 weeks prior to Day 1
   • Any drugs that are known inhibitors or inducers of Cytochrome P450 CYP2C9: 2 weeks prior to Day 1.
   • Systemic antibiotics: 4 weeks prior to Day 1
   • Topical steroids or tar preparations: 2 weeks prior to Day 1
   • Antihistamines, histamine-added gamma-globulin preparations, desensitization therapy, or other nonspecific disease-modifying therapies: 2 weeks prior to Day 1
   • Herbal preparation, cosmetic or emollient preparations other than those issued during the Screening and Placebo Run-in Periods: 2 weeks prior to Day

1. Use of cosmetic make-up will be allowed.

• Acetaminophen, acetaminophen-containing products, or non-steroidal anti-inflammatories (NSAIDs): 2 weeks prior to Day 1
• Any other investigational drug or device within 8 weeks of Day 1 8. Patient is willing to completely avoid the use of any prescription or nonprescription treatments for AD (including over-the-counter drugs or any topical preparations, other than those topical emollient preparations provided by the study site during the Screening, and thereafter, as needed. Use of hormone replacement therapy (for postmenopausal females) and/or use of hormonal contraceptives, intrauterine device, or double barrier contraception, i.e., condom + diaphragm, condom or diaphragm + spermicidal gel or foam will be allowed. Use of topical antibiotics will be allowed during the study.

Exclusion Criteria:

1. Patient is under the age of legal consent, is mentally or legally incapacitated; has significant emotional problems at the time of Study Entry.
2. Patient has an active dermatologic condition other than AD which may confound the diagnosis or evaluation of atopic dermatitis, such as scabies, allergic contact dermatitis, seborrheic dermatitis, cutaneous lymphoma, ichthyosis, or psoriasis.
3. History of malignancy not in remission for >5 years, with the exception of Cutaneous Basal Cell Carcinoma and Cutaneous Squamous Cell Carcinoma.

4. Presence of comorbid conditions that would preclude participation in the study, including:

   • Immune compromised state, including recent chemotherapy, immunotherapy, or organ transplant.
   • History or clinical manifestations of significant metabolic, hepatic, renal, hematological, pulmonary, cardiovascular, gastrointestinal or urological disease.
   • Signs and symptoms of eczema herpeticum within the preceding 12 months or cellulitis within the preceding 3 months.
   • Positive results for Human Immunodeficiency Virus (HIV) infection at Screening.
   • History or clinical manifestations of significant neurological (e.g., epilepsy) or psychiatric disorders (e.g., history of suicide attempt; history of psychiatric episodes resulting in hospitalization).
   • An active intercurrent infection.
   • History of clinically significant hypersensitivity, anaphylaxis, or allergies to any drug compound, which resulted in a severe AE.
   • Values for liver function tests (ALT, AST) >1.25 times the upper limit of normal at Screening (refer to Covance Lab Manual for reference ranges).

   NOTE: Under no circumstances should a patient who did not qualify regarding Liver Function Tests (alanine aminotransferase [ALT] and/or aspartate aminotransferase [AST] be re-screened and/or re-qualified.

5. Patient has any acute or chronic condition or prior therapy that, in the opinion of the Investigator, would limit the patient's ability to complete and/or participate in this clinical study or otherwise would make the patient unsuitable for this study.
6. Patient has a history of drug abuse within 1 year prior to Day 1.
7. Patient consumes excess amounts of alcohol, defined as exceeding an average of 14 drinks/week (1 drink = 5 ounces of wine or 12 ounces of beer or 1.5 ounces of hard liquor, or any combination of them) within 2 months prior to Day -14 (beginning of Single-blind Period), or is unwilling to comply with the restricted use of alcohol (as defined above, no more than 14 drinks/week) from screening, throughout the study, and until study completion (Follow-up visit).
8. Patient uses any prohibited concomitant medications at any time during the study.
9. Patient is pregnant or lactating or intends to become pregnant or, in the case of a male patient, intends to father a child during the study period and for 2 weeks after the last dose of study medication.
10. Patient has poor peripheral venous access that may limit blood sampling for clinical laboratory or PK analysis.
11. Patient has participated in any other investigational study drug or device trial in which receipt of an investigational study drug or device occurred within 8 weeks prior to Day 1.
12. Prior exposure to S-777469.
13. Any reason which, in the opinion of the Investigator, interferes with the ability of the patient to participate in or complete the trial.