In Part A of the study, oral difelikefalin as adjunct to topical corticosteroids (TCS) did not demonstrate meaningful clinical benefit compared to TCS alone.

This is a two-part, multicenter, randomized, double-blind study to evaluate the efficacy and safety of oral difelikefalin as adjunct therapy to a topical corticosteroid (TCS) for moderate-to-severe pruritus in adult subjects with atopic dermatitis (AD).

Part A of this study includes a 12-week Double-blind Treatment Period and a 52-week Open-label Extension Period. Subjects will be randomized to receive oral difelikefalin 0.25 mg tablets BID plus TCS cream, difelikefalin 0.5 mg tablets BID plus TCS cream, placebo tablets BID plus TCS cream or placebo tablets BID plus vehicle cream.

Part B of this study includes a 12-week Double-blind Treatment Period and 52-week Open-label Extension Period. Subjects will be randomized to receive oral difelikefalin 0.25 mg or 0.5 mg tablets BID plus TCS cream or oral placebo tablets BID plus TCS cream. Part A results at week 12 will inform Part B.

Subjects who participated in Part A of the study may not participate in Part B.

All subjects will sign an informed consent form (ICF) and undergo screening for study eligibility.

Key Inclusion Criteria:

To be eligible for inclusion into the study, a patient must meet the following criteria:

• Subject has clinically confirmed diagnosis of active AD;
• Subject has chronic pruritus related to AD;
• Subject has moderate to severe pruritus;
• Female subject is not pregnant or nursing during any period of the study.

Key Exclusion Criteria:

A patient will be excluded from the study if any of the following criteria are met:

• Subject has clinically infected AD;
• Subject has pruritus attributed to a cause other than AD;
• Subject has any clinically significant medical condition or physical/laboratory/ECG/vital signs abnormality that would, in the opinion of the investigator, put the subject at undue risk or interfere with interpretation of study results.