A Study to Assess Molecular Changes in Adult Participants With Moderate to Severe Hidradenitis Suppurativa or With Moderate to Severe Atopic Dermatitis Receiving Subcutaneous Injections of Lutikizumab

A Multicenter Open-Label Interventional Biomarker Study of Lutikizumab in Adult Subjects With Moderate-to-Severe Hidradenitis Suppurativa or Adult Subjects With Moderate-to-Severe Atopic Dermatitis

Hidradenitis suppurativa (HS) and atopic dermatitis (AD) are chronic inflammatory skin diseases that lead to the development of skin lesions and symptoms such as pain and discomfort. The purpose of this study is to assess molecular changes in adult participants with moderate to severe HS or with moderate to severe AD.

Lutikizumab (ABT-981) is an investigational drug being developed for the treatment of HS and AD. This study will consist of 2 sub-studies: Sub-Study 1 moderate to severe hidradenitis suppurativa and Sub-Study 2 moderate to severe atopic dermatitis. Approximate 60 participants will be enrolled in the study at approximately 2 sites in the US.

In Sub-Study 1 HS participants will receive subcutaneous (SC) injections of lutikizumab for up to week 15 with a 70-day follow-up period. In Sub-Study 2 AD, participants will receive subcutaneous (SC) injections of lutikizumab for up to week 14 with a 70-day follow-up period. The study duration for Sub-Studies 1 and 2 is expected to last up to 30 weeks.

Participants in Sub-Study 1 (HS) who complete Week 16 and showed a therapeutic benefit to lutikizumab, as confirmed by the investigator, will have the option to enter an open-label long-term extension (LTE) to continue to receive lutikizumab for up to an additional 140 weeks, followed by a 70-day follow-up period.

There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at a hospital or clinic and may require frequent medical assessments, blood tests, and biomarker collections.

Inclusion Criteria:

• Sub-Study 1 hidradenitis suppurativa (HS):
• Participants with a diagnosis of moderate-to-severe HS for at least 6 months prior to Baseline as determined by the investigator
• Participants naïve to biologic treatment for HS or must have a prior inadequate response or loss of response to anti-TNF therapy for HS (>= 12 weeks of therapy).
• Sub-Study 2 atopic dermatitis (AD):
• Participants with a diagnosis of moderate-to-severe AD with onset of symptoms at least 1 year prior to Baseline.
• Participants naïve to biologic treatment for AD or must have a prior inadequate response or loss of response to dupilumab for AD (defined as >= 8 weeks of therapy with dupilumab).

Exclusion Criteria:

• History of any malignancy within the last 5 years except for successfully treated nonmelanoma skin cancer (NMSC) or localized carcinoma in situ of the cervix.
• History of active skin disease (other than HS for Sub-Study 1 or AD for Sub-Study 2) that could interfere with the assessment of HS (for Sub-Study 1) or AD (for Sub-Study 2), including skin infections (e.g., bacterial, fungal, or viral) requiring systemic treatment within 4 weeks of the Baseline.