This is a multicenter open-label mode of action study. Twenty patients with moderate to severe hidradenitis suppurativa will be treated with guselkumab 200 mg Q4W subcutaneously. Main objectie is to investigate changes in inflammatory pathways induced by IL-23p19 blockade with guselkumab, in HS lesional skin.

The total duration of the treatment period per subject is 16 weeks.

Key Inclusion Criteria:

• moderate to severe HS
• treatment history of at least one systemic anti-inflammatory / immunosuppressive agent;
• HS diagnosis of at least 1 year;
• minimum of two anatomical locations with HS lesions
• minimum of 4 active abscesses and/or inflammatory nodules (AN).

Key Exclusion Criteria:

• contra-indication for guselkumab;
• previous use of guselkumab;
• use of treatment with biologics or any immunosuppressives for HS in the last 3 months prior to randomization;
• presence of other uncontrolled major disease;
• pregnant or lactating women