A Study to Evaluate the Efficacy and Safety of Povorcitinib (INCB054707) in Participants With Moderate to Severe Hidradenitis Suppurativa

Inclusion Criteria:

1. Diagnosis of moderate to severe HS for at least 3 months prior to the screening visit.
2. Total abscess and inflammatory nodule count of at least 5 at both the screening and baseline visits
3. HS lesions in at least 2 distinct anatomical areas (examples include but are not limited to left and right axilla or left and right inguinocrural fold), 1 of which must be at least Hurley Stage II or Hurley Stage III, at both the screening and baseline visits
4. Documented history of inadequate response to at least a 3-month course of at least 1 conventional systemic therapy (oral antibiotic or biologic drug) for HS (or demonstrated intolerance to, or have a contraindication to, a conventional systemic therapy for treatment of their HS).
5. Agreement to NOT use topical and systemic antibiotics for treatment of HS during the placebo-controlled period.
6. Agreement to NOT use a diluted bleach bath or topical antiseptic washes containing chlorhexidine gluconate or benzoyl peroxide on the areas affected by HS lesions during the placebo-controlled period. Note: Over-the-counter soap and water is allowed.
7. Agreement to use contraception
8. Willing and able to comply with the study protocol and procedures.

* Further inclusion criteria apply.

Exclusion Criteria:

1. Presence of > 20 draining tunnels (fistulas) at either the screening or baseline visit.
2. Women who are pregnant (or who are considering pregnancy) or breastfeeding.
3. Medical history including thrombocytopenia, coagulopathy or platelet dysfunction, Q-wave interval abnormalities, current or history of certain infections, cancer, lymphoproliferative disorders and other medical conditions at the discretion of the investigator.
4. Laboratory values outside of the protocol-defined ranges.

* Further exclusion criteria apply.