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

Inclusion Criteria:

1. Male and female participants ≥ 18 years of age.
2. Diagnosis of moderate to severe HS ≥ 3 months prior to Screening visit.
3. HS lesions present in ≥ 2 distinct anatomic areas, 1 of which must be at least Hurley Stage II or Hurley Stage III, at both the Screening and Baseline visits.
4. Total abscess and inflammatory nodule (AN) count ≥ 5 at both the Screening and Baseline visits.
5. History of inadequate response to an appropriate course of at least 1 conventional systemic therapy for HS (or demonstrated intolerance to, or have a contraindication to, a conventional systemic therapy for HS)
6. Agree to not use certain topical antiseptics on the areas affected by HS lesions during the placebo-controlled period.
7. Willingness to avoid pregnancy or fathering children.

* Other inclusion criteria apply.

Exclusion Criteria:

1. Draining tunnel count of > 20 at Screening or Baseline visits.
2. Women who are pregnant (or who are considering pregnancy) or breastfeeding.
3. Medical history including thrombocytopenia, coagulopathy or platelet dysfunction; venous and arterial thrombosis, deep vein thrombosis, pulmonary embolism, stroke, moderate to severe heart failure, cerebrovascular accident, myocardial infarction, or other significant cardiovascular diseases; Q-wave interval abnormalities; disseminated herpes zoster or dermatomal herpes zoster; disseminated herpes simplex; chronic/recurrent infections; malignancies.
4. Evidence of infection with TB, HBV, HCV or HIV.
5. History of failure to JAK inhibitor treatment of any inflammatory disease.
6. Laboratory values outside of the protocol-defined ranges.

* Other exclusion criteria apply.