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

Inclusion Criteria:

• Male and female participants ≥ 18 years of age.

• Diagnosis of moderate to severe HS ≥ 3 months prior to Screening visit.

• HS lesions present in ≥ 2 distinct anatomic areas, 1 of which must be at leastHurley Stage II or Hurley Stage III, at both the Screening and Baseline visits.

• Total abscess and inflammatory nodule (AN) count ≥ 5 at both the Screening andBaseline visits.

• History of inadequate response to an appropriate course of at least 1 conventionalsystemic therapy for HS (or demonstrated intolerance to, or have a contraindicationto, a conventional systemic therapy for HS)

• Agree to not use certain topical antiseptics on the areas affected by HS lesionsduring the placebo-controlled period.

• Willingness to avoid pregnancy or fathering children.

• Other inclusion criteria apply.

Exclusion Criteria:

• Draining tunnel count of > 20 at Screening or Baseline visits.

• Women who are pregnant (or who are considering pregnancy) or breastfeeding.

• 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.

• Evidence of infection with TB, HBV, HCV or HIV.

• History of failure to JAK inhibitor treatment of any inflammatory disease.

• Laboratory values outside of the protocol-defined ranges.

• Other exclusion criteria apply.