A Study to Evaluate the Efficacy and Safety Study of Povorcitinib in Participants With Prurigo Nodularis (STOP-PN1)

Inclusion Criteria:

• Male and female participants 18 to 75 years of age.

• Clinical diagnosis of PN for at least 3 months prior to Screening visit.

• Pruritus, defined as an average Itch NRS score ≥ 7 during the 7 days prior to Day 1/Baseline.

• Total of ≥ 20 pruriginous lesions on ≥ 2 different body regions (both legs, and/orboth arms, and/or trunk) at Screening and Day 1/Baseline.

• Documented history of treatment failure, demonstrated intolerance, orcontraindication to a previous PN treatment.

• Willingness to avoid pregnancy or fathering children.

Exclusion Criteria:

• Chronic pruritus due to a condition other than PN or neuropathic and psychogenicpruritus.

• Diagnosis of PN secondary to medications.

• Active AD lesions (signs and symptoms other than dry skin) within 3 months prior toScreening visit.

• Women who are pregnant (or 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 any topical or systemic JAK or TYK2 inhibitor as treatment ofPN or any inflammatory disease.

• Laboratory values outside of the protocol-defined ranges.

Other protocol-defined Inclusion/Exclusion Criteria apply.