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

Primary Outcome Measures

1. Proportion of participants who achieve Hidradenitis Suppurativa Clinical Response (HiSCR)
   HiSCR is defined as at least a 50% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining tunnel count.

Secondary Outcome Measures

1. Proportion of participants who achieve Hidradenitis Suppurativa Clinical Response 75 (HiSCR75)
   HiSCR75 is defined as at least a 75% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining tunnel count.
2. Proportion of participants with flare
   Participants who experience at least 1 flare over 12 weeks; flare is defined as at least a 25% increase in the total abscess and inflammatory nodule count with a minimum increase of 2 relative to baseline.
3. Proportion of participants with a ≥ 3-point decrease in Skin Pain Numeric Rating Scale (NRS) score among participants with baseline Skin Pain NRS score ≥ 3
   Participants with a Skin Pain score of at least 3 at baseline and who experience at least a 3-point decrease in Skin Pain score at Week 12, relative to baseline. Skin Pain is an 11-point NRS, ranging from 0 (no skin pain) to 10 (worst skin pain).
4. Proportion of participants who achieve Skin Pain NRS30 at Week 12 among participants with baseline Skin Pain NRS score ≥ 3.
   Participants with a Skin Pain score of at least 3 at baseline and who achieve at Week 12 Skin Pain NRS30, defined as at least a 30% reduction and at least 1-unit reduction from baseline in the Skin Pain NRS.
5. Proportion of participants with a ≥ 4-point increase from baseline in Functional Assessment of Chronic Illness Therapy - Fatigue (FACIT-F) score
   Participants with a baseline FACIT-F score ≤ 48 and who experience at least a 4-point increase in FACIT-F score at Week 12, relative to baseline. The FACIT-F scale is a 13-item questionnaire that assesses self-reported fatigue and its impact upon daily activities and function over the past 7 days, with scores ranging from 0 (worst fatigue) to 52 (no fatigue).
6. Mean change from baseline in Dermatology Life Quality Index (DLQI) score
   The DLQI is a skin disease specific questionnaire aimed at the evaluation of how symptoms and treatment affect participants' health-related quality of life (QoL). The DLQI total score ranges from 0 to 30, with higher scores indicating lower skin health related QoL.
7. Mean change from baseline in abscess count
   Defined as mean change of abscess(es) count relative to baseline.
8. Percentage change from baseline in abscess count
   Percent Change from baseline in number of abscess(es)
9. Mean change from baseline in inflammatory nodule count
   Defined as mean change of inflammatory nodule count relative to baseline.
10. Percentage change from baseline in inflammatory nodule count
    Defined as percent change from baseline in number of inflammatory nodule(s)
11. Mean change from baseline in draining tunnel count
    Defined as mean change of draining tunnel count relative to baseline.
12. Percentage change from baseline in draining tunnel count
    Defined as Percent change from baseline in number of draining tunnel(s)
13. Extension Period: Proportion of participants who achieve HiSCR
    HiSCR is defined as at least a 50% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining tunnel count.
14. Extension Period: Proportion of participants who achieve HiSCR75
    HiSCR75 is defined as at least a 75% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining tunnel count.
15. Extension Period: Proportion of participants with flare
    Participants who experience at least 1 flare over the period under assessment; flare is defined as at least a 25% increase in the total abscess and inflammatory nodule count with a minimum increase of 2 relative to baseline.
16. Extension Period: Proportion of participants who achieved Skin Pain NRS30 among participants with baseline Skin Pain NRS score ≥ 3.
    Skin Pain NRS30 defined as at least a 30% reduction and at least 1-unit reduction from baseline in the Skin Pain NRS.
17. Extension Period: Proportion of participants who achieve HiSCR
    HiSCR is defined as at least a 50% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining tunnel count.
18. Extension Period: Proportion of participants who achieve HiSCR75
    HiSCR75 is defined as at least a 75% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining tunnel count.
19. Extension Period: Proportion of participants with flare
    Participants who experience at least 1 flare over the period under assessment; flare is defined as at least a 25% increase in the total abscess and inflammatory nodule count with a minimum increase of 2 relative to baseline
20. Extension Period: Proportion of participants who achieved Skin Pain NRS30 among participants with baseline Skin Pain NRS score ≥ 3.
    Participants with a Skin Pain score of at least 3 at baseline and who achieve Skin Pain NRS30, defined as at least a 30% reduction and at least 1-unit reduction from baseline in the Skin Pain NRS.
21. Extension Period: Proportion of participants who achieve maintenance of HiSCR or greater response at each visit
    Maintenance of response defined as participants who achieve HiSCR at Week 12 and maintain it or achieve greater response at each visit during the EXT period.
22. Extension Period: Proportion of participants who achieve maintenance of HiSCR75 or greater response at each visit
    Maintenance of response defined as participants who achieve HiSCR75 at Week 12 and maintain it or achieve greater response at each visit during the EXT period.