1. Hidradenitis Suppurativa Clinical Response 75 [Week 16]
   Percentage of participants achieving Hidradenitis Suppurativa Clinical Response 75 (HiSCR75), where HiSCR75 is defined as at least a 75% reduction from baseline in abscess and inflammatory nodule (AN) count, with no increase from baseline in abscess or draining fistula count.

1. Hidradenitis Suppurativa Clinical Response 50 (HiSCR50) [Week 16]
   Percentage of participants achieving HiSCR50
2. Change in International Hidradenitis Suppurativa Severity Score System [Week 16]
   Absolute change from baseline in International Hidradenitis Suppurativa Severity Score System (IHS4)
   
   The IHS4 score is calculated as follows: number of nodules (multiplied by 1) + number of abscesses (multiplied by 2) + number of draining tunnels (multiplied by 4). A total score of 3 or less signifies mild, 4 to 10 signifies moderate, and 11 or higher signifies severe disease.
3. Dermatology Life Quality Index (DLQI) [Week 16]
   Percentage of participants achieving a DLQI total reduction of ≥4 minimal clinically important difference among participants with a baseline DLQI ≥4. DLQI produces a numeric score that can range from 0 to 30. A higher score indicates greater health related quality of life impairment.
4. Reduction from Numerical Rating Scale (NRS30 & NRS50) in Patient's Global Assessment of Skin Pain (PGA Skin Pain) [week 16]
   Percentage of participants achieving at least ≥30% (and ≥50%) reduction and at least 2-unit reduction from Baseline in Numerical Rating Scale (NRS30 & NRS50) in Patient's Global Assessment of Skin Pain (PGA Skin Pain) among subjects with Baseline NRS ≥3
5. Patient Global Impression - Severity of Illness - Hidradenitis Suppurativa at Week 16 [Week 16]
   Percentage of participants with minimal or absent symptoms using the Patient Global Impression - Severity of Illness - Hidradenitis Suppurativa at Week 16. Participants choose the response that best describes the severity of their disease. The question is rated on a 7-point scale ranging from 0 to 6 (0=absent; 1=minimal; 2=mild; 3=moderate; 4=moderately severe; 5=severe; 6=very severe).
6. Resolution of draining tunnels (DT100) [Week 16 and Week 52]
   Percentage of participants with zero draining tunnels in the subgroup of participants with at least one draining tunnel at baseline (DT100)

• Hidradenitis Suppurativa

Drug: Sonelokimab

Sonelokimab

Experimental: sonelokimab
Subjects randomized to this arm will receive sonelokimab 120 mg Q2W from Weeks 0 to 6 then 120 mg Q4W starting at Week 8 up to Week 48.

• Drug: Sonelokimab

Placebo Comparator: Placebo
Subjects randomized to this arm will receive placebo Q2W from Weeks 0 to 6 then Q4W starting at Week 8 up to Week 16. They will receive sonelokimab 120 mg Q2W for 4 doses from Weeks 16 to 22 then Q4W from Week 24 up to Week 48

• Drug: Placebo

Inclusion Criteria:

• Participants must be at least 18 years of age at the time of signing the informed consent.
• Participants who are diagnosed with hidradenitis suppurativa as determined by the investigator and have a history of signs and symptoms of hidradenitis suppurativa for at least 6 months before signing the informed consent.
• Participants who have had an inadequate response to appropriate systemic antibiotics for treatment of hidradenitis suppurativa (or demonstrated intolerance to, or had a contraindication to, systemic antibiotics for treatment of their HS), in the investigator's opinion.
• Participants who have a total AN count of ≥5.
• Participants who have HS lesions present in ≥2 distinct anatomical areas, at least one of which must contain single or multiple fistulas (ie, be Hurley Stage II or III).

Exclusion Criteria:

• Participants with a known hypersensitivity to sonelokimab or any of its excipients.
• Participants with any other active skin disease or condition that may, in the opinion of the investigator, interfere with the assessment of HS.
• Participants with underlying conditions that, in the opinion of the investigator, potentially places the participant at unacceptable risk.
• Participants with current severe or uncontrolled disease(s) that put(s) the participant at increased risk in the investigator's opinion, would preclude the participant from adhering to the protocol or completing the study per protocol.
• Participants with any other known autoimmune disease or any medical condition that in the opinion of the investigator would interfere with an accurate assessment of clinical symptoms of HS.
• Participants with a gastrointestinal condition including inflammatory bowel disease or diagnosis of ulcerative colitis or Crohn's disease.

Contact: Moonlake Clinical Trial Helpdesk, phone: +41 41 510 8022, email: ClinicalTrials@moonlaketx.com

Studies a U.S. FDA-regulated Drug Product: Yes

Studies a U.S. FDA-regulated Device Product: No

Product Manufactured in and Exported from the U.S.: Not Provided