This is a multinational, randomized, double-blind, placebo-controlled, Phase 2, dose finding study to evaluate the efficacy and safety of different doses of SAR445399 in adult participants with moderate to severe hidradenitis suppurativa.

The purpose of this study is to assess the efficacy and safety of two doses of SAR445399 compared with placebo in adult participants with moderate to severe hidradenitis suppurativa.

The study duration (per participant) will be up to 46 weeks with a total of 16 visits. The treatment duration will be 32 weeks which includes 16-week double-blinded initial treatment period and a 16-week treatment-blinded extension period.

Inclusion Criteria:

Participants are eligible to be included in the study only if all of the following criteria apply:

• Participants with a history of signs and symptoms consistent with hidradenitis suppurativa (HS) for at least 6 months prior to Baseline
• Participants must have HS lesions present in at least 2 distinct anatomic areas (eg, left, and right axilla; or left axilla and left inguino-crural fold), with at least 1 body site being Hurley Stage II or III.
• Participant must have a total abscess and inflammatory nodule (AN) count of ≥5 at the Baseline Visit.
• Participant must have had an inadequate response to a trial of an oral antibiotic for treatment of HS, exhibited recurrence after discontinuation of antibiotics or demonstrated intolerance to antibiotics or has a contraindication to oral antibiotics for treatment of their HS as assessed by the Investigator through participant interview and review of medical history.
• Participants in the biologic-naïve stratum must be naïve to any prior use of biologic therapy with a potential impact on HS; Participants in the biologic-experienced stratum must have documented history of use of at least one dose of biologic therapy for HS.

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply:

• Any other active skin disease or condition (eg, bacterial, fungal, or viral infection) that may interfere with assessment of HS.
• History of recurrent or recent serious infection
• Known history of or suspected current immunosuppression
• History of solid organ transplant or stem cell transplant.
• History of splenectomy
• History of malignancy or lymphoproliferative disease other than adequately treated or nonmetastatic squamous cell carcinoma of the skin that was excised and completely cured or nonmetastatic basal cell carcinoma of the skin that was excised and completely cured.
• Any other medical condition or severe, concomitant illness, including psychiatric illness and substance abuse, that may present an unreasonable risk to the study participants, make participants unreliable or may interfere with study assessments

The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

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