Sponsor decision; the decision is not related to any safety concern

This is a parallel, Phase 2, 2-arm, double-blind, randomized, multicenter, multinational, placebo-controlled study to evaluate efficacy, safety, pharmacokinetics (PK), and biological effects of treatment of subcutaneous injection of amlitelimab compared with placebo in male and female participants aged 18 to 70 years with moderate to severe hidradenitis suppurativa (HS).

The purpose of this study is to measure standardized clinician reported and participant-reported outcomes (ClinRO and PRO), safety, and drug concentration. An optional long-term extension (LTE) period will assess chronic safety and efficacy over an additional 80 weeks of amlitelimab treatment.

Study details include:

• The study duration will be up to 116 weeks, including a 4-week Screening period, a 16-week double-blind treatment period (DBT), an optional 80-week LTE period and a 16-week post-treatment follow-up period.
• All participants who complete the 16-week DBT period will be offered entry into an optional LTE.
• Participants who do not wish to enter the optional LTE period or who stop treatment prior to Week 16 (Visit 6) or stop investigational medicinal product (IMP) administration prior to completing the LTE period will proceed into the 16-week post-treatment follow-up period.
• The number of planned in clinic visits will be up to six during the DBT period with an additional nine during the LTE period, plus one post-treatment follow-up end-of-study visit. Up to 11 optional in clinic visits are allowed for participants who do not wish to self-administer IMP between scheduled in clinic visits during the LTE period.

The study duration per participant will be up to 116 weeks.

Inclusion Criteria:

• Participant must be 18 (or country's age of majority if >18) years to 70 years of age inclusive, at the time of signing the informed consent.
• Participants with a history of signs and symptoms consistent with HS for at least 1 year 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), 1 of which must be Hurley Stage II or Hurley Stage III.
• Participant must have had an inadequate response to at least a 12-week trial of an oral antibiotic for treatment of HS

Exclusion Criteria:

• Participants with a diagnosis of inflammatory conditions other than HS (including but not limited to systemic lupus erythematosus, systemic sclerosis, myositis, rheumatoid arthritis, inflammatory bowel disease, primary biliary cirrhosis, multiple sclerosis, Behcet's disease, sarcoidosis, etc)
• Any other active skin disease or condition (eg, bacterial, fungal, or viral infection) that may interfere with assessment of HS

The above information is not intended to contain all considerations relevant to a 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