A Study to Evaluate the Efficacy and Safety of Subcutaneous Amlitelimab Monotherapy Compared With Placebo in Adult Participants With Severe Alopecia Areata

This is a parallel, Phase 2 multinational, multicenter, randomized, double-blind, placebo-controlled, 3-arm study to investigate the efficacy and safety of subcutaneous (SC) injections of amlitelimab treatment as monotherapy in participants aged 18 years and older with severe alopecia areata (AA). At the end of the double-blind treatment period, all participants will have the option to enter the open-label extension (OLE) period. The study duration will be up to 160 weeks for participants entering the OLE period including a 2-to-4-week screening, a 36-week randomized double-blind period, an optional OLE period (104 weeks) and a 16-week safety follow-up. The open-label extension period is optional and open to all participants who have completed the double-blind treatment period. The total number of visits will be up to 38 visits (or 12 visits for those not entering the OLE study).

Inclusion Criteria: * Definitive diagnosis of AA of more than 6 months. * Diagnosis of severe AA, as determined by all of the following: 1. Hair loss affecting ≥50% of the scalp, as measured by Severity of Alopecia Tool (SALT) at both screening and baseline visits. 2. Current episode of severe hair loss of less than 8 years. Participants with a history of AA of more than 8 years who have observed episodes of terminal hair regrowth over their scalp ("moving patches" spontaneously or following treatment) in the past 8 years can be included. 3. Stable disease: no evidence of terminal hair regrowth within 6 months (less than 10% improvement over the past 6 months). (guidance: if participant reports to have quite a bit more hair than 6 months prior, then patient cannot be included). * Willingness in maintaining a consistent hair style and hair care, including hair products, and to refrain from weaves, extensions, adhesive wigs, other than banded perimeter devices, refrain from shaving of scalp hair for 2 weeks prior to each study visit from baseline to the end of study. Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: * Participants that are currently experiencing other forms of alopecia, including but not limited to: androgenetic alopecia, trichotillomania, telogen effluvium, traction alopecia, scarring alopecia. * Participants currently with any local or systemic active medical conditions, which in the opinion of the Investigator would interfere with evaluations of the IMP effect on AA due to scalp inflammation, including but not limited to seborrheic dermatitis requiring topical treatment to the scalp, lupus erythematosus, lichen planus, psoriasis, secondary syphilis, tinea capitis, thyroiditis, systemic sclerosis, hair transplants, micropigmentation/tattoo of the scalp. * Received the specified treatment regimens within the timeframe outlined in the protocol. * Prior use of any oral JAKi or the topical JAKi ruxolitinib for more than 24 months, regardless if washout period is respected. * Participants with shaved heads must not enter the study until hair has grown back and SALT score can be reliably administered. The above information is not intended to contain all considerations relevant to a potential participation in a clinical trial