A Study to Investigate Improvement in Pruritus of Lichen Simplex Chronicus With Dupilumab Injections Compared With Placebo in Male and Female Participants Aged at Least 18 Years (STYLE 1)

Inclusion Criteria:

Participants are eligible to be included in the study only if all of the following criteria apply (at screening and baseline unless otherwise specified):

• Participant must be at least 18 years of age or the legal age of consent in thejurisdiction in which the study is taking place at the time of signing the informedconsent.

• Participants with moderate-to-severe LSC, as defined by Investigator's GlobalAssessment (IGA) score ≥3 and one or more of the following:

• at least 1 single anogenital lesion;

• at least 2 lesions including 1 lesion of ≥3 cm in diameter;

• at least 1 severe lesion (IGA score = 4).

• History of LSC for at least 6 months prior to the screening visit.

• On the Worst-Itch Numerical Rating Scale (WI-NRS) ranging from 0 to 10, participantsmust have an average worst-itch of LSC score of ≥7 in the 7 days prior to Day 1. Aminimum of 4 daily scores out of the 7 days is required to calculate the baselineaverage score. For participants who do not have at least 4 daily scores reportedduring the 7 days immediately preceding the planned randomization date,randomization can be postponed until this requirement is met, but without exceedingthe 28-day maximum duration of the screening period.

• History of failing a 2-week course of medium-to-superpotent topical corticosteroid (TCS) +/- topical calcineurin inhibitor (TCI) for the treatment of LSC within thelast 6 months, unless TCS/TCI are medically not advisable. Patients with documentedsystemic treatment for LSC (other than antihistamines) in the past 6 months are alsoconsidered as inadequate responders to topical treatments and are potentiallyeligible for treatment with dupilumab after appropriate washout.

• Appropriate contraceptive measures

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply (at screening and baseline unless otherwise specified):

• Participants diagnosed with active lesions of prurigo nodularis (broadly distributednodules) or active lesions of atopic dermatitis (AD) within 6 months, contactdermatitis, psoriasis, cutaneous T-cell lymphoma (CTCL) XE "CTCL" \f Abbreviation \t "cutaneous T-cell lymphoma" (or suspected of CTCL), vulvar lichen planus, or vulvarlichen sclerosus.

• Presence of skin morbidities other than LSC that, in the opinion of theInvestigator, may interfere with the assessment of the study outcomes. For example:scabies, insect bite, folliculitis, lymphomatoid papulosis, chronic actinicdermatitis, dermatitis herpetiformis, sporotrichosis, bullous disease, lichen planushypertrophicus.

• Severe concomitant illness(es) that, in the Investigator's judgment, would adverselyaffect the participant's participation in the study.

• Severe psychiatric disease that, in the Investigator's judgement, would affect thestudy intervention evaluation.

• Having received or planning to use any of the treatments within the timeframe asspecified in the protocol.

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