∙ 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 the jurisdiction in which the study is taking place at the time of signing the informed consent.

• Participants with moderate-to-severe LSC, as defined by Investigator's Global Assessment (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, participants must have an average worst-itch of LSC score of ≥7 in the 7 days prior to Day 1. A minimum of 4 daily scores out of the 7 days is required to calculate the baseline average score. For participants who do not have at least 4 daily scores reported during the 7 days immediately preceding the planned randomization date, randomization can be postponed until this requirement is met, but without exceeding the 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 the last 6 months, unless TCS/TCI are medically not advisable. Patients with documented systemic treatment for LSC (other than antihistamines) in the past 6 months are also considered as inadequate responders to topical treatments and are potentially eligible for treatment with dupilumab after appropriate washout.

• Appropriate contraceptive measures