Dr. Warren reports receiving grant support and consulting fees from AbbVie, Almirall, Bristol-Myers Squibb, Eli Lilly, Janssen, LEO Pharma, Novartis, and UCB Pharma, consulting fees from Amgen, Arena Pharmaceuticals, Avillion, Boehringer Ingelheim, Celgene, Pfizer, Sanofi, Astellas, GlaxoSmithKline, Biogen, DiCE Molecules, Sun Pharma, and Union Therapeutics, and grant support from Medac; Dr. Blauvelt, receiving research funding and consulting fees from AbbVie, Amgen, Arcutis Biotherapeutics, Athenex, Boehringer Ingelheim, Bristol-Myers Squibb, Dermavant Sciences, Eli Lilly, Evommune, Incyte, Janssen, LEO Pharma, Novartis, Pfizer, Regeneron Pharmaceuticals, Sun Pharma, and UCB Pharma and consulting fees from Aligos Therapeutics, Almirall, Arena Pharmaceuticals, Forte Biosciences, Galderma, Rapt Therapeutics, and Sanofi Genzyme; Dr. Bagel, receiving grant support from Arcutis Biotherapeutics, Boehringer Ingelheim, Corrona, Dermavant Sciences, Dermira, Glenmark Pharmaceuticals, Kadmon, LEO Pharma, Lycera, Menlo Therapeutics, Pfizer, Regeneron Pharmaceuticals, Taro Pharmaceutical Industries, and Ortho Dermatologics, grant support, consulting fees, and lecture fees from AbbVie, Celgene, Eli Lilly, Janssen Biotech, and Novartis, and grant support and consulting fees from Amgen, Bristol-Myers Squibb, Sun Pharmaceutical Industries, and UCB Pharma; Dr. Papp, receiving grant support, consulting fees, fees for serving on a speakers bureau, steering committee fees, and advisory board fees, all paid to his institution, and honoraria from AbbVie, Amgen, Celgene, Eli Lilly, Janssen, Merck (Merck Sharp & Dohme), Novartis, Pfizer, Sanofi Genzyme, and Bausch Health, grant support and consulting fees, all paid to his institution, and honoraria from Akros Pharma, Coherus BioSciences, Mitsubishi Pharma, Takeda, and PRCL Research, grant support, paid to his institution, from Anacor Pharmaceuticals, GlaxoSmithKline, MedImmune, Gilead Sciences, and Moberg Pharma, grant support and consulting fees, all paid to his institution, from Arcutis Biotherapeutics, Baxalta, Can-Fite BioPharma, Dermira, Genentech, Meiji Seika Pharma, Roche, Evelo Biosciences, Galapagos, Avillion, and DiCE Molecules, grant support, consulting fees, fees for serving on a speakers bureau, and advisory board fees from Astellas, grant support, consulting fees, steering committee fees, and advisory board fees, all paid to his institution, and honoraria from Boehringer Ingelheim and Regeneron Pharmaceuticals, grant support, consulting fees, and advisory board fees, all paid to his institution, from Bristol-Myers Squibb, Dow Pharma, and Dermavant Sciences, grant support, consulting fees, fees for serving on a speakers bureau, and advisory board fees, all paid to his institution, and honoraria from Galderma, grant support, consulting fees, fees for serving on a speakers bureau, and advisory board fees, all paid to his institution, and honoraria from Kyowa Hakko Kirin, grant support, consulting fees, and fees for serving on a speakers bureau, all paid to his institution, from LEO Pharma and Incyte, grant support, consulting fees, and steering committee fees, all paid to his institution, and honoraria from Merck Serono, grant support, consulting fees, and advisory board fees, all paid to his institution, and honoraria from UCB Pharma, and grant support and advisory board fees, all paid to his institution, from Sun Pharma; Dr. Yamauchi, receiving lecture fees, consulting fees, and investigator fees from AbbVie, Amgen, Eli Lilly, Janssen, Novartis, Ortho Dermatologics, Sun Pharma, and UCB Pharma; Dr. Armstrong, receiving grant support, advisory fees, and lecture fees from AbbVie and Regeneron Pharmaceuticals, grant support and advisory fees from Bristol-Myers Squibb, Dermavant Sciences, Dermira, Eli Lilly, LEO Pharma, Novartis, and UCB Pharma, advisory fees from Janssen, Modernizing Medicine, Ortho Dermatologics, Sanofi Genzyme, Sun Pharma, and Pfizer, grant support from Kyowa Kirin and Galderma, and fees for serving on a data and safety monitoring board from Boehringer Ingelheim and Parexel; Dr. Langley, receiving grant support, advisory board fees, investigator fees, and lecture fees from AbbVie, Amgen, Centocor, Eli Lilly, Janssen, LEO Pharma, Novartis, UCB Pharma, and Celgene and grant support, advisory board fees, and investigator fees from Boehringer Ingelheim, Bristol-Myers Squibb, Pfizer, and Merck; Ms. Vanvoorden, Drs. De Cuyper and Cioffi, Mr. Peterson, and Dr. Cross, being employed by and owning shares in UCB Pharma; and Dr. Reich, receiving grant support, consulting fees, and lecture fees from AbbVie, Almirall, Biogen Idec, Celgene, Eli Lilly, Janssen-Cilag, LEO Pharma, Medac, Merck Sharp & Dohme, Novartis, and Sanofi, grant support and consulting fees from Affibody, Boehringer Ingelheim, Covagen, Forward Pharma, Galderma, Kyowa Kirin, Ocean Pharma, Pfizer, Sun Pharma, Takeda, UCB Pharma, and Bristol-Myers Squibb, consulting fees from Amgen, GlaxoSmithKline, Samsung Bioepis, and XenoPort, lecture fees from Valeant Pharmaceuticals and Sandoz, and grant support from Fresenius Medical Care, Galapagos, Miltenyi Biotec, and XBiotech. No other potential conflict of interest relevant to this article was reported.

This article was published on April 23, 2021, at NEJM.org.

A data sharing statement provided by the authors is available with the full text of this article at NEJM.org.

We thank the patients and their caregivers in addition to all the investigators and their teams who contributed to this trial; Susanne Wiegratz, M.Sc., of UCB Pharma (Monheim, Germany) for publication coordination; Natalie Nunez Gomez, M.D., of UCB Pharma (Brussels) for critical review; and Ruth Moulson, M.P.H., of Costello Medical (London) for medical writing and editorial assistance with an earlier version of the manuscript, in accordance with Good Publication Practice 3 guidelines (http://www.ismpp.org/gpp3).