Background: The IL-17A inhibitor secukinumab has demonstrated consistent efficacy and safety in patients with moderate-to-severe plaque psoriasis, with normalization of molecular and histopathologic psoriasis markers., Objective: To investigate treatment effects of secukinumab on clinical signs and psoriatic inflammation markers over 52 weeks in patients with psoriasis., Methods: In the ObePso-S study (NCT03055494), patients with psoriasis were randomized 2:1 to receive secukinumab 300 mg (n = 54) or placebo (n = 28), stratified by body weight (<90 or ≥90 kg), for 52 weeks. At Week 12, patients receiving placebo were switched to secukinumab. Psoriasis Area and Severity Index improvement of 90% (PASI90) and Investigator's Global Assessment modified 2011 0/1 responses were assessed at Weeks 12 and 52. Immunohistochemistry for keratin 16 (K16) and gene expression profiles were evaluated in lesional and non-lesional skin biopsies collected at baseline, Week 12, and Week 52., Results: Of patients receiving secukinumab, 55.8% and 59.6% achieved PASI90 at Weeks 12 and 52, respectively. K16 was absent in 93.1% of Week 12 PASI90 responders and 93.6% of Week 52 PASI90 responders, which mirrored the down-regulated expression of psoriatic inflammation. Week 52 PASI90 non-responders experienced regression of clinical and inflammatory marker responses toward baseline levels. Lower control of inflammatory gene expression at Week 12 was associated with suboptimal clinical responses at Week 52., Conclusion: Sustained clinical responses with secukinumab were associated with rapid and sustained normalization of K16 and inflammatory gene expression in most patients. Molecular anti-inflammatory effects of secukinumab at Week 12 were associated with clinical responses at Week 52., Competing Interests: Conflicts of interest A. Blauvelt has served as a speaker/received honoraria from AbbVie and UCB; has served as a scientific advisor/received honoraria from AbbVie, Abcentra, Affibody, Aligos, Almirall, Alumis, Amgen, AnaptysBio, Arcutis, Arena, ASLAN, Athenex, Boehringer Ingelheim, Bristol Myers Squibb, Cara Therapeutics, Dermavant, EcoR1, Eli Lilly, Evelo, Evommune, Forte, Galderma, HighlightII Pharma, Incyte, Janssen, Landos, LEO Pharma, Merck, Novartis, Pfizer, Rapt, Regeneron, Sanofi Genzyme, Spherix Global Insights, Sun Pharma, TLL Pharmaceutical, TrialSpark, UCB, Vibliome, and Xencor; and has acted as a clinical study investigator/his institution has received clinical study funds from AbbVie, Acelyrin, Amgen, Arcutis, Athenex, Boehringer Ingelheim, Bristol Myers Squibb, Dermavant, Eli Lilly, Evelo, Galderma, Incyte, Janssen, LEO Pharma, Merck, Novartis, Pfizer, Regeneron, Sun Pharma, and UCB. D.M. Pariser has served as a consultant for and received honoraria from Abbott, Amgen, Astellas, Bausch Health, Bickel Biotechnology, Celgene, Dermira, DUSA, LEO Pharma, MELA Sciences, Novartis, and Procter & Gamble; has participated in advisory boards and received honoraria from Galderma, Genentech, Janssen Ortho, Medicis, Ortho Dermatologics, Pfizer, and Stiefel; and has served as an investigator for and received research grants from Abbott, Amgen, Astellas, Asubio, Basliea, Bausch Health, Celgene, Dow Pharmaceutical Sciences, Eli Lilly, Galderma, Graceway, Intendis, Johnson & Johnson, LEO Pharma, Novartis, Novo Nordisk, Ortho Dermatologics, Peplin, Pfizer, Photocure ASA, and Stiefel. S. Tyring has served as an investigator for Novartis. J. Bagel has served as an investigator, consultant, and/or speaker for AbbVie, Amgen, Bausch Health, Boehringer Ingelheim, Celgene, Eli Lilly, Janssen, LEO Pharma, Novartis, and Sun Pharma. A.F. Alexis has received grants or research support from AbbVie, Almirall, Amgen, Arcutis, ASLAN, Bristol Myers Squibb, Cara Therapeutics, Castle, Dermavant, Galderma, LEO Pharma, Novartis, Valeant (Bausch Health), and Vyne; has served as a consultant or on advisory boards for AbbVie, Allergan, Almirall, Amgen, Arcutis, Bausch Health, Beiersdorf, Bristol Myers Squibb, Cara Therapeutics, Cutera, Dermavant, Eli Lilly, EPI, Galderma, Janssen, LEO Pharma, L′Oréal, Novartis, Pfizer, Sanofi-Regeneron, Sol-Gel, Swiss American, UCB, Valeant (Bausch Health), VisualDx, and Vyne; and has served as a speaker for Bristol Myers Squibb, Pfizer, Regeneron, and Sanofi-Genzyme. J. Soung has received speaker honoraria from AbbVie, Actelion, Amgen, Celgene, Dermira, Eli Lilly, National Psoriasis Foundation, Novartis, Ortho Dermatologics, and Regeneron; has received consulting/advisory board honoraria from Eli Lilly, LEO Pharma, and Novartis; and has received grant/research grant funding from AbbVie, Actavis, Actelion, Allergan, Boehringer Ingelheim, Cassiopea, Dr Reddy’s, Galderma, GSK, Janssen, Kadmon, Kyowa Kirin, LEO Pharma, Menlo, Novan, Novartis, Ortho Dermatologics, Pfizer, and UCB. A.W. Armstrong has served as research investigator and/or scientific advisor to AbbVie, ASLAN, Boehringer Ingelheim, Bristol Myers Squibb, Dermavant, Dermira, Eli Lilly, EPI, Incyte, Janssen, LEO Pharma, Modmed, Novartis, Ortho Dermatologics, Pfizer, Regeneron, Sanofi, Sun Pharma, and UCB. E. Muscianisi, F. Kianifard, R. Prasad Sarkar, and J. Steadman are employees and stockholders of Novartis. S. Garcet has nothing to disclose. J.G. Krueger has received grants paid to The Rockefeller University from Amgen, Boehringer Ingelheim, Bristol Myers Squibb, Dermira, Eli Lilly, Innovaderm, Janssen, Kadmon, Kineta, Kyowa, LEO Pharma, Novartis, Paraxel, Pfizer, Provectus, Regeneron, and Vitae; and has received personal fees from AbbVie, Baxter, Biogen Idec, Boehringer Ingelheim, Bristol Myers Squibb, Delenex, Dermira, Eli Lilly, Janssen, Kadmon, Kineta, Merck, Novartis, Pfizer, Sanofi, EMD Serono, and XenoPort., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)