Sonelokimab in Patients With Active Psoriatic Arthritis Who Are Naive to Biologic DMARDs: Phase 2 ARGO Analysis and Phase 3 IZAR-1 Study Design

Philip J. Mease¹, Laure Gossec², Atul Deodhar³, Xenofon Baraliakos⁴, Frank Behrens⁵, Joseph F Merola⁶, Lihi Eder⁷, Ana-Maria Orbai⁸, Andreas Ramming⁹, Iain McInnes¹⁰, Alexis Ogdie¹¹, Dennis McGonagle¹², Christopher Ritchlin¹³, Nuala Brennan¹⁴, Ben Porter-Brown¹⁴, Eva Cullen¹⁴, Matthew R. Thomas¹⁴, Marius Albulescu¹⁴, Alex Godwood¹⁴, Kristian Reich¹⁵ and Laura Coates¹⁶, ¹Department of Rheumatology, Providence-Swedish Medical Center and University of Washington, Seattle, WA, ²Sorbonne Universite and Pitie-Salpetriere Hospital, Paris, France, ³Division of Arthritis and Rheumatic Diseases, Oregon Health & Science University, Portland, OR, ⁴Rheumazentrum Ruhrgebiet Herne, Ruhr-University Bochum, Herne, Germany, ⁵Rheumatology, Immunology - Inflammation Medicine, University Hospital Goethe-University & Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Frankfurt am Main, Germany, ⁶Department of Dermatology and Department of Medicine, UT Southwestern Medical Center, Dallas, TX, ⁷University of Toronto, Toronto, ON, Canada, ⁸Division of Rheumatology, Johns Hopkins University School of Medicine, Baltimore, MD, ⁹Department of Internal Medicine ³, Rheumatology & Immunology, Friedrich-Alexander-University (FAU) & Universitätsklinikum Erlangen, Erlangen, Germany, ¹⁰University of Glasgow, Glasgow, United Kingdom, ¹¹University of Pennsylvania, Philadelphia, PA, ¹²Leeds Institute of Rheumatic and Musculoskeletal Medicine (LIRMM), University of Leeds, Leeds, United Kingdom, ¹³University of Rochester Medical Center, Canandaigua, NY, ¹⁴MoonLake Immunotherapeutics AG, Zug, Switzerland, ¹⁵MoonLake Immunotherapeutics AG and Translational Research in Inflammatory Skin Diseases, Institute for Health Services Research in Dermatology and Nursing, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, Zug, Switzerland, ¹⁶Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, England, United Kingdom

Meeting: ACR Convergence 2025

Keywords: American College of Rheumatology Criteria, clinical trial, Outcome measures, Psoriatic arthritis, Randomized Trial

Session Information

Date: Monday, October 27, 2025

Title: (1434–1466) Spondyloarthritis Including Psoriatic Arthritis – Treatment Poster II

Session Type: Poster Session B

Session Time: 10:30AM-12:30PM

Background/Purpose: Sonelokimab (SLK), a novel Nanobody that binds to both IL-17A and IL-17F with similarly high affinity, is designed to target difficult-to-reach sites of inflammation due to its small size and albumin-binding domain. ARGO was a Phase 2 trial of SLK in active PsA, which met its primary endpoint of ACR50 vs. placebo at Week (W) 12 for SLK 60mg and 120mg (with induction [WI]). Here, we report W24 data in the ARGO trial from a subset of patients naive to bDMARDs (prior biologic use was a stratification factor). We also describe the design of the Phase 3 IZAR-1 trial, which will further evaluate SLK 60mg WI and SLK 60mg with no induction (NI) in this patient population.

Methods: ARGO (NCT05640245) was a 24-week, global, randomized, placebo-controlled, double-blind trial of adults with active PsA (TJC68 ≥3 and SJC66 ≥3). Three SLK doses were assessed: 60mg NI (Q4W), SLK 60mg WI, and SLK 120mg WI (induction doses at W0, 2, 4, and 6; Q4W from W8). In this exploratory analysis, we assessed outcomes at W24 in patients without prior bDMARD exposure treated with SLK 60mg with or without induction (IZAR-1 doses).

Results: Of the 207 patients enrolled in ARGO (Table), 171 patients (82.6%) were naive to bDMARDs. SLK 60mg resulted in clinical responses at W24 in patients naive to bDMARDs (SLK 60mg WI, n=34; SLK 60mg NI, n=33), including ACR50 (SLK 60mg WI: 61.8%; SLK 60mg NI: 63.6%), the higher threshold of ACR70 (SLK 60mg WI: 41.2%; SLK 60mg NI: 45.5%), and the composite endpoint of minimal disease activity ([MDA]; SLK 60mg WI: 58.8%; SLK 60mg NI: 48.5%). For patients naive to bDMARDs with skin involvement (SLK 60mg WI, n=22; SLK 60mg NI, n=28), treatment with SLK resulted in notable PASI 90 (SLK 60mg WI: 81.8%; SLK 60mg NI: 67.9%) and PASI 100 responses (SLK 60mg WI: 68.2%; SLK 60mg NI: 57.1%). SLK was well tolerated, with a safety profile consistent with IL-17 inhibition. Based on these findings, we have designed a 52-week, global, randomized, double-blind, PBO‑controlled, Phase 3 trial in this patient population (IZAR-1; NCT06641076; Figure). An estimated 960 patients will be randomized 1:1:1 to receive SLK 60mg Q4W WI, SLK 60mg Q4W NI, or PBO (SLK 60mg WI from W16). Given the results from ARGO, this sample size should provide sufficient power to demonstrate a statistically significant difference for each SLK arm vs. PBO on the primary outcome of ACR50 at W16. Eligible participants will have a confirmed diagnosis of PsA (CASPAR criteria), active disease (TJC68 ≥3; SJC66 ≥3), currently active or dermatologist-confirmed historical psoriasis, inadequate response to ≥1 conventional DMARD, and ≥1 erosion on hands-and-feet X-ray or hs-CRP > the ULN. Key secondary outcomes (all vs. PBO at W16) include ACR20, PASI 90, and MDA; the PROs HAQ-DI and SF-36 Physical Component Summary; and radiographic progression (vdH-mTSS).

Conclusion: The Phase 2 ARGO study demonstrated high levels of clinical response with SLK, including in patients with active PsA naive to bDMARDs. The randomized Phase 3 IZAR-1 study will further assess outcomes with SLK in patients naive to bDMARDs and is actively recruiting, including at sites across the USA.

Table. Baseline characteristics from the ARGO trial

Figure. Study design

Disclosures: P. Mease: AbbVie, 2, 5, 6, Acelyrin, 2, 5, Amgen, 2, 5, 6, BMS, 2, 5, Century, 2, Cullinan, 2, Eli Lilly and Company, 2, 5, 6, Inmagene, 2, J&J Innovative Medicine, 2, 5, 6, MoonLake Immunotherapeutics, 2, Novartis, 2, 5, 6, Pfizer, 2, 5, 6, Sana, 5, Spyre, 5, Takeda, 2, UCB, 2, 5, 6; L. Gossec: AbbVie, 2, 5, Amgen, 2, Biogen, 5, BMS, 2, Celltrion, 2, Eli Lilly, 2, 5, Janssen, 2, MSD, 2, Novartis, 2, 5, Pfizer, 2, UCB, 2, 5; A. Deodhar: BMS, 2, 5, Eli Lilly and Company, 2, 5, 6, J&J, 2, 5, 6, MoonLake Immunotherapeutics, 2, Novartis, 2, 5, 6, Pfizer, 2, 5, 6, UCB, 2, 5, 6; X. Baraliakos: AbbVie, 2, 5, 6, 12, Paid Instructor, Advanz, 2, 6, 12, Paid instructor, Alexion, 2, 6, 12, Paid instructor, Alphasigma, 2, 6, 12, Paid instructor, Amgen, 2, 6, 12, Paid instructor, BMS, 2, 6, 12, Paid instructor, Celgene, 6, Celltrion, 2, 5, 6, 12, Paid instructor, Cesas, 2, 6, 12, Paid instructor, Chugai, 2, 6, Clarivate, 6, 12, Paid instructor, Galapagos, 2, 6, 12, Paid instructor, J&J, 2, 6, 12, Paid instructor, Janssen, 5, Lilly, 2, 6, 12, Paid instructor, Merck, 6, MoonLake, 2, 5, 6, 12, Paid instructor, MSD, 2, Novartis, 2, 5, 6, 12, Paid instructor, Peervoice, 2, 6, 12, Paid instructor, Pfizer, 2, 6, 12, Paid instructor, Roche, 2, 6, 12, Paid instructor, Sandoz, 2, 6, 12, Paid instructor, Springer, 2, 6, 12, Paid instructor, Stada, 2, 6, 12, Paid instructor, Takeda, 2, 6, 12, Paid instructor, UCB, 2, 6, 12, Paid instructor, Zuellig, 2, 6, 12, Paid instructor; F. Behrens: AbbVie, 2, 6, 12, Support for attending meetings and/or travel, Acelyrin, 2, 6, Amgen, 2, 6, AstraZeneca, 6, Chugai Pharmaceuticals, 2, 5, 6, Cilag, 2, 6, Eli Lilly, 2, 6, GlaxoSmithKlein(GSK), 2, Janssen Pharmaceuticals, 2, 5, 6, Novartis, 2, 6, Pfizer, 2, 6, Roche, 2, 5, Sandoz, 6, UCB, 2, 6, 12, Support for attending meetings and/or travel; J. Merola: AbbVie, 2, Amgen, 2, 5, AstraZeneca, 2, 5, Biogen, 2, 5, Boehringer Ingelheim, 2, 5, Bristol Myers Squibb, 2, 5, Dermavant, 2, 5, Eli Lilly and Company, 2, 5, Incyte, 2, Janssen, 2, 5, LEO Pharma, 2, MoonLake Immunotherapeutics, 2, 5, Novartis, 2, Pfizer, 2, Sanofi-Regeneron, 2, 5, Sun Pharma, 5, UCB, 2, 5; L. Eder: AbbVie, 1, 2, 5, 6, BMS, 1, 2, Eli Lilly, 1, 2, 5, 6, Fresenius Kabi, 1, 5, J&J, 1, 2, 5, Janssen, 1, 5, Novartis, 1, 2, 5, 6, Pfizer, 1, 2, 5, UCB, 1, 2, 5; A. Orbai: AbbVie, 5, Amgen, 5, BMS, 2, Janssen, 2, 5, Sanofi, 2, UCB, 2; A. Ramming: Boehringer-Ingelheim, 2, Johnson & Johnson, 2, MoonLake Immunotherapeutics AG, 2, 5, Novartis Pharma GmbH, 2, UCB, 2; I. McInnes: AbbVie, 2, 6, AstraZeneca, 2, 6, BMS, 2, 5, 6, Boehringer Ingelheim, 2, 5, 6, Cabaletta, 2, 6, Causeway Therapeutics, 2, 6, Celgene, 2, 5, Eli Lilly and Company, 2, 6, Evelo, 2, Gilead, 5, 6, Janssen, 2, 5, 6, MoonLake Immunotherapeutics, 2, 6, Novartis, 2, 5, 6, Pfizer, 5, 6, Sanofi/Regeneron, 5, 6, UCB, 2, 5, 6; A. Ogdie: AbbVie, 2, 5, Amgen, 2, 5, 11, Bristol Myers Squibb, 2, 5, Celgene, 2, 5, CorEvitas, LLC, 2, 5, Eli Lilly, 2, 5, Forward Databank, 5, Gilead, 1, 2, Janssen, 2, 5, Kopa/Twill Health, 2, NIH/NIAMS, National Psoriasis Foundation, 5, Novartis, 2, 5, 11, Pfizer, 2, 5, 11, Rheumatology Research Foundation, 5, Spyre, 2, Takeda, 2, UCB, 2, 5, University of Pennsylvania, 5; D. McGonagle: AbbVie, 2, 5, 6, Celgene, 2, 5, 6, Janssen, 2, 5, 6, Merck, 2, 5, 6, MoonLake Immunotherapeutics AG, 2, 5, 6, Novartis, 2, 5, 6, Pfizer, 2, 5, 6, Sobi, 2, 5, 6, UCB, 2, 6; C. Ritchlin: AbbVie, 2, Amgen, 2, Bristol-Myers Squibb(BMS), 2, Eli Lilly, 2, Janssen, 2, 5, MoonLake Pharma, 2, Novartis, 2, 5, Solara, 2, UCB, 2; N. Brennan: MoonLake Immunotherapeutics AG, 3, 11; B. Porter-Brown: MoonLake Immunotherapetics, 3, 11, Sanofi, 3, 11; E. Cullen: MoonLake Immunotherapeutics AG, 3, 11; M. Thomas: MoonLake Immunotherapeutics AG, 3, 11; M. Albulescu: MoonLake Immunotherapeutics, 3, 11; A. Godwood: MoonLake Immunotherapeutics, 3, 11; K. Reich: AbbVie, 1, 6, 12, Participated in clinical trials, Almirall, 1, 6, 12, Participated in clinical trials, Amgen, 1, 6, 12, Participated in clinical trials, Boehringer Ingelheim, 1, 6, 12, Participated in clinical trials, Bristol-Myers Squibb(BMS), 1, 6, 12, Participated in clinical trials, Eli Lilly, 1, 6, 12, Participated in clinical trials, Galderma, 1, 6, 12, Participated in clinical trials, Janssen-Cilag, 1, 6, 12, Participated in clinical trials, Kyowa Kirin, 1, 6, 12, Participated in clinical trials, LEO Pharma, 1, 6, 12, Participated in clinical trials, Medac, 1, 6, 12, participated in clinical trials, MoonLake Immunotherapeutics AG, 3, 11, Novartis, 1, 6, 12, participated in clinical trials, Ocean Pharma, 1, 6, 12, participated in clinical trials, Pfizer, 1, 6, 12, participated in clinical trials, Sanofi, 1, 6, 12, participated in clinical trials, UCB, 1, 6, 12, participated in clinical trials; L. Coates: AbbVie, 2, 5, 6, Amgen, 2, 5, 6, Biogen, 6, BMS, 2, Boehringer Ingelheim, 2, Celgene, 2, 5, 6, Domain, 2, Eli Lilly and Company, 2, 5, 6, Galapagos, 2, 6, Gilead, 2, 5, 6, GSK, 6, Janssen, 2, 5, 6, Medac, 6, MoonLake Immunotherapeutics, 2, Novartis, 2, 5, 6, Pfizer, 2, 5, 6, UCB, 2, 5, 6.

To cite this abstract in AMA style:

Mease P, Gossec L, Deodhar A, Baraliakos X, Behrens F, Merola J, Eder L, Orbai A, Ramming A, McInnes I, Ogdie A, McGonagle D, Ritchlin C, Brennan N, Porter-Brown B, Cullen E, Thomas M, Albulescu M, Godwood A, Reich K, Coates L. Sonelokimab in Patients With Active Psoriatic Arthritis Who Are Naive to Biologic DMARDs: Phase 2 ARGO Analysis and Phase 3 IZAR-1 Study Design [abstract]. Arthritis Rheumatol. 2025; 77 (suppl 9). https://acrabstracts.org/abstract/sonelokimab-in-patients-with-active-psoriatic-arthritis-who-are-naive-to-biologic-dmards-phase-2-argo-analysis-and-phase-3-izar-1-study-design/. Accessed .

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