argenx Advances Clinical Development of ARGX-119 in Congenital Myasthenic Syndromes
argenx SE (Nasdaq: ARGX) announced plans to advance ARGX-119, their first-in-class agonist antibody targeting muscle-specific kinase (MuSK), to a registrational study for congenital myasthenic syndromes (CMS) following positive Phase 1b results.
The Phase 1b multicenter, randomized, double-blinded, placebo-controlled trial demonstrated a favorable safety and tolerability profile for ARGX-119. The study showed consistent improvements in DOK7-CMS patients across multiple efficacy measures throughout the 12-week study period, including Six-Minute Walk Test, Quantitative Myasthenia Gravis score, and Myasthenia Gravis Activities of Daily Living score.
The trial design included a 4:1 randomization to ARGX-119 or placebo, with an 11-month duration comprising screening, treatment, and follow-up periods. ARGX-119 represents the sixth successful molecule developed through argenx's Immunology Innovation Program (IIP), validating their collaborative discovery model.
argenx SE (Nasdaq: ARGX) ha annunciato l'intenzione di avanzare con ARGX-119, il loro anticorpo agonista di prima classe che mira alla chinasi muscolo-specifica (MuSK), verso uno studio registrativo per le sindromi miasteniche congenite (CMS) dopo i risultati positivi della Fase 1b.
Lo studio di Fase 1b, multicentrico, randomizzato, in doppio cieco e controllato con placebo, ha dimostrato un profilo di sicurezza e tollerabilità favorevole per ARGX-119. La ricerca ha evidenziato miglioramenti costanti nei pazienti con DOK7-CMS su molteplici parametri di efficacia durante le 12 settimane dello studio, inclusi il Test del Cammino di Sei Minuti, il punteggio Quantitativo della Miastenia Gravis e il punteggio delle Attività Quotidiane della Miastenia Gravis.
Il disegno dello studio prevedeva una randomizzazione 4:1 tra ARGX-119 e placebo, con una durata complessiva di 11 mesi comprendente screening, trattamento e follow-up. ARGX-119 rappresenta la sesta molecola di successo sviluppata tramite il Programma di Innovazione Immunologica (IIP) di argenx, confermando il valore del loro modello collaborativo di scoperta.
argenx SE (Nasdaq: ARGX) anunció sus planes para avanzar con ARGX-119, su anticuerpo agonista de primera clase dirigido a la quinasa específica del músculo (MuSK), hacia un estudio registracional para los síndromes miasténicos congénitos (CMS) tras resultados positivos en la Fase 1b.
El ensayo multicéntrico, aleatorizado, doble ciego y controlado con placebo de Fase 1b demostró un perfil favorable de seguridad y tolerabilidad para ARGX-119. El estudio mostró mejoras consistentes en pacientes con DOK7-CMS en múltiples medidas de eficacia durante las 12 semanas del estudio, incluyendo la prueba de caminata de seis minutos, la puntuación cuantitativa de miastenia gravis y la puntuación de actividades diarias de miastenia gravis.
El diseño del ensayo incluyó una aleatorización 4:1 a ARGX-119 o placebo, con una duración de 11 meses que abarcó los periodos de selección, tratamiento y seguimiento. ARGX-119 representa la sexta molécula exitosa desarrollada a través del Programa de Innovación en Inmunología (IIP) de argenx, validando su modelo colaborativo de descubrimiento.
argenx SE (나스닥: ARGX)는 근육 특이 키나제(MuSK)를 표적으로 하는 최초의 작용제 항체인 ARGX-119를 선천성 중증근무력증(CMS) 등록 연구로 진행할 계획을 발표했습니다. 이는 1b상 긍정적 결과에 따른 것입니다.
1b상 다기관, 무작위배정, 이중맹검, 위약대조 시험에서 ARGX-119는 우수한 안전성 및 내약성 프로파일을 보였습니다. 연구 기간 12주 동안 6분 걷기 검사, 정량적 중증근무력증 점수, 중증근무력증 일상활동 점수를 포함한 여러 효능 지표에서 DOK7-CMS 환자들의 지속적인 개선이 관찰되었습니다.
시험 설계는 ARGX-119와 위약을 4:1 비율로 무작위 배정했으며, 선별, 치료 및 추적 관찰 기간을 포함해 총 11개월 동안 진행되었습니다. ARGX-119는 argenx의 면역학 혁신 프로그램(IIP)을 통해 개발된 여섯 번째 성공적인 분자로, 협력적 발견 모델의 타당성을 입증합니다.
argenx SE (Nasdaq : ARGX) a annoncé son intention de faire progresser ARGX-119, leur premier anticorps agoniste ciblant la kinase spécifique au muscle (MuSK), vers une étude d’enregistrement pour les syndromes myasthéniques congénitaux (CMS) suite à des résultats positifs de la phase 1b.
L’essai multicentrique, randomisé, en double aveugle et contrôlé par placebo de phase 1b a démontré un profil de sécurité et de tolérance favorable pour ARGX-119. L’étude a montré des améliorations constantes chez les patients DOK7-CMS sur plusieurs critères d’efficacité tout au long de la période de 12 semaines, incluant le test de marche de six minutes, le score quantitatif de la myasthénie grave et le score des activités de la vie quotidienne liées à la myasthénie grave.
Le protocole de l’essai comprenait une randomisation 4:1 entre ARGX-119 et placebo, avec une durée totale de 11 mois incluant les phases de sélection, traitement et suivi. ARGX-119 représente la sixième molécule réussie développée via le Programme d’Innovation en Immunologie (IIP) d’argenx, validant leur modèle collaboratif de découverte.
argenx SE (Nasdaq: ARGX) gab Pläne bekannt, ARGX-119, ihren erstklassigen Agonisten-Antikörper, der auf muskelspezifische Kinase (MuSK) abzielt, nach positiven Ergebnissen der Phase 1b in eine Zulassungsstudie für kongenitale myasthene Syndrome (CMS) zu überführen.
Die multizentrische, randomisierte, doppelblinde, placebokontrollierte Phase-1b-Studie zeigte ein günstiges Sicherheits- und Verträglichkeitsprofil für ARGX-119. Die Studie belegte konsequente Verbesserungen bei DOK7-CMS-Patienten über mehrere Wirksamkeitsparameter während des 12-wöchigen Studienzeitraums, darunter der Sechs-Minuten-Gehtest, der Quantitative Myasthenia Gravis-Score und der Myasthenia Gravis Alltagsaktivitäten-Score.
Das Studiendesign sah eine 4:1-Randomisierung zu ARGX-119 oder Placebo vor, mit einer Gesamtdauer von 11 Monaten, einschließlich Screening, Behandlung und Nachbeobachtung. ARGX-119 stellt das sechste erfolgreiche Molekül dar, das im Rahmen des Immunologie-Innovationsprogramms (IIP) von argenx entwickelt wurde und bestätigt das kooperative Entdeckungsmodell.
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Insights
argenx's ARGX-119 shows promising Phase 1b results in rare CMS, advancing to registrational studies with favorable safety and efficacy signals.
The advancement of ARGX-119 to a registrational study represents a significant milestone in argenx's rare disease pipeline. This first-in-class MuSK agonist antibody demonstrated both a favorable safety profile and consistent functional improvements across multiple efficacy measures in patients with DOK7 congenital myasthenic syndromes (CMS), an ultra-rare disorder affecting patients from birth.
What's particularly notable is the comprehensive efficacy assessment conducted across multiple clinically relevant endpoints including the Six-Minute Walk Test, Quantitative Myasthenia Gravis score, and Myasthenia Gravis Activities of Daily Living score. The consistent improvements observed across these measures strengthen the evidence for ARGX-119's therapeutic potential in this underserved patient population.
This development also validates argenx's Immunology Innovation Program (IIP), their collaborative discovery model, as ARGX-119 becomes the sixth molecule from this platform to demonstrate proof-of-concept. This success rate underscores the company's expertise in antibody engineering and deep understanding of immunological pathways.
The company's strategic approach is further evidenced by their initiation of an observational natural history study in 2024, which has enrolled almost all Phase 1b participants. This parallel effort demonstrates argenx's commitment to thoroughly understanding the patient journey and disease burden in this rare condition, which should inform and strengthen their development pathway toward potential regulatory approval.
For a rare disease with limited treatment options, advancing to a registrational study based on promising Phase 1b data represents meaningful progress toward addressing a significant unmet medical need.
Phase 1b study supports proof-of-concept in DOK7 congenital myasthenic syndromes
Decision informed by favorable safety profile and consistent functional improvement over time across multiple efficacy measures
Advancing ARGX-119 further validates strong track record of Immunology Innovation Program (IIP), argenx's collaborative discovery model
June 30, 2025, 7:00 AM CET
Amsterdam, the Netherlands – argenx SE (Euronext & Nasdaq: ARGX), a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases, today announced its plan to advance the clinical development of ARGX-119, a first-in-class agonist antibody to muscle-specific kinase (MuSK), to a registrational study in patients with congenital myasthenic syndromes (CMS) following the analysis of topline data from the Phase 1b study. Detailed results will be presented at a future medical meeting.
“The results of our Phase 1b ARGX-119 study in congenital myasthenic syndromes, an ultra-rare disorder that affects patients from birth, builds on our experience and understanding of myasthenic disorders and aligns with our aspiration to serve even more patients living with these debilitating diseases,” said Luc Truyen, M.D., Ph.D., Chief Medical Officer of argenx.
“ARGX-119 is the sixth molecule developed through our Immunology Innovation Program to show proof-of-concept, reflecting the strength of our innovation model where our deep knowledge of the biology and expertise in antibody engineering come together to push the boundaries of what’s possible. argenx remains focused on uncovering new biological insights into misunderstood diseases to meaningfully change the lives of patients who have long-been underserved,” said Peter Ulrichts, Ph.D., Chief Scientific Officer of argenx.
The decision to advance the development of ARGX-119 in CMS is supported by the results of the Phase 1b study. ARGX-119 demonstrated a favorable safety and tolerability profile, which was the primary endpoint. Efficacy was evaluated across multiple secondary and exploratory endpoints, including Six-Minute Walk Test (6MWT), Quantitative Myasthenia Gravis (QMG) score and Myasthenia Gravis Activities of Daily Living (MG-ADL) score. Consistent improvements were observed in treated DOK7-CMS patients through the 12-week study across multiple efficacy scores.
Phase 1b CMS Study Design
The Phase 1b, multicenter, randomized, double-blinded, placebo-controlled clinical trial assessed safety, tolerability, PK, immunogenicity, and preliminary efficacy of ARGX-119 in participants with DOK7-CMS. The study was also designed to demonstrate proof-of-biology through preliminary efficacy assessments, including muscle weakness, fatigability, daily activities and patient-reported global health outcomes. The clinical trial spanned approximately 11 months across a screening period (up to 28 days), a 12-week treatment period and a follow-up period of nearly seven months. At baseline, eligible participants were randomized 4:1 to receive intravenous ARGX-119 or placebo. The primary objective was to evaluate safety and tolerability; secondary objectives included PK, immunogenicity and preliminary efficacy of ARGX-119 in participants with DOK7-CMS. All but one of the patients enrolled in the Phase 1b study also participated in an observational natural history study initiated by argenx in 2024 to better understand the CMS patient journey and disease burden, helping to inform future development plans.
About Congenital Myasthenic Syndromes
Congenital Myasthenic Syndromes (CMS) are an ultra-rare and heterogenous group of congenital neuromuscular disorders caused by genetic defects that are essential for the integrity of the neuromuscular junction. Early age of onset and fatigable muscle weakness are considered clinical hallmarks of CMS. Muscle weakness can be debilitating and life-threatening causing difficulties in speaking or swallowing, impaired or absent mobility, proximal arm and leg weakness, and respiratory insufficiency. DOK7 variations are one of the more frequent and severe causes of CMS, accounting for approximately
About ARGX-119
ARGX-119 is a first-in-class humanized agonist monoclonal antibody (mAb) that specifically targets and activates muscle-specific tyrosine kinase (MuSK) to promote maturation and stabilization of the neuromuscular junction (NMJ). It is a mAb derived from llamas and discovered using the argenx SIMPLE Antibody™ platform technology. ARGX-119 is being developed for patients with neuromuscular disease, including congenital myasthenic syndromes (CMS), amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). ARGX-119 was developed through argenx’s IIP program in collaboration with the world’s leading key opinion leaders on MuSK and the NMJ, Professor Steven J. Burden from MGH, Professor Shohei Koide from NYU and Professor Jan Verschuuren and Associate Professor Maartje Huijbers from LUMC.
About argenx
argenx is a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases. Partnering with leading academic researchers through its Immunology Innovation Program (IIP), argenx aims to translate immunology breakthroughs into a world-class portfolio of novel antibody-based medicines. argenx developed and is commercializing the first approved neonatal Fc receptor (FcRn) blocker and is evaluating its broad potential in multiple serious autoimmune diseases while advancing several earlier stage experimental medicines within its therapeutic franchises. For more information, visit www.argenx.com and follow us on LinkedIn, Instagram, Facebook, and YouTube.
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Forward Looking Statements
The contents of this announcement include statements that are, or may be deemed to be, “forward looking statements.” These forward-looking statements can be identified by the use of forward-looking terminology, including the terms “aims,” “committed,” or “plan” and include statements argenx makes concerning its commitment to improving the lives of people suffering from severe autoimmune diseases; its plan to advance the clinical development of ARGX-119 to a registrational study in CMS patients; and its goal of translating immunology breakthroughs into a world-class portfolio of novel antibody-based medicines. By their nature, forward-looking statements involve risks and uncertainties and readers are cautioned that any such forward-looking statements are not guarantees of future performance. argenx’s actual results may differ materially from those predicted by the forward-looking statements as a result of various important factors, including but not limited to, the results of argenx’s clinical trials; expectations regarding the inherent uncertainties associated with the development of novel drug therapies; preclinical and clinical trial and product development activities and regulatory approval requirements; the acceptance of its products and product candidates by its patients as safe, effective and cost-effective; the impact of governmental laws and regulations, including tariffs, export controls, sanctions and other regulations on its business; its reliance on third-party suppliers, service providers and manufacturers; inflation and deflation and the corresponding fluctuations in interest rates; and regional instability and conflicts. A further list and description of these risks, uncertainties and other risks can be found in argenx’s U.S. Securities and Exchange Commission (SEC) filings and reports, including in argenx’s most recent annual report on Form 20-F filed with the SEC as well as subsequent filings and reports filed by argenx with the SEC. Given these uncertainties, the reader is advised not to place any undue reliance on such forward-looking statements. These forward-looking statements speak only as of the date of publication of this document. argenx undertakes no obligation to publicly update or revise the information in this press release, including any forward-looking statements, except as may be required by law.
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