Immunology company argenx SE (Euronext Brussels:ARGX) (Nasdaq:ARGX) on Monday announced plans to advance ARGX-119, a first-in-class agonist antibody targeting muscle-specific kinase (MuSK), to a registrational study in patients with congenital myasthenic syndromes (CMS).

This decision follows topline data from a Phase 1b study showing a favourable safety profile and consistent functional improvements in DOK7-CMS patients across several efficacy endpoints.

Measured improvements included results from the Six-Minute Walk Test, Quantitative Myasthenia Gravis score, and Myasthenia Gravis Activities of Daily Living score over a 12-week period.

ARGX-119 becomes the sixth molecule from the company's Immunology Innovation Program to demonstrate proof-of-concept.

CMS is an ultra-rare neuromuscular disorder with no approved treatments. DOK7 mutations account for approximately 24% of cases, with an estimated prevalence of 1.2 per 1 million.

ARGX-119 is designed to activate MuSK to enhance neuromuscular junction function and is also in development for other neuromuscular diseases, including amyotrophic lateral sclerosis and spinal muscular atrophy.

The antibody was discovered using argenx's SIMPLE Antibody platform.

Detailed results from the Phase 1b study will be presented at an upcoming medical meeting.