ARTHEx Biotech Publishes First Demonstration of Improvement in a DM1-related Behavioral Alteration in a Preclinical Model of Myotonic Dystrophy Type 1 (DM1)

New data show systemic delivery of antimiR-23b developed on ARTHEx BOOST-ON™ platform reaches the brain, corrects disease biology, and improves behavior—highlighting potential to address CNS manifestations of DM1

VALENCIA, Spain, July 23, 2026 /PRNewswire/ -- Arthex Biotech, a clinical-stage biotechnology company advancing RNA-based therapeutics for neuromuscular disorders, today announced the publication of new preclinical data demonstrating central nervous system (CNS) activity of its investigational antimiR-23b therapy, ATX-01, in Myotonic Dystrophy Type 1 (DM1).  ATX-01 is ARTHEx's investigational RNA therapeutic designed to address the underlying genetic cause of DM1, a highly disabling neuromuscular disorder with no known cure or approved treatment. 

The study, titled "Fatty-acid–based antimiR-23b delivery in the DMSXL model: a potential therapeutic strategy for brain dysfunction in Myotonic Dystrophy Type 1," provides the first known scientific evidence linking molecular correction in the brain with functional behavioral improvements in a DM1 animal model, representing a significant advancement for the field. The study was published in Cell Reports Medicine, a Cell Press journal, and can be accessed here.

DM1 is a multisystemic neurological disorder affecting not only muscle but also the brain, where patients experience cognitive impairment, behavioral changes, and reduced quality of life. Despite this, most therapeutic approaches have historically been unable to effectively reach the central nervous system (CNS).

"This research represents a major step forward for the DM1 field," said Beatriz Llamusí, Ph.D., Co-founder and Chief Scientific Officer of ARTHEx Biotech. "For the first time, we are seeing a clear connection between improvement of molecular alterations in the brain and meaningful functional improvements in a DM1 model. Importantly, this was achieved through systemic delivery using our BOOST-ON™ platform, which has the potential to simplify treatment while addressing the full spectrum of the disorder."

In the preclinical studies, ARTHEx's proprietary lipid-conjugated antimiR-23b demonstrated:

• Systemic brain delivery, crossing the blood-brain barrier following intravenous administration
• Mechanistic engagement, increasing MBNL1/2 protein levels and reducing toxic DMPK transcripts in the brain 
• Correction of disease biology, including partial rescue of splicing abnormalities across multiple brain regions in an animal model that express a long tract of CTG repeats in the range on congenital, which supports that ATX-01 could be beneficial for congenital patients
• Functional improvement, with normalization of behavioral alterations such as exploratory activity
• Favorable tolerability, with no significant toxicity or neuroinflammation observed

Together, these findings suggest the potential for a disease-modifying approach that addresses both muscular and neurological aspects of DM1.

"This publication further strengthens our conviction in the ArthemiR program" said Frédéric Legros, Executive Chairman and CEO of ARTHEx Biotech. "While our clinical efforts have been focused on addressing the systemic and muscular manifestations of DM1, these new preclinical results highlight the potential to also impact central nervous system involvement—an area of significant unmet need. Importantly, this work reinforces the breadth of our approach as we continue advancing the ArthemiR trial, with the goal of delivering meaningful benefits across the full spectrum of DM1."

ATX-01 is designed to inhibit microRNA-23b (miR-23b), a natural suppressor of muscleblind-like (MBNL) protein expression. In individuals with DM1, loss of functional MBNL activity occurs through two complementary mechanisms: first, upregulation of miR-23b reduces MBNL protein expression; and second, expanded toxic DMPK mRNA sequesters MBNL proteins within the nucleus. The resulting depletion of available MBNL proteins leads to widespread RNA mis-splicing (spliceopathy), which underlies the multisystem symptoms characteristic of DM1. These symptoms primarily affect the skeletal muscle, cardiac, and central nervous systems, though additional organ systems may also be involved. Disease onset most commonly occurs during adolescence, and DM1 is associated with progressive disability and reduced life expectancy.

ARTHEx is currently advancing ATX-01 in the Phase I/IIa ArthemiR study and continues to work closely with regulatory authorities, clinical investigators, and patient advocacy groups to accelerate progress. Please visit the Company's Clinical Trials and Patients pages of its website for more information.

About BOOST-ON™

BOOST-ON™ is ARTHEx's proprietary platform for the development of next-generation RNA therapeutics. By combining selective oligonucleotides with optimized tissue delivery, BOOST-ON™ is designed to reach skeletal muscle, heart, and brain—supporting the development of therapies that address the multisystem nature of diseases such as myotonic dystrophy type 1 (DM1). Previously published preclinical data showed demonstration of functional improvement in the muscle in a DM1 model, and these new preclinical data highlight the effects seen in the CNS, and the platform's potential to address both muscle and CNS diseases.

About ARTHEx Biotech

ARTHEx Biotech is a clinical-stage company developing targeted RNA medicines designed to precisely modulate gene expression. Its proprietary platform, BOOST-ON™ pairs selective oligonucleotides with enhanced tissue delivery to reach skeletal muscle, heart, and brain. Its lead program, ATX-01, is in clinical evaluation for myotonic dystrophy type 1 (DM1), a rare neuromuscular disorder, in the Phase I/IIa ArthemiR™ trial. Building on this foundation, ARTHEx is advancing a pipeline of therapies for additional areas of high unmet need across muscular, CNS and cardiac diseases.

The Company headquarters are in Valencia, Spain. 

For more information on ArthemiR™, please visit https://www.arthemir.com or https://clintrials.gov. 
For more information, please visit www.arthexbiotech.com and engage with us on LinkedIn.