Evry, France (March 9, 2026) –  Atamyo Therapeutics, a biotechnology company specializing in the development of next-generation gene therapies for limb-girdle muscular dystrophy (LGMD), announced at the MDA (Muscular Dystrophy Association) Conference 2026 the first safety, pharmacodynamics, and efficacy results for its ATA-200 gene therapy in  LGMD-2C/R5 limb-girdle muscular dystrophy associated with γ-sarcoglycan deficiency (SGCG, gamma-sarcoglycanopathy). The results are from the first patients treated in the clinical trial conducted at the Powell Gene Therapy Center at the University of Florida by Dr. Barry Byrne and supported by The Dion Foundation for Children with Rare Diseases.

LGMD-2C/R5 is a severe form of muscular dystrophy that appears in childhood and causes loss of walking ability before adulthood, respiratory and heart failure, and premature death. This Phase 1b/2 clinical trial (NCT05973630) is a single-center study evaluating the safety, pharmacodynamics, efficacy, and immunogenicity of ATA-200 in children aged 6 to 13 years. ATA-200 is an adeno-associated virus (AAV) gene therapy carrying a normal copy of the human SGCG gene and administered as a single intravenous injection at a dose of 1.0E+14 vg/kg. This gene therapy product was developed by Isabelle Richard, a pioneer in the study of limb-girdle muscular dystrophies and the development of innovative therapies at Genethon.

At a dose of 1.0E+14 vg/kg, the following was observed in the first two patients treated with ATA-200:

• More than 90% of muscle fibers expressing the SGCG protein—demonstrating that almost all muscle fibers had received the therapeutic gene (90.2% for patient 1 and 92.1% for patient 2, biopsies at 6 months).  

• A significant and sustained reduction in CPK levels (a biomarker of muscle damage) and a decrease in transaminases 9 months after treatment, demonstrating the significant efficacy of ATA-200 gene therapy.

• Also 9 months post-treatment, clinical benefitswere observed on several other important parameters in ambulatory patients, particularly in timed functional tests.

No serious side effects were observed in the four patients treated, confirming the safety of the product. 

 “These initial results are very encouraging and demonstrate the potential of our product with biological data rarely seen in neuromuscular diseases and at such an early stage of the trial. I would like to commend the quality of the work done by the teams at Atamyo Therapeutics and, in particular, the commitment and determination of Isabelle Richard, which has made it possible to offer this hope to patients and their families. We are deeply grateful for the collaboration with the Dion Foundation and Dr. Barry Byrne of the Powell Gene Therapy Center and proud to offer children with LGMD-R5 the opportunity to receive a treatment that could change their lives.” — Angela Columbano, CEO, Atamyo Therapeutics.

Further results from this ongoing study are expected to be published in the coming months, when new longer-term follow-up data becomes available.

We are grateful to the Dion Foundation for Children with Rare Diseases and CureSCG for their financial contributions that made it possible to launch the trial.

About the ATA-200 program in LGMD-2C/R5

About the ATA-200 program in LGMD-2C/R5 LGMD-2C/R5 is a rare genetic disease caused by mutations in the gene that produces γsarcoglycan, a transmembrane protein that is involved in the connection between muscle fibers and their environment. It affects an estimated 2,000 people in Europe and in the US. In the classical form, symptoms appear in early childhood and patients suffer from progressive muscular weakness leading to loss of ambulation before adulthood. Cardiac involvement, typically presented as dilated cardiomyopathy, is reported in approximately half of patients and will eventually impact life expectancy. There is no curative treatment. The management of LGMD-2C/R5 is solely supportive.
ATA-200, Atamyo’s gene therapy for LGMD-2C/R5, delivers a normal copy of the gene for production of γ-sarcoglycan. In preclinical mice models, ATA-200 demonstrated its tolerability and capability to correct symptoms and biomarkers of the pathology. 

ATA-200 has been awarded Orphan Drug Designation in the US and Europe, and Rare Pediatric Disease Designation by the US FDA. 

The therapy is based on the research of Atamyo Chief Scientific Officer Isabelle Richard, Ph.D., Research Director at CNRS who heads the Progressive Muscular Dystrophies Laboratory at Genethon. 

Evry, France (9 mars 2026) –  Atamyo Therapeutics, société de biotechnologie spécialisée dans le développement de thérapies géniques de nouvelle génération pour les dystrophies musculaires des ceintures (limb-girdle muscular dystrophy, LGMD), a dévoilé lors de la Conférence MDA (Muscular Dystrophy Association) 2026 les premiers résultats de sécurité, de pharmacodynamie et d’efficacité de sa thérapie génique ATA-200 dans  la myopathie des ceintures LGMD-2C/R5 liée au déficit en γ-sarcoglycane (SGCG, gamma-sarcoglycanopathie) chez les premiers patients traités dans le cadre d’un essai clinique mené au Powell Gene Therapy Center de l’Université de Floride par le Dr Barry Byrne et soutenu par The Dion Foundation for Children with Rare Diseases.

La LGMD-2C/R5 est une dystrophie musculaire sévère apparaissant dans l’enfance et causant une perte de la marche avant l’âge adulte, une insuffisance respiratoire et cardiaque et un décès prématuré. Cet essai clinique de phase 1b/2 (NCT05973630) est une étude monocentrique évaluant la sécurité, la pharmacodynamique, l’efficacité et l’immunogénicité de l’ATA-200 chez des enfants de 6 à 13 ans, une thérapie génique par virus adéno-associé (AAV) transportant une copie normale du gène humain SGCG et administré en une injection intraveineuse unique à la dose de 1.0E+14 vg/kg. Ce produit de thérapie génique a été mis au point par Isabelle Richard, pionnière dans l’étude des dystrophies musculaires des ceintures et du développement de thérapies innovantes à Généthon.

À la dose de 1.0E+14 vg/kg, on observe chez les deux premiers patients traités par ATA-200 : 

• Plus de 90% de fibres musculaires exprimant la protéine SGCG-démontrant que la presque totalité des fibres musculaires avaient reçu le gène thérapeutique (90.2% pour le patient 1 et 92.1% pour le patient 2, biopsies à 6 mois).  

• Une réduction significative et durable des taux de CPK (un biomarqueur de souffrance musculaire) et une baisse des transaminases 9 mois après le traitement, démontrant une efficacité significative de la thérapie génique ATA-200.

• 9 mois post-traitement également, des bénéfices cliniques ont été observés sur plusieurs autres paramètres importants chez les patients ambulants, notamment lors de tests fonctionnels chronométrés.

Chez les 4 patients traités, aucun effet secondaire grave n’a été observé, confirmant la sécurité du produit. 

 « Ces premiers résultats sont très encourageants et démontrent le potentiel de notre produit avec des données biologiques rarement observées dans des pathologies neuromusculaires et à un stade aussi précoce de l’essai. Je veux saluer la qualité du travail des équipes d’Atamyo Therapeutics et, particulièrement, l’engagement et la détermination d’Isabelle Richard qui permettent d’offrir cet espoir aux malades et à leurs familles. Nous sommes profondément reconnaissants de la collaboration avec la Fondation Dion et le Dr Barry Byrne du Powell Gene Therapy Center et fiers d’offrir aux enfants atteints de LGMD-R5 la possibilité de recevoir un traitement susceptible de changer leur vie. » — Angela Columbano, PDG, Atamyo Therapeutics.

D’autres résultats de cette étude en cours devraient être publiés dans les prochains mois, lorsque de nouvelles données de suivi à plus long terme seront disponibles.

Nous sommes reconnaissants à Dion Foundation for Children with Rare Diseases et à CureSCG pour leurs contributions financières ayant permis le lancement de l’essai.

A propos du programme ATA-200 dans la LGMD-2C/R5

La LGMD-2C/R5 est une maladie génétique rare causée par des mutations du gène qui produit la protéine γ-sarcoglycane, une protéine transmembranaire impliquée dans l’ancrage des fibres musculaires à leur environnement. Elle touche environ 2 000 personnes en Europe et aux Etats-Unis. Dans sa forme typique, les symptômes apparaissent à la petite enfance et les malades souffrent d’un affaiblissement musculaire progressif conduisant à la perte de la marche avant l’âge adulte. Une atteinte cardiaque, qui se manifeste souvent sous la forme d’une cardiomyopathie, est présente chez la moitié des patients environ et affecte la durée de vie des patients. Il n’existe aujourd’hui aucun traitement pour la LGMD-2C/R5.

ATA-200 est une thérapie génique à injection unique qui transporte une copie normale du gène produisant l’γ-sarcoglycane. Dans des modèles précliniques, ATA-200 a démontré une excellente tolérance et une capacité à corriger les symptômes et les biomarqueurs de la pathologie. 

ATA-200 a le statut de médicament orphelin (« Orphan Drug Designation ») aux Etats-Unis et en Europe et le statut de maladie pédiatrique rare (« Rare Pediatric Disease Designation ») par la FDA aux Etats-Unis.

Cette thérapie s’appuie sur les recherches d’Isabelle Richard, Ph.D., directrice de CNRS, responsable du laboratoire des dystrophies musculaires progressives à Généthon, et Directrice Scientifique d’Atamyo. 

Atamyo acknowledges the support of CureSCG, whose contribution has played an important role in supporting the ongoing clinical trial. CureSCG is a patient advocacy organization committed to accelerating research efforts in LGMD sarcoglycanopathies and supporting families affected by the disease. Their involvement reflects a shared commitment to advancing therapeutic innovation for the patient community. 

 “This new step reflects the coordinated efforts of clinical teams, the trust of patients, and the commitment of our partners. The support from CureSCG demonstrates the strength of a community working together to advance therapeutic options for individuals living with γSGC.” — Angela Columbano, CEO, Atamyo Therapeutics.

“We are proud to contribute to the advancement of this important clinical program and deeply grateful to the Dion Foundation for initiating this effort in collaboration with Atamyo. We also thank Atamyo and the clinical teams for their continued dedication. Supporting the dosing of the fourth patient represents a meaningful step forward for the γ-SGC community, and we remain committed to helping move this research forward for families who are waiting for treatment options.” — Rana Abu Khadra, Co-Founder, CureSCG.

CureSCG intends to continue supporting the program as it advances, both within and outside the United States, in alignment with its long term mission to advance scientific and clinical efforts for individuals living with LGMD sarcoglycanopathies.

Atamyo remains firmly committed to advancing safe and innovative gene therapies for rare neuromuscular diseases and looks forward to the continued progression of the γSGC clinical program. 

Evry, France and Boston, MA (February 3, 2026) – Atamyo Therapeutics and The Dion Foundation for Children with Rare Diseases, today announced the expansion of their partnership to support financing of the first-in-human clinical trial of ATA-200, Atamyo’s gene therapy for the treatment of the γ-sarcoglycan related limb-girdle muscular dystrophy Type 2C/R5 (LGMD2C/R5), and the dosing of a third US pediatric patient.

The Phase1b/2 open-label dose escalation study (NCT05973630) evaluates safety, pharmacodynamics, efficacy, and immunogenicity in children receiving intravenous ATA-200, a single-dose Adeno-Associated Virus (AAV) gene therapy carrying the human γ-sarcoglycan transgene. The study is being conducted at the Powell Gene Therapy Center, University of Florida, by Dr. Barry Byrne.

Additional results from this ongoing study are expected to be published in the coming months as further follow-up data become available.

“We are delighted to expand our partnership with Atamyo to treat more U.S. children in the very first clinical trial for children with LGMD2C/R5,” said Courtney Dion, Co-Founder and President of the Dion Foundation. “The Dion Foundation fully supports Atamyo’s ATA-200 program and the promise it holds to bring real, lasting impact to children living with LGMD2C and their families.”

“We are deeply grateful of the collaboration with The Dion Foundation and with Dr. Barry Byrne at the Powell Gene Therapy Center.” said Angela Columbano, Chief Executive Officer of Atamyo Therapeutics. With the support of Atamyo’s shareholder, Genethon, we are delighted of the progress of this first-in-human trial in LGMD-R5. Beyond the children currently enrolled, this study contributes important scientific and clinical knowledge that helps advance the field of therapies for LGMD for patients around the world, and we are proud of giving children affected by LGMD-R5 the opportunity to receive a treatment that could be life-changing.”

“We have been delighted to work with Atamyo and the Dion Foundation in the design and conduct of the ATA-200 study.” said Dr. Barry Byrne, Associate Chair of Pediatrics and Director of the Powell Gene Therapy Center, University of Florida, in Gainesville, Florida, where the first three patients were dosed, and principal investigator of this trial. “We look forward to continuing assessing the potential benefit of ATA-200 in the first children to receive the product.”

About the ATA-200 program in LGMD-2C/R5

LGMD-2C/R5 is a rare genetic disease caused by mutations in the gene that produces γ-sarcoglycan, a transmembrane protein that is involved in the connection between muscle fibers and their environment. It affects an estimated 2,000 people in Europe and in the US. In the classical form, symptoms appear in early childhood and patients suffer from progressive muscular weakness leading to loss of ambulation before adulthood. Cardiac involvement, typically presented as dilated cardiomyopathy, is reported in approximately half of patients and will eventually impact life expectancy. There is no curative treatment. The management of LGMD-2C/R5 is solely supportive.

ATA-200, Atamyo’s gene therapy for LGMD-2C/R5, delivers a normal copy of the gene for production of γ-sarcoglycan. In preclinical mice models, ATA-200 demonstrated its tolerability and capability to correct symptoms and biomarkers of the pathology. 

ATA-200 has been awarded Orphan Drug Designation in the US and Europe, and Rare Pediatric Disease Designation by the US FDA.

The therapy is based on the research of Atamyo Chief Scientific Officer Isabelle Richard, Ph.D., Research Director at CNRS who heads the Progressive Muscular Dystrophies Laboratory at Genethon.

US & Europe contacts: contact@atamyo.com
Stephanie Bardon – communication@genethon.fr /+33 (0)6 45 15 95 87
Daniel Eramian Opus Biotech Communications – danieleramian@comcast.net