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REGENXBIO Announces Publication of Preclinical Results Demonstrating Functional Benefits of Novel Microdystrophin Construct in RGX-202 Investigational Gene Therapy for Duchenne Muscular Dystrophy

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REGENXBIO (NASDAQ:RGNX) has published significant preclinical results for RGX-202, their novel gene therapy for Duchenne Muscular Dystrophy. The research, published in Molecular Therapy Methods and Clinical Development, demonstrates that their unique microdystrophin construct containing the C-terminal (CT) domain shows superior performance compared to versions without it.

The studies in mdx mice revealed that the CT domain-containing construct achieved higher protein levels, increased muscle force, and improved resistance to damage. RGX-202 is currently the only microdystrophin gene therapy candidate that includes the CT domain, making it closest to natural dystrophin. These findings support positive interim results from the ongoing Phase I/II AFFINITY DUCHENNE® trial, with REGENXBIO planning a BLA submission in mid-2026 using the accelerated approval pathway.

REGENXBIO (NASDAQ:RGNX) ha pubblicato risultati preclinici significativi per RGX-202, la loro nuova terapia genica per la distrofia muscolare di Duchenne. La ricerca, pubblicata su Molecular Therapy Methods and Clinical Development, dimostra che il loro costrutto unico di microdistrofina contenente il dominio C-terminale (CT) mostra prestazioni superiori rispetto alle versioni che ne sono prive.

Gli studi sui topi mdx hanno evidenziato che il costrutto contenente il dominio CT ha raggiunto livelli proteici più elevati, maggiore forza muscolare e una migliore resistenza ai danni. RGX-202 è attualmente l'unico candidato alla terapia genica con microdistrofina che include il dominio CT, rendendolo il più simile alla distrofina naturale. Questi risultati supportano i positivi risultati intermedi della fase I/II dello studio AFFINITY DUCHENNE®, con REGENXBIO che prevede una presentazione della BLA a metà 2026 utilizzando la via di approvazione accelerata.

REGENXBIO (NASDAQ:RGNX) ha publicado resultados preclínicos significativos para RGX-202, su novedosa terapia génica para la distrofia muscular de Duchenne. La investigación, publicada en Molecular Therapy Methods and Clinical Development, demuestra que su constructo único de microdistrofina que contiene el dominio C-terminal (CT) muestra un rendimiento superior en comparación con las versiones que no lo incluyen.

Los estudios en ratones mdx revelaron que el constructo con el dominio CT logró niveles de proteína más altos, mayor fuerza muscular y mejor resistencia al daño. RGX-202 es actualmente el único candidato a terapia génica de microdistrofina que incluye el dominio CT, acercándose más a la distrofina natural. Estos hallazgos respaldan los resultados interinos positivos del ensayo en curso de Fase I/II AFFINITY DUCHENNE®, con REGENXBIO planeando una presentación de la BLA a mediados de 2026 utilizando la vía de aprobación acelerada.

REGENXBIO (NASDAQ:RGNX)� 듀� 근이영양증을 위한 새로� 유전� 치료제인 RGX-202� 대� 중요� 전임� 결과� 발표했습니다. Molecular Therapy Methods and Clinical Development� 게재� 연구� C-말단(CT) 도메인을 포함� 독특� 마이크로디스트로핀 구조체가 이를 포함하지 않은 버전보다 우수� 성능� 보인다는 것을 입증했습니다.

mdx 생쥐� 대상으� � 연구에서 CT 도메인을 포함� 구조체가 � 높은 단백� 수치, 근육 � 증가, 손상� 대� 저항성 향상� 달성� 것으� 나타났습니다. RGX-202� 현재 CT 도메인을 포함하는 유일� 마이크로디스트로핀 유전� 치료 후보� 자연 디스트로핀� 가� 가깝습니다. � 결과� 진행 중인 1/2� AFFINITY DUCHENNE® 임상시험� 긍정적인 중간 결과� 뒷받침하�, REGENXBIO� 가� 승인 절차� 활용� 2026� 중반� BLA 제출� 계획하고 있습니다.

REGENXBIO (NASDAQ:RGNX) a publié des résultats précliniques significatifs pour RGX-202, leur nouvelle thérapie génique contre la dystrophie musculaire de Duchenne. La recherche, publiée dans Molecular Therapy Methods and Clinical Development, démontre que leur construction unique de microdystrophine contenant le domaine C-terminal (CT) affiche des performances supérieures par rapport aux versions sans ce domaine.

Les études menées chez des souris mdx ont révélé que la construction contenant le domaine CT a permis d'obtenir des niveaux de protéine plus élevés, une force musculaire accrue et une meilleure résistance aux dommages. RGX-202 est actuellement le seul candidat en thérapie génique microdystrophine incluant le domaine CT, ce qui le rapproche le plus de la dystrophine naturelle. Ces résultats soutiennent les résultats intermédiaires positifs de l'essai de phase I/II AFFINITY DUCHENNE® en cours, REGENXBIO prévoyant une soumission de la BLA à la mi-2026 via la procédure d'approbation accélérée.

REGENXBIO (NASDAQ:RGNX) hat bedeutende präklinische Ergebnisse für RGX-202 veröffentlicht, ihre neuartige Gentherapie für die Duchenne-Muskeldystrophie. Die in Molecular Therapy Methods and Clinical Development veröffentlichte Forschung zeigt, dass ihr einzigartiges Mikrodystrophin-Konstrukt mit der C-terminalen (CT) Domäne eine bessere Leistung erzielt als Versionen ohne diese.

Studien an mdx-Mäusen zeigten, dass das Konstrukt mit CT-Domäne höhere Proteinkonzentrationen, erhöhte Muskelkraft und verbesserte Widerstandsfähigkeit gegen Schäden erreichte. RGX-202 ist derzeit der einzige Mikrodystrophin-Gentherapie-Kandidat, der die CT-Domäne enthält und somit der natürlichen Dystrophin am nächsten kommt. Diese Ergebnisse stützen die positiven Zwischenergebnisse der laufenden Phase I/II AFFINITY DUCHENNE®-Studie, wobei REGENXBIO plant, bis Mitte 2026 einen BLA-Antrag über das beschleunigte Zulassungsverfahren einzureichen.

Positive
  • Novel microdystrophin construct with CT domain demonstrated superior efficacy in preclinical studies
  • RGX-202 is the only gene therapy candidate including the CT domain, making it closest to natural dystrophin
  • Positive interim results from Phase I/II AFFINITY DUCHENNE trial support preclinical findings
  • BLA submission planned for mid-2026 using accelerated approval pathway
Negative
  • None.

Insights

REGENXBIO's gene therapy RGX-202 shows promising preclinical results with its unique CT domain-containing microdystrophin, supporting positive clinical trial data.

The publication of these preclinical results in Molecular Therapy Methods and Clinical Development represents a significant scientific validation for REGENXBIO's approach to Duchenne Muscular Dystrophy (DMD) treatment. The data demonstrates that their novel microdystrophin construct with the C-terminal (CT) domain provides superior functional benefits compared to constructs without this domain - a key differentiator for RGX-202 in the competitive gene therapy landscape.

What makes this particularly noteworthy is the mechanistic explanation for RGX-202's potential advantages. The inclusion of the CT domain appears to enable higher microdystrophin protein accumulation in muscles due to extended protein half-life, better recruitment of the dystrophin-associated protein complex to muscle membranes, increased muscle force, and improved resistance to contraction-induced damage. These factors directly address the fundamental pathology of DMD, where muscle damage leads to progressive weakness.

The timing of this publication aligns strategically with REGENXBIO's clinical development timeline. With positive interim results from their Phase I/II AFFINITY DUCHENNE® trial reported last month, this preclinical data provides the mechanistic foundation explaining those clinical observations. The company is now enrolling patients in the pivotal portion of their Phase I/II/III trial with plans to submit a Biologics License Application via the accelerated approval pathway by mid-2026.

For DMD patients, who currently have limited treatment options that address the underlying cause of the disease, RGX-202's differentiated approach could potentially deliver more meaningful and durable functional improvements than alternative gene therapies that lack this critical domain.

  • Construct including CT domain demonstrated higher levels of microdystrophin protein, increased muscle force, and improved resistance to damage in mice lacking dystrophin
  • REGENXBIO's next-generation investigational gene therapy, RGX-202, is the only microdystrophin construct that includes the CT domain
  • Findings support the positive functional data seen in Phase I/II AFFINITY DUCHENNE® trial of RGX-202

ROCKVILLE, Md., July 10, 2025 /PRNewswire/ -- REGENXBIO Inc. (Nasdaq: RGNX)today announced the publication of preclinical results comparing a microdystrophin gene therapy construct that included the C-terminal (CT) domain to a microdystrophin construct without the CT domain. The results, which were published in peer-reviewed journal , showed that the microdystrophin with the CT domain improved functional benefit compared to the microdystrophin without, supporting the potential of RGX-202 to drive functional improvements in patients with Duchenne Muscular Dystrophy.

RGX-202 is the only investigational or approved microdystrophin gene therapy candidate for the treatment of Duchenne muscular dystrophy (Duchenne) that includes the CT domain, a key portion of dystrophin, making it the closest to naturally occurring dystrophin.

"We specifically designed RGX-202 differently from other gene therapies with the goal of providing improved outcomes for patients, and this research further validates the potential therapeutic advantage of adding the CT domain and its importance in preventing the muscle breakdown associated with functional decline in Duchenne," said Olivier Danos, Ph.D., Chief Scientific Officer of REGENXBIO. "The positive interim results we've seen in the Phase I/II AFFINITY DUCHENNE® trial are reinforced by this preclinical research demonstrating how the novel construct of RGX-202 protects against muscle damage and supports the potential for durable, functional benefit for patients."

"AAV gene therapy holds great promise for Duchenne, and the community is in need of treatment options that have the potential to improve function and quality of life for patients," said Michael Kelly, Ph.D., Chief Scientific Officer, CureDuchenne. "The CT domain is a critical part of the large DMD gene and these preclinical results highlight its role in muscle health. With the science behind the novel microdystrophin construct of RGX-202, combined with the interim safety and efficacy profile seen to date in clinic, I am very encouraged by the potential of RGX-202 to be a meaningful, differentiated gene therapy for the community."

In this paper, titled "Enhanced therapeutic potential of a microdystrophin with an extended C-terminal domain," two AAV vectors, one encoding a microdystrophin protein with the CT domain and one encoding an otherwise equivalent microdystrophin protein without the CT domain, were evaluated across three studies in mdx mice, a preclinical model of Duchenne, to measure muscle force, protein levels, and protection from contraction-induced muscle injury.

Compared to the microdystrophin without the CT domain, the microdystrophin that included the CT domain was found to be maintained at higher levels in transduced muscles, recruited the dystrophin-associated protein complex more effectively to the muscle membrane, and increased muscle force and resistance to damage in mice lacking dystrophin. These are key factors in supporting the preservation of muscle health, as muscle damage leads to disease progression in Duchenne.

These findings indicate that incorporation of the CT domain enhances the microdystrophin design by allowing for higher levels of microdystrophin to accumulate in the muscle � primarily attributed to the longer half-life of the extended microdystrophin � and may improve the functional benefit of microdystrophin gene replacement. Interim results from the Phase I/II AFFINITY DUCHENNE clinical trial of RGX-202 show that RGX-202 demonstrated consistent evidence of positively changing the disease trajectory of patients with Duchenne and a favorable safety profile.

REGENXBIO is enrolling participants in the pivotal portion of the Phase I/II/III AFFINITY DUCHENNE trial of RGX-202 and expects to submit a Biologics License Application (BLA) using the accelerated approval pathway in mid-2026.

About RGX-202
RGX-202 is a potential best-in-class investigational gene therapy designed for improved function and outcomes in Duchenne. RGX-202 is the only gene therapy approved or in late-stage development for Duchenne with a differentiated microdystrophin construct that encodes key regions of naturally occurring dystrophin, including the C-Terminal (CT) domain.

Additional design features such as codon optimization may potentially improve gene expression, increase protein translation efficiency and reduce immunogenicity. RGX-202 is designed to support the delivery and targeted expression of microdystrophin throughout skeletal and heart muscle using the NAV® AAV8 vector and a well-characterized muscle-specific promoter (Spc5-12). RGX-202 is manufactured by REGENXBIO using its proprietary, high-yielding NAVXpress® suspension-based platform process.

About Duchenne Muscular Dystrophy
Duchenne is a severe, progressive, degenerative muscle disease, affecting 1 in 3,500 to 5,000 boys born each year worldwide. Duchenne is caused by mutations in the Duchenne gene which encodes for dystrophin, a protein involved in muscle cell structure and signaling pathways. Without dystrophin, muscles throughout the body degenerate and become weak, eventually leading to loss of movement and independence, required support for breathing, cardiomyopathy and premature death.

ABOUT REGENXBIO Inc.
REGENXBIO is a biotechnology company on a mission to improve lives through the curative potential of gene therapy. Since its founding in 2009, REGENXBIO has pioneered the field of AAV gene therapy. REGENXBIO is advancing a late-stage pipeline of one-time treatments for rare and retinal diseases, including RGX-202 for the treatment of Duchenne; clemidsogene lanparvovec (RGX-121) for the treatment of MPS II and RGX-111 for the treatment of MPS I, both in partnership with Nippon Shinyaku; and surabgene lomparvovec (ABBV-RGX-314) for the treatment of wet AMD and diabetic retinopathy, in collaboration with AbbVie. Thousands of patients have been treated with REGENXBIO's AAV platform, including those receiving Novartis' ZOLGENSMA®. REGENXBIO's investigational gene therapies have the potential to change the way healthcare is delivered for millions of people. For more information, please visit .

FORWARD-LOOKING STATEMENTS
This press release includes "forward-looking statements," within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These statements express a belief, expectation or intention and are generally accompanied by words that convey projected future events or outcomes such as "believe," "may," "will," "estimate," "continue," "anticipate," "assume," "design," "intend," "expect," "could," "plan," "potential," "predict," "seek," "should," "would" or by variations of such words or by similar expressions. The forward-looking statements include statements relating to, among other things, REGENXBIO's future operations and clinical trials. REGENXBIO has based these forward-looking statements on its current expectations and assumptions and analyses made by REGENXBIO in light of its experience and its perception of historical trends, current conditions and expected future developments, as well as other factors REGENXBIO believes are appropriate under the circumstances. However, whether actual results and developments will conform with REGENXBIO's expectations and predictions is subject to a number of risks and uncertainties, including the timing of enrollment, commencement and completion and the success of clinical trials conducted by REGENXBIO, its licensees and its partners, the timely development and launch of new products, the ability to obtain and maintain regulatory approval of product candidates, the ability to obtain and maintain intellectual property protection for product candidates and technology, trends and challenges in the business and markets in which REGENXBIO operates, the size and growth of potential markets for product candidates and the ability to serve those markets, the rate and degree of acceptance of product candidates, and other factors, many of which are beyond the control of REGENXBIO. Refer to the "Risk Factors" and "Management's Discussion and Analysis of Financial Condition and Results of Operations" sections of REGENXBIO's Annual Report on Form 10-K for the year ended December 31, 2024, and comparable "risk factors" sections of REGENXBIO's Quarterly Reports on Form 10-Q and other filings, which have been filed with the SEC and are available on the SEC's website at . All of the forward-looking statements made in this press release are expressly qualified by the cautionary statements contained or referred to herein. The actual results or developments anticipated may not be realized or, even if substantially realized, they may not have the expected consequences to or effects on REGENXBIO or its businesses or operations. Such statements are not guarantees of future performance and actual results or developments may differ materially from those projected in the forward-looking statements. Readers are cautioned not to rely too heavily on the forward-looking statements contained in this press release. These forward-looking statements speak only as of the date of this press release. Except as required by law, REGENXBIO does not undertake any obligation, and specifically declines any obligation, to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

Zolgensma® is a registered trademark of Novartis AG. All other trademarks referenced herein are registered trademarks of REGENXBIO.

Contacts:
Dana Cormack
Corporate Communications
[email protected]

Investors:
George E. MacDougall
Investor Relations
[email protected]

Cision View original content to download multimedia:

SOURCE REGENXBIO Inc.

FAQ

What makes REGENXBIO's RGX-202 gene therapy unique for Duchenne Muscular Dystrophy treatment?

RGX-202 is the only microdystrophin gene therapy that includes the C-terminal (CT) domain, making it the closest to naturally occurring dystrophin. This unique design has shown superior protein levels and muscle protection in preclinical studies.

What were the key findings of RGNX's preclinical studies for RGX-202?

The studies showed that microdystrophin with CT domain achieved higher protein levels, increased muscle force, and improved resistance to damage compared to versions without the CT domain in mdx mice.

When does REGENXBIO plan to submit the BLA for RGX-202?

REGENXBIO plans to submit a Biologics License Application (BLA) for RGX-202 using the accelerated approval pathway in mid-2026.

What is the current development status of REGENXBIO's RGX-202?

RGX-202 is currently in the pivotal portion of the Phase I/II/III AFFINITY DUCHENNE trial, with positive interim results reported in June 2025 showing evidence of changing disease trajectory and favorable safety profile.

How does the CT domain in RGX-202 benefit Duchenne patients?

The CT domain allows for higher levels of microdystrophin to accumulate in muscles due to a longer half-life, leading to better muscle protection and potentially improved functional benefits for patients with Duchenne Muscular Dystrophy.
Regenxbio

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