REGENXBIO Announces FDA Review Extension of BLA for RGX-121 to Treat Patients with MPS II
REGENXBIO (Nasdaq: RGNX) announced that the FDA has extended its review timeline for RGX-121, a potential treatment for Hunter syndrome (MPS II). The PDUFA date has been pushed from November 9, 2025 to February 8, 2026 following the company's submission of additional 12-month clinical data for all 13 patients in the pivotal study.
The FDA's extension comes after completing a pre-license inspection with no observations, and notably, no safety concerns have been raised during the BLA review. RGX-121 holds multiple FDA designations including Orphan Drug, Rare Pediatric Disease, Fast Track, and RMAT. If approved, it would become the first one-time therapy targeting the genetic cause of Hunter syndrome.
REGENXBIO (Nasdaq: RGNX) ha annunciato che la FDA ha esteso i tempi di revisione per RGX-121, un potenziale trattamento per la sindrome di Hunter (MPS II). La data PDUFA 猫 stata posticipata dall'9 novembre 2025 all'8 febbraio 2026 a seguito della presentazione da parte della societ脿 di dati clinici aggiuntivi a 12 mesi relativi a tutti i 13 pazienti dello studio chiave.
L'estensione da parte della FDA segue il completamento di un'ispezione pre-autorizzazione senza rilievi e, cosa importante, durante la revisione della BLA non sono emerse preoccupazioni di sicurezza. RGX-121 dispone di numerose designazioni FDA, tra cui Orphan Drug, Rare Pediatric Disease, Fast Track e RMAT. Se approvato, sarebbe la prima terapia somministrata una sola volta che agisce sulla causa genetica della sindrome di Hunter.
REGENXBIO (Nasdaq: RGNX) anunci贸 que la FDA ha ampliado su calendario de revisi贸n para RGX-121, un posible tratamiento para el s铆ndrome de Hunter (MPS II). La fecha PDUFA se ha retrasado del 9 de noviembre de 2025 al 8 de febrero de 2026 tras la presentaci贸n por parte de la compa帽铆a de datos cl铆nicos adicionales a 12 meses de los 13 pacientes del estudio pivotal.
La extensi贸n de la FDA se produce despu茅s de completar una inspecci贸n previa a la licencia sin observaciones y, de forma destacada, durante la revisi贸n de la BLA no se han planteado preocupaciones de seguridad. RGX-121 cuenta con varias designaciones de la FDA, incluidas Orphan Drug, Rare Pediatric Disease, Fast Track y RMAT. Si se aprueba, ser铆a la primera terapia de una sola administraci贸n que aborda la causa gen茅tica del s铆ndrome de Hunter.
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FDA鞚� 鞐办灔鞚� 靷爠 項堦皜(inspections) 瓴�靷棎靹� 氍胳牅 鞐嗢澊 鞕勲霅� 雿� 霐半ジ 瓴冹溂搿�, BLA(靸濍鞚橃暯頀� 項堦皜鞁犾箔) 瓴�韱� 欷� 鞎堨爠靹� 鞖半牑電� 鞝滉赴霅橃 鞎婌晿鞀惦媹雼�. RGX-121鞚� 頋穩鞚橃暯頀�(Orphan Drug), 頋穩靻岇晞歆堩櫂(Rare Pediatric Disease), 韺姢韸疙姼霝�(Fast Track), RMAT 霌� 鞐煬 FDA 歆�鞝� 靸來儨毳� 氤挫湢頃橁碃 鞛堨姷雼堧嫟. 鞀轨澑霅� 瓴届毎 項岉劙 歃濏泟甑办潣 鞙犾爠鞝� 鞗愳澑鞚� 響滌爜鞙茧 頃橂姅 鞚柬殞靹� 旃橂鞝滊電� 斓滌磮臧� 霅╇媹雼�.
REGENXBIO (Nasdaq: RGNX) a annonc茅 que la FDA a prolong茅 son d茅lai d'examen pour RGX-121, un traitement potentiel du syndrome de Hunter (MPS II). La date PDUFA a 茅t茅 report茅e du 9 novembre 2025 au 8 f茅vrier 2026 suite 脿 la soumission par la soci茅t茅 de donn茅es cliniques suppl茅mentaires 脿 12 mois pour les 13 patients de l'茅tude pivot.
Cette prolongation de la FDA intervient apr猫s la r茅alisation d'une inspection pr茅-autorisatoire sans observations et, fait notable, aucune pr茅occupation de s茅curit茅 n'a 茅t茅 soulev茅e lors de l'examen du BLA. RGX-121 b茅n茅ficie de plusieurs d茅signations FDA, y compris Orphan Drug, Rare Pediatric Disease, Fast Track et RMAT. Si elle est approuv茅e, ce serait la premi猫re th茅rapie en dose unique visant la cause g茅n茅tique du syndrome de Hunter.
REGENXBIO (Nasdaq: RGNX) teilte mit, dass die FDA die Pr眉fungsfrist f眉r RGX-121, einen potenziellen Behandlungsansatz f眉r das Hunter-Syndrom (MPS II), verl盲ngert hat. Das PDUFA-Datum wurde nach Einreichung zus盲tzlicher 12-Monats-Daten f眉r alle 13 Patienten der Schl眉sslestudie vom 9. November 2025 auf den 8. Februar 2026 verschoben.
Die Verl盲ngerung durch die FDA erfolgte, nachdem eine Vorlizenzinspektion ohne Beanstandungen abgeschlossen wurde; bemerkenswert ist, dass w盲hrend der BLA-Pr眉fung keine Sicherheitsbedenken ge盲u脽ert wurden. RGX-121 verf眉gt 眉ber mehrere FDA-Zulassungsdesignationen, darunter Orphan Drug, Rare Pediatric Disease, Fast Track und RMAT. Bei Zulassung w盲re es die erste einmalig verabreichte Therapie, die die genetische Ursache des Hunter-Syndroms adressiert.
- None.
- FDA review timeline extended by 3 months
- Additional data submission required by FDA
Insights
FDA extends RGNX-121 review timeline to February 2026; appears procedural rather than safety-related, with commercial launch plans unchanged.
The FDA has extended its review of REGENXBIO's Biologics License Application (BLA) for RGX-121, pushing the decision date from November 9, 2025 to February 8, 2026. This three-month extension follows the company's submission of additional 12-month clinical data for all 13 patients in the pivotal study, which the FDA had specifically requested.
Several key factors suggest this delay is procedural rather than reflecting concerns about the therapy's viability:
- The FDA completed pre-license and bioresearch monitoring inspections with no observations - a positive signal
- No safety-related concerns have been raised during the BLA review process
- The additional data submitted reportedly remains consistent with previously submitted results
- The company maintains its commercial launch timeline remains on track
RGX-121 is positioned as potentially the first one-time therapy designed to address the genetic cause of Hunter syndrome, a rare disorder where patients currently have no treatments for neurodevelopmental decline. The therapy carries multiple regulatory designations including Orphan Drug, Rare Pediatric Disease, Fast Track, and Regenerative Medicine Advanced Therapy status from the FDA.
This type of review extension is not uncommon when additional data is submitted during the review period, as the FDA typically requires additional time to thoroughly evaluate new information. The company plans to present the updated pivotal data at the International Congress of Inborn Errors of Metabolism in September 2025, which should provide further insights into the therapy's efficacy profile.
- RGX-121 would be the first and only potential one-time commercially-available therapy designed to directly address the underlying genetic cause of Hunter syndrome, if approved
- Commercial launch plans remain on track听
- REGENXBIO plans to present updated pivotal data during the ICIEM meeting in September 2025
The extension follows the Company's submission of longer-term clinical data for all patients in the pivotal study of RGX-121 (n=13) in response to an FDA information request.听These positive 12-month clinical data are consistent with biomarker and neurodevelopmental data previously submitted on the same patients in the BLA and will be presented during the International Congress of Inborn Errors of Metabolism (ICIEM) in September 2025.
In August 2025, the FDA completed a pre-license inspection and bioresearch monitoring information inspection for the RGX-121 BLA with no observations. No safety-related concerns have been raised by the FDA during the BLA review.
"Boys with this rare, devastating disease have no treatment options to address neurodevelopmental decline, and the Hunter syndrome community is in urgent need for a therapeutic option with the potential to improve these patients' lives," said Curran M. Simpson, President and Chief Executive Officer of听REGENXBIO. "We promptly provided the FDA with the information requested and expect the commercial launch plans remain on track."
RGX-121 has received Orphan Drug Product, Rare Pediatric Disease, Fast Track and Regenerative Medicine Advanced Therapy (RMAT) designations from the听FDA听and advanced therapy medicinal products (ATMP) classification from the听European Medicines Agency.听
About RGX-121 (clemidsogene lanparvovec)
RGX-121听is a potential one-time AAV therapeutic for the treatment of boys with MPS II, designed to deliver the iduronate-2-sulfatase (IDS) gene to the central nervous system (CNS). Delivery of the IDS gene within cells in the CNS could provide a permanent source of secreted iduronate-2-sulfatase (I2S) protein beyond the blood-brain barrier, allowing for long-term cross correction of cells throughout the CNS. RGX-121 expressed protein is structurally identical to normal I2S.
About Mucopolysaccharidosis Type II (MPS II)
MPS II, or Hunter Syndrome, is a rare, X-linked recessive disease caused by a deficiency in the lysosomal enzyme I2S leading to an accumulation of glycosaminoglycans (GAGs), including heparan sulfate (HS) in tissues which ultimately results in cell, tissue, and organ dysfunction, including in the CNS. In severe forms of the disease, early developmental milestones may be met, but developmental delay is readily apparent by 18 to 24 months. Specific treatment to address the neurological manifestations of MPS II remains a significant unmet medical need. Key biomarkers of I2S enzymatic activity in MPS II patients include its substrate heparan sulfate (HS) D2S6, which has been shown to correlate with neurocognitive manifestations of the disorder.
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庐. 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, clinical trials, costs and cash flow. 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 timing of commencement and completion and the success of preclinical studies conducted by REGENXBIO and its development partners, the timing or likelihood of payments from AbbVie or Nippon Shinyaku, the monetization of any priority review voucher, 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庐 is a registered trademark of Novartis Gene Therapies. All other trademarks referenced herein are registered trademarks of REGENXBIO.
CONTACTS:
Dana Cormack
Corporate Communications
[email protected]
George E. MacDougall
Investor Relations
[email protected]
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FAQ
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