REGENXBIO Presents Positive Twelve-Month Pivotal Data from Phase I/II/III CAMPSIITE® Trial of RGX-121 for Treatment of MPS II
REGENXBIO (NASDAQ:RGNX) has announced positive 12-month pivotal data from its Phase I/II/III CAMPSIITE® trial of RGX-121 for treating MPS II (Hunter syndrome). The trial demonstrated an 82% median reduction in CSF levels of HS D2S6, a key biomarker of MPS II brain disease, sustained through one year.
The study met its primary endpoint with statistical significance (p < 0.0001), showing strong correlation between biomarker levels and neurodevelopmental improvements. Patients demonstrated neurodevelopmental skill acquisition or stability across all sub-scales of the BSID-III assessment at one year.
The FDA completed pre-license and bioresearch monitoring inspections with no observations, and RGX-121 has been well-tolerated in all 26 patients. A decision on the Biologics License Application is expected by February 8, 2026. If approved, RGX-121 would become the first one-time therapy targeting the genetic cause of Hunter syndrome.
REGENXBIO (NASDAQ:RGNX) ha annunciato dati positivi a 12 mesi dallo studio pivotale di fase I/II/III CAMPSIITE® su RGX-121 per il trattamento della MPS II (sindrome di Hunter). Lo studio ha mostrato una riduzione mediana dell'82% dei livelli di HS D2S6 nel liquor, un biomarcatore chiave della malattia cerebrale della MPS II, mantenuta per un anno.
Lo studio ha raggiunto l'endpoint primario con significatività statistica (p < 0,0001), evidenziando una forte correlazione tra i livelli del biomarcatore e i miglioramenti neuroevolutivi. I pazienti hanno mostrato acquisizione o stabilità delle abilità neuroevolutive in tutte le sottoscale della valutazione BSID-III dopo un anno.
La FDA ha completato le ispezioni pre-licenza e di bioresearch monitoring senza osservazioni, e RGX-121 è stato ben tollerato in tutti i 26 pazienti. Una decisione sulla Biologics License Application è prevista per il 8 febbraio 2026. In caso di approvazione, RGX-121 sarebbe la prima terapia somministrata una sola volta a colpire la causa genetica della sindrome di Hunter.
REGENXBIO (NASDAQ:RGNX) ha anunciado datos positivos a 12 meses del ensayo pivotal de fase I/II/III CAMPSIITE® con RGX-121 para el tratamiento de la MPS II (síndrome de Hunter). El ensayo mostró una reducción mediana del 82% en los niveles de HS D2S6 en LCR, un biomarcador clave de la enfermedad cerebral de la MPS II, mantenida durante un año.
El estudio alcanzó su endpoint primario con significación estadística (p < 0,0001), mostrando una fuerte correlación entre los niveles del biomarcador y las mejoras en el desarrollo neurológico. Los pacientes demostraron adquisición o estabilidad de habilidades neurodesarrollativas en todas las subescalas de la evaluación BSID-III a un año.
La FDA completó las inspecciones previas a la licencia y de bioresearch monitoring sin observaciones, y RGX-121 ha sido bien tolerado en los 26 pacientes. Se espera una decisión sobre la Biologics License Application para el 8 de febrero de 2026. Si se aprueba, RGX-121 sería la primera terapia de dosis única que actúa sobre la causa genética del síndrome de Hunter.
REGENXBIO (NASDAQ:RGNX)는 MPS II(헌터 증후군) 치료를 위한 RGX-121의 1/2/3상 CAMPSIITE® 중추임상시험에서 12개월 핵심 데이터가 긍정적이었다고 발표했습니다. 이 임상에서는 MPS II 뇌질환의 주요 바이오마커인 뇌척수액 HS D2S6 수치가 중앙값 기준 82% 감소하며 1년 동안 유지되는 것으로 나타났습니다.
연구는 주요 평가변수에서 통계적으로 유의미한 결과(p < 0.0001)를 보였으며, 바이오마커 수치와 신경발달 개선 사이에 강한 상관관계가 확인되었습니다. 환자들은 1년 시점에 BSID-III 검사 모든 하위척도에서 신경발달 능력의 획득 또는 안정성을 보였습니다.
FDA는 허가 전 검사 및 생물연구 모니터링 점검을 관찰사항 없이 완료했으며, RGX-121은 26명 전원에서 잘 견뎌졌다. 생물의약품 허가신청(BLA)에 대한 결정은 2026년 2월 8일로 예상됩니다. 승인되면 RGX-121은 헌터 증후군의 유전적 원인을 표적으로 하는 최초의 일회성 치료제가 됩니다.
REGENXBIO (NASDAQ:RGNX) a annoncé des données positives à 12 mois issues de l'essai pivotal de phase I/II/III CAMPSIITE® de RGX-121 pour le traitement de la MPS II (syndrome de Hunter). L'étude a montré une réduction médiane de 82% des niveaux de HS D2S6 dans le LCR, un biomarqueur clé de la maladie cérébrale liée à la MPS II, maintenue pendant un an.
L'étude a atteint son critère principal avec une signification statistique (p < 0,0001), mettant en évidence une forte corrélation entre les niveaux du biomarqueur et les améliorations du développement neuro‑comportemental. Les patients ont présenté, à un an, une acquisition ou une stabilité des compétences neurodéveloppementales sur toutes les sous‑échelles de l'évaluation BSID-III.
La FDA a terminé les inspections pré‑autorisation et de bioresearch monitoring sans observations, et RGX-121 a été bien toléré chez les 26 patients. Une décision concernant la Biologics License Application est attendue pour le 8 février 2026. En cas d'approbation, RGX-121 deviendrait la première thérapie administrée une seule fois ciblant la cause génétique du syndrome de Hunter.
REGENXBIO (NASDAQ:RGNX) hat positive 12-Monats-Daten aus der pivotalen Phase I/II/III-Studie CAMPSIITE® zu RGX-121 zur Behandlung von MPS II (Hunter-Syndrom) veröffentlicht. Die Studie zeigte eine medianmäßige Reduktion von 82% der HS D2S6-Werte im Liquor, einem wichtigen Biomarker der MPS-II-Hirnerkrankung, die über ein Jahr anhielt.
Die Studie erreichte das primäre Endpunktziel mit statistischer Signifikanz (p < 0,0001) und zeigte eine starke Korrelation zwischen Biomarker-Werten und neuroentwicklungsbezogenen Verbesserungen. Die Patienten zeigten nach einem Jahr in allen Subskalen der BSID-III-Bewertung entweder Erwerb oder Erhalt neuroentwicklungsbezogener Fähigkeiten.
Die FDA hat Vorlizenz- und Bioresearch-Monitoring-Inspektionen ohne Beanstandungen abgeschlossen, und RGX-121 wurde bei allen 26 Patienten gut vertragen. Eine Entscheidung zur Biologics License Application wird bis zum 8. Februar 2026 erwartet. Bei Zulassung wäre RGX-121 die erste einmalige Therapie, die die genetische Ursache des Hunter-Syndroms adressiert.
- Met primary endpoint with statistical significance (p < 0.0001)
- 82% median reduction in key biomarker (CSF HS D2S6) sustained for 1 year
- Strong correlation between biomarker levels and neurodevelopmental improvements
- Clean FDA inspection with no observations
- Well-tolerated safety profile across all 26 patients
- None.
Insights
REGENXBIO's MPS II therapy shows promising 12-month data with sustained 82% biomarker reduction and positive neurodevelopmental outcomes; FDA decision expected February 2026.
REGENXBIO's latest data from their CAMPSIITE trial represents a significant clinical milestone for clemidsogene lanparvovec (RGX-121), their one-time gene therapy for Hunter syndrome. The 82% median reduction in CSF levels of heparan sulfate D2S6 sustained through 12 months is particularly meaningful, as this biomarker directly correlates with brain disease progression in MPS II patients.
The data demonstrates three critical aspects of potential efficacy: sustained biomarker reduction, correlation between biomarker and clinical outcomes, and neurodevelopmental stability or improvement measured by the Bayley Scales. This trifecta strengthens the therapy's case for approval under the FDA's accelerated pathway, which allows authorization based on surrogate endpoints reasonably likely to predict clinical benefit.
Hunter syndrome is a devastating X-linked disorder affecting primarily boys, causing progressive neurodegeneration with no current treatments addressing the CNS manifestations. The correlation between week 16 biomarker levels and one-year neurodevelopmental outcomes provides compelling evidence for the surrogate biomarker approach, potentially establishing a new regulatory precedent for lysosomal storage disorders.
With the FDA's pre-license inspection completed with no observations and a PDUFA date of February 8, 2026, RGX-121 appears well-positioned for potential approval. If authorized, this would represent the first gene therapy for MPS II and could fundamentally change treatment paradigms from chronic enzyme replacement to one-time intervention targeting the genetic root cause of the disease.
- 12-month pivotal data further demonstrate the ability of one-time RGX-121 treatment to improve outcomes for patients with MPS II
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80% reduction in CSF levels of HS D2S6, key biomarker of MPS II brain disease, sustained through 1 year - Pivotal patients demonstrate continued skill acquisition or stability, stratified by baseline function, through 1 year
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- Primary endpoint of CSF HS D2S6 reduction at week 16 met; strong correlation to neurodevelopmental outcomes at 1 year, supporting HS D2S6 as surrogate biomarker reasonably likely to predict clinical benefit
- 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
"These positive biomarker and functional data provide further evidence of the long-term potential of RGX-121 to change the trajectory of Hunter syndrome for boys with this devastating, degenerative disease," said Steve Pakola, M.D., Chief Medical Officer of REGENXBIO. "The sustained reductions in CSF HS D2S6 and evidence of the strong correlation between biomarker level and neurodevelopmental improvement are highly encouraging as we look toward potential accelerated approval early next year."
"I am highly encouraged by the 12-month pivotal data and continued safety and efficacy profile of RGX-121," said Roberto Giugliani, M.D., Ph.D., Professor, Department of Genetics, UFRGS, Medical Genetics Service, HCPA, Porto Alegre, Brazil. "The vast majority of Hunter syndrome patients have no current treatment options to address the neurodevelopmental decline of this disease and are in urgent need of new therapies, and a one-time treatment option, like RGX-121, could make a meaningful impact on their lives."
Data Summary
In the pivotal phase of the CAMPSIITE trial (n=13), participants through one year sustained an
Positive neurodevelopmental outcomes were observed in the pivotal and dose-finding phases of the CAMPSIITE trial. Pivotal participants demonstrated neurodevelopmental skill acquisition or stability on all sub-scales of the Bayley Scales of Infant and Toddler Development, 3rd Edition (BSID-III) at one year.
New data from both the dose-finding and pivotal phases of the CAMPSIITE trial demonstrate a strong correlation between measured CSF HS D2S6 levels at week 16 and neurocognitive outcomes at one year. This correlation supports the use of CSF HS D2S6, a type of glycosaminoglycan (GAG), as a surrogate endpoint reasonably likely to predict clinical benefit under the accelerated approval pathway, as the buildup of GAGs in MPS II leads to clinical manifestations including neurodevelopmental deficits.
RGX-121 BLA
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, and RGX-121 has been well tolerated in all 26 patients dosed across all phases of the CAMPSIITE trial as of August 20, 2024. The FDA is expected to make a decision on the application by February 8, 2026.
About RGX-121 (clemidsogene lanparvovec)
RGX-121 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.
RGX-121 has received Orphan Drug Product, Rare Pediatric Disease, Fast Track and Regenerative Medicine Advanced Therapy (RMAT) designations from the FDA and advanced therapy medicinal products (ATMP) classification from the European Medicines Agency.
About the CAMPSIITE® Trial
CAMPSIITE is a Phase I/II/III multicenter, open-label trial for boys aged four months up to five years with neuronopathic MPS II. The primary endpoint of the trial is measurement of CSF GAGs. Accurate and sensitive measurements of CSF GAGs, such as HS D2S6, have the potential to be considered a surrogate endpoint that is reasonably likely to predict clinical benefit in MPS II disease under the accelerated approval pathway, as buildup of GAGs in the CSF of MPS II patients correlates with clinical manifestations including neurodevelopmental deficits.
The pivotal program uses commercial-scale cGMP material from REGENXBIO's proprietary, high-yielding suspension-based manufacturing process, named NAVXpress®. In addition to measuring GAGs in the CSF, the trial will continue to collect neurodevelopmental data and caregiver-reported outcomes.
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®. REGENXBIO's investigational gene therapies have the potential to change the way healthcare is delivered for millions of people. For more information, please visit www.REGENXBIO.com.
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 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 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 WWW.SEC.GOV. 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 Gene Therapies. All other trademarks referenced herein are registered trademarks of REGENXBIO.
CONTACTS:
Dana Cormack
Corporate Communications
Dcormack@regenxbio.com
George E. MacDougall
Investor Relations
IR@regenxbio.com
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SOURCE REGENXBIO Inc.
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