Regenxbio Inc. · NASDAQ:RGNX
Regenxbio — ICIEM 2025
17 slides from Regenxbio's conference presentation, Sep 5, 2025
Slide 1: CAMPSIITE Phase I/II/III: Interim clinical update of RGX-121 for neuronopathic MPS II
CAMPSIITE® Phase I/II/III: Interim clinical update of clemidsogene lanparvovec (RGX-121), an investigational gene therapy for treatment of neuronopathic mucopolysaccharidosis type II (MPS II) Roberto Giugliani, MD September 5, 2025 ICIEM 2025 RGX-121 is an investigational product that has not been a
Slide 2: AAV Gene Therapy Has the Potential to Address the High Disease and Treatment Burden in MPS II
AAV Gene Therapy Has the Potential to Address the High Disease and Treatment Burden in MPS II High Unmet Need in MPS II Potential of RGX-121 for MPS II ▪ MPS II, also known as Hunter syndrome, is a rare X- AAV9 Vector + IDS linked recessive genetic disease Transgene ▪ Caused by a deficiency of iduro
Slide 3: CAMPSIITE Phase I/II/III Study of RGX-121 as a Potential One-Time Treatment for MPS II
CAMPSIITE® Phase I/II/III Study of RGX-121 as a Potential One-Time Treatment for MPS II CAMPSIITE Part 11, Dose-Finding (n = 13) CAMPSIITE Part 22 (n = 13) Used to Inform Pivotal Design Pivotal for BLA Dose Level 1 Dose Level 2 Dose Level 3 Dose 3 Chosen Dose Level 3 1.3x1010 GC/g Brain 6.5x1010 GC/
Slide 4: CAMPSIITE Phase I/II/III Study Design
CAMPSIITE® Phase I/II/III Study Design Severe (Neuronopathic MPS II Participants) >4 Months to < 5 Years of Age Part 1: Dose-Finding ( Dose Level 1, 2,& 3) Baseline Treatment Evaluation Assessment Immunosuppression Regimen ( 48 weeks) Screening Day 1 24 Weeks 1 Year 2 Years RGX-121 Primary Endpoint
Slide 5: CAMPSIITE Study - Demographics
CAMPSIITE Study - Demographics ▪ 26 neuronopathic MPS II participants dosed (13 dose-finding & 13 pivotal) ▪ Age at dosing ranged from 5 months to 59 months ▪ IDS mutations included deletion, frameshift, gene inversion, insertion, missense, splicing, and substitution Trial Dose IC / IVR1 Route of Ph
Slide 6: Clemidsogene Lanparvovec (RGX-121) Was Well Tolerated
Clemidsogene Lanparvovec (RGX-121) Was Well Tolerated Dose-Finding (n = 13) Pivotal (n = 13) Treatment Emergent Week 24 2 years > 1 Year* Adverse Events (Primary Endpoint) (End of Study) n = participants (%) n = participants (%) n = participants (%) All SAEs 3 (23%) 6 (46%) 5 (38%) RGX-121 Related S
Slide 7: RGX-121 Gene Therapy for Severe MPS II: Biomarker Endpoint
RGX-121 Gene Therapy for the Treatment of Severe Mucopolysaccharidosis Type II (MPS II): CSF HS D2S6 Biomarker Endpoint
Slide 8: Dose-Finding: Sustained Dose-Dependent Decreases in CSF HS D2S6 at 2 Years
Dose-Finding: Sustained Dose-Dependent Decreases in CSF HS D2S6 at 2 Years CSF HS D2S6 is a Surrogate Endpoint Reasonably Likely to Predict Clinical Benefit in Neuronopathic MPS II 400 Dose Level (median) % reduction 350 ** Dose Week Week Week Year Year Level 8 16 24 1 2 300 -40.49% -30.24% -32.97%
Slide 9: Pivotal: Primary Endpoint Achieved with Sustained Reduction in CSF D2S6 through 1 Year
Pivotal: Primary Endpoint Achieved with Sustained Reduction in CSF D2S6 through 1 Year CSF HS D2S6 is a Surrogate Endpoint Reasonably Likely to Predict Clinical Benefit in Neuronopathic MPS II Week 16 Week 24 1 Year Proportion of Participants with CSF HS D2S6 at or 9/13 10/13 8/11** below maximum Pr
Slide 10: Bayley Scales of Infant and Toddler Development, 3rd Edition (BSID-III)
RGX-121 Gene Therapy for the Treatment of Severe Mucopolysaccharidosis Type II (MPS II): Bayley Scales of Infant and Toddler Development, 3rd Edition (BSID-III) Neurodevelopmental Endpoint
Slide 11: BSID-III Used to Determine Baseline Status and Measure Neurodevelopmental Change After Dosing
BSID-III Used to Determine Baseline Status and Measure Neurodevelopmental Change After Dosing Bayley Scales of Infant and Toddler Development, 3 Edition (BSID-III) rd ▪ Natural history suggest different phases of disease reflected in neurodevelopmental trajectory ▪ Participants were stratified by ba
Slide 12: Dose-Finding: Continued Neurodevelopmental Skill Acquisition or Stability at 2 Years
1 2 Dose-Finding: Continued Neurodevelopmental Skill Acquisition or Stability in the Majority of Participants at 2 Years Majority of Participants Continued to Gain Skills Majority of Participants Stabilized Baseline BSID-III Cognitive Function > -2SD Baseline BSID-III Cognitive Function < -2SD 42 +/
Slide 13: Pivotal: Neurodevelopmental Skill Acquisition or Stability on all BSID-III Subscales at 1 year
Pivotal: Neurodevelopmental Skill Acquisition or Stability on all BSID-III Subscales in Participants at 1 year Above/Equal to -2SD Below -2SD AEq (SE) AEq (SE) N=5 N=8 BSID-III Baseline Year 1 Change from Baseline Year 1 Change from Subscale Baseline Baseline Cognitive 15.7 24.2 + 8.5 13.9 16.6 + 2.
Slide 14: CSF HS D2S6 at Week 16 and Neurocognitive Outcomes Show Correlation
Dose-finding & Interim Pivotal CSF HS D2S6 at Week 16 and Neurocognitive Outcomes in Participants Show Correlation at 1 Year Baseline BSID-III Cognitive Function > -2SD Baseline BSID-III Cognitive Function < -2SD 20 20 15.6 15 15 10 10 5.9 5 5 4.4 1.0 0 0 D2S6 D2S6 D2S6 D2S6 < 100 ng/ml > 100 ng/ml
Slide 15: Significant Correlation Between 1 Year Developmental Outcomes and D2S6 Level at Week 16
Dose-finding & Significant Correlation Between 1 Year Developmental Interim Pivotal Outcomes and Measured CSF HS D2S6 Level at Week 16 Cognitive Subdomain 40 Baseline Cognitive Function ≥ -2 SD One Year CFB in Cognitive Raw Score 35 30 25 20 15 10 5 0 -5 Dose Level 1 Spearman Rank Sum Correlation Do
Slide 16: Summary of CAMPSIITE Study
Summary of CAMPSIITE Study Clemidsogene lanparvovec (RGX-121) was well tolerated in 26 patients Pivotal primary endpoint (CSF HS D2S6 at 16 weeks) was met with sustained reductions through 1 year Continued neurodevelopmental skill acquisition or stabilization demonstrated post RGX-121 administration
Slide 17: Acknowledgements
Acknowledgements The RGX-121-101 Investigators REGENXBIO ▪ Debra Day-Salvatore, St. Peter’s University ▪ Nidal Boulos ▪ Jacqueline Gofshteyn Hospital ▪ Yoonjin Cho ▪ Joe Hagood ▪ Can Ficicioglu, Children’s Hospital of Philadelphia ▪ Stacey Curtiss ▪ Caroline Mulatya ▪ Roberto Giugliani, Hospital de