AFFINITY DUCHENNE: RGX-202 Gene Therapy in Participants With Duchenne Muscular Dystrophy (DMD)

A Phase 1/2/3 Open-label Study to Evaluate the Safety, Tolerability, Efficacy, Pharmacodynamics, and Pharmacokinetics of Intravenous RGX-202 Gene Therapy in Males With Duchenne Muscular Dystrophy (DMD)

RGX-202 is a gene therapy designed to deliver a transgene for a novel microdystrophin that includes functional elements of naturally-occurring dystrophin including the C-Terminal (CT) domain.

This is a multicenter, open-label dose evaluation clinical study to assess the safety, tolerability, and clinical efficacy of a one-time intravenous (IV) dose of RGX-202 in participants with Duchenne.

For additional information on how to participate (or be considered for the study), please follow this link: https://mytomorro.ws/affinity-ct-gov

Study Overview

• Status: Recruiting
• Conditions: Duchenne Muscular Dystrophy
• Intervention / Treatment: Genetic: RGX-202

Detailed Description

Duchenne muscular dystrophy (Duchenne) is a rare genetic disorder, caused by mutations in the gene responsible for making dystrophin, a protein of central importance for muscle cell structure and function. The absence of functional dystrophin protein in individuals with Duchenne results in cell damage during muscle contraction leading to cell death, inflammation, and fibrosis in muscle tissues, and ultimately progressive muscle weakness. RGX-202 is designed to use the AAV8 vector to deliver a transgene to muscle cells that encodes a novel microdystrophin that includes the functional elements of naturally occurring dystrophin including the C-Terminal (CT) domain.

This is a multicenter, phase I/II/III, open-label study to evaluate the safety, tolerability, pharmacodynamics (microdystrophin protein levels), pharmacokinetic, and clinical efficacy of RGX-202 when administered IV as one-time dose to ambulant male participants with Duchenne. A comprehensive, short-term, prophylactic immunosuppression regimen will be administered during treatment to mitigate a potential immune response. This study is being conducted in three sequential parts: a phase I/II study (Part 1), a phase 3 pivotal study (Part 2) and a confirmatory study (Part 3). Part 1 will study a one-time dose of RGX-202 (1x10^14 or 2x10^14 GC/kg) in up to 15 participants with Duchenne. In part 1, the primary objective is to evaluate the safety and tolerability of RGX-202 through 52 weeks. Part 2 (Pivotal Expansion) will study a single dose of RGX-202 (2x10^14 GC/kg) in approximately 30 participants. After the last Part 2 participant is dosed, enrollment into the confirmatory study (Part 3) will be initiated. The target enrollment for the confirmatory study (Part 3) is approximately 30 participants. Participants will be assessed at various time points for 104 weeks after receiving RGX-202. All participants will be given the opportunity to enroll in a separate long-term follow-study in accordance with the US federal government guidelines for the safety follow-up of patients receiving gene therapy.

• Study Type: Interventional
• Enrollment (Estimated): 65
• Phase: Phase 2; Phase 3

Contacts and Locations

• Study Contact: Name: Patient Advocacy; Phone Number: (833) 711-0349; Email: Duchenne@regenxbio.com

Study Locations

• Canada
  • Alberta
    • Calgary, Alberta, Canada, T3B 6A
      • Not yet recruiting
      • Alberta Children's Hospital
      • Principal Investigator: Jean Mah, MD
      • Contact: Israt Yasmeen, MBT; Phone Number: 587-943-0851; Email: Israt.Yasmeen@ahs.ca
  • British Columbia
    • Vancouver, British Columbia, Canada, V65 3N1
      • Recruiting
      • BC Children's Hospital
      • Principal Investigator: Kathryn Selby, MD
      • Contact: Nela Martic; Phone Number: 6549 604-875-2345; Email: nmartic3@cw.bc.ca
  • Ontario
    • London, Ontario, Canada
      • Recruiting
      • Children's Hospital London Health Science Centre
      • Principal Investigator: Craig Campbell, MD
      • Contact: Rhiannon Hicks; Phone Number: 58441 519-685-8500; Email: rhiannon.hicks@lhsc.on.ca
    • Ottawa, Ontario, Canada, K1H 8L1
      • Recruiting
      • Children's Hospital of Eastern Ontario
      • Principal Investigator: Hugh McMillan, MD
      • Contact: Laura Thompson; Phone Number: 6051 613-737-7600; Email: lathompson@cheo.on.ca
• United States
  • Arkansas
    • Little Rock, Arkansas, United States, 72202
      • Recruiting
      • Arkansas Children's Hospital
      • Principal Investigator: Aravindhan Veerapandiyan, MD
      • Contact: Amber Evans; Phone Number: 501-364-2259; Email: evansa17@archildrens.org
  • California
    • Palo Alto, California, United States, 94304
      • Recruiting
      • Stanford School of Medicine /Division of Neuromuscular Medicine
      • Contact: Phone Number: 650-725-4341; Email: NeuromuscularResearch@stanford.edu
      • Principal Investigator: Carolina Tesi-Rocha, MD
  • Colorado
    • Aurora, Colorado, United States, 80045
      • Recruiting
      • Children's Hospital Colorado
      • Principal Investigator: Michele Yang, MD
      • Contact: Michele Yang; Phone Number: 720-777-6895; Email: Michele.Yang@childrenscolorado.org
      • Contact: Hannah Kleiner; Phone Number: 720-777-1377; Email: Hannah.Kleiner@childrenscolorado.org
  • Florida
    • Gainesville, Florida, United States, 32610
      • Recruiting
      • University of Florida
      • Contact: Melissa Lewis; Phone Number: 352-273-8218; Email: melissa.lewis@peds.ufl.edu
      • Principal Investigator: Barry Byrne, MD
  • Georgia
    • Atlanta, Georgia, United States, 30329
      • Recruiting
      • Rare Disease Research
      • Principal Investigator: Han Phan, MD
      • Contact: Lily Goggans; Phone Number: 470-600-9134; Email: lily.goggans@rarediseaseresearch.com
      • Contact: Maureen Ikpeoha; Phone Number: 470-666-1884; Email: maureen.ikpeoha@rarediseaseresearch.com
  • Illinois
    • Chicago, Illinois, United States, 60611
      • Recruiting
      • Ann & Robert H. Lurie Children's Hospital of Chicago
      • Principal Investigator: Nancy L Kuntz, MD
      • Contact: Nicole Geanous; Phone Number: 312-227-3019; Email: ngeanous@luriechildrens.org
  • Iowa
    • Iowa City, Iowa, United States, 52242
      • Recruiting
      • University Of Iowa
      • Contact: Laura Knosp; Phone Number: 319-384-6277; Email: laura-knosp@uiowa.edu
      • Principal Investigator: Dimah Saade, MD
  • Massachusetts
    • Worcester, Massachusetts, United States, 01608
      • Recruiting
      • University of Massachusetts Chan Medical School
      • Contact: Tyler Mola; Phone Number: 978-503-9219; Email: tyler.mola@umassmed.edu
      • Principal Investigator: Eleonora D'Ambrosio, MD
  • Ohio
    • Cincinnati, Ohio, United States, 45229
      • Recruiting
      • Cincinnati Children's
      • Principal Investigator: Cuixia Tian, MD
      • Contact: Angela Edmondson; Phone Number: 513-636-9285; Email: Angela.Edmondson@cchmc.org
  • Oregon
    • Portland, Oregon, United States, 97239
      • Recruiting
      • Oregon Health & Science University
      • Principal Investigator: Erika Finanger, MD
      • Contact: Beata Dyar; Phone Number: 503-494-8216; Email: dyar@ohsu.edu
  • Texas
    • Dallas, Texas, United States, 75390
      • Recruiting
      • The University of Texas Southwestern Medical Center
      • Principal Investigator: Susan Iannaccone, MD
      • Contact: Elaine Most; Phone Number: 214-456-2463; Email: elaine.most@utsouthwestern.edu
  • Virginia
    • Norfolk, Virginia, United States, 23510
      • Recruiting
      • Children's Hospital of The King's Daughters
      • Principal Investigator: Crystal Proud, MD
      • Contact: Erika Paradiso; Phone Number: 757-668-6981; Email: proud.research@chkd.org
    • Richmond, Virginia, United States, 23298
      • Recruiting
      • Children's Hospital of Richmond at Virginia Commonwealth University
      • Principal Investigator: Amy Harper, MD
      • Contact: Falgun Patel; Phone Number: (804) 827-9731; Email: Falgun.Patel@vcuhealth.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 4 years to 11 years (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Part 1 - Key Inclusion Criteria:

• The participant's legal guardian(s) is (are) willing and able to provide written, signed informed consent prior to any study-related procedures; and, where applicable, the minor participant has provided written or verbal assent according to local requirements.
• Is a male at least 4 years of age and less than 12 years of age at consent or 1 to <4 years of age at the time of dosing and ≥ 10 kg at the time of screening.

• Must meet any of the following criteria:

  • DMD gene mutation in exons 18 and above, and a clinical picture consistent with typical DMD with the exception of a participant (Cohort 1b) with DMD gene mutation in exons 12-17.
  • Participant is able to walk 100 meters independently without assistive devices. Cohort 2c participant must be able to walk 10 meters independently without assistive devices. Cohort 1b participant must be able to walk with or without assistive devices.
  • Participant is able to complete the TTSTAND per protocol-specific criteria.
  • Participant has been on a stable dose of systemic glucocorticoids according to the standard of care for at least 12 weeks. Cohort 2c participants must be consistently on or off a stable dose of systemic glucocorticoids according to the standard of care for at least 12 weeks.
  • Clinical laboratory test results, including hepatic and renal function, are within the normal range during screening, or if abnormal, are not clinically significant, in the opinion of the investigator.
  • Documentation is provided at screening visit for participant's adherence to the local country's vaccination schedule. The parent(s) or legal guardian(s) must be willing to have their child receive a meningococcal vaccine, if not already vaccinated.
  • Participant and parent(s)/legal guardian(s) are willing and able to comply with scheduled visits, study intervention administration plan, and study procedures.

Part 2 and 3 Inclusion Criteria:

• The participant's legal guardian(s) is (are) willing and able to provide written, signed informed consent prior to any study-related procedures; and, where applicable, the minor participant has provided written or verbal assent according to local requirements.
• DMD gene mutation with any mutation except for those with deletions or point mutations in exons 8, 9 and/or 10.
• Participant is able to complete the TTSTAND per protocol-specific criteria.
• Clinical laboratory test results, including hepatic and renal function, are within the normal range during screening, or if abnormal, are not clinically significant, in the opinion of the investigator.
• Documentation is provided at screening visit for participant's adherence to the local country's vaccination schedule. The parent(s) or legal guardian(s) must be willing to have their child receive a meningococcal vaccine, if not already vaccinated.
• Participant and parent(s)/legal guardian(s) are willing and able to comply with scheduled visits, study intervention administration plan, and study procedures.
• Is a male at least 1 year of age and ≥ 10 kg at the time of screening.

• Participants 1 to <4 years of age must meet the following criteria:

  • is able to walk 10 meters independently without assistive devices.
  • must be consistently on or off a stable dose of systemic glucocorticoids according to the standard of care for at least 12 weeks.

• Participants 4 years and older must meet the following criteria:

  • are able to walk 100 meters independently without assistive devices.
  • have been on a stable dose of systemic glucocorticoids according to the standard of care for at least 12 weeks.
  • have a NSAA total score ≥16.

Part 1 Exclusion Criteria:

• Participant has any condition that would contraindicate treatment with immunosuppression.
• Participant has received ataluren (a protein restoration therapy) or an exon-skipping therapy for the treatment of DMD within 6 months of study entry or is unable to refrain from taking ataluren or exon-skipping therapy for a duration of 5 years from the time of RGX-202 administration.
• Participant has received any investigational or commercial gene therapy product over his lifetime.
• Participant is currently taking any other investigational intervention (other than corticosteroids) or has taken any other investigational intervention (other than corticosteroids) within 3 months prior to the scheduled Day 1 intervention. If your corticosteroid is vamorolone, the participant will be asked to temporarily convert his daily dosing to prednisolone/prednisone during a short period of time around RGX-202 administration. He will be allowed to revert back to his baseline vamorolone regimen at the original per kilogram dose at which he entered the study and should remain on this for 24 months unless the investigator determines that this is not clinically indicated or possible.
• Participant has impaired cardiac function defined as a left ventricular ejection fraction of < 55% on screening cardiac assessments (echocardiogram or MRI).
• Participant is not a good candidate for the study, in the opinion of the investigator.

Part 2 and 3 Exclusion Criteria:

• Participant has any condition that would contraindicate treatment with immunosuppression.
• Participant has received givinostat within 3 months of study entry or has received ataluren (a protein restoration therapy) or an exon-skipping therapy for the treatment of DMD within 6 months of study entry or is unable to refrain from taking ataluren or exon-skipping therapy for a duration of 5 years from the time of RGX-202 administration.
• Participant has received any investigational or commercial gene therapy product over his lifetime.
• Participant is currently taking any other investigational intervention (other than corticosteroids) or has taken any other investigational intervention (other than corticosteroids) within 3 months prior to the scheduled Day 1 intervention. If your corticosteroid is vamorolone, the participant will be asked to temporarily convert his daily dosing to prednisolone/prednisone during a short period of time around RGX-202 administration. He will be allowed to revert back to his baseline vamorolone regimen at the original per kilogram dose at which he entered the study and should remain on this for 24 months unless the investigator determines that this is not clinically indicated or possible.
• Participant has detectable AAV8 total binding antibodies in serum.
• Participant has impaired cardiac function defined as a left ventricular ejection fraction of < 55% on screening cardiac assessments echocardiogram or MRI).
• Participant is not a good candidate for the study, in the opinion of the investigator.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Part 1: Cohort 1 and 1b: RGX-202 Dose 1; A single IV infusion of RGX-202 at a dose of 1×10^14 GC/kg body weight	Genetic: RGX-202; RGX-202 is a recombinant AAV8 containing a transgene encoding a novel microdystrophin
Experimental: Part 1: Cohort 2, 2c;, and Part 2; and Part 3: RGX-202 Dose 2; A single IV infusion of RGX-202 at a dose of 2x10^14 GC/kg body weight	Genetic: RGX-202; RGX-202 is a recombinant AAV8 containing a transgene encoding a novel microdystrophin

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Part 1 Safety measured by incidence of Adverse Events and Serious Adverse Events	Evaluate incidences of AEs and SAEs	52 weeks
Part 2 and 3 Pharmacodynamic	Proportion of participants whose RGX-202 microdystrophin protein expression determined in their muscle biopsy is ≥ 10%	12 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to Walk/Run 10 meters (TTWR)	Values will include time (seconds) and velocity (meters/second)	52 Weeks (Part 1) and 104 Weeks (Part 2 &3)
Part 2 and 3: Stride velocity 95th centile	Assessment of peak ambulatory performance captured by wearable activity monitoring device. For velocity measures, higher values indicate greater function.	104 weeks
Part 1 Vector Shedding	Vector genome concentrations as measured by polymerase chain reaction [PCR] to RGX-202 deoxyribonucleic acid [DNA] in urine.	52 weeks
Part 2 and 3 Microdystrophin protein expression	RGX-202 microdystrophin protein levels determined in muscle biopsy.	12 weeks
Part 2 and 3 Safety measured by incidence of Adverse Events and Serious Adverse Events	Evaluate incidences of AEs and SAEs	104 weeks
Time to Stand (TTSTAND)	Values will include time (seconds) and velocity (tasks/second)	52 Weeks (Part 1); 52 and 104 Weeks (Part 2 &3)
Time to Climb 4 Stairs (TTCLIMB)	Values will include time (seconds) and velocity (tasks/second)	52 Weeks (Part 1); 52 and 104 Weeks (Part 2 &3)
North Star Ambulatory Assessment (NSAA)	Performance-based assessment of muscle strength and function using a 17-item scale, with all items rated 0,1, or 2, with higher score indicating better performance. The NSAA total score is the sum of the 17 items, ranging from 0 to 34. NSAA linearized score ranges from 0 to 100.	52 Weeks (Part 1) and; 52 and 104 Weeks (Part 2 &3)
Peabody Developmental Motor Scale, Third Edition (PDMS-3); Body Control Subtest	The PDMS-3 is a norm-referenced developmental assessment that measures motor skills of young children. The Body Control subtest measures the child's ability to maintain balance and postural reactions in a variety of positions. Motor skills appropriate for the child's developmental level are administered and rated 0, 1, or 2, with higher score indicating better performance. Body Control subtest total raw scores range from 0 to 112. Age equivalent and scaled scores will also be generated. PDMS-3 Body Control subtests is included for participants age <4 at screening.	52 Weeks (Part 1); 52 and 104 Weeks (Part 2 &3)
Peabody Developmental Motor Scale, Third Edition (PDMS-3); Body Transport Subtest	The PDMS-3 is a norm-referenced developmental assessment that measures motor skills of young children. The Body Transport subtest measures the child's ability to move from one place to another, including walking, running, jumping forward, and skipping. Motor skills appropriate for the child's developmental level are administered and rated 0, 1, or 2, with higher score indicating better performance. Body Transport subtest total raw score ranges from 0 to 63. Age equivalent and scaled scores will also be generated. PDMS-3 Body Control subtests is included for participants age <4 at screening.	52 Weeks (Part 1); 52 and 104 Weeks (Part 2 &3)
Part 1 Microdystrophin protein expression	RGX-202 microdystrophin protein levels determined in muscle biopsy.	12 weeks
Part 1 Pharmacokinetics (PK)	Vector genome concentrations as measured by polymerase chain reaction [PCR] to RGX-202 deoxyribonucleic acid [DNA] in muscle and serum.	12 weeks (muscle) and 52 weeks (serum)
Part 2 and 3 Pharmacokinetics (PK)	Vector genome concentrations as measured by polymerase chain reaction [PCR] to RGX-202 deoxyribonucleic acid [DNA] in muscle and serum.	12 weeks (muscle) 52 weeks (serum)
Part 2 and 3 Vector Shedding	Vector genome concentrations as measured by polymerase chain reaction [PCR] to RGX-202 deoxyribonucleic acid [DNA] in urine, feces, and saliva.	52 weeks

Collaborators and Investigators

• Sponsor: REGENXBIO Inc.

Publications and helpful links

Helpful Links

• For additional information on how to participate (or be considered for the study) please follow this link.
• Related Info

Study record dates

Study Major Dates

• Study Start (Actual): January 4, 2023
• Primary Completion (Estimated): February 1, 2026
• Study Completion (Estimated): August 1, 2028

Study Registration Dates

• First Submitted: January 4, 2023
• First Submitted That Met QC Criteria: January 12, 2023
• First Posted (Actual): January 20, 2023

Study Record Updates

• Last Update Posted (Estimated): December 17, 2025
• Last Update Submitted That Met QC Criteria: December 12, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Duchenne Muscular Dystrophy; DMD; Gene therapy; Duchenne
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Nervous System Diseases; Muscular Diseases; Neuromuscular Diseases; Genetic Diseases, Inborn; Genetic Diseases, X-Linked; Muscular Disorders, Atrophic; Muscular Dystrophies; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Muscular Dystrophy, Duchenne
• Other Study ID Numbers: RGX-202-1101

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No