AFFINITY BEYOND®: Anti-AAV8 Antibody Assessment Study of Boys with Duchenne Muscular Dystrophy (DMD)
REGENXBIO is currently recruiting participants for a non-interventional study, called AFFINITY BEYOND®, to understand how many boys with Duchenne might have AAV8 antibodies.
If you enroll your child in AFFINITY BEYOND, your child’s AAV8 antibody status will be tested and provided to you. Your child’s AAV8 antibody result can help determine potential eligibility for the AFFINITY DUCHENNE gene therapy study. Results of this study do not guarantee acceptance into AFFINITY DUCHENNE. To learn more, visit the AFFINITY BEYOND study page (identifier NCT05683379) on ClinicalTrials.gov.
Key eligibility criteria include boys who:
- Are 0 to 11 years old
- Has a genetic diagnosis of Duchenne Muscular Dystrophy
- Have not received any investigational or commercial gene therapy product over their lifetime
This study consists of:
- A phone/video interview to begin the informed consent process and to provide medical history
- A home health visit to a collect blood sample for antibody testing
- A phone/video call for communication of AAV8 antibody test results
The study may enroll up to 200 U.S. participants.
Participation in AFFINITY BEYOND does not require travel to a study site; eligible participants will be able to take part in the study remotely and close to home. REGENXBIO will cover all reasonable study-related costs.
Participants who test negative for AAV8 may be referred to a site for the AFFINITY DUCHENNE® trial if they would like to be evaluated for eligibility in that gene therapy study. The results of this blood test cannot be used to determine eligibility for studies not affiliated with REGENXBIO, as different studies use different antibody tests.
Results of AFFINITY BEYOND do not guarantee enrollment in the AFFINITY DUCHENNE trial.
What are antibodies?
Antibodies are proteins produced by the immune system as part of the body’s defense against foreign substances such as bacteria or viruses.5
Antibodies provide protection against unwanted or foreign substances when they enter the body. Those antibodies remain in the body and protect against that substance in case the body is exposed to it again in the future.5
What do antibodies have to do with gene therapy?
If a person has been exposed to naturally occurring adeno-associated viruses (AAVs), one’s immune system may have antibodies that recognize those AAVs, such as the AAV vector used in a gene therapy. Once the immune system recognizes the AAV vector, antibodies may neutralize the gene therapy vector (make it inactive) before it can deliver the therapeutic gene into the cell. When these antibodies are present in a potential candidate for a gene therapy study, that person may not be eligible to participate.6
Different gene therapies use different vectors to deliver the gene to cells; the presence of certain antibodies may prevent a person from participating in one study but not another.
Adeno-Associated Virus (AAV) Vectors are not known to cause disease in humans.6 People can be exposed to AAVs in the environment without getting sick.
5. Antibody. National Institutes of Health, National Human Genome Research Institute; 2025. https://www.genome.gov/genetics-glossary/Antibody. Accessed January 15, 2025. | 6. AAV immune challenges. Parent Project Muscular Dystrophy (PPMD); 2025. https://www.parentprojectmd.org/library/aav-immune-challenges/. Accessed January 15, 2025.
