A new clinical trial is now recruiting boys with Duchenne muscular dystrophy (DMD) to investigate the prevalence of antibodies to adeno-associated virus (AAV) serotype 8 (AAV8).

The observational screening study, called AFFINITY BEYOND (NCT05683379), will use the prevalence data to help identify potential participants for clinical trials of investigational gene therapy for DMD using a diagnostic test called AAV8 DetectCDX.

An estimated 200 boys with DMD aged less than 12 years will be recruited for the trial. The study will consist of an initial phone or video interview to provide electronic consent to participation in the study along with a discussion of medical history. Afterward, a single home health visit will be performed to collect a blood sample for the AAV. Then a final phone or video call will inform the participants of the results of the antibody test results.

Continue Reading

In addition to the primary outcome of AAV8 prevalence, the prevalence of AAV serotype 9 (AAV9) antibodies will also be assessed. To be eligible for the study, participants must have a diagnosis of DMD, be less than 12 years old, and must not have received a prior gene therapy or participated in a gene therapy trial.

Read more about experimental DMD therapies.

Participants are being recruited at Rare Disease Research, an independent clinical research site in Atlanta, Georgia. The study began in December 2022 and is estimated to complete by December 2024.

The study is sponsored by REGENXBIO Inc., a clinical-stage biotechnology company focused on curing diseases using AAV gene therapy. REGENXBIO is currently developing an AAV8 gene therapy called RGX-202 which is being tested in a phase 1/2 clinical trial called AFFINITY DUCHENNE (NCT05693142).

“RGX-202 is designed to deliver a transgene for a novel microdystrophin that includes the functional elements of the C-Terminal (CT) domain found in naturally occurring dystrophin. Presence of the CT domain has been shown in preclinical studies to recruit several key proteins to the muscle cell membrane, leading to improved muscle resistance to contraction-induced muscle damage in dystrophic mice,” the company’s website says.


AFFINITY BEYOND: Anti-AAV8 antibody assessment study of boys with DMD. ClinicalTrials.gov. January 13, 2023.

Therapeutic programs. Regenxbio.com. Accessed February 9, 2023.