A Study to Evaluate AAV9 Neutralizing Antibody Seroconversion in Household Contacts.

Study Overview
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Brief Summary
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This study will include male and female participants who live or work in the same household as a patient in one of the fordadistrogene movaparvovec interventional studies. Up to 5 participants from the same household may be enrolled. The objective is to estimate the likelihood of NAb seroconversion to AAV9 in household contacts of a patient in one of the interventional studies who is treated with fordadistrogene movaparvovec gene therapy.

Detailed Description
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This single center study will include approximately 50 to 250 participants and is designed to estimate the likelihood of NAb seroconversion to AAV9 because of exposure to shed viral vector material released by a DMD patient treated with fordadistrogene movaparvovec in an interventional study. Eligible participants will undergo a blood draw provided by a Home Health Care Vendor at three home visits. The total duration of participation in this study is about 4 months, including up to 48 days for the screening/baseline period and about 56 days after the DMD patient of the same household is dosed with the investigational gene therapy in the interventional study. To maintain the blind in the blinded interventional studies, all C3391007 study participants and investigators as well as the sponsor will remain blinded to the Cohort assignment of the interventional study patient until the interventional study becomes unblinded.

Official Title
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A Low-Interventional Study Of AAV9 Neutralizing Antibody Seroconversion in Household Contacts of Participants Within the C3391003 Clinical Trial

Conditions
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Household Contacts

Intervention / Treatment
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* Other: Blood Draw


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Males or females who weigh at least 9 kg. Anticipated to be living or working in the same household as a patient in one of the fordadistrogene movaparvovec interventional studies for at least 4 months. Anticipated to have > 10 hours of contact per week and expected to have direct contact with the interventional study patient. The interventional patient is dosed in the interventional study. Exclusion Criteria: Prior treatment with gene therapy utilizing AAV vectors of any serotype.

Ages Eligible for Study
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Minimum Age: 0 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| All participants<br>Household contacts of a DMD patient in an interventional study of fordadistrogene movaparvovec. | Other: Blood Draw<br>* Blood Samples for NAb and ADA to AAV9<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To quantify the proportion of participants (previously seronegative for NAb to AAV9) who develop NAb to AAV9 (ie, seroconversion). | Development of NAb to AAV9 (ie, NAb seroconversion). | Day 28 after the interventional study patient is dosed | 
| To quantify the proportion of participants (previously seronegative for NAb to AAV9) who develop NAb to AAV9 (ie, seroconversion). | Development of NAb to AAV9 (ie, NAb seroconversion). | Day 56 after the interventional study patient is dosed | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To quantify the proportion of participants (previously seronegative for ADA to AAV9) who develop ADA to AAV9. | Development of ADA to AAV9 (ie, ADA seroconversion). | Day 28 after the interventional study patient is dosed | 
| To quantify the proportion of participants (previously seronegative for ADA to AAV9) who develop ADA to AAV9. | Development of ADA to AAV9 (ie, ADA seroconversion). | Day 56 after the interventional study patient is dosed | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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seroconversion, viral shedding, DNA vector shedding