June 8, 2023

Dear U.S. Duchenne Community,

Today we are sharing an update with you about the ENVISION study (SRP-9001-303). 

We have been invited to share a full description of this study by Parent Project Muscular Dystrophy, and a webinar date will be announced by them in the coming days. More information about this study may be found on clinicaltrials.gov (NCT05881408)

ENVISION is a large study of SRP-9001 (delandistrogene moxeparvovec) in older ambulatory and non-ambulatory individuals living with Duchenne muscular dystrophy that is intended to support global regulatory approval. The study has a double blind, 72-week placebo control design with crossover. This means that half of the enrolled participants would be dosed with SRP-9001 in the first part of the study while the other half receives placebo. After 72 weeks, each participant will cross over, in other words, they would receive the opposite of what they received originally and observed for an additional 52 weeks.

ENVISION is a key component in our global regulatory strategy to reach the broadest patient population possible, as quickly as possible. As part of this strategy in the U.S., the ENVISION study is proposed to serve as the required post-marketing confirmatory trial to verify and describe clinical benefit in the non-ambulatory population. Our ability to bring this study to conclusion will be considered by the FDA at the time of the EMBARK study readout. 

Based on our current understanding of regulatory expectations, we have made some changes in our operational planning for the study. In the United States, ENVISION will enroll a limited number of participants into only the non-ambulatory cohort for a limited time, likely until mid-Autumn. Both cohorts, older ambulatory and non-ambulatory, will enroll outside of the United States. Given the limited time for U.S. enrollment, we expect that some study sites that were planning to participate in the study may not open and some families who were interested in participating in the U.S. will not have the chance to enroll. 

We want to take a moment to explain. Our hope is that the FDA will consider the broadest possible label if there is a positive read-out of the EMBARK study next year. If this happens, it may occur during enrollment, dosing, and data collection in the first part of the 72-week placebo controlled ENVSION study. If participants drop out of ENVISION because the therapy is approved in the U.S. for a broader population, it reduces the chances of study success and may lessen the opportunity to bring SRP-9001 forward for a broad population in the U.S. and across the world. 

If a therapy is approved, it is not an option to ask people in a clinical study to delay treatment for the better part of 18 months to protect a study. We know in our hearts and from the data how valuable time is to someone living with Duchenne. 

In the U.S. and worldwide, we hope that this decision will lead to more people with Duchenne being dosed with this investigational medicine or potentially approved therapy in a quicker amount of time, while also protecting the integrity of the ENVISION study which, when complete, will generate enormously important data to support regulatory approvals and patient access. 

The decision to limit U.S. enrollment in ENVISION is based on careful consideration. We will be flexible and adjust our plans if our underlying assumptions change. 

We are enormously thankful for every individual who comes forward to participate in clinical research. We hope that you understand the urgency that shaped this approach, recognizing that the impact of this change may directly affect your family’s hope to join the ENVISION study.  Please reach out to [email protected] if you have questions that might be answered by our team.

Sincerely,

The Patient Affairs Team