A clinical study of RGX-202, an investigational gene therapy, for boys with Duchenne

Duchenne is a serious condition that affects the muscles, causing them to become weaker and deteriorate over time. Individuals with Duchenne face challenges with mobility, typically requiring a wheelchair by adolescence due to progressive muscle loss. As the disease progresses, it may also affect the respiratory muscles leading to breathing difficulties. The heart muscle can also be affected, which may lead to a condition called cardiomyopathy, where the heart has trouble pumping blood effectively.

Duchenne primarily affects boys, occurring in about 1 in every 5,000 live male births worldwide, and rarely affects females. In the United States, around 15,000 boys are living with Duchenne, and there are approximately 300,000 people affected globally.

Duchenne is a genetic condition caused by changes in the DNA (mutations) within the dystrophin gene, located on the X chromosome. This gene is responsible for producing the dystrophin protein, which plays an important role in keeping muscle cells intact. Without enough dystrophin, muscles gradually become damaged and weaker.

Glucocorticoids are commonly used to treat Duchenne and can help slow down the decline in muscle strength for some patients, potentially reducing the risk of scoliosis and supporting lung function. However, glucocorticoids do not treat the underlying cause of the disease or prevent serious skeletal and heart complications, and they can have side effects. Other supportive measures are also available to help manage symptoms and improve quality of life. These may include physical therapy, orthopedic care, assistive devices, heart monitoring, and respiratory support.

Additionally, several approaches have been approved for the treatment of Duchenne in the last few years. These therapies are indicated for individuals who have the specific genetic mutations they target.

Clinical trials are research studies that evaluate the safety, tolerability, and effectiveness of investigational therapies. They play a crucial role in developing treatments with the aim of improving patient health. Watch our video to learn more. Clinical trials are essential to ensure treatments are safe for the public, to determine optimal administration methods, and to enhance scientific knowledge of diseases for better health outcomes.

The term ‘investigational medicine’ refers to a medication under research that has not yet received approval from regulatory authorities, such as the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA). As a result, it can only be utilized in clinical research studies and is not available for general use. These studies aim to evaluate the safety and efficacy of an investigational medicine before it can potentially become approved for widespread medical use.

Clinical trials have specific patient criteria, known as clinical trial eligibility criteria, which determine who can participate. These criteria are designed to identify individuals with specific symptoms or a particular diagnosis, while excluding those for whom trial participation would be inappropriate. By enrolling participants who are similar in their characteristics, such as the type of mutation and disease progression, clinical trial eligibility criteria ensure that the outcomes of the trial accurately reflect the effects of the investigational drug being evaluated. Furthermore, these criteria play a crucial role in ensuring the safety of the participants involved.

Clinical trials carry potential risks like treatment side effects, unknown treatment effectiveness, extra medical tests, and time commitments. These are carefully assessed and monitored, and risks and benefits are weighed by the Ethics Committees reviewing and approving the trial’s conduct. Clinical trials follow a specific set of standards and are closely regulated to help ensure the safety of all participants. Safety measures and informed consent processes help participants understand and manage these risks.

People participate in clinical trials for different reasons. Some may take part because they seek to learn more about their disease and the effects of potential new treatments on their body. Others volunteer to take part because they want to help researchers learn more about (the treatment of) a disease to potentially help themselves and others in the future. Others volunteer to contribute to the research of new investigational medicines that could potentially benefit themselves now or others in the future.

Yes. The participants, and their parents or caregivers receive detailed trial information, can ask questions, and decide freely. Informed consent ensures they understand the trial and can withdraw at any time without affecting the care or rights of the participants.

In this study, the gene therapy will be delivered through a one-time infusion. If the participant decides to withdraw after receiving the gene therapy, the gene therapy cannot be removed from the body. Gene therapy does not wash out of the body over time and cannot be reversed.

At myTomorrows, we assign a dedicated Patient Navigator to each patient, parent or caregiver. The Patient Navigator provides comprehensive support throughout the entire process, from assessing potential trial eligibility to addressing questions you may have during the participant’s clinical trial recruitment journey. Our Patient Navigators have medical backgrounds and are trained to explain complex medical concepts. However, they cannot give medical advice and do not replace the role of a physician. Our Patient Navigator team offers dependable, multilingual support covering all time zones, ensuring effective communication and understanding with patients from diverse backgrounds.

Yes, our services of providing information about clinical trials or other pre-approval treatment options and how to access them are always free of charge.

The purpose of this research is to study the safety, tolerability, pharmacodynamics, pharmacokinetics, and efficacy of a one-time intravenous (IV) dose of RGX-202 gene therapy in boys with Duchenne.

For more information about the trial, visit the study page at https://clinicaltrials.gov/study/NCT05693142

RGX-202 is an investigational gene therapy that has been developed by REGENXBIO as a potential one-time treatment for Duchenne. It is designed to use a viral (AAV) vector called NAV® AAV8 to deliver a transgene that provides the instructions for muscle cells to make a novel microdystrophin protein.

Microdystrophin is a shorter version of dystrophin, which is a naturally occurring protein needed for muscles to work properly. Researchers use microdystrophins in gene therapy because the gene that makes full-length dystrophin is too large to fit into the AAV vector that delivers the treatment.

Once the microdystrophin protein is made, it may protect muscle function.

Yes, all participants in the clinical research study will receive the investigational therapy.

Eligible participants must:

• Be male and at least one year of age.
• Have a confirmed diagnosis of Duchenne based on genotyping and clinical manifestations.
• Be able to walk independently without assistive devices for at least 100 meters in patients aged 4 years or older or at least 10 meters in patients aged 1 to 4 years.
• Be able to stand up from lying on his back without any help (within 3 – 7 seconds in patients aged 4 years or older, and no time limit for patients aged 1 to 4 years).
• Weigh at least 10 Kg (22Ibs) or more.
• Do not have pre-existing antibodies to the gene therapy (AAV8 capsid), potential participants will be tested before dosing.
• Have NOT received any investigational or commercial gene therapy product over his lifetime.

There are additional requirements, which, if connected with a trial site, the study team will discuss with potentially eligible individuals interested in participating.

The study is currently being conducted in the USA and Canada. Interested patients residing outside of USA/CAN may be evaluated for potential eligibility. If deemed eligible for screening, the participant could be connected to the study site closest to him to minimize the burden. If the participant needs to travel, arrangements can be made to cover reasonable costs and meal expenses to facilitate his participation. The study site and a patient concierge service can work with you to ensure the participant receives this. 

Participation in this study will last approximately 2 years after receiving one dose of RGX-202. The study will include:

• Informed Consent: The parent(s), legal guardian(s) or adult participant will be asked to review and sign an Informed Consent Form, which explains the potential risks and benefits of the participant’s enrollment in the study.    The study doctor will review this with you to help you decide whether you wish the participant to take part in this trial.
• Screening period: During screening, certain assessments and tests are performed to determine eligibility.  These could include function tests, an MRI, and a muscle biopsy.  The study team will review the participant’s health and possibly request medical records. The process for determining eligibility may take up to 2 months.
• Pre-infusion: Before receiving the investigational drug RGX-202, the participant will receive a prophylactic immunosuppression regimen to minimize the risk of an immune response to the treatment. The day before the administration procedure, the investigator will perform an evaluation to ensure the participant’s continuing good health and candidacy for dosing.
• Infusion: All participants will receive a single intravenous (IV) dose of RGX-202.
• Follow-up: during the 2 years of follow-up, the participant will have multiple visits to the study site to monitor the participant’s health and to complete different tests and assessments to see how the therapy may be working.