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Study on the Effects of Casimersen and Golodirsen for Patients with Duchenne Muscular Dystrophy Amenable to Exon 45 or 53 Skipping

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying a condition called Duchenne Muscular Dystrophy (DMD), which is a genetic disorder characterized by progressive muscle weakness and degeneration. The study is investigating two treatments, CASIMERSEN (SRP-4045) and GOLODIRSEN (SRP-4053), which are designed to help improve muscle function in patients with specific genetic mutations that allow for exon 45 or 53 skipping. These treatments are given as a solution through an intravenous infusion, which means they are administered directly into the bloodstream.

The purpose of the study is to evaluate the effectiveness and safety of these treatments compared to a placebo. Participants will receive either the active treatment or a placebo without knowing which one they are receiving. The study will monitor changes in the ability to walk, endurance, and overall muscle function over time. The study will also include an open-label extension, where all participants may receive the active treatment after the initial phase. The study will last for a period of time, during which participants will have regular check-ups and assessments to track their progress.

Throughout the study, participants will undergo various tests to measure muscle function, including a walking test known as the 6-Minute Walk Test (6MWT). This test helps assess how far a person can walk in six minutes, which is an indicator of their muscle strength and endurance. The study aims to provide valuable information on how these treatments can potentially benefit individuals with Duchenne Muscular Dystrophy and improve their quality of life.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, participation begins with a double-blind period. This means that neither the patient nor the researchers know who is receiving the actual medication or a placebo.

    The study involves two investigational medications: casimersen (SRP-4045) and golodirsen (SRP-4053), both administered through an intravenous infusion. This means the medication is given directly into a vein.

  2. Step 2

    Medication administration

    During the double-blind period, the patient receives either the investigational medication or a placebo. The placebo is a substance with no active medication, used to compare the effects.

    The medications are administered as a solution for infusion, which involves a liquid form of the drug being slowly introduced into the bloodstream.

  3. Step 3

    Evaluation of effects

    The main goal during this period is to evaluate the effect of the medications on walking ability, endurance, and muscle function. This is measured by a test called the 6-minute walk test (6MWT), which assesses how far the patient can walk in six minutes.

    The primary endpoint is the change from the baseline measurement at Week 96 in the 6MWT.

  4. Step 4

    Open-label extension

    After the double-blind period, the study includes an open-label extension. In this phase, all patients receive the investigational medication, and both the patient and researchers know which treatment is being administered.

    This phase allows for further evaluation of the medication's long-term effects and safety.

  5. Step 5

    Monitoring and assessments

    Throughout the study, regular monitoring and assessments are conducted. These include laboratory tests, physical examinations, and evaluations of heart function using an electrocardiogram (ECG).

    The study also monitors for any side effects or adverse events to ensure patient safety.

  6. Step 6

    Study completion

    The study is estimated to conclude by September 2025. At the end of the study, the collected data will be analyzed to determine the efficacy and safety of the investigational medications.

    The results will contribute to understanding the potential benefits and risks of the treatments for patients with Duchenne Muscular Dystrophy.

Who can join the trial?

11 criteria

  • The patient must be a male with a confirmed diagnosis of **Duchenne Muscular Dystrophy (DMD)**, which is a genetic disorder that affects muscles.
  • The patient must have a specific type of genetic change called an **out-of-frame deletion** that can be treated by skipping either **Exon 45** or **Exon 53**. This must be confirmed by a genetic test before starting the study.
  • The patient must be willing to agree to participate in the study, and their parent(s) or legal guardian(s) must provide written consent.
  • The patient must be between 6 and 13 years old if they can skip Exon 53, or between 7 and 13 years old if they can skip Exon 45.
  • The patient must have stable lung function, meaning their lungs work well enough and are not expected to get worse during the study.
  • The patient must have healthy right and left **biceps brachii muscles**, which are muscles in the upper arm, or two other upper arm muscle groups.
  • The patient must have been taking a stable dose of **oral corticosteroids**, which are medications that reduce inflammation, for at least 24 weeks before the study starts, and the dose should stay the same during the study.
  • If the patient is taking certain heart medications, like **ACE inhibitors** or **beta-blockers**, they must have been on a stable dose for at least 12 weeks before the study starts, and the dose should stay the same during the study.
  • The patient must be able to walk a distance of 300 to 450 meters without help during a test called the **6-Minute Walk Test (6MWT)**, which measures how far they can walk in six minutes. This must be confirmed at two different times before the study starts.
  • If the patient is sexually active, they must agree to use a male condom during sexual activity for the entire study and for 90 days after the last dose. Their partner must also use a medically approved form of birth control during this time.
  • The patient's parent(s) or legal guardian(s) must be able to understand and follow all the study requirements.

Who cannot join the trial?

3 criteria

  • Patients who do not have **Duchenne Muscular Dystrophy** that can be treated by skipping **Exon 45** or **Exon 53**. This means the specific type of genetic change in the muscle disease must be present.
  • Females cannot participate in this study. Only males are eligible.
  • Patients who are not considered part of a vulnerable population. This typically refers to groups that may need special protection or care.
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Investigated drugs

  • SRP-4045

    is a medication being studied for its potential to help patients with Duchenne Muscular Dystrophy. This condition affects muscle function, and the medication aims to improve walking ability, endurance, and overall muscle performance.

  • SRP-4053

    is another medication included in the study for Duchenne Muscular Dystrophy. Like SRP-4045, it is being tested to see if it can enhance the ability to walk, increase endurance, and improve muscle function in patients with this condition.

What is already known about the treatment

  • SRP-4045

    This medication is administered through intravenous infusion and is currently being studied in clinical trials for its effectiveness in treating Duchenne Muscular Dystrophy (DMD) in patients amenable to exon 45 skipping. It is not yet widely available in medical practice, as it is still under investigation. The main therapeutic indication is to improve muscle function and endurance in DMD patients. At the molecular level, SRP-4045 works by skipping exon 45 during the mRNA processing of the dystrophin gene, which helps produce a functional form of the dystrophin protein. It is classified as an antisense oligonucleotide.

  • SRP-4053

    This medication is also administered via intravenous infusion and is being evaluated in clinical trials for its potential to treat Duchenne Muscular Dystrophy in patients who can benefit from exon 53 skipping. Like SRP-4045, it is not yet approved for general medical use. The primary therapeutic goal is to enhance muscle function and endurance in affected individuals. SRP-4053 operates at the molecular level by skipping exon 53 in the dystrophin gene's mRNA, facilitating the production of a functional dystrophin protein. It belongs to the pharmacological class of antisense oligonucleotides.

Investigated diseases

Duchenne Muscular Dystrophy – Duchenne Muscular Dystrophy is a genetic disorder characterized by progressive muscle degeneration and weakness. It primarily affects boys and is caused by mutations in the dystrophin gene, which is crucial for maintaining muscle cell structure. The disease typically begins in early childhood, with symptoms such as difficulty walking, frequent falls, and challenges in rising from a sitting or lying position. As the condition progresses, muscle weakness spreads to the arms, neck, and other areas, leading to increased difficulty in performing daily activities. Over time, individuals may experience complications related to the heart and respiratory muscles. The progression of muscle weakness varies among individuals, but it generally leads to significant mobility challenges.
Trial detailsLast updated 7 Oct 2026
Age0-17PhasePhase IIITrial ID2024-514698-23-00Protocol code4045-301Estimated enrolment328 patientsSponsorSarepta Therapeutics Inc.

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