Gene Therapy for Duchenne Muscular Dystrophy (HORIZON Trial)
Palo Alto (17 mi)Age: < 18
Sex: Male
Travel: May be covered
Time Reimbursement: Varies
Trial Phase: Phase 1
Recruiting
Sponsor: Sarepta Therapeutics, Inc.
No Placebo Group
Approved in 1 jurisdiction
Trial Summary
What is the purpose of this trial?This is a gene transfer therapy study evaluating the safety of and delandistrogene moxeparvovec dystrophin protein expression from delandistrogene moxeparvovec following therapeutic plasma exchange (plasmapheresis) in ambulatory male participants with DMD and pre-existing antibodies to AAVrh74 over a period of 58 weeks.
Is delandistrogene moxeparvovec a promising treatment for Duchenne Muscular Dystrophy?Yes, delandistrogene moxeparvovec is a promising treatment for Duchenne Muscular Dystrophy. It is the first gene therapy approved in the USA for young children with this condition. The treatment helps deliver a special version of a protein called dystrophin, which is important for muscle function. Studies show that it can improve muscle strength and stability, potentially slowing down the disease's progression.12456
What safety data is available for gene therapy in Duchenne Muscular Dystrophy?The safety data for delandistrogene moxeparvovec (also known as SRP-9001, Elevidys, and other names) includes findings from clinical trials. In a Phase 2 study, common treatment-related adverse events (TRAEs) were vomiting, decreased appetite, and nausea, which mostly occurred within the first 90 days and resolved. Long-term safety and functional outcomes have been evaluated, indicating that the therapy may positively alter disease progression in patients with DMD. The therapy has been approved in the USA for ambulatory pediatric patients aged 4 through 5 years with a confirmed mutation in the DMD gene.45678
What data supports the idea that Gene Therapy for Duchenne Muscular Dystrophy is an effective treatment?The available research shows that Gene Therapy for Duchenne Muscular Dystrophy, specifically delandistrogene moxeparvovec, has been effective in increasing the expression of a key protein in muscle cells. In a study, children who received the treatment showed improvements in their ability to move and perform physical tasks compared to those who did not receive it. For example, in one part of the study, younger children who received the treatment improved by 2.5 points in a movement assessment, while those who did not receive it improved by only 0.9 points. Additionally, the treatment was shown to stabilize motor function for up to two years. This suggests that the treatment can help maintain or improve muscle function in children with Duchenne Muscular Dystrophy.34568
Do I have to stop taking my current medications for the trial?The trial protocol does not specify if you need to stop taking your current medications. However, you must be on a stable daily dose of oral corticosteroids for at least 12 weeks before the trial and continue this dose throughout the study.
Eligibility Criteria
This trial is for ambulatory male participants with Duchenne Muscular Dystrophy (DMD) who already have antibodies to AAVrh74. The study spans 58 weeks and involves a gene transfer therapy followed by plasmapheresis, a process that filters the blood.Inclusion Criteria
My genetic test shows a specific mutation in the DMD gene, not including exon 8 or 9.
I can participate in tests that assess my muscle movements.
I have been officially diagnosed with Duchenne Muscular Dystrophy.
Exclusion Criteria
My heart's pumping ability is lower than normal.
Treatment Details
The trial tests delandistrogene moxeparvovec's safety and its ability to express dystrophin protein in patients with DMD after they undergo therapeutic plasma exchange (plasmapheresis).
1Treatment groups
Experimental Treatment
Group I: Delandistrogene Moxeparvovec After Plasmapheresis ProcedureExperimental Treatment2 Interventions
Participants will receive a single intravenous (IV) infusion of delandistrogene moxeparvovec on Day 1 after plasmapheresis procedure if AAVrh74 antibodies are sufficiently low.
delandistrogene moxeparvovec is already approved in United States for the following indications:
🇺🇸 Approved in United States as Elevidys for:
- Duchenne muscular dystrophy (DMD) in ambulatory and non-ambulatory patients aged 4 years and older with a confirmed mutation in the DMD gene
Find a clinic near you
Research locations nearbySelect from list below to view details:
Washington University School of Medicine in St. LouisSaint Louis, MO
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Who is running the clinical trial?
Sarepta Therapeutics, Inc.Lead Sponsor
References
In vivo expression of full-length human dystrophin from adenoviral vectors deleted of all viral genes. [2012]Adenoviral vectors have been shown to effect efficient somatic gene transfer in skeletal muscle and thus offer potential for the development of therapy for Duchenne muscular dystrophy (DMD). Efficient transfer of recombinant genes has been demonstrated in skeletal muscle using recombinant adenoviruses deleted of E1. Application of this vector system to the treatment of DMD is limited by the vector immunogenicity, as well as by size constraints for insertion of recombinant genes, precluding the incorporation of a full-length dystrophin minigene construct. We describe in this study the use of helper adenovirus to generate a recombinant vector deleted of all viral open reading frames and containing a full-length dystrophin minigene. We show that this deleted vector (delta vector) is capable of efficiently transducing dystrophin in mdx mice, in myotubes in vitro and muscle fibers in vivo. Our modification of adenoviral vector technology may be useful for the development of gene therapies for DMD and other diseases.
AAV vector-mediated microdystrophin expression in a relatively small percentage of mdx myofibers improved the mdx phenotype. [2012]Duchenne muscular dystrophy (DMD) is a lethal disorder of skeletal muscle caused by mutations in the dystrophin gene. Adeno-associated virus (AAV) vector-mediated gene therapy is a promising approach to the disease. Although a rod-truncated microdystrophin gene has been proven to ameliorate dystrophic phenotypes, the level of microdystrophin expression required for effective gene therapy by an AAV vector has not been determined yet. Here, we constructed a recombinant AAV type 2 vector, AAV2-MCKDeltaCS1, expressing microdystrophin (DeltaCS1) under the control of a muscle-specific MCK promoter and injected it into TA muscles of 10-day-old and 5-week-old mdx mice. AAV2-MCKDeltaCS1-mediated gene transfer into 5-week-old mdx muscle resulted in extensive and long-term expression of microdystrophin and significantly improved force generation. Interestingly, 10-day-old injected muscle expressed microdystrophin in a limited number of myofibers but showed hypertrophy of microdystrophin-positive muscle fibers and considerable recovery of contractile force. Thus, we concluded that AAV2-MCKDeltaCS1 could be a powerful tool for gene therapy of DMD.
Assessment of Systemic Delivery of rAAVrh74.MHCK7.micro-dystrophin in Children With Duchenne Muscular Dystrophy: A Nonrandomized Controlled Trial. [2021]Micro-dystrophin gene transfer shows promise for treating patients with Duchenne muscular dystrophy (DMD) using recombinant adeno-associated virus serotype rh74 (rAAVrh74) and codon-optimized human micro-dystrophin driven by a skeletal and cardiac muscle-specific promoter with enhanced cardiac expression (MHCK7).
Expression of SRP-9001 dystrophin and stabilization of motor function up to 2 years post-treatment with delandistrogene moxeparvovec gene therapy in individuals with Duchenne muscular dystrophy. [2023]Introduction: Delandistrogene moxeparvovec (SRP-9001) is an investigational gene transfer therapy designed for targeted expression of SRP-9001 dystrophin protein, a shortened dystrophin retaining key functional domains of the wild-type protein. Methods: This Phase 2, double-blind, two-part (48 weeks per part) crossover study (SRP-9001-102 [Study 102]; NCT03769116) evaluated delandistrogene moxeparvovec in patients, aged ≥4 to <8 years with Duchenne muscular dystrophy. Primary endpoints (Part 1) were change from baseline (CFBL) in SRP-9001 dystrophin expression (Week 12), by Western blot, and in North Star Ambulatory Assessment (NSAA) score (Week 48). Safety assessments included treatment-related adverse events (TRAEs). Patients were randomized and stratified by age to placebo (n = 21) or delandistrogene moxeparvovec (n = 20) and crossed over for Part 2. Results: SRP-9001 dystrophin expression was achieved in all patients: mean CFBL to Week 12 was 23.82% and 39.64% normal in Parts 1 and 2, respectively. In Part 1, CFBL to Week 48 in NSAA score (least-squares mean, LSM [standard error]) was +1.7 (0.6) with treatment versus +0.9 (0.6) for placebo; p = 0.37. Disparity in baseline motor function between groups likely confounded these results. In 4- to 5-year-olds with matched baseline motor function, CFBL to Week 48 in NSAA scores was significantly different (+2.5 points; p = 0.0172), but not significantly different in 6-to-7-year-olds with imbalanced baseline motor function (-0.7 points; p = 0.5384). For patients treated with delandistrogene moxeparvovec in Part 2, CFBL to Week 48 in NSAA score was +1.3 (2.7), whereas for those treated in Part 1, NSAA scores were maintained. As all patients in Part 2 were exposed to treatment, results were compared with a propensity-score-weighted external control (EC) cohort. The LSM difference in NSAA score between the Part 2 treated group and EC cohort was statistically significant (+2.0 points; p = 0.0009). The most common TRAEs were vomiting, decreased appetite, and nausea. Most occurred within the first 90 days and all resolved. Discussion: Results indicate robust expression of SRP-9001 dystrophin and overall stabilization in NSAA up to 2 years post-treatment. Differences in NSAA between groups in Part 1 were not significant for the overall population, likely because cohorts were stratified only by age, and other critical prognostic factors were not well matched at baseline.
Delandistrogene Moxeparvovec: First Approval. [2023]Delandistrogene moxeparvovec (delandistrogene moxeparvovec-rokl; ELEVIDYS®) is an adeno-associated virus (AAV) vector-based gene therapy designed to deliver a gene encoding a micro-dystrophin protein [i.e. a shortened (138 kDa) version of the dystrophin protein expressed in normal muscle cells (427 kDa)] to all muscles involved in the pathology of Duchenne muscular dystrophy (DMD). Developed by Sarepta Therapeutics, it is the first gene therapy to be approved (in June 2023 under the Accelerated Approval pathway) for the treatment of DMD in the USA, where it is indicated for ambulatory paediatric patients aged 4 through 5 years with DMD and a confirmed mutation in the dystrophin (DMD) gene. The recommended dose of delandistrogene moxeparvovec is 1.33 × 1014 vector genomes per kg of body weight or 10 mL/kg body weight, administered as a single intravenous infusion. Delandistrogene moxeparvovec is undergoing clinical development in several countries/regions, including the EU and Japan. This article summarizes the milestones in the development of delandistrogene moxeparvovec leading to this first approval in the USA for the treatment of ambulatory paediatric patients aged 4 through 5 years with DMD and a confirmed mutation in the DMD gene.
Long-term safety and functional outcomes of delandistrogene moxeparvovec gene therapy in patients with Duchenne muscular dystrophy: A phase 1/2a nonrandomized trial. [2023]Delandistrogene moxeparvovec is indicated in the United States for the treatment of ambulatory pediatric patients aged 4 through 5 years with Duchenne muscular dystrophy (DMD) with a confirmed mutation in the DMD gene. Long-term delandistrogene moxeparvovec microdystrophin protein (a shortened dystrophin that retains key functional domains of the wild-type protein) expression may positively alter disease progression in patients with DMD. We evaluated long-term safety and functional outcomes of delandistrogene moxeparvovec in patients with DMD.
Expression and function of four AAV-based constructs for dystrophin restoration in the mdx mouse model of Duchenne muscular dystrophy. [2023]Robust expression of shortened, functional dystrophin provided impetus to develop adeno-associated virus (AAV)-based constructs for clinical application. Because several cassettes are being tested in clinical trials, this study compared the efficacies of four shortened dystrophin-promoter combinations with implications for outcomes in clinical trials: MHCK7 or MCK promoter with a shortened dystrophin transgene containing the N-terminus and spectrin repeats R1, R2, R3 and R24 (rAAVrh74.MHCK7.micro-dystrophin and rAAVrh74.MCK.micro-dystrophin, respectively); shortened dystrophin construct containing the neuronal nitric oxide (nNOS) binding site (rAAVrh74.MHCK7.DV.mini-dystrophin); and shortened dystrophin containing the C-terminus (rAAVrh74.MHCK7.micro-dystrophin.Cterm). Functional and histological benefit were examined at 4 weeks following intramuscular delivery in mdx mice. rAAVrh74.MHCK7.micro-dystrophin provided the most robust transgene expression and significantly increased specific force output in the tibialis anterior muscle. Muscle environment was normalized (i.e. reductions in central nucleation), indicating functional and histological advantages of rAAVrh74.MHCK7.micro-dystrophin. Thus, promoter choice and transgene design are critical for optimal dystrophin expression/distribution for maximal functional improvement.
Evaluation of an AAV9-mini-dystrophin gene therapy candidate in a rat model of Duchenne muscular dystrophy. [2023]Duchenne muscular dystrophy (DMD) is an X-linked disease caused by loss-of-function mutations in the dystrophin gene and is characterized by muscle wasting and early mortality. Adeno-associated virus-mediated gene therapy is being investigated as a treatment for DMD. In the nonclinical study documented here, we determined the effective dose of fordadistrogene movaparvovec, a clinical candidate adeno-associated virus serotype 9 vector carrying a human mini-dystrophin transgene, after single intravenous injection in a dystrophin-deficient (DMDmdx) rat model of DMD. Overall, we found that transduction efficiency, number of muscle fibers expressing the human mini-dystrophin polypeptide, improvement of the skeletal and cardiac muscle tissue architecture, correction of muscle strength and fatigability, and improvement of diastolic and systolic cardiac function were directly correlated with the amount of vector administered. The effective dose was then tested in older DMDmdx rats with a more dystrophic phenotype similar to the pathology observed in older patients with DMD. Except for a less complete rescue of muscle function in the oldest cohort, fordadistrogene movaparvovec was also found to be therapeutically effective in older DMDmdx rats, suggesting that this product may be appropriate for evaluation in patients with DMD at all stages of disease.