A first-in-human phase I/IIa gene transfer clinical trial for Duchenne muscular dystrophy using rAAVrh74.MCK.GALGT2

A systematic review of immunosuppressive protocols used in AAV gene therapy for monogenic disorders

The emergence of adeno-associated virus (AAV)-based gene therapy has brought hope to patients with severe monogenic disorders. However, immune responses to AAV vectors and transgene products present challenges that require effective immunosuppressive strategies. This systematic review focuses on the immunosuppressive protocols used in 38 clinical trials and 35 real-world studies, considering a range of monogenic diseases, AAV serotypes, and administration routes. The review underscores the need for a deeper understanding of immunosuppressive regimens to enhance the safety and effectiveness of AAV-based gene therapy. Characterizing the immunological responses associated with various gene therapy treatments is crucial for optimizing treatment protocols and ensuring the safety and efficacy of forthcoming gene therapy interventions. Further research and understanding of the impact of immunosuppression on disease, therapy, and route of administration will contribute to the development of more effective and safer gene therapy approaches in the future.

Dual FKRP/FST gene therapy normalizes ambulation, increases strength, decreases pathology, and amplifies gene expression in LGMDR9 mice

Recent clinical studies of single gene replacement therapy for neuromuscular disorders have shown they can slow or stop disease progression, but such therapies have had little impact on reversing muscle disease that was already present. To reverse disease in patients with muscular dystrophy, new muscle mass and strength must be rebuilt at the same time that gene replacement prevents subsequent disease. Here, we show that treatment of FKRPP448L mice with a dual FKRP/FST gene therapy packaged into a single adeno-associated virus (AAV) vector can build muscle strength and mass that exceed levels found in wild-type mice and can induce normal ambulation endurance in a 1-h walk test. Dual FKRP/FST therapy also showed more even increases in muscle mass and amplified muscle expression of both genes relative to either single gene therapy alone. These data suggest that treatment with single AAV-bearing dual FKRP/FST gene therapies can overcome loss of ambulation by improving muscle strength at the same time it prevents subsequent muscle damage. This design platform could be used to create therapies for other forms of muscular dystrophy that may improve patient outcomes.

Adeno-associated virus as a delivery vector for gene therapy of human diseases

Adeno-associated virus (AAV) has emerged as a pivotal delivery tool in clinical gene therapy owing to its minimal pathogenicity and ability to establish long-term gene expression in different tissues. Recombinant AAV (rAAV) has been engineered for enhanced specificity and developed as a tool for treating various diseases. However, as rAAV is being more widely used as a therapy, the increased demand has created challenges for the existing manufacturing methods. Seven rAAV-based gene therapy products have received regulatory approval, but there continue to be concerns about safely using high-dose viral therapies in humans, including immune responses and adverse effects such as genotoxicity, hepatotoxicity, thrombotic microangiopathy, and neurotoxicity. In this review, we explore AAV biology with an emphasis on current vector engineering strategies and manufacturing technologies. We discuss how rAAVs are being employed in ongoing clinical trials for ocular, neurological, metabolic, hematological, neuromuscular, and cardiovascular diseases as well as cancers. We outline immune responses triggered by rAAV, address associated side effects, and discuss strategies to mitigate these reactions. We hope that discussing recent advancements and current challenges in the field will be a helpful guide for researchers and clinicians navigating the ever-evolving landscape of rAAV-based gene therapy.

Diagnostic Accuracy of Creatine Kinase Isoenzyme-MM Test in Newborn Screening for Duchenne Muscular Dystrophy: A Systematic Review and Meta-Analysis

BACKGROUND

To systematically evaluate the diagnostic accuracy of the creatine kinase isoenzyme-MM (CK-MM) test in newborn screening for Duchenne muscular dystrophy (DMD).

METHODS

A comprehensive literature search was conducted up to October 31, 2022, in PubMed, Embase, Cochrane Library, Web of Science, and Scopus Database. To evaluate the diagnostic value, the sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), area under the curve (AUC), and Q∗ index were pooled. Threshold effect followed by subgroup analysis and meta-regression were performed to explore the source of heterogeneity. Sensitivity analysis was used to verify the robustness of the findings.

RESULTS

A total seven studies with 248,853 newborns was included in our meta-analysis. The pooled SEN and SPE were 1.00 (95% confidence interval [CI]: 0.89∼1.00) and 1.00 (95% CI: 1.00 to 1.00), respectively; the PLR and NLR were 1004.59 (95% CI: 251.37∼4014.91) and 0.13 (95% CI: 0.05∼0.34), respectively; the DOR was 877.96 (95% CI: 983.24∼78,366.32); the AUC and Q index were 0.8683 and 0.9326, respectively. Sensitivity analysis showed that two studies had an impact on the pooled results and mainly contributed to the heterogeneity.

CONCLUSIONS

CK-MM test demonstrated high accuracy in newborn screening for DMD and may be a valuable alternative in the early diagnosis of the disease followed by confirmatory genetic testing.

Interspecies Scaling of Transgene Products for Viral Vector Gene Therapies: Method Assessment Using Data from Eleven Viral Vectors

The prediction of transgene product expression in human is important to guide first-in-human (FIH) dose selection for viral vector-based gene replacement therapies. Recently, allometric scaling from preclinical data and interspecies normalization of dose-response (D-R) relationship have been used to predict human transgene product expression of adeno-associated virus (AAV) vectors. In this study, we assessed two interspecies allometric scaling methods and two dose-response methods in predicting human transgene product expression of nine intravenously administered AAV vectors, one intramuscularly administered AAV vector, and one intravesical administered adenoviral vector. Among the four methods, normalized D-R method generated the highest prediction accuracy, with geometric mean fold error (GMFE) of 2.9 folds and 75% predictions within fivefold deviations of observed human transgene product levels. The vg/kg-based D-R method worked well for locally delivered vectors but substantially overpredicted human transgene product levels of some hemophilia A and B vectors. For both intravenously and locally administered vectors, the prediction accuracy of allometric scaling using body weight^-0.25 (AS by W^-0.25) was superior to allometric scaling using log(body weight) (AS by logW). This study successfully extended the use of allometric scaling and interspecies D-R normalization methods for human transgene product prediction from intravenous viral vectors to locally delivered viral vectors.

Cardiac therapies for Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a devastating disease that results in life-limiting complications such as loss of skeletal muscle function as well as respiratory and cardiac complications. Advanced therapeutics in pulmonary care have significantly reduced respiratory complication-related mortality, making cardiomyopathy the main determinant factor of survival. While there are multiple therapies such as the use of anti-inflammatory drugs, physical therapy, and ventilatory assistance targeted toward delaying the disease progression in DMD, a cure remains elusive. In the last decade, several therapeutic approaches have been developed to improve patient survival. These include small molecule-based therapy, micro-dystrophin gene delivery, CRISPR-mediated gene editing, nonsense readthrough, exon skipping, and cardiosphere-derived cell therapy. Associated with the specific benefits of each of these approaches are their individual risks and limitations. The variability in the genetic aberrations leading to DMD also limits the widespread use of these therapies. While numerous approaches have been explored to treat DMD pathophysiology, only a handful have successfully advanced through the preclinical stages. In this review, we summarize the currently approved as well as the most promising therapeutics undergoing clinical trials aimed toward treating DMD with a focus on its cardiac manifestations.

Gene therapy for Duchenne muscular dystrophy: an update on the latest clinical developments

INTRODUCTION

Duchenne muscular dystrophy (DMD) is one of the most severe and devastating neuromuscular hereditary diseases with a male newborn incidence of 20 000 cases each year. The disease caused by mutations (exon deletions, nonsense mutations, intra-exonic insertions or deletions, exon duplications, splice site defects, and deep intronic mutations) in the DMD gene, progressively leads to muscle wasting and loss of ambulation. This situation is painful for both patients and their families, calling for an emergent need for effective treatments.

AREAS COVERED

In this review, the authors describe the state of the gene therapy approach in clinical trials for DMD. This therapeutics included gene replacement, gene substitution, RNA-based therapeutics, readthrough mutation, and the CRISPR approach.

EXPERT OPINION

Only a few drug candidates have yet been granted conditional approval for the treatment of DMD. Most of these therapies have only a modest capability to restore the dystrophin or improve muscle function, suggesting an important unmet need in the development of DMD therapeutics. Complementary genes and cellular therapeutics need to be explored to both restore dystrophin, improve muscle function, and efficiently reconstitute the muscle fibers in the advanced stage of the disease.