Systematic review and meta-analysis determining the benefits of in vivo genetic therapy in spinal muscular atrophy rodent models

Preclinical evaluation of AAV9-coSMN1 gene therapy for spinal muscular atrophy: efficacy and safety in mouse models and non-human primates

BACKGROUND

Spinal muscular atrophy (SMA) is a severe neuromuscular disorder caused by the loss of motor neurons in the spinal cord. Our team has initiated clinical trials using adeno-associated virus serotype 9 (AAV9) vectors carrying a codon-optimized human SMN1 (coSMN1) gene, delivered via intrathecal (IT) injection. Here, we present the preclinical research that laid the groundwork for these trials, offering comprehensive data on the efficacy and safety of AAV9-coSMN1 in both murine models and non-human primates.

MATERIAL AND METHOD

We developed a codon-optimized hSMN1 expression cassette and analyzed SMN protein levels using Western blot and immunofluorescence. Taiwanese SMA-like mouse model was employed to assess tail length preservation, as well as to examine motor neuron and skeletal muscle pathological phenotypes through immunofluorescence and histopathological staining. Serum biomarkers in both mice and cynomolgus monkeys were measured using a blood chemistry analyzer. The in-vivo biodistribution of AAV9-coSMN1 and toxicological profile were investigated through quantitative Polymerase Chain Reaction(qPCR) and histopathological staining.

RESULTS

Codon optimization of hSMN1 led to enhanced gene expression and increased SMN protein levels in vitro. AAV9-coSMN1 demonstrated significant therapeutic efficacy in a Type 3 SMA mouse model, effectively rescuing motor neurons, preserving tail integrity, and improving skeletal muscle histopathology. In vivo studies, both mice and cynomolgus monkeys revealed widespread CNS distribution following a single intracerebroventricular or intrathecal injection, with no observed toxic inflammatory responses in the dorsal root ganglia. Peripheral organs also showed detectable levels of the vector gene, indicating effective systemic distribution.

CONCLUSION

The preclinical evaluation confirms that AAV9-coSMN1 is a safe and effective therapeutic candidate for SMA, with potential applicability across various phenotypes. The study provides critical data supporting its advancement to clinical trials, underscoring its promise for broader neurological applications.

Splice-switching antisense oligonucleotide controlling tumor suppressor REST is a novel therapeutic medicine for neuroendocrine cancer

RNA splicing regulation has revolutionized the treatment of challenging diseases. Neuroendocrine cancers, including small cell lung cancer (SCLC) and neuroendocrine prostate cancer (PCa), are highly aggressive, with metastatic neuroendocrine phenotypes, leading to poor patient outcomes. We investigated amido-bridged nucleic acid (AmNA)-based splice-switching oligonucleotides (SSOs) targeting RE1-silencing transcription factor (REST) splicing as a novel therapy. We designed AmNA-based SSOs to alter REST splicing. Tumor xenografts were generated by subcutaneously implanting SCLC or PCa cells into mice. SSOs or saline were intraperitoneally administered and tumor growth was monitored. Blood samples were collected from mice after SSO administration, and serum alanine aminotransferase and aspartate aminotransferase levels were measured to assess hepatotoxicity using a biochemical analyser. In vitro, REST_SSO reduced cancer cell viability. In a tumor xenograft model, it exhibited significant antitumor effects. It repressed REST-controlled RE1-harboring genes and upregulated miR-4516, an SCLC biomarker. Our findings suggest that REST_SSO suppresses tumorigenesis in neuroendocrine cancers by restoring REST function. This novel therapeutic approach holds promise for intractable neuroendocrine cancers such as SCLC and neuroendocrine PCa.

Advanced biomanufacturing and evaluation of adeno-associated virus

Recombinant adeno-associated virus (rAAV) has been developed as a safe and effective gene delivery vehicle to treat rare genetic diseases. This study aimed to establish a novel biomanufacturing process to achieve high production and purification of various AAV serotypes (AAV2, 5, DJ, DJ8). First, a robust suspensive production process was developed and optimized using Gibco Viral Production Cell 2.0 in 30-60 mL shaker flask cultures by evaluating host cells, cell density at the time of transfection and plasmid amount, adapted to 60-100 mL spinner flask production, and scaled up to 1.2-2.0-L stirred-tank bioreactor production at 37 °C, pH 7.0, 210 rpm and DO 40%. The optimal process generated AAV titer of 7.52-8.14 × 1010 vg/mL. Second, a new AAV purification using liquid chromatography was developed and optimized to reach recovery rate of 85-95% of all four serotypes. Post-purification desalting and concentration procedures were also investigated. Then the generated AAVs were evaluated in vitro using Western blotting, transmission electron microscope, confocal microscope and bioluminescence detection. Finally, the in vivo infection and functional gene expression of AAV were confirmed in tumor xenografted mouse model. In conclusion, this study reported a robust, scalable, and universal biomanufacturing platform of AAV production, clarification and purification.

Fetal gene therapy

Fetal gene therapy was first proposed toward the end of the 1990s when the field of gene therapy was, to quote the Gartner hype cycle, at its "peak of inflated expectations." Gene therapy was still an immature field but over the ensuing decade, it matured and is now a clinical and market reality. The trajectory of treatment for several genetic diseases is toward earlier intervention. The ability, capacity, and the will to diagnose genetic disease early-in utero-improves day by day. A confluence of clinical trials now signposts a trajectory toward fetal gene therapy. In this review, we recount the history of fetal gene therapy in the context of the broader field, discuss advances in fetal surgery and diagnosis, and explore the full ambit of preclinical gene therapy for inherited metabolic disease.

The role of autophagy-lysosomal pathway in motor neuron diseases

Motor neuron diseases (MNDs) include a broad group of diseases in which neurodegeneration mainly affects upper and/or lower motor neurons (MNs). Although the involvement of specific MNs, symptoms, age of onset, and progression differ in MNDs, the main pathogenic mechanism common to most MNDs is represented by proteostasis alteration and proteotoxicity. This pathomechanism may be directly related to mutations in genes encoding proteins involved in the protein quality control system, particularly the autophagy-lysosomal pathway (ALP). Alternatively, proteostasis alteration can be caused by aberrant proteins that tend to misfold and to aggregate, two related processes that, over time, cannot be properly handled by the ALP. Here, we summarize the main ALP features, focusing on different routes utilized to deliver substrates to the lysosome and how the various ALP pathways intersect with the intracellular trafficking of membranes and vesicles. Next, we provide an overview of the mutated genes that have been found associated with MNDs, how these gene products are involved in different steps of ALP and related processes. Finally, we discuss how autophagy can be considered a valid therapeutic target for MNDs treatment focusing on traditional autophagy modulators and on emerging approaches to overcome their limitations.

The Role of Small Heat Shock Proteins in Protein Misfolding Associated Motoneuron Diseases

Motoneuron diseases (MNDs) are neurodegenerative conditions associated with death of upper and/or lower motoneurons (MNs). Proteostasis alteration is a pathogenic mechanism involved in many MNDs and is due to the excessive presence of misfolded and aggregated proteins. Protein misfolding may be the product of gene mutations, or due to defects in the translation process, or to stress agents; all these conditions may alter the native conformation of proteins making them prone to aggregate. Alternatively, mutations in members of the protein quality control (PQC) system may determine a loss of function of the proteostasis network. This causes an impairment in the capability to handle and remove aberrant or damaged proteins. The PQC system consists of the degradative pathways, which are the autophagy and the proteasome, and a network of chaperones and co-chaperones. Among these components, Heat Shock Protein 70 represents the main factor in substrate triage to folding, refolding, or degradation, and it is assisted in this task by a subclass of the chaperone network, the small heat shock protein (sHSPs/HSPBs) family. HSPBs take part in proteostasis by bridging misfolded and aggregated proteins to the HSP70 machinery and to the degradative pathways, facilitating refolding or clearance of the potentially toxic proteins. Because of its activity against proteostasis alteration, the chaperone system plays a relevant role in the protection against proteotoxicity in MNDs. Here, we discuss the role of HSPBs in MNDs and which HSPBs may represent a valid target for therapeutic purposes.

The Net Benefit of Personalized Medicine: A Systematic Literature Review and Regression Analysis

OBJECTIVES

Amidst conflicting expectations about the benefits of personalized medicine (PM) and the potentially high implementation costs, we reviewed the available evidence on the cost-effectiveness of PM relative to non-PM.

METHODS

We conducted a systematic literature review of economic evaluations of PM and extracted data, including incremental quality-adjusted life-years (ΔQALYs) and incremental costs (Δcosts). ΔQALYs and Δcosts were combined with estimates of national cost-effectiveness thresholds to calculate incremental net monetary benefit (ΔNMB). Regression analyses were performed with these variables as dependent variables and PM intervention characteristics as independent variables. Random intercepts were used to cluster studies according to country.

RESULTS

Of 4774 studies reviewed, 128 were selected, providing cost-effectiveness data for 279 PM interventions. Most studies were set in the United States (48%) and the United Kingdom (16%) and adopted a healthcare perspective (82%). Cancer treatments (60%) and pharmaceutical interventions (72%) occurred frequently. Prognostic tests (19%) and tests to identify (non)responders (37%) were least and most common, respectively. Industry sponsorship occurred in 32%. Median ΔQALYs, Δcosts, and ΔNMB per individual were 0.03, Int$575, and Int$18, respectively. We found large heterogeneity in cost-effectiveness. Regression analysis showed that gene therapies were associated with higher ΔQALYs than other interventions. PM interventions for neoplasms brought higher ΔNMB than PM interventions for other conditions. Nonetheless, average ΔNMB in the 'neoplasm' group was found to be negative.

CONCLUSIONS

PM brings improvements in health but often at a high cost, resulting in 0 to negative ΔNMB on average. Pricing policies may be needed to reduce the costs of interventions with negative ΔNMB.