Viral Gene Therapy Research Articles

Immuno-oncology CMC aspects

<div class="authors authors-lg"><div class="author"><div class="author-img"><img src="https://cdn.insights.bio/uploads/Anurag Khetan copy.jpg" data-image="1"></div><div class="author-det"> <b>Anurag Khetan</b> heads the Global Upstream and Cell Line Development area of Biologics Development in Bristol-Myers Squibb based in New Jersey in USA. His end-to-end team interfaces with Discovery and Manufacturing and carries out process development of biologics and viral gene therapy programs ranging from molecular biology and analytics, cell line development, and upstream process development. Anurag has a BTech in Chemical Engineering from Indian Institute of Technology, Delhi and a PhD from the Department of Chemical engineering at the University of Minnesota. Anurag has had sustained contributions over nearly two decades in the biotechnology industry at Merck, Biogen, Boehringer Ingelheim and BMS in areas ranging from early and late process development, post-approval development, manufacturing support, and GMP manufacturing. </div></div></div>

In vivo genome editing at the albumin locus to treat methylmalonic acidemia

Methylmalonic acidemia (MMA) is a metabolic disorder most commonly caused by mutations in the methylmalonyl-CoA mutase (MMUT) gene. Although adeno-associated viral (AAV) gene therapy has been effective at correcting the disease phenotype in MMA mouse models, clinical translation may be impaired by loss of episomal transgene expression and magnified by the need to treat patients early in life. To achieve permanent correction, we developed a dual AAV strategy to express a codon-optimized MMUT transgene from Alb and tested various CRISPR-Cas9 genome-editing vectors in newly developed knockin mouse models of MMA. For one target site in intron 1 of Alb, we designed rescue cassettes expressing MMUT behind a 2A-peptide or an internal ribosomal entry site sequence. A second guide RNA targeted the initiator codon, and the donor cassette encompassed the proximal albumin promoter in the 5′ homology arm. Although all editing approaches were therapeutic, targeting the start codon of albumin allowed the use of a donor cassette that also functioned as an episome and after homologous recombination, even without the expression of Cas9, as an integrant. Targeting the albumin locus using these strategies would be effective for other metabolic disorders where early treatment and permanent long-term correction are needed.

A short hepatitis C virus NS5A peptide expression by AAV vector modulates human T cell activation and reduces vector immunogenicity

Viral vector-mediated gene therapies have the potential to treat many human diseases; however, host immune responses against the vector and/or the transgene pose a safety risk to the patients and can negatively impact product efficacy. Thus, novel strategies to reduce vector immunogenicity are critical for the advancement of these therapies. T cell activation (TCA) is required for the development of immune responses during gene therapy. We hypothesized that modulation of TCA by incorporating a novel viral immunomodulatory factor into a viral vector may reduce unwanted TCA and immune responses during gene therapy. To test this hypothesis, we identified an immunomodulatory domain of the hepatitis C virus (HCV) NS protein 5A (NS5A) protein and studied the effect of viral vectors expressing NS5A peptide on TCA. Lentiviral vector-mediated expression of a short 20-mer peptide derived from the NS5A protein in human T cells was sufficient to inhibit TCA. Synthetic 20-mer NS5A peptide also inhibited TCA in primary human T cells. Mechanistically, the NS5A protein interacted with Lck and inhibited proximal TCR signaling. Importantly, NS5A peptide expression did not cause global T cell signaling dysfunction as distal T cell signaling was not inhibited. Finally, recombinant adeno-associated virus (AAV) vector expressing the 20-mer NS5A peptide reduced both the recall antigen and the TCR-mediated activation of human T cells and did not cause global T cell signaling dysfunction. Together, these data suggest that expression of a 20-mer NS5A peptide by an AAV vector may reduce unwanted TCA and may contribute to lower vector immunogenicity during gene therapy.

Glioblastoma: a molecular genetic portrait and modern therapeutic strategies for drug treatment

Glioblastoma multiforme is the most common and malignant primary tumor of the central nervous system. Despite the existing modern complex therapy and advances in the study of molecular genetic changes in this tumor, the prognosis for patients with glioblastoma is one of the most unfavorable in oncology. This overview reviews existing therapeutic agents and clinical studies of potential drugs for the treatment of patients with glioblastoma multiforme.Next-generation sequencing has become firmly established in the clinical practice of oncologists and allows detecting gene mutations in tumor cells, some of which can serve as targets for therapy. Glioblastoma is characterized by a large number of potentially targeted molecular genetic disorders. As in the case of other solid tumors, targeted and immunotherapy for glioblastomas is being actively studied, including the combination of drugs with physical methods of exposure. To date, new treatment methods of glioblastoma, including antiangiogenic therapy, immunotherapy, oncolytic viral therapy and gene therapy still have uncertain or very modest clinical results. There are many reasons for the lack of progress in the treatment of glioblastoma – from the banal inability of most molecules to overcome the blood-brain barrier to the wide genetic heterogeneity of these tumors. The most promising direction of studies is immunotherapy. But at this stage, we cannot say that there is an effective monotherapy for glioblastoma. The combination treatment with radiation therapy and chemotherapy increases the mutational load, the expression of stress and other factors, therefore, the researchers pin great hopes on the combined methods of treatment.

First-in-Human Dose-Finding Study of AAVhu37 Vector-Based Gene Therapy: BAY 2599023 Has Stable and Sustained Expression of FVIII over 2 Years

▪BackgroundGene therapy for hemophilia A has the potential to reduce the treatment burden for patients and their care providers by eliminating the need for regular factor VIII (FVIII) prophylaxis through long-term expression of endogenous FVIII at levels sufficient to provide bleed protection. Ongoing phase 3 gene therapy trials for hemophilia A show promise but can result in unpredictable FVIII expression of uncertain durability. Gene therapy must evolve to meet patient expectations of a durable, efficacious and safe treatment.BAY 2599023 (AAVhu37.hFVIIIco) is the first, clinical stage adeno-associated virus (AAV) gene therapy vector, based on the AAVhu37 serotype. BAY 2599023 is a non-replicating AAV vector and contains a single-stranded DNA genome encoding a B-domain-deleted FVIII, under the control of a liver-specific promoter/enhancer combination, optimized for transgenic expression. The AAVhu37 capsid is a member of the hepatotropic clade E family and was selected based on preclinical studies demonstrating efficient, liver-directed FVIII gene transfer, favorable biodistribution and durable FVIII expression. Here, we report safety and FVIII activity levels achieved to date in this first-in-human, dose-finding study of BAY 2599023.MethodsThe ongoing BAY 2599023 phase 1/2, open-label, dose-finding study (NCT03588299) included male patients aged ≥18 years with severe hemophilia A, no history of FVIII inhibitors, no detectable neutralizing immunity against AAVhu37 (neutralizing antibody titer ≤5), and ≥150 exposure days to FVIII products. Patients received a single intravenous infusion of BAY 2599023 and were enrolled sequentially into three dose cohorts (0.5 × 10 13 GC/kg, 1.0 × 10 13 GC/kg and 2.0 × 10 13 GC/kg), each comprising at least two patients. Patients to be enrolled in a fourth cohort will receive a single infusion of 4 × 10 13 GC/kg (Figure 1). Primary endpoints were adverse events (AEs), serious AEs (SAEs) and AEs/SAEs of special interest (S/AESIs). The secondary endpoint was FVIII activity over time. Informed patient consent and ethics committee approval were obtained.ResultsThree cohorts of ≥2 patients each (N = 9) were enrolled sequentially (Figure 1). At the data cutoff (May 2021), FVIII activity data were available for the first eight patients.BAY 2599023 delivered sustained FVIII expression levels for up to >23 months, with evidence of bleed protection. Patients in Cohorts 2 and 3 have all been off prophylaxis with FVIII products since approximately 6-12 weeks after gene transfer. To date, it has been observed that no spontaneous bleeds requiring treatment have been reported once FVIII levels >11 IU/dL were achieved. Of the 9 patients treated, 5 patients developed an AESI: mild/moderate alanine aminotransferase (ALT) elevations observed in Cohort 2 (n =1) and Cohort 3 (n = 3) were managed with corticosteroid treatment; another ALT elevation was reported as study-drug-related SAE in Cohort 3 (n = 1) but returned to normal a few weeks after interruption of the H2 blocker famotidine. The latest follow-up data for up to 28 months will be presented.ConclusionsBAY 2599023 was designed to enhance efficacy and durability of FVIII expression with a favorable safety profile. Sustained FVIII levels allowed suspension of FVIII prophylaxis in the majority of patients, with asymptomatic ALT elevations that respondedto corticosteroids, making BAY 2599023 a key candidate in the evolution of gene therapy in hemophilia A. [Display omitted] DisclosuresPipe: Genventiv: Consultancy; Regeneron/ Intellia: Consultancy; uniQure: Consultancy, Other; Spark Therapeutics: Consultancy; Takeda: Consultancy; Sanofi: Consultancy, Other; Sangamo Therapeutics: Consultancy; Roche/Genentech: Consultancy, Other; Pfizer: Consultancy; Novo Nordisk: Consultancy; Freeline: Consultancy, Other: Clinical trial investigator; HEMA Biologics: Consultancy; CSL Behring: Consultancy; Catalyst Biosciences: Consultancy; Biomarin: Consultancy, Other: Clinical trial investigator; Bayer: Consultancy; ASC Therapeutics: Consultancy; Apcintex: Consultancy; Grifols: Consultancy; Octapharma: Consultancy; Shire: Consultancy. Sheehan: BioMarin: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Bayer: Consultancy, Research Funding. Coppens: Portola/Alexion: Research Funding; CSL Behring: Consultancy, Research Funding; Bayer: Consultancy, Research Funding; Roche: Research Funding; Daiichi Sankyo: Research Funding; Sanquin Blood Supply: Research Funding; uniQure: Research Funding; Medcon International: Consultancy; MEDtalks: Consultancy; Novo Nordisk: Consultancy; Pfizer: Consultancy; Sobi: Consultancy. Eichler: Takeda: Consultancy, Honoraria; BioMarin: Consultancy, Research Funding; Roche: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; CSL Behring: Consultancy, Honoraria; Pfizer: Research Funding; Novo Nordisk: Consultancy, Research Funding; Biotest: Consultancy, Honoraria; Bayer: Consultancy, Research Funding. Linardi: Bayer: Current Employment. Wiegmann: Bayer: Current Employment. Hay: Pfizer: Consultancy, Research Funding; Inspiration: Consultancy, Honoraria; BioMarin: Consultancy, Honoraria; Roche: Consultancy, Research Funding; Bayer: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Spark Therapeutics: Consultancy, Research Funding. Lissitchkov: Bayer: Other: Principal Investigator of Clinical Trials; Catalist: Other: Principal Investigator of Clinical Trials; Grifols: Other: Principal Investigator of Clinical Trials.

Follow-up of More Than 5 Years in a Cohort of Patients with Hemophilia B Treated with Fidanacogene Elaparvovec Adeno-Associated Virus Gene Therapy

Follow-up of More Than 5 Years in a Cohort of Patients with Hemophilia B Treated with Fidanacogene Elaparvovec Adeno-Associated Virus Gene Therapy

Relationship between Endogenous, Transgene FVIII Expression and Bleeding Events Following Valoctocogene Roxaparvovec Gene Transfer for Severe Hemophilia A: A Post-Hoc Analysis of the GENEr8-1 Phase 3 Trial

Relationship between Endogenous, Transgene FVIII Expression and Bleeding Events Following Valoctocogene Roxaparvovec Gene Transfer for Severe Hemophilia A: A Post-Hoc Analysis of the GENEr8-1 Phase 3 Trial

Understanding Drivers of Ocular Fibrosis: Current and Future Therapeutic Perspectives.

Ocular fibrosis leads to severe visual impairment and blindness worldwide, being a major area of unmet need in ophthalmology and medicine. To date, the only available treatments are antimetabolite drugs that have significant potentially blinding side effects, such as tissue damage and infection. There is thus an urgent need to identify novel targets to prevent/treat scarring and postsurgical fibrosis in the eye. In this review, the latest progress in biological mechanisms underlying ocular fibrosis are discussed. We also summarize the current knowledge on preclinical studies based on viral and non-viral gene therapy, as well as chemical inhibitors, for targeting TGFβ or downstream effectors in fibrotic disorders of the eye. Moreover, the role of angiogenetic and biomechanical factors in ocular fibrosis is discussed, focusing on related preclinical treatment approaches. Moreover, we describe available evidence on clinical studies investigating the use of therapies targeting TGFβ-dependent pathways, angiogenetic factors, and biomechanical factors, alone or in combination with other strategies, in ocular tissue fibrosis. Finally, the recent progress in cell-based therapies for treating fibrotic eye disorders is discussed. The increasing knowledge of these disorders in the eye and the promising results from testing of novel targeted therapies could offer viable perspectives for translation into clinical use.

Analytical toolkit for rapid formulation development of rAAV gene therapies

Recombinant adeno-associated virus (rAAV) gene therapy products have been studied in hundreds of clinical trials for treating multiple rare and monogenic disorders. Commercial success of rAAV gene therapy is also coming to fruition, as two products have recently achieved FDA approval for the treatment of Leber Congenital Amaurosis and Spinal Muscular Atrophy. Driven by clinical and commercial demand, significant advances have been made to analytical methods to characterize and release these products. rAAV vectors have demonstrated sustained stability across diverse bioprocessing conditions and are assumed to be stable in the Phosphate Buffered Saline (PBS) buffer with low levels of surfactant. Still, relatively few accounts of rAAV product formulation and stability data have been published to date, likely caused by substantial sample requirement, time urgency, and limited analytical tools. The traditional formulation development methods are few and many of which have low efficiency, poor precision, or accuracy. Here we present an updated panel of analytical methods compared to conventional methods with a focus on measuring stability-indicating attributes. This analytical toolkit has the capability of examining rAAV at the molecular level under various stress conditions to provide a holistic view of the physical and biochemical attributes of the product. The increased throughput and fast turn-around using small amount of material, while providing multi-attribute monitoring, enables rapid formulation development for fast decision-making and accelerated speed to clinic.

Viral vector-based gene therapies in the clinic.

Gene therapies are currently one of the most investigated therapeutic modalities in both the preclinical and clinical settings and have shown promise in treating a diverse spectrum of diseases. Gene therapies aim at introducing a gene material in target cells and represent a promising approach to cure diseases that were thought to be incurable by conventional modalities. In many cases, a gene therapy requires a vector to deliver gene therapeutics into target cells; viral vectors are among the most widely studied vectors owing to their distinguished advantages such as outstanding transduction efficiency. With decades of development, viral vector‐based gene therapies have achieved promising clinical outcomes with many products approved for treating a range of diseases including cancer, infectious diseases and monogenic diseases. In addition, a number of active clinical trials are underway to further expand their therapeutic potential. In this review, we highlight the diversity of viral vectors, review approved products, and discuss the current clinical landscape of in vivo viral vector‐based gene therapies. We have reviewed 13 approved products and their clinical applications. We have also analyzed more than 200 active trials based on various viral vectors and discussed their respective therapeutic applications. Moreover, we provide a critical analysis of the major translational challenges for in vivo viral vector‐based gene therapies and discuss possible strategies to address the same.

Quantifying inter-organelle membrane contact sites using proximity ligation assay in fixed optic nerve sections

Membrane contact sites (MCS) play crucial roles in cell physiology with dysfunction in several MCS proteins being linked with neurological and optic nerve diseases. Although there have been significant advances in imaging these interactions over the past two decades with advanced electron microscopy techniques, super-resolution imaging and proximity-dependent fluorescent reporters, a technique to observe and quantify MCS in mammalian optic nerve tissues has not yet been reported. We demonstrate for the first time that proximity ligation assay (PLA), a technique already used in mammalian cell lines, can be used as an efficient method of quantifying inter-organelle contact sites, namely mitochondria-endoplasmic reticulum (ER) and mitochondria-late-endosomes, in mammalian optic nerve tissues treated with adeno-associated virus (AAV) gene therapy with wild-type or phosphomimetic (active) protrudin. PLA utilises complementary single-stranded DNA oligomers bound to secondary antibodies that hybridise and complete a circular piece of DNA when the primary antibodies of interest interact. These interactions can be detected by amplifying the circular DNA and adding fluorescent probes. We show that PLA is a useful method that can be used to quantify MCS in optic nerve tissues. We have found that upregulation of protrudin with gene therapy significantly increases the number of mitochondria-ER and mitochondria-Rab7-late endosomes contact sites in optic nerves.

Long-term functional correction of cystathionine β-synthase deficiency in mice by adeno-associated viral gene therapy.

Cystathionine β-synthase (CBS) deficiency is a recessive inborn error of sulfur metabolism characterized by elevated blood levels of total homocysteine (tHcy). Patients diagnosed with CBS deficiency are currently treated by a combination of vitamin supplementation and restriction of foods containing the homocysteine precursor methionine, but the effectiveness of this therapy is limited due to poor compliance. A mouse model for CBS deficiency (Tg-I278T Cbs-/- ) was used to evaluate a potential gene therapy approach to treat CBS deficiency utilizing an AAVrh.10-based vector containing the human CBS cDNA downstream of the constitutive, strong CAG promoter (AAVrh.10hCBS). Mice were administered a single dose of virus and followed for up to 1 year. The data demonstrated a dose-dependent increase in liver CBS activity and a dose-dependent decrease in serum tHcy. Liver CBS enzyme activity at 1 year was similar to Cbs+/- control mice. Mice given the highest dose (5.6 × 1011 genomes/mouse) had mean serum tHcy decrease of 97% 1 week after injection and an 81% reduction 1 year after injection. Treated mice had either full- or substantial correction of alopecia, bone loss, and fat mass phenotypes associated with Cbs deficiency in mice. Our findings show that AAVrh.10-based gene therapy is highly effective in treating CBS deficiency in mice and supports additional pre-clinical testing for eventual use human trials.

Industrializing viral vector manufacture

Daniel Teasley has worked at Merck for over 6 years, serving in product management and product strategy roles across multiple portfolios including custom cell line engineering services, regenerative medicine products for research, cell therapy manufacturing, and viral gene therapy manufacturing. For the past three years, he has been a Senior Product Manager responsible for the development, launch, and marketing of products and services that enable at-scale viral vector manufacturing. He also supports cross-business strategic initiatives in novel modality manufacturing. Dr. Teasley holds a PhD in Molecular Genetics and Genomics from Washington University in St. Louis and a BS in Biology from the College of William and Mary.Katherine (Katie) Schewe has worked at Merck for over 4 years in various roles from product management in Viral &amp; Gene Therapy to quality assurance of Active Pharmaceutical Ingredient manufacturing. Katie holds a MS in Chemistry from Indiana University Purdue University – Indianapolis and a BS in Chemistry from Southern Illinois University – Edwardsville.

SMA - TREATMENT: EP.283 Nusinersen in children with spinal muscular atrophy (SMA) who received onasemnogene abeparvovec: Design of the phase 4, open-label respond study

Nusinersen is an antisense oligonucleotide that has shown significant and clinically meaningful efficacy on motor function and survival endpoints across a broad spectrum of SMA phenotypes. Onasemnogene abeparvovec is an intravenous adeno-associated viral (AAV) vector gene therapy for SMA. Preclinical studies demonstrate incomplete transduction of neurons by the AAV9 vector. There have been reports of SMA patients receiving nusinersen after onasemnogene abeparvovec treatment; however, no systematic evaluation of clinical outcomes or treatment safety with nusinersen following onasemnogene abeparvovec has occurred.

Evaluation of the Humoral Response to Adeno-Associated Virus-Based Gene Therapy Modalities Using Total Antibody Assays.

The number of viral vector-based gene therapies (GTx) continues to grow with two products (Zolgensma® and Luxturna®) approved in the USA as of March 2021. To date, the most commonly used vectors are adeno-associated virus-based (AAV). The pre-existing humoral immunity against AAV (anti-AAV antibodies) has been well described and is expected as a consequence of prior AAV exposure. Anti-AAV antibodies may present an immune barrier to successful AAV transduction and hence negatively impact clinical efficacy and may also result in adverse events (AEs) due to the formation of large immune complexes. Patients may be screened for the presence of anti-AAV antibodies, including neutralizing (NAb) and total binding antibodies (TAb) prior to treatment with the GTx. Recommendations for the development and validation of anti-AAV NAb detection methods have been presented elsewhere. This manuscript covers considerations related to anti-AAV TAb-detecting protocols, including the advantages of the use of TAb methods, selection of assay controls and reagents, and parameters critical to monitoring assay performance. This manuscript was authored by a group of scientists involved in GTx development representing eleven organizations. It is our intent to provide recommendations and guidance to industry sponsors, academic laboratories, and regulatory agencies working on AAV-based GTx viral vector modalities with the goal of achieving a more consistent approach to anti-AAV TAb assessment. Graphical abstract

Reversibly Modulating the Blood-Brain Barrier by Laser Stimulation of Molecular-Targeted Nanoparticles.

The blood-brain barrier (BBB) is highly selective and acts as the interface between the central nervous system and circulation. While the BBB is critical for maintaining brain homeostasis, it represents a formidable challenge for drug delivery. Here we synthesized gold nanoparticles (AuNPs) for targeting the tight junction specifically and demonstrated that transcranial picosecond laser stimulation of these AuNPs post intravenous injection increases the BBB permeability. The BBB permeability change can be graded by laser intensity, is entirely reversible, and involves increased paracellular diffusion. BBB modulation does not lead to significant disruption in the spontaneous vasomotion or the structure of the neurovascular unit. This strategy allows the entry of immunoglobulins and viral gene therapy vectors, as well as cargo-laden liposomes. We anticipate this nanotechnology to be useful for tissue regions that are accessible to light or fiberoptic application and to open new avenues for drug screening and therapeutic interventions in the central nervous system.

Quantitation of Trace Levels of DNA Released from Disrupted Adeno-Associated Virus Gene Therapy Vectors.

Adeno-associated virus (AAV) vectors for gene therapy have potential to provide a durable treatment response for a number of diseases with unmet need. DNA is released from AAV capsids at high temperatures. Less is known about DNA release that may occur under conditions relevant to clinical and commercial manufacturing, storage, and distribution. In this work we developed and applied a sensitive fluorescent dye-based method to quantitate trace levels of DNA released from AAV capsids. The method was used to characterize the impact of manufacturing process steps on the increase (up to 1.5%) and removal (down to 0.2%) of free DNA. Free DNA increased by 0.3% per day at 37°C and by 0.4% per freeze/thaw cycle in a phosphate-buffered saline formulation. When stored for 2 years at different temperatures, free DNA remained low (<0.6%) at both ≤ -60°C and at 2-8°C but was higher (2.6%) when the same sample was stored at -20°C. The dye-based method may be used to further characterize release of free DNA for different processes, formulations, and stress conditions. Overall, release of free DNA was a relatively minor degradation pathway under the conditions studied in this work.

Real-time MR tracking of AAV gene therapy with βgal-responsive MR probe in a murine model of GM1-gangliosidosis

Transformative results of adeno-associated virus (AAV) gene therapy in patients with spinal muscular atrophy and Leber’s congenital amaurosis led to approval of the first two AAV products in the United States to treat these diseases. These extraordinary results led to a dramatic increase in the number and type of AAV gene-therapy programs. However, the field lacks non-invasive means to assess levels and duration of therapeutic protein function in patients. Here, we describe a new magnetic resonance imaging (MRI) technology for real-time reporting of gene-therapy products in the living animal in the form of an MRI probe that is activated in the presence of therapeutic protein expression. For the first time, we show reliable tracking of enzyme expression after a now in-human clinical trial AAV gene therapy (ClinicalTrials.gov: NTC03952637) encoding lysosomal acid beta-galactosidase (βgal) using a self-immolative βgal-responsive MRI probe. MRI enhancement in AAV-treated enzyme-deficient mice (GLB-1−/−) correlates with βgal activity in central nervous system and peripheral organs after intracranial or intravenous AAV gene therapy, respectively. With >1,800 gene therapies in phase I/II clinical trials (ClinicalTrials.gov), development of a non-invasive method to track gene expression over time in patients is crucial to the future of the gene-therapy field.

Intravenous delivery of adeno-associated viral gene therapy in feline GM1 gangliosidosis

GM1 gangliosidosis is a fatal neurodegenerative disease caused by a deficiency of lysosomal β-galactosidase. In its most severe form, GM1 gangliosidosis causes death by 4 years of age, and no effective treatments exist. Previous work has shown that injection of the brain parenchyma with an adeno-associated viral (AAV) vector provides pronounced therapeutic benefit in a feline GM1 model. To develop a less invasive treatment for the brain and increase systemic biodistribution, intravenous injection of AAV9 was evaluated. AAV9 expressing feline β-galactosidase was intravenously administered at 1.5×1013 vector genomes/kg body weight to six GM1 cats at ∼1 month of age. The animals were divided into two cohorts: (i) a long-term group, which was followed to humane end point; and (ii) a short-term group, which was analysed 16 weeks post-treatment. Clinical assessments included neurological exams, CSF and urine biomarkers, and 7 T MRI and magentic resonance spectroscopy (MRS). Post-mortem analysis included β-galactosidase and virus distribution, histological analysis and ganglioside content. Untreated GM1 animals survived 8.0 ± 0.6 months while intravenous treatment increased survival to an average of 3.5 years (n = 2) with substantial improvements in quality of life and neurological function. Neurological abnormalities, which in untreated animals progress to the inability to stand and debilitating neurological disease by 8 months of age, were mild in all treated animals. CSF biomarkers were normalized, indicating decreased CNS cell damage in the treated animals. Urinary glycosaminoglycans decreased to normal levels in the long-term cohort. MRI and MRS showed partial preservation of the brain in treated animals, which was supported by post-mortem histological evaluation. β-Galactosidase activity was increased throughout the CNS, reaching carrier levels in much of the cerebrum and normal levels in the cerebellum, spinal cord and CSF. Ganglioside accumulation was significantly reduced by treatment. Peripheral tissues such as heart, skeletal muscle, and sciatic nerve also had normal β-galactosidase activity in treated GM1 cats. GM1 histopathology was largely corrected with treatment. There was no evidence of tumorigenesis or toxicity. Restoration of β-galactosidase activity in the CNS and peripheral organs by intravenous gene therapy led to profound increases in lifespan and quality of life in GM1 cats. These data support the promise of intravenous gene therapy as a safe, effective treatment for GM1 gangliosidosis.

Transcriptome of HPβCD-treated Niemann-Pick disease type C1 cells highlights GPNMB as a biomarker for therapeutics

The rare, fatal neurodegenerative disorder Niemann-Pick disease type C1 (NPC1) arises from lysosomal accumulation of unesterified cholesterol and glycosphingolipids. These subcellular pathologies lead to phenotypes of hepatosplenomegaly, neurological degeneration and premature death. The timing and severity of NPC1 clinical presentation is extremely heterogeneous. This study analyzed RNA-Seq data from 42 NPC1 patient-derived, primary fibroblast cell lines to determine transcriptional changes induced by treatment with 2-hydroxypropyl-β-cyclodextrin (HPβCD), a compound currently under investigation in clinical trials. A total of 485 HPβCD-responsive genes were identified. Pathway enrichment analysis of these genes showed significant involvement in cholesterol and lipid biosynthesis. Furthermore, immunohistochemistry of the cerebellum as well as measurements of plasma from Npc1m1N null mice treated with HPβCD and adeno-associated virus gene therapy suggests that one of the identified genes, GPNMB, may serve as a useful biomarker of treatment response in NPC1 disease. Overall, this large NPC1 patient-derived dataset provides a comprehensive foundation for understanding the genomic response to HPβCD treatment.