New Molecular Surrogate Assay for Genotoxicity Assessment of Gene Therapy Vectors (SAGA)

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4710-4710 ◽  
Author(s):  
Adrian Schwarzer ◽  
Steven R Talbot ◽  
Oliver Dittrich-Breiholz ◽  
Adrian J Thrasher ◽  
Bobby Gaspar ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Clinical Trials ◽  
Insertional Mutagenesis ◽  
Lentiviral Vectors ◽  
Mutagenic Potential ◽  
In Vivo Models ◽  
Core Set ◽  
Gene Therapy Vectors ◽  
Surrogate Assay

Abstract The variety of gene therapy vectors for a multitude of different diseases has increased tremendously over the years. However, a number of patients that underwent gene therapy in different trials developed hematological malignancy caused by integration of the provirus in the vicinity of proto-oncogenes. These severe adverse advents prompted intense research efforts towards safer gene therapy, leading to the removal of the long terminal repeat enhancer elements and the use of internal promoters in retroviral vectors. Still, a bottleneck of transition from basic research to clinical application is the test for safety of integrating retro- and lentiviral vectors. Instead of laborious in vivo models with limited predictive value, in vitro assays to screen for insertional mutagenesis are strongly desirable. A decade ago, our lab developed the in vitro immortalization (IVIM) assay to quantify the genotoxic potential of viral vectors, which has been widely used to complete preclinical safety documentation of newly developed integrating vector systems. Despite general acceptance in the field of hematopoietic gene therapy, bias for insertional mutants of the myeloid lineage, a low sensitivity and a long assay run time are clear limitations. We now developed the molecular surrogate assay for genotoxicity assessment (SAGA). The new test is more robust, sensitive and biologically informative. As input we used murine lineage-negative hematopoietic stem and progenitor cells (HSPC) that were cultured as described for the IVIM assay. The murine HSPC were transduced with a number of different gammaretro- and lentiviral vectors, including vectors that have been employed in clinical trials for X-SCID and Wiskott-Aldrich Syndrome. After 14 days, whole mRNA was isolated from transduced and non-transduced samples and analyzed by Agilent custom microarrays (n=86) and qPCR from nine independent SAGA assays. We applied several Machine Learning algorithms to derive a core set of genes which distinguishes transformed from non-transformed samples in each individual SAGA assay. This set of genes from the individual analysis was further analyzed to derive a core set of genes that is able to robustly separate transformed from non-transformed samples in all assays performed. In order to account for platform-specific effects we validated all microarray results by conventional qPCR-methodology. The SAGA gene set was then cross-validated in an independent validation cohort of SAGA-assays that were not part of the SAGA-training set from which the signature was derived from. The SAGA assay was used to quantify the mutagenic potential of several benchmark vectors. It correctly assigned a high mutagenic potential to vectors (MFG.yc and CMMP.WASP) which led to serious adverse events (SAEs) in clinical trials. Most importantly, the SAGA assay reliably scored high for mutagenic vectors, even when the vector did not transform in IVIM-assays conducted in parallel, demonstrating the higher sensitivity of the SAGA-principle. In contrast, SIN lentiviral vectors with weaker internal promoters (LV.EFS.yc and LV.EFS.ADA) showed no enrichment of the SAGA-core signature and hence scored much safer in the SAGA test. We present the results for these vectors side-by-side either using IVIM or SAGA. In summary, we generated an advanced version of the currently used in vitro insertional mutagenesis screening system by integrating a molecular read-out which enhances reproducibility, sensitivity and reduces assay duration, paving the way for a better preclinical risk assessment of gene therapy vectors. Disclosures No relevant conflicts of interest to declare.

scholarly journals Non-Integrating Lentiviral Vectors in Clinical Applications: A Glance Through

Biomedicines ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 107
Author(s):  
Narmatha Gurumoorthy ◽  
Fazlina Nordin ◽  
Gee Jun Tye ◽  
Wan Safwani Wan Kamarul Zaman ◽  
Min Hwei Ng
Keyword(s):  
Gene Therapy ◽  
Clinical Trials ◽  
Transient Expression ◽  
Clinical Studies ◽  
Insertional Mutagenesis ◽  
Cell Transformation ◽  
Induced Pluripotent Stem Cell ◽  
Lentiviral Vectors ◽  
Malignant Cell ◽  
Target Cells

Lentiviral vectors (LVs) play an important role in gene therapy and have proven successful in clinical trials. LVs are capable of integrating specific genetic materials into the target cells and allow for long-term expression of the cDNA of interest. The use of non-integrating LVs (NILVs) reduces insertional mutagenesis and the risk of malignant cell transformation over integrating lentiviral vectors. NILVs enable transient expression or sustained episomal expression, especially in non-dividing cells. Important modifications have been made to the basic human immunodeficiency virus (HIV) structures to improve the safety and efficacy of LVs. NILV-aided transient expression has led to more pre-clinical studies on primary immunodeficiencies, cytotoxic cancer therapies, and hemoglobinopathies. Recently, the third generation of self-inactivating LVs was applied in clinical trials for recombinant protein production, vaccines, gene therapy, cell imaging, and induced pluripotent stem cell (iPSC) generation. This review discusses the basic lentiviral biology and the four systems used for generating NILV designs. Mutations or modifications in LVs and their safety are addressed with reference to pre-clinical studies. The detailed application of NILVs in promising pre-clinical studies is also discussed.

scholarly journals Lentiviral Vectors for the Treatment and Prevention of Cystic Fibrosis Lung Disease

Genes ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 218 ◽  
Author(s):  
Laura Marquez Loza ◽  
Eric Yuen ◽  
Paul McCray
Keyword(s):  
Cystic Fibrosis ◽  
Gene Therapy ◽  
Clinical Trials ◽  
Insertional Mutagenesis ◽  
Primary Cultures ◽  
Severe Combined Immunodeficiency ◽  
Lentiviral Vectors ◽  
Retroviral Vectors ◽  
Airway Epithelia

Despite the continued development of cystic fibrosis transmembrane conductance regulator (CFTR) modulator drugs for the treatment of cystic fibrosis (CF), the need for mutation agnostic treatments remains. In a sub-group of CF individuals with mutations that may not respond to modulators, such as those with nonsense mutations, CFTR gene transfer to airway epithelia offers the potential for an effective treatment. Lentiviral vectors are well-suited for this purpose because they transduce nondividing cells, and provide long-term transgene expression. Studies in primary cultures of human CF airway epithelia and CF animal models demonstrate the long-term correction of CF phenotypes and low immunogenicity using lentiviral vectors. Further development of CF gene therapy requires the investigation of optimal CFTR expression in the airways. Lentiviral vectors with improved safety features have minimized insertional mutagenesis safety concerns raised in early clinical trials for severe combined immunodeficiency using γ-retroviral vectors. Recent clinical trials using improved lentiviral vectors support the feasibility and safety of lentiviral gene therapy for monogenetic diseases. While work remains to be done before CF gene therapy reaches the bedside, recent advances in lentiviral vector development reviewed here are encouraging and suggest it could be tested in clinical studies in the near future.

scholarly journals Recombinant Adeno-Associated Viral Vectors (rAAV)-Vector Elements in Ocular Gene Therapy Clinical Trials and Transgene Expression and Bioactivity Assays

2020 ◽  
Vol 21 (12) ◽  
pp. 4197 ◽  
Author(s):  
Thilo Buck ◽  
Jan Wijnholds
Keyword(s):  
Gene Therapy ◽  
Clinical Trials ◽  
Viral Vectors ◽  
Ex Vivo ◽  
Meta Analysis ◽  
Production Yield ◽  
Gene Cassettes ◽  
Gene Therapies ◽  
Gene Therapy Vectors

Inherited retinal dystrophies and optic neuropathies cause chronic disabling loss of visual function. The development of recombinant adeno-associated viral vectors (rAAV) gene therapies in all disease fields have been promising, but the translation to the clinic has been slow. The safety and efficacy profiles of rAAV are linked to the dose of applied vectors. DNA changes in the rAAV gene cassette affect potency, the expression pattern (cell-specificity), and the production yield. Here, we present a library of rAAV vectors and elements that provide a workflow to design novel vectors. We first performed a meta-analysis on recombinant rAAV elements in clinical trials (2007–2020) for ocular gene therapies. We analyzed 33 unique rAAV gene cassettes used in 57 ocular clinical trials. The rAAV gene therapy vectors used six unique capsid variants, 16 different promoters, and six unique polyadenylation sequences. Further, we compiled a list of promoters, enhancers, and other sequences used in current rAAV gene cassettes in preclinical studies. Then, we give an update on pro-viral plasmid backbones used to produce the gene therapy vectors, inverted terminal repeats, production yield, and rAAV safety considerations. Finally, we assess rAAV transgene and bioactivity assays applied to cells or organoids in vitro, explants ex vivo, and clinical studies.

scholarly journals Single-cell RNA sequencing reveals distinct cellular factors for response to immunotherapy targeting CD73 and PD-1 in colorectal cancer

2021 ◽  
Vol 9 (7) ◽  
pp. e002503
Author(s):  
Miok Kim ◽  
Yong Ki Min ◽  
Jinho Jang ◽  
Hyejin Park ◽  
Semin Lee ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Clinical Trials ◽  
T Cells ◽  
T Cell ◽  
In Vivo Models ◽  
Single Cell Rna Sequencing ◽  
Tcr Diversity ◽  
Cancer Immunotherapies

BackgroundAlthough cancer immunotherapy is one of the most effective advanced-stage cancer therapies, no clinically approved cancer immunotherapies currently exist for colorectal cancer (CRC). Recently, programmed cell death protein 1 (PD-1) blockade has exhibited clinical benefits according to ongoing clinical trials. However, ongoing clinical trials for cancer immunotherapies are focused on PD-1 signaling inhibitors such as pembrolizumab, nivolumab, and atezolizumab. In this study, we focused on revealing the distinct response mechanism for the potent CD73 ectoenzyme selective inhibitor AB680 as a promising drug candidate that functions by blocking tumorigenic ATP/adenosine signaling in comparison to current therapeutics that block PD-1 to assess the value of this drug as a novel immunotherapy for CRC.MethodsTo understand the distinct mechanism of AB680 in comparison to that of a neutralizing antibody against murine PD-1 used as a PD-1 blocker, we performed single-cell RNA sequencing of CD45+ tumor-infiltrating lymphocytes from untreated controls (n=3) and from AB680-treated (n=3) and PD-1-blockade-treated murine CRC in vivo models. We also used flow cytometry, Azoxymethane (AOM)/Dextran Sulfate Sodium (DSS) models, and in vitro functional assays to validate our new findings.ResultsWe initially observed that the expressions of Nt5e (a gene for CD73) and Entpd1 (a gene for CD39) affect T cell receptor (TCR) diversity and transcriptional profiles of T cells, thus suggesting their critical roles in T cell exhaustion within tumor. Importantly, PD-1 blockade significantly increased the TCR diversity of Entpd1-negative T cells and Pdcd1-positive T cells. Additionally, we determined that AB680 improved the anticancer functions of immunosuppressed cells such as Treg and exhausted T cells, while the PD-1 blocker quantitatively reduced Malat1high Treg and M2 macrophages. We also verified that PD-1 blockade induced Treg depletion in AOM/DSS CRC in vivo models, and we confirmed that AB680 treatment caused increased activation of CD8+ T cells using an in vitro T cell assay.ConclusionsThe intratumoral immunomodulation of CD73 inhibition is distinct from PD-1 inhibition and exhibits potential as a novel anticancer immunotherapy for CRC, possibly through a synergistic effect when combined with PD-1 blocker treatments. This study may contribute to the ongoing development of anticancer immunotherapies targeting refractory CRC.

Development of Megakaryocyte-Specific Lentiviral Vectors for Gene Therapy of Platelet Disorders.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 5143-5143
Author(s):  
Liesbeth De Waele ◽  
Kathleen Freson ◽  
Chantal Thys ◽  
Christel Van Geet ◽  
Désiré Collen ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Transgene Expression ◽  
Ex Vivo ◽  
Phosphoglycerate Kinase ◽  
Lentiviral Vectors ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Platelet Disorders

Abstract The prevalence of congenital platelet disorders has not been established but for some life-threatening bleeding disorders the current therapies are not adequate, justifying the development of alternative strategies as gene therapy. In the case of platelet dysfunction and thrombocytopenia as described for GATA1 deficiency, potentially lethal internal bleedings can occur. The objective of the study is to develop improved lentiviral vectors for megakaryocyte(MK)-specific long term gene expression by ex vivo transduction of hematopoietic stem cells (HSC) to ultimately use for congenital thrombopathies as GATA1 deficiency. Self-inactivating lentiviral vectors were constructed expressing GFP driven by the murine (m) or human (h) GPIIb promoter. These promoters contain multiple Ets and GATA binding sites directing MK-specificity. To evaluate the cell lineage-specificity and transgene expression potential of the vectors, murine Sca1+ and human CD34+ HSC were transduced in vitro with Lenti-hGPIIb-GFP and Lenti-mGPIIb-GFP vectors. After transduction the HSC were induced to differentiate in vitro along the MK and non-MK lineages. The mGPIIb and hGPIIb promoters drove GFP expression at overall higher levels (20% in murine cells and 25% in human cells) than the ubiquitous CMV (cytomegalovirus) or PGK (phosphoglycerate kinase) promoters, and this exclusively in the MK lineage. Interestingly, in both human and murine HSC the hGPIIb promoter with an extra RUNX and GATA binding site, was more potent in the MK lineage compared to the mGPIIb promoter. Since FLI1 and GATA1 are the main transcription factors regulating GPIIb expression, we tested the Lenti-hGPIIb-GFP construct in GATA1 deficient HSC and obtained comparable transduction efficiencies as for wild-type HSC. To assess the MK-specificity of the lentiviral vectors in vivo, we transplanted irradiated wild-type C57Bl/6 mice with Sca1+ HSC transduced with the Lenti-hGPIIb-GFP constructs. Six months after transplantation we could detect 6% GFP positive platelets without a GFP signal in other cell lineages. Conclusion: In vitro and in vivo MK-specific transgene expression driven by the hGPIIb and mGPIIb promoters could be obtained after ex vivo genetic engineering of HSC by improved lentiviral vectors. Studies are ongoing to study whether this approach can induce phenotypic correction of GATA1 deficient mice by transplantation of ex vivo Lenti-hGPIIb-GATA1 transduced HSC.

scholarly journals Immunological Characterization Of Multipotent Mesenchymal Stromal Cells. The International Society For Cellular Therapy (ISCT) Working Proposal

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5438-5438
Author(s):  
Mauro Krampera ◽  
Jacques Galipeau ◽  
Yufang Shi ◽  
Karin Tarte ◽  
Luc Sensebé
Keyword(s):  
Clinical Trials ◽  
Mesenchymal Stromal Cells ◽  
International Society ◽  
Stromal Cells ◽  
Quantitative Methods ◽  
Multipotent Mesenchymal Stromal Cells ◽  
In Vivo Models ◽  
Immunological Characterization

Abstract The large number of experimental approaches, culture conditions, qualitative and quantitative methods, and in vitro and in vivo models employed so far to assess immune regulatory properties of multipotent mesenchymal stromal cells (MSC) has led to an excess of literature data that sometimes are poorly comparable, redundant, and even contradictory. Thus, quite paradoxically, the risk is that pre-clinical literature data may become eventually weak and scarcely useful, in both researchers’ and Regulatory Authorities’ opinion, for supporting experimentally specific MSC-based clinical trials aimed at treating autoimmune and inflammatory diseases. However, some data in this field appear more solid and reproducible and may be generally accepted to suggest reproducible immunological assays to quantify the differences in immune modulatory properties of MSCs produced according to Good Manufacturing Practice (GMP). The MSC Committee of the International Society of Cell Therapy (ISCT) released a statement paper in 2006 that established the minimal criteria characterizing human MSC, without focusing particularly on their immunological properties. In the 7 years following the publication of this statement paper, more than 10,000 manuscripts on MSC, and many of them deal with immune regulation. To consolidate the scientific research in this field, the MSC Committee of the ISCT is publishing a working proposal paper aimed at stimulating the general discussion about the need of shared guidelines for the immunological characterization of MSCs for clinical use: 1. A standard immune plasticity assay should be implemented by using IFN-γ + TNF-α as model in vitro priming agent 2. Functional analysis of an expanded cell product may provide mechanistic insights on intra- and inter- study variance in clinical response amongst patients 3. The use of purified responders would be widely practicable and should provide more generalizable guidance on relative functional potency of MSC and as a companion to clinical trials 4. Interrogating the IDO response as part of an in vitro licensing assay should be considered central 5. Conclusions based on xenorecipient animal models on how to conduct clinical trials should be drawn with caution 6. The prospective hypothesis-driven analysis of lymphocyte populations in patients groups treated with MSC should be encouraged 7. Clinical analysis should also include the monitoring of whether injected MSCs are the target of an immune response. Disclosures: No relevant conflicts of interest to declare.

scholarly journals A Review on SARS-CoV-2 Virology, Pathophysiology, Animal Models, and Anti-Viral Interventions

Pathogens ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 426 ◽  
Author(s):  
Sabari Nath Neerukonda ◽  
Upendra Katneni
Keyword(s):  
Clinical Trials ◽  
Animal Models ◽  
Human Population ◽  
Randomized Clinical Trials ◽  
Lessons Learned ◽  
Highly Pathogenic ◽  
In Vivo Models ◽  
Antiviral Therapies

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of CoV disease 2019 (COVID-19) is a highly pathogenic and transmissible CoV that is presently plaguing the global human population and economy. No proven effective antiviral therapy or vaccine currently exists, and supportive care remains to be the cornerstone treatment. Through previous lessons learned from SARS-CoV-1 and MERS-CoV studies, scientific groups worldwide have rapidly expanded the knowledge pertaining to SARS-CoV-2 virology that includes in vitro and in vivo models for testing of antiviral therapies and randomized clinical trials. In the present narrative, we review SARS-CoV-2 virology, clinical features, pathophysiology, and animal models with a specific focus on the antiviral and adjunctive therapies currently being tested or that require testing in animal models and randomized clinical trials.

Gene therapy for PNP deficiency protocol

2018 ◽  
Vol 5 (3) ◽  
pp. 115-120
Author(s):  
Linda Vong
Keyword(s):  
Gene Therapy ◽  
Stem Cell ◽  
Insertional Mutagenesis ◽  
First Generation ◽  
Therapeutic Option ◽  
Lentiviral Vectors ◽  
Retroviral Vectors ◽  
Post Transplantation ◽  
Hematopoietic Stem ◽  
Key Enzyme

Purine nucleoside phosphorylase (PNP) is a key enzyme required for the degradation of purine nucleosides into uric acid or their salvage into nucleic acids. Patients who are deficient in PNP suffer from progressive T cell immunodeficiency, with increased susceptibility to infections, autoimmunity, and neurologic abnormalities. In the absence of successful treatment to restore immune function, these patients rarely survive to adulthood. Hematopoietic stem cell transplantation is the only known cure for PNP deficiency. Use of an HLA-matched donor is preferable as the outcome with alternative donors have been variable; however, this option is rarely available. Gene therapy represents a therapeutic option that bypasses the need for a donor, and thus associated complications. Although first generation γ-retroviral vectors have been successful in some immunodeficiencies, in others, evidence of insertional mutagenesis prompted a halt in their use. More recently, the introduction of safer lentiviral vectors holds promise in offering a viable option to treat immunodeficiency. Here, we present a clinical trial protocol utilizing self-inactivating lentiviral vectors to treat PNP deficiency. Patients will be evaluated up to 3 years post-transplantation to determine the safety of lentiviral-treated stem cell infusion, as well as the extent of immune reconstitution. Statement of novelty: This protocol describes the novel treatment of PNP deficiency using lentiviral-based gene therapy.

scholarly journals Characteristics of Medical Products Comprising Human Cells, Genes, or Tissues Developed in Japan and the European Union Compared via Public Assessment Reports

2020 ◽  
Vol 8 ◽  
Author(s):  
Ryosuke Kurauchi ◽  
Hiroi Kasai ◽  
Tatsuya Ito
Keyword(s):  
Gene Therapy ◽  
European Union ◽  
Clinical Trials ◽  
Cell Therapy ◽  
Human Cells ◽  
The European Union ◽  
Medical Products ◽  
The Eu ◽  
Assessment Reports

Medical products comprising human cells, genes, and tissues have been developed for clinical applications worldwide, and their developmental environment has been established. These products can be imported and exported, but marketing authorization regulations are complicated among regions. This investigation was conducted to identify the characteristics of medical products comprising human cells, genes, and tissues. We used website data, books from survey companies, and reports from public agencies to conduct two investigations. We used website data to conduct a general information survey of 143 cell-therapy and gene-therapy products sold in 24 countries and public assessment reports to individually survey non-clinical and clinical developments of 18 cell-therapy and gene-therapy products developed in Japan and the European Union (EU). The first survey revealed that the numbers of products used in orthopedic surgery and dermatology have increased since 2000, and the numbers of hematological products have increased since 2011. The second investigation revealed that fewer orphaned products were developed in Japan than in the EU. The most appropriate dose was 1.2 × 108 cells per injection per adult. Clinical trials to determine the most appropriate dose were conducted in the EU but not in Japan. No non-clinical immunogenicity tests for autogenous products were conducted in Japan or the EU. Pharmacokinetics tests were not individually performed for sheet-form products. Both in vivo and in vitro pharmacological tests were more likely to be conducted in the EU, while only one or the other was conducted in Japan. Furthermore, in Japan, carcinogenicity tests were performed based on non-clinical technical guidance, while in the EU, these tests were determined according to each product's features. Fewer clinical trials were performed, and fewer subjects per product were used in Japan than in the EU. Many aspects of the clinical and non-clinical development of medical products comprising human cells, genes, and tissues differ between Japan and the EU. Analyzing these differences will enable the safe and rapid distribution of these products to clinical sites.

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