A simple and effective method to generate lentiviral vectors for ex vivo gene delivery to mature human peripheral blood lymphocytes

Comparison of the efficacy of second and third generation lentiviral vector transduced CAR CD19 T cells for use in the treatment of acute lymphoblastic leukemia both in vitro and in vivo models

T cells genetically engineered to express a chimeric antigen receptor (CAR) specifically binding to a CD19 antigen has become the frontline of hematological malignancies immunotherapy. Their remarkable antitumor effect has exerted complete remission in treating B-cell malignancies. Although successful patient treatment has been shown, improvement to the structure of CAR to enhance its safety and efficacy profile is warranted. Transduction with a lentiviral vector (LVV) leading to the expression of CARs is also a critical step in redirecting T cells to target specific tumor antigens. To improve the efficacy of CD19 CARs in this study, the transduction ability of second and third generations LVV were compared. Ex vivo expansion of CD19 CARs T cells from healthy donors' peripheral blood mononuclear cells was performed after transduction of T cells with second and third generations LVV. Transduction efficacy of transduced T cells was determined to show a higher percentage in the third generations LVV transduced cells, with no changes in viability and identity of cells characterized by immunophenotyping. Testing the cytotoxic capacity of third generations LVV-transduced T cells against target cells showed higher reactivity against control cells. Cytokine expression was detected on the CD19 CARs T cells, suggesting that these cells limit in vitro growth of B-cell leukemia via secretion of the pro-inflammatory cytokine IFN γ. To investigate whether the third generation LVV transduced T cells can limit CD19 lymphoma growth in vivo, an analysis of tumor burden in a mouse model assessed by bioluminescence imaging was performed. We found that, in the presence of CD19 CARs T cells, the level of tumor burden was markedly reduced. In addition, an increase in the length of survival in mice receiving CAR-CD19 T cells was also observed. This suggests that transduction with third generations LVV generate a functional CAR-CD19 T cells, which may provide a safer and effective therapy for B-cell malignancies.

FGF21-Sirtuin 3 Axis Confers the Protective Effects of Exercise Against Diabetic Cardiomyopathy by Governing Mitochondrial Integrity

BACKGROUND

Exercise is an effective nonpharmacological strategy to alleviate diabetic cardiomyopathy (DCM) through poorly defined mechanisms. FGF21 (fibroblast growth factor 21), a peptide hormone with pleiotropic benefits on cardiometabolic homeostasis, has been identified as an exercise responsive factor. This study aims to investigate whether FGF21 signaling mediates the benefits of exercise on DCM, and if so, to elucidate the underlying mechanisms.

METHODS

The global or hepatocyte-specific FGF21 knockout mice, cardiomyocyte-selective β-klotho (the obligatory co-receptor for FGF21) knockout mice, and their wild-type littermates were subjected to high-fat diet feeding and injection of streptozotocin to induce DCM, followed by a 6-week exercise intervention and assessment of cardiac functions. Cardiac mitochondrial structure and function were assessed by electron microscopy, enzymatic assays, and measurements of fatty acid oxidation and ATP production. Human induced pluripotent stem cell-derived cardiomyocytes were used to investigate the receptor and postreceptor signaling pathways conferring the protective effects of FGF21 against toxic lipids-induced mitochondrial dysfunction.

RESULTS

Treadmill exercise markedly induced cardiac expression of β-klotho and significantly attenuated diabetes-induced cardiac dysfunction in wild-type mice, accompanied by reduced mitochondrial damage and increased activities of mitochondrial enzymes in hearts. However, such cardioprotective benefits of exercise were largely abrogated in mice with global or hepatocyte-selective ablation of FGF21, or cardiomyocyte-specific deletion of β-klotho. Mechanistically, exercise enhanced the cardiac actions of FGF21 to induce the expression of the mitochondrial deacetylase SIRT3 by AMPK-evoked phosphorylation of FOXO3, thereby reversing diabetes-induced hyperacetylation and functional impairments of a cluster of mitochondrial enzymes. FGF21 prevented toxic lipids-induced mitochondrial dysfunction and oxidative stress by induction of the AMPK/FOXO3/SIRT3 signaling axis in human induced pluripotent stem cell-derived cardiomyocytes. Adeno-associated virus-mediated restoration of cardiac SIRT3 expression was sufficient to restore the responsiveness of diabetic FGF21 knockout mice to exercise in amelioration of mitochondrial dysfunction and DCM.

CONCLUSIONS

The FGF21-SIRT3 axis mediates the protective effects of exercise against DCM by preserving mitochondrial integrity and represents a potential therapeutic target for DCM.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03240978.

Lentiviral globin gene therapy with reduced-intensity conditioning in adults with β-thalassemia: a phase 1 trial

β-Thalassemias are inherited anemias that are caused by the absent or insufficient production of the β chain of hemoglobin. Here we report 6-8-year follow-up of four adult patients with transfusion-dependent β-thalassemia who were infused with autologous CD34+ cells transduced with the TNS9.3.55 lentiviral globin vector after reduced-intensity conditioning (RIC) in a phase 1 clinical trial ( NCT01639690) . Patients were monitored for insertional mutagenesis and the generation of a replication-competent lentivirus (safety and tolerability of the infusion product after RIC-primary endpoint) and engraftment of genetically modified autologous CD34+ cells, expression of the transduced β-globin gene and post-transplant transfusion requirements (efficacy-secondary endpoint). No unexpected safety issues occurred during conditioning and cell product infusion. Hematopoietic gene marking was very stable but low, reducing transfusion requirements in two patients, albeit not achieving transfusion independence. Our findings suggest that non-myeloablative conditioning can achieve durable stem cell engraftment but underscore a minimum CD34+ cell transduction requirement for effective therapy. Moderate clonal expansions were associated with integrations near cancer-related genes, suggestive of non-erythroid activity of globin vectors in stem/progenitor cells. These correlative findings highlight the necessity of cautiously monitoring patients harboring globin vectors.

Production of CAR T-cells by GMP-grade lentiviral vectors: latest advances and future prospects

Chimeric antigen receptor (CAR) T-cells represent a paradigm shift in cancer immunotherapy and a new milestone in the history of oncology. In 2017, the Food and Drug Administration approved two CD19-targeted CAR T-cell therapies (Kymriah™, Novartis, and Yescarta™, Kite Pharma/Gilead Sciences) that have remarkable efficacy in some B-cell malignancies. The CAR approach is currently being evaluated in multiple pivotal trials designed for the immunotherapy of hematological malignancies as well as solid tumors. To generate CAR T-cells ex vivo, lentiviral vectors (LVs) are particularly appealing due to their ability to stably integrate relatively large DNA inserts, and to efficiently transduce both dividing and nondividing cells. This review discusses the latest advances and challenges in the design and production of CAR T-cells, and the good manufacturing practices (GMP)-grade production process of LVs used as a gene transfer vehicle. New developments in the application of CAR T-cell therapy are also outlined with particular emphasis on next-generation allogeneic CAR T-cells.

Deliverable transgenics & gene therapy possibilities for the testes

Male infertility and hypogonadism are clinically prevalent conditions with a high socioeconomic burden and are both linked to an increased risk in cardiovascular-metabolic diseases and earlier mortality. Therefore, there is an urgent need to better understand the causes and develop new treatments for these conditions that affect millions of men. The accelerating advancement in gene editing and delivery technologies promises improvements in both diagnosis as well as affording the opportunity to develop bespoke treatment options which would both prove beneficial for the millions of individuals afflicted with these reproductive disorders. In this review, we summarise the systems developed and utilised for the delivery of gene therapy and discuss how each of these systems could be applied for the development of a gene therapy system in the testis and how they could be of use for the future diagnosis and repair of common male reproductive disorders.

False-positive HIV nucleic acid amplification testing during CAR T-cell therapy

Advancements in immunotherapy have opened a new era in oncology, to include genetic modification of human T-cells to express a chimeric antigen receptor (CAR) that enables targeted tumor recognition (Kochenderfer et al., 2015; Lee et al., 2015; Maus and Levine 2016; Rosenberg et al., 2008). Herein, we report a false-positive HIV testing in a patient who had undergone CAR T-cell therapy created with a lentiviral vector.

Sources of Error in Mammalian Genetic Screens

Genetic screens are invaluable tools for dissection of biological phenomena. Optimization of such screens to enhance discovery of candidate genes and minimize false positives is thus a critical aim. Here, we report several sources of error common to pooled genetic screening techniques used in mammalian cell culture systems, and demonstrate methods to eliminate these errors. We find that reverse transcriptase-mediated recombination during retroviral replication can lead to uncoupling of molecular tags, such as DNA barcodes (BCs), from their associated library elements, leading to chimeric proviral genomes in which BCs are paired to incorrect ORFs, shRNAs, etc This effect depends on the length of homologous sequence between unique elements, and can be minimized with careful vector design. Furthermore, we report that residual plasmid DNA from viral packaging procedures can contaminate transduced cells. These plasmids serve as additional copies of the PCR template during library amplification, resulting in substantial inaccuracies in measurement of initial reference populations for screen normalization. The overabundance of template in some samples causes an imbalance between PCR cycles of contaminated and uncontaminated samples, which results in a systematic artifactual depletion of GC-rich library elements. Elimination of contaminating plasmid DNA using the bacterial endonuclease Benzonase can restore faithful measurements of template abundance and minimize GC bias.

Potential limitations of the NSG humanized mouse as a model system to optimize engineered human T cell therapy for cancer

The genetic modification of peripheral blood lymphocytes using retroviral vectors to redirect T cells against tumor cells has been recently used as a means to generate large numbers of antigen-specific T cells for adoptive cell therapy protocols. However, commonly used retroviral vector-based genetic modification requires T cells to be driven into cell division; this potent mitogenic stimulus is associated with the development of an effector phenotype that may adversely impact upon the long-term engraftment potential and subsequent antitumor effects of T cells. To investigate whether the cytokines used during culture impact upon the engraftment potential of gene-modified T cells, a humanized model employing T cells engrafted with a MART-1-specific T cell receptor adoptively transferred into NOD/Shi-scid IL-2rγ(-/-) (NSG) immune-deficient mice bearing established melanoma tumors was used to compare the effects of the common γ chain cytokines IL-2, IL-7, and IL-15 upon gene-modified T cell activity. MART-1-specific T cells cultured in IL-7 and IL-15 demonstrated greater relative in vitro proliferation and viability of T cells compared with the extensively used IL-2. Moreover, the IL-15 culture prolonged the survival of animals bearing melanoma tumors after adoptive transfer. However, the combination of IL-7 and IL-15 produced T cells with improved engraftment potential compared with IL-15 alone; however, a high rate of xenogeneic graft-versus-host disease prevented the identification of a clear improvement in antitumor effect of these T cells. These results clearly demonstrate modulation of gene-modified T cell engraftment in the NSG mouse, which supports the future testing of the combination of IL-7 and IL-15 in adoptive cell therapy protocols; however, this improved engraftment is also associated with the long-term maintenance of xenoreactive T cells, which limits the ultimate usefulness of the NSG mouse model in this situation.

Novel gene delivery systems

Gene therapy is an emerging field in medical and pharmaceutical sciences because of its potential in treating chronic diseases like cancer, viral infections, myocardial infarctions, and genetic disorders. Application of gene therapy is limited because of lack of suitable methods for proper introduction of genes into cells and therefore, this is an area of interest for most of the researchers. To achieve successful gene therapy, development of proper gene delivery systems could be one of the most important factors. Several nonviral and viral gene transfer methods have been developed. Even though the viral agents have a high transferring efficiency, they are difficult to handle due to their toxicity. To overcome the safety problems of the viral counterpart, several nonviral in vitro and in vivo gene delivery systems are developed. Out of these, the most promising and latest systems include polymer-based nonviral gene carriers, dendrimers, and physical means like electroporation, microinjection, etc., Shunning of possible immunogenicity and toxicity, and the feasibility of repeated administration are some of the merits of nonviral gene delivery systems over viral gene delivery. An ideal nonviral gene carrying system should possess all these merits without any compromise to its gene transferring efficiency. The viral gene delivery systems include lytic and nonlytic vectors for drug delivery. Inspite of its toxicity they are still preferred because of their long term expression, stability, and integrity. This review explores the recent developments and relevancy of the novel gene delivery systems in gene therapy.

Autologous regulatory T cells for the treatment of type 1 diabetes

The immune system is tasked with defending the host from a wide array of pathogens and environmental insults. When uncontrolled, this endeavor may lead to off-target reactivity to self-tissues resulting in multiple autoimmune diseases including type 1 diabetes (T1D). This multifactorial disease process involves over 40 susceptibility genes and is influenced by poorly characterized environmental factors. While many questions regarding the pathogenesis of the disease process remain, it has become increasingly clear that the progression to disease results from a breakdown in the processes that maintain peripheral immune tolerance. The end result of this process is localized tissue inflammation, islet dysfunction, and ultimately the destruction of pancreatic β cells due to concomitant defects in innate and adaptive immune responses. A number of immunomodulatory intervention trials have now been conducted in patients at risk for or with recent onset T1D, often with the goal of restoring immune tolerance by inducing regulatory T cells (Tregs). Unfortunately, many of these trials have fallen short of inducing persistent immune regulation. This shortfall has led to additional efforts to more directly shift the balance from destructive effector T cell (Teff) responses to favor Tregs, including the use of autologous Treg cell therapy. In this review we will discuss key concepts related to the use of autologous Treg cell therapy for the treatment of T1D. Among these topics, we will discuss the notions of genetic control of Treg activity, Treg cellular plasticity, and requirements for antigen-specificity.