Gene Therapy For Primary Immunodeficiencies Research Articles

The Role of Gene Therapy for Primary Immunodeficiency

Primary Immunodeficiency disease (PID) is a wide genre of inborn defects that affect the patients immune system. More than 430 distinct phenotypes have been reported and more are being identified. Traditional treatments to PID include clearance or prevention of infections, avoidance of exposure to pathogen and live vaccines, immunoglobulin replacement therapy, and haematopoietic stem cell transplantation (HSCT). Mostly HSCT would be the only feasible radical solution, while others only offer temporary suppression of the condition. On the other hand, with the advancements in technology, gene therapy starts to show promising effects in multiple diseases including PID. In this review, we mainly discussed the effect and resent progresses of gene therapy on two common kinds of PID, SCID and WAS.

In Utero Gene Therapy for Primary Immunodeficiencies.

Primary immunodeficiencies (PIDs) have become a prime target for gene therapy given the morbidity, mortality, and the single gene etiology. Given that outcomes are better the earlier gene therapy is implemented, it is possible that fetal gene therapy may be an important future direction for the treatment of PIDs. In this chapter, the current treatments available for several PIDs will be reviewed, as well as the history and current status of gene therapy for PIDs. The possibility of in utero gene therapy as a possibility will then be discussed.

Gene Therapy for Primary Immunodeficiency.

Over the past 3 decades, there has been significant progress in refining gene therapy technologies and procedures. Transduction of hematopoietic stem cells ex vivo using lentiviral vectors can now create a highly effective therapeutic product, capable of reconstituting many different immune system dysfunctions when reinfused into patients. Here, we review the key developments in the gene therapy landscape for primary immune deficiency, from an experimental therapy where clinical efficacy was marred by adverse events, to a commercialized product with enhanced safety and efficacy. We also discuss progress being made in preclinical studies for challenging disease targets and emerging gene editing technologies that are showing promising results, particularly for conditions where gene regulation is important for efficacy.

Gene therapy for primary immunodeficiencies.

Primary immunodeficiencies (PIDs) are a group of rare inherited disorders of the immune system. Many PIDs are devastating and require a definitive therapy to prevent progressive morbidity and premature mortality. Allogeneic haematopoietic stem cell transplantation (alloHSCT) is curative for many PIDs, and while advances have resulted in improved outcomes, the procedure still carries a risk of mortality and morbidity from graft failure or graft-versus-host disease (GvHD). Autologous haematopoietic stem cell gene therapy (HSC GT) has the potential to correct genetic defects across haematopoietic lineages without the complications of an allogeneic approach. HSC GT for PID has been in development for the last two decades and the first licensed HSC-GT product for adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) is now available. New gene editing technologies have the potential to circumvent some of the problems associated with viral gene-addition. HSC GT for PID shows great promise, but requires a unique approach for each disease and carries risks, notably insertional mutagenesis from gamma-retroviral gene addition approaches and possible off-target toxicities from gene-editing techniques. In this review, we discuss the development of HSC GT for PID and outline the current state of clinical development before discussing future developments in the field.

Gene therapy for primary immunodeficiency.

Gene therapy is now being trialled as a therapeutic option for an expanding number of conditions, based primarily on the successful treatment over the past two decades of patients with specific primary immunodeficiencies (PIDs) including severe combined immunodeficiency and Wiskott-Aldrich syndrome and metabolic conditions such as leukodystrophy. The field has evolved from the use of gammaretroviral vectors to more sophisticated lentiviral platforms that offer an improved biosafety profile alongside greater efficiency for hematopoietic stem cells gene transfer. Here we review more recent developments including licensing of gene therapies, use of gene corrected autologous T cells as an alternative strategy for some PIDs and the potential of targeted gene correction using various gene editing platforms. Given the promising results of recent clinical trials, it is likely that autologous gene therapies will become standard of care for a number of devastating diseases in the coming decade.

Gene therapy for primary immunodeficiency

The former definition of gene therapy was the infusion of genes or cells transduced with genes into humans for the treatment or prevention of a disease, i.e., gene therapy adds a functional gene into the patients' genome, whereas the mutated gene remains as it is. Because most of the immune immunodeficiency disorders (PID) are caused by single gene mutations, this therapeutic option may provide a clinical effect. However, the treatment has a severe problem of leukemogenesis caused by insertional mutagenesis; therefore, it is not applicable for diseases caused by the gain-of-function of mutated genes. To address this, gene therapy using gene correction techniques will come to the forefront of the mainstream research. Herein, I have focused on the present outline of gene therapy by gene addition and described the future prospects of gene therapy by gene correction for PID.

High Efficiency Gene Correction in Hematopoietic Cells by Donor-Template-Free CRISPR/Cas9 Genome Editing.

The CRISPR/Cas9 prokaryotic adaptive immune system and its swift repurposing for genome editing enables modification of any prespecified genomic sequence with unprecedented accuracy and efficiency, including targeted gene repair. We used the CRISPR/Cas9 system for targeted repair of patient-specific point mutations in the Cytochrome b-245 heavy chain gene (CYBB), whose inactivation causes chronic granulomatous disease (XCGD)—a life-threatening immunodeficiency disorder characterized by the inability of neutrophils and macrophages to produce microbicidal reactive oxygen species (ROS). We show that frameshift mutations can be effectively repaired in hematopoietic cells by non-integrating lentiviral vectors carrying RNA-guided Cas9 endonucleases (RGNs). Because about 25% of most inherited blood disorders are caused by frameshift mutations, our results suggest that up to a quarter of all patients suffering from monogenic blood disorders could benefit from gene therapy employing personalized, donor template-free RGNs.

Advances in basic and clinical immunology in 2016

Advances in basic immunology in 2016 included studies that further characterized the role of different proteins in the differentiation of effector T and B cells, including cytokines and proteins involved in the actin cytoskeleton. Regulation of granule formation and secretion in cytotoxic cells was also further described by examining patients with familial hemophagocytic lymphohistiocytosis. The role of prenylation in patients with mevalonate kinase deficiency leading to inflammation has been established. We reviewed advances in clinical immunology, as well as new approaches of whole-genome sequencing and genes newly reported to be associated with immunodeficiency, such as linker of activation of T cells (LAT); B-cell CLL/lymphoma 11B (BCL11B); RGD, leucine-rich repeat, tropomodulin domain, and proline-rich domain-containing protein (RLTPR); moesin; and Janus kinase 1 (JAK1). Trials of hematopoietic stem cell transplantation and gene therapy for primary immunodeficiency have had relative success; the use of autologous virus-specific cytotoxic T cells has proved effective as well. New medications are being explored, such as pioglitazone, which is under study for its role in enhancing the oxidative burst in patients with chronic granulomatous disease. Development of vaccines for HIV infection continues to provide insight into the immune response against a virus with an extraordinary mutation rate.

Targeting safety in the clinic for precise genome editing using CRISPR: a genotoxicologist's perspective.

Targeting safety in the clinic for precise genome editing using CRISPR: a genotoxicologist's perspective.

Advances of gene therapy for primary immunodeficiencies.

In the recent past, the gene therapy field has witnessed a remarkable series of successes, many of which have involved primary immunodeficiency diseases, such as X-linked severe combined immunodeficiency, adenosine deaminase deficiency, chronic granulomatous disease, and Wiskott-Aldrich syndrome. While such progress has widened the choice of therapeutic options in some specific cases of primary immunodeficiency, much remains to be done to extend the geographical availability of such an advanced approach and to increase the number of diseases that can be targeted. At the same time, emerging technologies are stimulating intensive investigations that may lead to the application of precise genetic editing as the next form of gene therapy for these and other human genetic diseases.

Gene therapy for monogenic disorders of the bone marrow

Ex-vivo gene transfer of autologous haematopoietic stem cells in patients with monogenic diseases of the bone marrow has emerged as a new therapeutic approach, mainly in patients lacking a suitable donor for transplant. The encouraging results of initial clinical trials of gene therapy for primary immunodeficiencies were tempered by the occurrence of genotoxicity in a number of patients. Over the last decade, safer viral vectors have been developed to overcome the risk of insertional mutagenesis and have led to impressive clinical outcomes with considerably improved safety. We review the efforts in specific immunodeficiencies including adenosine deaminase deficiency, X-linked severe combined immunodeficiency, chronic granulomatous disease and Wiskott Aldrich syndrome. Major recent progress has also been made in haemoglobinopathies, such as beta-thalassaemia, sickle cell disease and Fanconi anaemia, and also specific lysosomal storage diseases, which, although not strictly bone marrow specific conditions, have been effectively treated by bone marrow-based treatment. The success of these recent studies and the advent of new technologies, such as gene editing, suggest that gene therapy could become a more generally applied treatment modality for a number of haematopoietic disorders.

Clinical applications of gene therapy for primary immunodeficiencies.

Primary immunodeficiencies (PIDs) have represented a paradigmatic model for successes and pitfalls of hematopoietic stem cells gene therapy. First clinical trials performed with gamma retroviral vectors (γ-RV) for adenosine deaminase severe combined immunodeficiency (ADA-SCID), X-linked SCID (SCID-X1), and Wiskott-Aldrich syndrome (WAS) showed that gene therapy is a valid therapeutic option in patients lacking an HLA-identical donor. No insertional mutagenesis events have been observed in more than 40 ADA-SCID patients treated so far in the context of different clinical trials worldwide, suggesting a favorable risk-benefit ratio for this disease. On the other hand, the occurrence of insertional oncogenesis in SCID-X1, WAS, and chronic granulomatous disease (CGD) RV clinical trials prompted the development of safer vector construct based on self-inactivating (SIN) retroviral or lentiviral vectors (LVs). Here we present the recent results of LV-mediated gene therapy for WAS showing stable multilineage engraftment leading to hematological and immunological improvement, and discuss the differences with respect to the WAS RV trial. We also describe recent clinical results of SCID-X1 gene therapy with SIN γ-RV and the perspectives of targeted genome editing techniques, following early preclinical studies showing promising results in terms of specificity of gene correction. Finally, we provide an overview of the gene therapy approaches for other PIDs and discuss its prospects in relation to the evolving arena of allogeneic transplant.

Gene therapy for primary immunodeficiencies.

Gene therapy has effectively entered Medicine via the field of primary immunodeficiencies (PID). Because hematopoietic stem cells are accessible and because it was understood that genetic correction of lymphocyte progenitor cells carrying a genetic defect impairing differentiation, could result in the production of long-lived T lymphocytes, it was reasoned that ex vivo gene transfer in hematopoietic cells could lead to disease phenotype correction. Retroviral vectors were designed to ex vivo transduce such cells. This has indeed been shown to lead to sustained correction of the T cell immunodeficiency associated with two forms of severe combined immunodeficiencies (SCID) for now more than ten years. Occurrence in some patients of genotoxicity related to retroviral vectors integration close to and transactivation of oncogenes has led to the development of retroviral vectors devoid of its enhancer element. Results of recent trials performed for several forms of PID indeed suggest that their use is both safe and efficacious. It is thus anticipated that their application to the treatment of many more life threatening PID will be developed over the coming years.

Progress in gene therapy for primary immunodeficiencies using lentiviral vectors.

This review gives an overview over the most recent progress in the field of lentiviral gene therapy for primary immunodeficiencies (PIDs). The history and state-of-the-art of lentiviral vector development are summarized and the recent advancements for a number of selected diseases are reviewed in detail. Past retroviral vector trials for these diseases, the most recent improvements of lentiviral vector platforms and their application in preclinical development as well as ongoing clinical trials are discussed. Main focus is on the preclinical studies and clinical trials for the treatment of Wiskott-Aldrich syndrome, chronic granulomatous disease, adenosine deaminase deficient severe combined immunodeficiency (ADA-SCID) and X-linked severe combined immunodeficiency with lentiviral gene therapy. Gene therapy for PIDs is an effective treatment, providing potential long-term clinical benefit for affected patients. Substantial progress has been made to make lentiviral gene therapy platforms available for a number of rare genetic diseases. Although many ongoing gene therapy trials are based on ex-vivo approaches with autologous hematopoietic stem cells, other approaches such as in-vivo gene therapy or gene-repair platforms might provide further advancement for certain PIDs.

Gene therapy for primary immunodeficiencies: current status and future prospects.

Gene therapy using autologous haematopoietic stem cells offers a valuable treatment option for patients with primary immunodeficiencies who do not have access to an HLA-matched donor, although such treatments have not been without their problems. This review details gene therapy trials for X-linked and adenosine deaminase (ADA)-deficient severe combined immunodeficiency (SCID), Wiskott-Aldrich syndrome (WAS) and chronic granulomatous disease (CGD). X-linked SCID was chosen for gene therapy because of previous 'natural' genetic correction through a reversion event in a single lymphoid precursor, demonstrating limited thymopoiesis and restricted T-lymphocyte receptor repertoire, showing selective advantage of progenitors possessing the wild-type gene. In early studies, patients were treated with long terminal repeats-intact gamma-retroviral vectors, without additional chemotherapy. Early results demonstrated gene-transduced cells, sustained thymopoiesis, and a diverse T-lymphocyte repertoire with normal function. Serious adverse effects were subsequently reported in 5 of 20 patients, with T-lymphocyte leukaemia developing, secondary to the viral vector integrating adjacent to a known oncogene. New trials using self-inactivating gamma-retroviral vectors are progressing. Trials for ADA-SCID using gamma-retroviral vectors have been successful, with no similar serious adverse effects reported; trials using lentiviral vectors are in progress. Patients with WAS and CGD treated with early gamma-retroviral vectors have developed similar lymphoproliferative adverse effects to those seen in X-SCID--current trials are using new-generation vectors. Targeted gene insertion using homologous recombination of corrected gene sequences by cellular DNA repair pathways following targeted DNA breakage will improve efficacy and safety of gene therapy. A number of new techniques are discussed.

Gene transfer into hematopoietic stem cells as treatment for primary immunodeficiency diseases

Gene transfer into the hematopoietic stem cell has shown curative potential for a variety of hematological disorders. Primary immunodeficiency diseases have led to the way in this field of gene therapy as an example and a model. Clinical results from the past 15 years have shown that significant improvement and even cure can be achieved for diseases such as X-linked severe combined immunodeficiency, adenosine deaminase deficiency, chronic granulomatous disease and Wiskott-Aldrich syndrome. Unfortunately, with the initial clear clinical benefits, the first serious complications of gene therapy have also occurred. In a significant number of patients treated using vectors based on murine gamma-retroviruses and carrying powerful viral enhancer elements, insertional oncogenesis events have resulted in acute leukemias that, in some cases, have had fatal outcomes. These serious adverse events have sparked a revision of the assessment of risks and benefits of integrating gene transfer for hematological diseases and prompted the development and application of new generations of viral vectors with recognized superior safety characteristics. This review summarizes the clinical experience of gene therapy for primary immunodeficiencies and discusses the likely avenues of progress in the future development of this expanding field of clinical investigations.

Current progress on gene therapy for primary immunodeficiencies

Primary immunodeficiencies have played a major role in the development of gene therapy for monogenic diseases of the bone marrow. The last decade has seen convincing evidence of long-term disease correction as a result of ex vivo viral vector-mediated gene transfer into autologous haematopoietic stem cells. The success of these early studies has been balanced by the development of vector-related insertional mutagenic events. More recently the use of alternative vector designs with self-inactivating designs, which have an improved safety profile has led to the initiation of a wave of new studies that are showing early signs of efficacy. The ongoing development of safer vector platforms and gene-correction technologies together with improvements in cell-transduction techniques and optimised conditioning regimes is likely to make gene therapy amenable for a greater number of PIDs. If long-term efficacy and safety are shown, gene therapy will become a standard treatment option for specific forms of PID.

Current status and future prospects of stem cell gene therapy for primary immunodeficiency

Patients affected by primary immunodeficiency (PID) can be cured by allogeneic hematopoietic stem cell transplantation (HSCT). In the absence of HLA-matched donors, however, incidence of HSCT-related complications is observed. Therefore, gene therapy has been developed as a highly desirable alternative treatment for patients lacking suitable donors. Retrovirus-based gene therapy was begun in 1990 for the patients of adenosine deaminase deficiency, followed by X-linked severe combined immunodeficiency, Wiskott-Aldrich syndrome and chronic granulomatous disease. Although treated patients have had excellent immune reconstitution and resolution of ongoing infections, complications such as a lymphoproliferative syndrome and a disappearance of gene-modified cells were observed in some clinical trials. To overcome these, ongoing and upcoming clinical trials use some new strategies. The use of preconditioning chemotherapy makes space in the bone marrow for the gene-treated stem cells and allows engraftment of multi lineage stem/progenitor cells. Self-inactivating vectors in which strong enhancers of long terminal repeat are eliminated may reduce the risk of insertional activation of proto-oncogene resulting in leukemia. These modifications will surely increase the safety and efficacy of stem cell gene therapy for PID.

Gene therapy for primary immunodeficiencies

Primary immunodeficiencies (PIDs) are an often-devastating class of genetic disorders that can be effectively treated by hematopoietic stem cell transplantation, but the lack of a suitable donor precludes this option for many patients. Gene therapy overcomes this obstacle by restoring gene expression in autologous hematopoietic stem cells and has proven effective in clinical trials, but widespread use of this approach has been impeded by the occurrence of serious complications. In this review, we discuss recent advances in gene therapy with an emphasis on strategies to improve safety, including the emergence of gene targeting technologies for the treatment of PIDs. New viral vectors, including lentiviral vectors with self-inactivating long terminal repeats, have been shown to have improved safety profiles in preclinical studies, and clinical trials using these vectors are now underway. Preclinical studies using engineered nucleases to stimulate precise gene targeting have also demonstrated correction of disease phenotypes for X-linked severe combined immunodeficiency, chronic granulomatous disease, and other diseases. Advances in viral vector design and the development of new technologies that allow precise alteration of the genome have the potential to begin a new chapter for gene therapy where effective treatment of PIDs is achieved without serious risk for patients.

Gene Therapy for Primary Immunodeficiencies

For over 40 years, primary immunodeficiencies (PIDs) have featured prominently in the development and refinement of human allogeneic hematopoietic stem cell transplantation. More recently, ex vivo somatic gene therapy using autologous cells has provided remarkable evidence of clinical efficacy in patients without HLA-matched stem cell donors and in whom toxicity of allogeneic procedures is likely to be high. Together with improved preclinical models, a wealth of information has accumulated that has allowed development of safer, more sophisticated technologies and protocols that are applicable to a much broader range of diseases. In this review we summarize the status of these gene therapy trials and discuss the emerging application of similar strategies to other PIDs.