Insertional mutagenesis combined with acquired somatic mutations causes leukemogenesis following gene therapy of SCID-X1 patients

Non-viral, high throughput genetic engineering of primary immune cells using nanostraw-mediated transfection

Transfection of proteins, mRNA, and chimeric antigen receptor (CAR) transgenes into immune cells remains a critical bottleneck in cell manufacturing. Current methods, such as viruses and bulk electroporation, are hampered by low transfection efficiency, unintended transgene integration, and significant cell perturbation. The Nanostraw Electro-actuated Transfection (NExT) technology offers a solution by using high aspect-ratio nanostraws and localized electric fields to precisely deliver biomolecules into cells with minimal disruption. We demonstrate that NExT can deliver proteins, polysaccharides, and mRNA into primary human CD8+ and CD4+ T cells, and achieve CRISPR/Cas9 gene knockout of CXCR4 and TRAC in CD8+ T cells. We showcase NExT's versatility across a range of primary human immune cells, including CD4+ T cells, γδ-T cells, dendritic cells, NK cells, Treg cells, macrophages, and neutrophils. Finally, we developed a scalable, high-throughput multiwell NExT system capable of transfecting over 14 million cells and delivering diverse cargoes into multiple cell types from various donors simultaneously. This technology holds promise for streamlining high-throughput screening of allogeneic donors and reducing optimization costs for large-scale CAR-immune cell transfection.

Gene therapy then and now: A look back at changes in the field over the past 25 years

Since the inception of Molecular Therapy in 2000, the field of gene therapy has made remarkable progress, evolving from no approved clinical products to 23 clinical gene therapy products today. In this review, we aim to capture the transformative changes in the field by surveying the literature over this period, with a particular focus on advancements in gene delivery vector technology, disease and tissue targeting, and the revolutionary molecular tools that have become central to the field. We also discuss the current challenges facing gene therapy and the need for greater collaboration to ensure its accessibility worldwide.

Ex vivo modification of hematopoietic stem and progenitor cells for gene therapy

The development of viral vectors has been particularly critical for genetic therapies of hematological diseases. Before the development of retrovirus vectors (RVVs), gene transfer into mammalian cells was accomplished by transduction of DNA plasmids by chemical means and later by electroporation. The main limitation of these methods is the inefficiency of transfer of intact sequences, and particularly with electroporation significant cell death of the manipulated cells. The earliest successful human gene therapy trials utilized γ-RVVs and many of the techniques developed in the 1980s. A breakthrough for the field was the exploitation and development of HIV for transfer vectors, termed lentivirus vectors. In this review, we highlight uses of retro- and lentivirus vectors in monogenic diseases in which hematopoietic stem cells are used in the autologous setting to treat immunodeficiencies, hemoglobinopathies and metabolic diseases. The three authors' perspective represent experiences in the field over four decades that encompasses both basic translational research and development and oversight of early and ongoing gene therapy trials utilizing viral vectors.

Progress and Challenges in the Treatment of Fabry Disease

Fabry disease is a rare but life-threatening, X-linked, inherited lysosomal storage disorder in which globotriaosylceramide is insufficiently metabolized because of reduced α-galactosidase A activity. Cellular globotriaosylceramide accumulation causes a multisystemic disease, which, if left untreated, reduces life expectancy in female and male individuals by around 10 and 20 years, respectively, leading to progressive renal failure, hypertrophic cardiomyopathy, cardiac arrhythmia, and premature cerebral infarction. The method of choice for confirming the diagnosis is the determination of reduced α-galactosidase A activity in leukocytes in male individuals and the molecular genetic detection of a disease-causing mutation in female individuals. Current approved treatment includes enzyme replacement therapy (agalsidase alfa [0.2 mg/kg body weight], agalsidase beta or pegunigalsidase alfa [both 1.0 mg/kg body weight]) every other week intravenously or, if a responding ('amenable') α-galactosidase A mutation is present, oral pharmacological chaperone therapy (migalastat 123 mg, every other day). Future therapeutic options may include substrate reduction therapy, gene therapy, messenger RNA therapy, and/or vesicle-packaged enzyme replacement therapy. This review presents current and future treatment options with advantages and disadvantages of the different treatment options.

Gene therapy: principles, challenges and use in clinical practice

INTRODUCTION

Gene therapy is an emerging topic in medicine. The first products have already been licensed in the European Union for the treatment of immune deficiency, spinal muscular atrophy, hemophilia, retinal dystrophy, a rare neurotransmitter disorder and some hematological cancers, while many more are being assessed in preclinical and clinical trials.

OBJECTIVE

The purpose of this review is to provide an overview of the core principles of gene therapy along with information on challenges and risks. Benefits, adverse effects and potential risks are illustrated based on the examples of hemophilia and spinal muscular atrophy.

RESULTS

At present, in-vitro and in-vivo gene addition or gene augmentation is the most commonly established type of gene therapy. More recently, more sophisticated and precise approaches such as in situ gene editing have moved into focus. However, all types of gene therapy require long-term observation of treated patients to ensure safety, efficacy, predictability and durability. Important safety concerns include immune reactions to the vector, the foreign DNA or the new protein resulting from gene therapy, and a remaining low cancer risk based on insertional mutagenesis. Ethical and regulatory issues need to be addressed, and new reimbursement models are called for to ease the financial burden that this new treatment poses for the health care system.

CONCLUSION

Gene therapy holds great promise for considerable improvement or even cure of genetic diseases with serious clinical consequences. However, a number of questions and issues need to be clarified to ensure broad accessibility of safe and efficacious products.

Donor insertion into CX3CR1 allows epigenetic modulation of a constitutive promoter on hematopoietic stem cells and its activation upon myeloid differentiation

To improve ex vivo gene therapy strategies involving hematopoietic stem and progenitor cells (HSPCs), we propose a novel knock-in strategy (named KI-Ep) aiming to achieve transgene regulation of the inserted cassette through the acquisition of naturally occurring epigenetic marks. Based on this hypothesis, we selected CX3CR1 (a myeloid-specific gene presenting a poised histone signature on primitive HSPCs) as safe harbor to generate KI-Ep HSPCs. We demonstrated that, unlike the expression pattern achieved with lentiviral vectors (LVs), the insertion of a constitutive expression cassette into the intron 1 of the CX3CR1 locus (CX3CR1-I) in HSPCs resulted in very low expression levels in the more primitive HSPCs but, crucially, strong expression in HSPC-differentiated populations (especially myeloid cells), both in vitro and in vivo. Furthermore, we showed that the promoter of the expression cassette inserted into CX3CR1-I acquired epigenetic marks associated with poised genes during the HSPC stage. These marks transitioned to activated histone states upon KI-Ep HSPCs differentiation. In summary, here, we introduce the KI-Ep concept which enables the epigenetic modulation of the inserted transgene during the HSPCs stem cell stages and its subsequent activation upon differentiation.

High-Throughput Screening to Identify Novel Compounds Affecting the Genome Editing Efficiency of CRISPR System

Genome editing is a promising therapeutic strategy for genetic disorders by modifying the genome precisely, especially the CRISPR/Cas9 system. However, a major limitation of CRISPR/Cas9 in gene therapy is the biosafety issues caused by off-target effects. Compounds that can modulate the genome editing efficiency of the CRISPR/Cas9 system, especially those reducing the off-target effects, are potentially useful pharmacological tools for improving the effectiveness and safety of genome editing. Here, we performed high-throughput screening in HEK 293FT cells to discover compounds that decrease or increase the genome editing efficiency of the CRISPR/Cas9 system from 9930 compounds. After two rounds of screening, we identified that CP-724714, a ErbB2 (HER2) tyrosine kinase inhibitor, decreased the CRISPR/Cas9 efficiency and reduced the off-target effects by suppressing the efficiency of CRISPR/Cas9, and was thus named a CRISPR decelerator (or inhibitor), while Clofarabine, a DNA synthesis inhibitor, increased the efficiency of CRISPR/Cas9, and was named a CRISPR accelerator. We further identified four compounds (Tranilast, Cerulenin, Rosolic acid and Resveratrol) that affected the efficiency of single-strand annealing (SSA) repair. Among them, Tranilast, Cerulenin and Rosolic acid are potential SSA decelerators, while Resveratrol is a potential SSA accelerator. These identified compounds may be useful in optimizing mammalian genetic manipulation techniques.

Current landscape of vector safety and genotoxicity after hematopoietic stem or immune cell gene therapy

Malignant transformation of gene modified haematopoietic stem cells caused anxiety following adverse events in early clinical trials using gamma-retroviral vectors (γRV) to correct haematopoietic stem cells (HSC) in monogenic immune disorders. Adoption of HIV-derived lentiviral vectors (LV) with SIN (self-inactivating) configurations greatly reduced risks and subsequently hundreds of patients have been dosed with HSC gene therapy for blood, immune and metabolic conditions. Nevertheless, as experience builds, it's now well recognised that vector integration can drive clonal expansions and these may carry long term safety risks. Documented cases of haematological malignancy after SIN-LV gene therapy have recently emerged, in particular where heterologous retroviral promoters were employed and there are concerns around certain insulator elements and other possible contributors to clonal expansions. Similarly, tens of thousands of subjects have now received engineered T cell products, and longstanding dogma that mature T cells cannot be transformed is being questioned, with reports of a small number of malignant transformation events and wider concerns around secondary malignancies in some groups of patients. We summarize current clinical information and revisit genotoxicity risks following ex-vivo gene modification of HSC and T cells.

Long-term safety of lentiviral or gammaretroviral gene-modified T cell therapies

Long-term risks of gene therapy are not fully understood. In this study, we evaluated safety outcomes in 783 patients over more than 2,200 total patient-years of observation from 38 T cell therapy trials. The trials employed integrating gammaretroviral or lentiviral vectors to deliver engineered receptors to target HIV-1 infection or cancer. Eighteen patients (2.3%) developed secondary malignancies after treatment, with a median onset of 1.94 years (range: 51 d to 14 years). Where possible, incident tumor samples were analyzed for vector copy number, revealing no evidence of high-level marking or other indications of insertional mutagenesis. One T cell lymphoma was detected, but malignant T cells were not marked by vector integration. Analysis of vector integration sites in 176 patients revealed no pathological insertions linked to secondary malignancies, although, in some cases, integration in or near specific genes, including tumor suppressor genes, was associated with modest clonal expansion and sustained T cell persistence. These findings highlight the safety of engineered T cell therapies.

Ex vivo HIV DNA integration in STAT3 drives T cell persistence-A model of HIV-associated T cell lymphoma

Oncogenic retroviruses are known for their pathogenesis via insertional mutagenesis, in which the presence of a provirus and its transcriptional control elements alter the expression of a nearby or surrounding host gene. There are reports of proviral integration driving oncogenesis in people with HIV and the use of HIV-derived vectors for gene therapy has raised concern about oncogenic side effects. To study this issue, we used an ex vivo human CD4+ T cell infection model developed in our laboratory to identify HIV-1 integration sites that might influence cell proliferation or survival. Combining integration site analysis and bulk RNA sequencing, we established that an upregulated STAT3 signature due to proviral insertional mutagenesis was associated with persistent HIV-infected CD4+ T cells. HIV+ persistent cells also expressed a STAT3-related anti-apoptotic and cytotoxic phenotype that resembles that of HIV-associated T cell lymphomas. HIV insertional mutagenesis of STAT3 and expression of its downstream targets provides a model of HIV-associated T cell lymphomas that can be used to further determine the oncogenic drivers of HIV-associated lymphomas, both AIDS- and gene therapy-associated, and, potentially, to evaluate therapeutics against these HIV-associated cancers.

Author Summary

The effects of HIV proviral insertional mutagenesis have been demonstrated in a handful of HIV-associated T cell lymphomas, where integration of an HIV provirus within intron 1 of STAT3 , results in increased expression of the STAT3 protein. To study the effects of HIV insertional mutagenesis, we established an ex vivo culture protocol of primary human CD4+ T cells infected with a replication-incompetent HIV vector with a gfp-reporter. After infection, the HIV/GFP+ cells from all three donors declined, but, over time, 3/6 replicates from one donor populations of infected cells rebounded. The resurgent HIV/GFP+ cells contained a provirus integrated within intron 1 of STAT3 , which led to increases in gene expression, STAT3 activation, and upregulation of a STAT3 -associated anti-apoptotic and cytotoxic phenotype. The STAT3 -associated gene signature shared similarities to the HIV-associated lymphomas with similar integration sites. Additionally, in all 3 replicates, insertional mutagenesis of genes other than STAT3 may have also contributed to clonal expansion of HIV/GFP+ T cells. Overall, we have demonstrated that HIV provirus insertional mutagenesis can influence T cell persistence. Our study provides a primary T cell culture model system that can be used to further study how proviral insertional mutagenesis influences HIV-associated T cell lymphomas and the safety of lentiviral vectors used in gene and cell therapies.

Role of miRNA‑145‑5p in cancer (Review)

MicroRNA‑145‑5p (miRNA‑145‑5p) is a short non‑coding RNA located at chromosome 5q33.1, which has gained significant attention in several aspects of cellular regulation and biological functions. In malignant tumours, miRNA‑145‑5p may function as either a tumour suppressor or an oncogene, affecting tumour progression by targeting downstream genes or modulating their expression through upstream regulators. However, the full extent of miRNA‑145‑5p's role in cancer has remained to be determined. This review provides an overview of the role of miRNA‑145‑5p in cancer, investigates its potential as a biomarker for diagnosis, prognosis and treatment response, and evaluates its influence on cancer chemotherapy and radiotherapy. Finally, current strategies for systemic delivery of miRNA‑145‑5p in cancer therapies are summarized.

Nano Approaches to Nucleic Acid Delivery: Barriers, Solutions, and Current Landscape

Nucleic acid (NA) therapy holds tremendous potential for treating a wide range of genetic diseases by the delivery of therapeutic genes into target cells. However, significant challenges exist in safely and effectively delivering these genes to their intended locations. Viral vectors, though efficient, pose risks such as immunogenicity and mutagenesis. This has resulted in growing interest in non-viral, nanoparticle-based NA delivery systems. This review article describes various physiological barriers to NA delivery and explores nanoparticle-based NA delivery systems, including bioengineered nanoparticles, peptides, lipid nanoparticles, and polymeric nanoparticles, highlighting their unique features to overcome in vivo barriers for NA delivery. While these nanoparticle-based NA delivery systems offer a promising alternative to viral vectors, challenges related to cytotoxicity, reproducible synthesis, and cost need to be addressed. The current clinical landscape of NA delivery is also discussed, emphasizing the need for safer, scalable, and cost-effective solutions. Nanoparticles represent a promising future in NA therapy, with the possibility of developing clinically relevant, non-toxic, stable, and non-immunogenic delivery vehicles, paving the way for broader therapeutic applications and improved clinical outcomes.

In-depth analysis of the safety of CAR-T cell therapy for solid tumors

In recent years, the rapid progress in oncology, immunology, and molecular biology has dramatically advanced cancer immunotherapy, particularly CAR-T cell therapy. This innovative approach involves engineering a patient's T cells to express receptors that specifically target tumor antigens, enhancing their ability to identify and eliminate cancer cells. However, the effectiveness of CAR-T therapy in solid tumors is often hampered by the challenging tumor microenvironment (TME). The complex TME includes dense stroma that obstructs T cell infiltration, abnormal blood vessel structures leading to hypoxia, and an acidic pH, all of which hinder CAR-T cell function. Additionally, the presence of immunosuppressive factors in the TME reduces the efficacy of CAR-T cells, making successful targeting of tumors more difficult. The safety of CAR-T therapy has gained interest, especially CAR-T therapy has shown considerable effectiveness in various cancers, with notable results in multiple myeloma and hepatocellular carcinoma, among others. Nonetheless, CAR-T cell therapy is associated with several adverse reactions primarily driven by heightened levels of proinflammatory cytokines. These reactions include cytokine release syndrome (CRS), neurotoxicity (CANS), and organ toxicity, often leading to serious complications. CRS, characterized by systemic inflammation due to cytokine release, can escalate to severe organ dysfunction. It typically occurs within the first week post-infusion, correlating with CAR-T cell expansion and often presents with fever and hypotension. Meanwhile, CANS encompasses neurological issues ranging from mild symptoms to severe seizures, possibly exacerbated by CRS. Organ toxicity can also arise from CAR-T therapy, with potential damage affecting the gastrointestinal tract, kidneys, liver, and lungs, often tied to shared antigens found in both tumor and healthy tissues. Moreover, long-term effects like cytokine-associated hematotoxicity (CAHT) and secondary malignancies represent significant concerns that could affect the patient's quality of life post-treatment. The long-term adverse effects and challenges in treating solid tumors underscore the need for ongoing research. Strategies to improve CAR-T cell efficacy, minimize adverse reactions, and enhance patient safety are critical. Future explorations could include designing CAR-T cells to better navigate the TME, identifying specific target antigen profiles to minimize off-target damage, and developing adjunct therapies to mitigate cytokine-related toxicity. Continued monitoring for long-term effects will also be paramount in improving patient outcomes and maintaining their quality of life. Overall, while CAR-T therapy holds great promise, it must be administered with careful consideration of potential side effects and rigorous management strategies to ensure patient safety and treatment efficacy.

Antitumor Efficacy of Interleukin 12-Transfected Mesenchymal Stem Cells in B16-F10 Mouse Melanoma Tumor Model

Background/Objectives: Mesenchymal stromal cells (MSCs) hold the potential for tumor-targeted gene delivery due to their ex vivo manipulability, low immunogenicity, scalability, and inherent tumor-homing properties. Despite the widespread use of viral vectors for MSC genetic modification, safety concerns have prompted interest in non-viral alternatives, such as gene electrotransfer (GET). This study aimed to optimize GET parameters for MSCs transfection, assess MSCs biodistribution after in vivo administration, and evaluate the therapeutic potential of interleukin-12 (IL-12)-modified MSCs in a mouse melanoma model. Methods: Human MSCs were isolated from umbilical cords under ethically approved protocols. GET protocols were optimized using a fluorescent reporter gene to evaluate transfection efficiency and cell viability. MSC biodistribution was examined following intravenous and intratumoral injections in murine tumor models using luminescent reporter gene. The therapeutic efficacy of IL-12-modified MSCs was assessed in a syngeneic mouse melanoma model. Results: Optimized GET protocols achieved a transfection efficiency of 80% and a cell viability of 90%. Biodistribution studies demonstrated effective tumor retention of MSCs following intratumoral injections, whereas intravenous administration resulted in predominant cell localization in the lungs. IL-12-modified MSCs injected intratumorally significantly inhibited tumor growth, delaying tumor progression by five days compared to controls. Conclusions: Optimized GET conditions enabled high-efficiency, high-viability MSCs transfection, facilitating their use as effective vehicles for localized cytokine delivery. While the innate tumor tropism of MSCs was not conclusively demonstrated, the study highlights the potential of GET as a reliable non-viral gene delivery platform and underscores the therapeutic promise of IL-12-modified MSCs in tumor-targeted gene therapy.

Translational nanorobotics breaking through biological membranes

In the dynamic realm of translational nanorobotics, the endeavor to develop nanorobots carrying therapeutics in rational in vivo applications necessitates a profound understanding of the biological landscape of the human body and its complexity. Within this landscape, biological membranes stand as critical barriers to the successful delivery of therapeutic cargo to the target site. Their crossing is not only a challenge for nanorobotics but also a pivotal criterion for the clinical success of therapeutic-carrying nanorobots. Nevertheless, despite their urgency, strategies for membrane crossing in translational nanorobotics remain relatively underrepresented in the scientific literature, signaling an opportunity for further research and innovation. This review focuses on nanorobots with various propulsion mechanisms from chemical and physical to hybrid mechanisms, and it identifies and describes four essential biological membranes that represent the barriers needed to be crossed in the therapeutic journey of nanorobots in in vivo applications. First is the entry point into the blood stream, which is the skin or mucosa or intravenous injection; next is the exit from the bloodstream across the endothelium to the target site; further is the entry to the cell through the plasma membrane and, finally, the escape from the lysosome, which otherwise destroys the cargo. The review also discusses design challenges inherent in translating nanorobot technologies to real-world applications and provides a critical overview of documented membrane crossings. The aim is to underscore the need for further interdisciplinary collaborations between chemists, materials scientists and chemical biologists in this vital domain of translational nanorobotics that has the potential to revolutionize the field of precision medicine.

Pilocytic astrocytoma in a child with spinal muscular atrophy treated with onasemnogene abeparvovec

Spinal muscular atrophy (SMA) is a severe neuromuscular disease, leading to progressive muscle weakness and potentially early mortality if untreated. Onasemnogene abeparvovec is a recombinant adeno-associated virus serotype 9 (rAAV9)-based gene therapy that has demonstrated improvements in survival and motor function for SMA patients. Here, we present a case of a patient diagnosed with a grade 1 pilocytic astrocytoma at the age of 2 years, approximately 8 months after onasemnogene abeparvovec treatment. Although vector genomes delivered by rAAVs persist primarily as episomes, rare integration events have been linked to tumor formation in neonate murine models. Therefore, we investigated the presence and possible integration of onasemnogene abeparvovec in formalin-fixed paraffin embedded (FFPE) and frozen tumor samples. In situ hybridization demonstrated variable transduction levels in individual tumor cells, while droplet digital PCR measured an average vector copy number ranging from 0.7 to 4.9 vector genomes/diploid genome. Integration site analysis identified a low number of integration sites that were not conserved between technical replicates, nor between FFPE and frozen samples, indicating that cells hosting integrating vector genomes represented a minority in the overall cell population. Thus, molecular analysis of the tumor tissue suggests that tumorigenesis was causally independent of the administration of onasemnogene abeparvovec.

Gene Therapy: An Historical Overview for Familial Hearing Loss

Gene therapy is a promising molecular approach for the management of familial hearing loss. This type of molecular therapy is the physical manifestation of genetic determinism-the notion that individual genes cause individual phenotypes. The current composition weaves through various branches of the biomedical sciences to uncover the molecular biologic premise for genetic determinism and the impetus behind gene therapy. Consequently, it is revealed that the underlying molecular biologic premise was scaffolded on successful observations from simple biologic assays that were devoid of the complexities of human disease biology. Furthermore, modern successful gene therapies are largely driven by commercial and academic incentives at the cost of scientific rigor. This poses several perverse challenges for patients, clinicians and the public at large. Issues concerning safety, efficacy, and ethics are far from resolved despite regulatory agency approvals, the media's bias for gene therapy and the many lucrative investor positions. Lastly, the therapeutic claims regarding gene therapy are the most ambitious claims made within the hearing sciences. Therefore, scientists, clinicians, and patients must be equipped with the tools needed to appropriately consume and appraise such claims. These and other issues are also directly addressed, with the aim of providing a realistic sense of whether current human gene therapies are ready to be positioned within our routine clinical armamentarium against hearing loss.

CAR T-cell-associated secondary malignancies challenge current pharmacovigilance concepts

Suspected adverse reactions following chimeric antigen receptor T-cell (CAR T) treatment include more and more cases of secondary T-cell malignancies. The causality assessment of such suspected reactions challenges established evaluation practices due to (i) patient and product-specific risk factors and (ii) incomplete data available with post-marketing reports submitted to competent authorities. This is of particular relevance for gene therapy products that integrate into the host genome. We present a summary of case reports related to different CAR T products and the rationale for case causality assessment. In this context, possible pathophysiologic mechanisms and differences between CAR T products to be taken into account are discussed. The unparalleled complexity of the case follow-up and the multistep process of cancer development necessitates a case-by-case consideration. This highlights challenges in the pharmacovigilance of advanced therapy medicinal products and underlines the importance of testing for vector presence, integration location and gene expression profile for an informed case assessment of suspected secondary malignancies with the aim to obtain a better understanding of contributing factors.

Leveraging Vector-Based Gene Disruptions to Enhance CAR T-Cell Effectiveness

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy represents a breakthrough in the treatment of relapsed and refractory B-cell malignancies, such as chronic lymphocytic leukemia (CLL), inducing long-term, sometimes curative, responses. However, fewer than 30% of CLL patients achieve such outcomes. It has been shown that a smaller subset of T cells capable of expansion and persistence is crucial for treatment effectiveness. Notably, a pre-existing mutation in the epigenetic regulator TET2, combined with CAR vector-induced disruption of the other intact allele, significantly enhanced the potency of the CAR-engineered T-cell clone in one CLL patient. This finding aligns with independent research, suggesting that the CAR gene's genomic insertion site influences tumor-targeting capability. Thus, it is plausible that vector-induced gene disruptions affect CAR T-cell function. This review synthesizes existing knowledge on vector integration into the host genome and its impact on clinical outcomes in CAR T-cell therapy patients. Our aim is to inform the development of improved therapies and enhance their overall efficacy.

Cutting-edge Strategies for Overcoming Therapeutic Barriers in Alzheimer's Disease

Alzheimer's disease (AD) remains one of the hardest neurodegenerative diseases to treat due to its enduring cognitive deterioration and memory loss. Despite extensive research, few viable treatment approaches have been found; these are mostly due to several barriers, such as the disease's complex biology, limited pharmaceutical efficacy, and the BBB. This presentation discusses current strategies for addressing these therapeutic barriers to enhance AD treatment. Innovative drug delivery methods including liposomes, exosomes, and nanoparticles may be able to pass the blood-brain barrier and allow medicine to enter specific brain regions. These innovative strategies of medicine distribution reduce systemic side effects by improving absorption. Moreover, the development of disease-modifying treatments that target tau protein tangles, amyloid-beta plaques, and neuroinflammation offers the chance to influence the course of the illness rather than only treat its symptoms. Furthermore, gene therapy and CRISPR-Cas9 technologies have surfaced as potentially groundbreaking methods for addressing the underlying genetic defects associated with AD. Furthermore, novel approaches to patient care may involve the utilization of existing medications having neuroprotective properties, such as those for diabetes and cardiovascular conditions. Furthermore, biomarker research and personalized medicine have made individualized therapy approaches possible, ensuring that patients receive the best care possible based on their unique genetic and molecular profiles.

Pharmacological and pre-clinical safety profile of rSIV.F/HN, a hybrid lentiviral vector for cystic fibrosis gene therapy

RATIONALE AND OBJECTIVE

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. CFTR modulators offer significant improvements, but ∼10% of patients remain nonresponsive or are intolerant. This study provides an analysis of rSIV.F/HN, a lentiviral vector optimised for lung delivery, including CFTR protein expression, functional correction of CFTR defects and genomic integration site analysis in preparation for a first-in-human clinical trial.

METHODS

Air-liquid interface cultures of primary human bronchial epithelial cells (HBECs) from CF patients (F508del/F508del), as well as a CFTR-deficient immortalised human lung epithelial cell line mimicking class I (CFTR-null) homozygous mutations, were used to assess transduction efficiency. Quantification methods included a novel proximity ligation assay for CFTR protein expression. For assessment of CFTR channel activity, Ussing chamber studies were conducted. The safety profile was assessed using integration site analysis and in vitro insertional mutagenesis studies.

RESULTS

rSIV.F/HN expressed CFTR and restored CFTR-mediated chloride currents to physiological levels in primary F508del/F508del HBECs as well as in a class I cells. In contrast, the latter could not be achieved by small-molecule CFTR modulators, underscoring the potential of gene therapy for this mutation class. Combination of rSIV.F/HN-CFTR with the potentiator ivacaftor showed a greater than additive effect. The genomic integration pattern showed no site predominance (frequency of occurrence ≤10%), and a low risk of insertional mutagenesis was observed in an in vitro immortalisation assay.

CONCLUSIONS

The results underscore rSIV.F/HN as a promising gene therapy vector for CF, providing a mutation-agnostic treatment option.

Multiple gene therapy as a tool for regulating the expression of molecules involved in neovascular age-related macular degeneration

Anti-vascular endothelial growth factor (VEGF) therapies have revolutionized the treatment of neovascular age-related macular degeneration (nAMD) and other retinal diseases. However, the necessity for repeated intravitreal injections and the observation of variable treatment responses calls for new treatment modalities where fewer and more effective interventions can result in a clinical effect. Gene therapy might be such an alternative, and therefore the development and clinical application of gene therapy aimed at modifying gene expression has received considerable attention. The article reviews current knowledge of the background, pathophysiological mechanisms, technologies, limitations, and future directions for gene therapy aimed at modifying the synthesis of compounds involved in acquired and senescent retinal disease. The authors have contributed to the field by developing gene therapy to reduce the expression of vascular endothelial growth factor (VEGF), as well as multiple gene therapy for simultaneous downregulation of the synthesis of VEGF and upregulation of pigment epithelium-derived factor (PEDF) using adeno-associated virus (AAV) vectors. It is suggested that such multi-target gene therapy might be included in future treatments of retinal diseases where the underlying mechanisms are complex and cannot be attributed to one specific mediator. Such diseases might include dry AMD (dAMD) with geographic atrophy, but also diabetic macular edema (DME) and retinal vein occlusion (RVO). Gene therapy can be expected to be most beneficial for the patients in need of multiple intra-vitreal injections and in whom the therapeutic response is insufficient. It is concluded, that in parallel with basic research, there is a need for clinical studies aimed at identifying factors that can be used to identify patients who will benefit from gene therapy already at the time of diagnosis of the retinal disease.

[A CRISPR/Cas approach to β-haemoglobinopathies]

Beta-haemoglobinopathies are severe genetic anemias caused by mutations that affect adult haemoglobin production. Many therapeutic approaches aim to reactivate the expression of the fetal hemoglobin genes. To this end, the CRISPR/Cas9 system has recently been used to genetically modify patients' hematopoietic stem/progenitor cells ex vivo and reactivate fetal hemoglobin expression in their erythroid progeny. More than 70 patients with severe β-thalassemia and sickle cell disease have been treated with the Casgevy® therapy. Most have achieved a significant improvement of clinical phenotype, with high editing efficiency in hematopoietic cells associated with normal or near normal hemoglobin levels. While the long-term safety and efficacy of this powerful approach still need to be evaluated, new strategies are being developed to further improve therapeutic outcomes, reduce potential genotoxicity and lower the costs of therapy.

Genetic engineering and the eye

The transformative potential of genetic engineering in ophthalmology is remarkable, promising new treatments for a wide range of blinding eye diseases. The eye is an attractive target organ for genetic engineering approaches, in part due to its relatively immune-privileged status, its accessibility, and the ease of monitoring of efficacy and safety. Consequently, the eye has been at the forefront of genetic engineering advances in recent years. The development of Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9), base editors, prime editors, and transposases have enabled efficient and specific gene modification. Ocular gene therapy continues to progress, with recent advances in delivery systems using viral / non-viral vectors and novel promoters and enhancers. New strategies to achieve neuroprotection and neuroregeneration are evolving, including direct in-vivo cell reprogramming and optogenetic approaches. In this review, we discuss recent advances in ocular genetic engineering, examine their current therapeutic roles, and explore their potential use in future strategies to reduce the growing burden of vision loss and blindness.

Gene therapy for sickle cell disease: recent advances, clinical trials and future directions

Sickle cell disease (SCD) is the most common inherited blood disorder worldwide, impacting millions and imposing severe healthcare challenges, particularly in resource-limited regions. Current treatments have variable efficacy and require lifelong adherence. Allogeneic Hematopoietic Stem Cell Transplantation can be curative but comes with significant side effects and limited donor availability limits its widespread applicability. Gene therapy, by addressing the root genetic causes, offers a revolutionary alternative. This article discusses the molecular mechanisms of SCD and β-thalassemia and highlights advancements in gene therapy, such as gene addition via lentiviral vectors and gene editing with CRISPR/Cas9 technology. Clinical trials have brought about significant progress but challenges remain, including leukemogenesis, delivery efficiency and cost. Future efforts must focus on enhancing efficiency, reducing costs, developing nongenotoxic conditioning regimens and methods for in vivo application.

Gene Therapy in Cardiovascular Disease: Recent Advances and Future Directions in Science: A Science Advisory From the American Heart Association

Cardiovascular disease remains the foremost cause of morbidity and mortality globally, affecting millions of individuals. Recent discoveries illuminate the substantial role of genetics in cardiovascular disease pathogenesis, encompassing both monogenic and polygenic mechanisms and identifying tangible targets for gene therapies. Innovative strategies have emerged to rectify pathogenic variants that cause monogenic disorders such as hypertrophic, dilated, and arrhythmogenic cardiomyopathies and hypercholesterolemia. These include delivery of exogenous genes to supplement insufficient protein levels caused by pathogenic variants or genome editing to correct, delete, or modify mutant sequences to restore protein function. However, effective delivery of gene therapy to specified cells presents formidable challenges. Viral vectors, notably adeno-associated viruses and nonviral vectors such as lipid and engineered nanoparticles, offer distinct advantages and limitations. Additional risks and obstacles remain, including treatment durability, tissue-specific targeting, vector-associated adverse events, and off-target effects. Addressing these challenges is an ongoing imperative; several clinical gene therapy trials are underway, and many more first-in-human studies are anticipated. This science advisory reviews core concepts of gene therapy, key obstacles, patient risks, and ongoing research endeavors to enable clinicians to understand the complex landscape of this emerging therapy and its remarkable therapeutic potential to benefit cardiovascular disease.

Emerging Diabetes Therapies: Regenerating Pancreatic β Cells

The incidence of diabetes mellitus (DM) is steadily increasing annually, with 537 million diabetic patients as of 2021. Restoring diminished β cell mass or impaired islet function is crucial in treating DM, particularly type 1 DM. However, the regenerative capacity of islet β cells, which primarily produce insulin, is severely limited, and natural regeneration is only observed in young rodents or children. Hence, there is an urgent need to develop advanced therapeutic approaches that can regenerate endogenous β cells or replace them with stem cell (SC)-derived or engineered β-like cells. Current strategies for treating insulin-dependent DM mainly include promoting the self-replication of endogenous β cells, inducing SC differentiation, reprogramming non-β cells into β-like cells, and generating pancreatic-like organoids through cell-based intervention. In this Review, we discuss the current state of the art in these approaches, describe associated challenges, propose potential solutions, and highlight ongoing efforts to optimize β cell or islet transplantation and related clinical trials. These effective cell-based therapies will generate a sustainable source of functional β cells for transplantation and lay strong foundations for future curative treatments for DM.

Long-term tracking of haematopoietic clonal dynamics and mutations in non-human primate undergoing transplantation of lentivirally barcoded haematopoietic stem and progenitor cells

Haematopoietic stem and progenitor cell (HSPC) autologous gene therapies are promising treatment for a variety of blood disorders. Investigation of the long-term HSPC clonal dynamics and other measures of safety and durability following lentiviral-mediated gene therapies in predictive models are crucial for assessing risks and benefits in order to inform decisions regarding wider utilization. We established an autologous lentivirally barcoded HSPC transplantation model in rhesus macaque (RM), a model offering insights into haematopoiesis and gene therapies with direct relevance to human. Healthy young adult RMs underwent total body irradiation, followed by transplantation of autologous HSPCs transduced with a lentiviral vector containing a diverse genetic barcode library, uniquely labelling individual HSPCs and their progeny. With up to 131 months of follow-up, we now report quantitative clonal dynamics, characterizing the number, diversity, stability and lineage bias of hundreds of thousands of HSPC clones tracked in five RMs. We documented long-term stable and multi-lineage output from a highly polyclonal pool of HSPCs. Clonal succession after stable haematopoietic reconstitution was minimal. There was no evidence for accelerated acquisition of acquired somatic mutations following autologous lentivirally transduced HSPC transplantation. Our results provide relevant insights into long-term HSPC behaviours in vivo following transplantation and gene therapies.

Gene therapy strategies for RAG1 deficiency: Challenges and breakthroughs

Mutations in the recombination activating genes (RAG) cause various forms of immune deficiency. Hematopoietic stem cell transplantation (HSCT) is the only cure for patients with severe manifestations of RAG deficiency; however, outcomes are suboptimal with mismatched donors. Gene therapy aims to correct autologous hematopoietic stem and progenitor cells (HSPC) and is emerging as an alternative to allogeneic HSCT. Gene therapy based on viral gene addition exploits viral vectors to add a correct copy of a mutated gene into the genome of HSPCs. Only recently, after a prolonged phase of development, viral gene addition has been approved for clinical testing in RAG1-SCID patients. In the meantime, a new technology, CRISPR/Cas9, has made its debut to compete with viral gene addition. Gene editing based on CRISPR/Cas9 allows to perform targeted genomic integrations of a correct copy of a mutated gene, circumventing the risk of virus-mediated insertional mutagenesis. In this review, we present the biology of the RAG genes, the challenges faced during the development of viral gene addition for RAG1-SCID, and the current status of gene therapy for RAG1 deficiency. In particular, we highlight the latest advances and challenges in CRISPR/Cas9 gene editing and their potential for the future of gene therapy.

Sonogenetics in the Treatment of Chronic Diseases: A New Method for Cell Regulation

Sonogenetics is an innovative technology that integrates ultrasound with genetic editing to precisely modulate cellular activities in a non-invasive manner. This method entails introducing and activating mechanosensitive channels on the cell membrane of specific cells using gene delivery vectors. When exposed to ultrasound, these channels can be manipulated to open or close, thereby impacting cellular functions. Sonogenetics is currently being used extensively in the treatment of various chronic diseases, including Parkinson's disease, vision restoration, and cancer therapy. This paper provides a comprehensive review of key components of sonogenetics and focuses on evaluating its prospects and potential challenges in the treatment of chronic disease.

CIRCLE-Seq for Interrogation of Off-Target Gene Editing

Circularization for In Vitro Reporting of Cleavage Effects by Sequencing (CIRCLE-seq) is a novel technique developed for the impartial identification of unintended cleavage sites of CRISPR-Cas9 through targeted sequencing of CRISPR-Cas9 cleaved DNA. The protocol involves circularizing genomic DNA (gDNA), which is subsequently treated with the Cas9 protein and a guide RNA (gRNA) of interest. Following treatment, the cleaved DNA is purified and prepared as a library for Illumina sequencing. The sequencing process generates paired-end reads, offering comprehensive data on each cleavage site. CIRCLE-seq provides several advantages over other in vitro methods, including minimal sequencing depth requirements, low background, and high enrichment for Cas9-cleaved gDNA. These advantages enhance sensitivity in identifying both intended and unintended cleavage events. This study provides a comprehensive, step-by-step procedure for examining the off-target activity of CRISPR-Cas9 using CIRCLE-seq. As an example, this protocol is validated by mapping genome-wide unintended cleavage sites of CRISPR-Cas9 during the modification of the AAVS1 locus. The entire CIRCLE-seq process can be completed in two weeks, allowing sufficient time for cell growth, DNA purification, library preparation, and Illumina sequencing. The input of sequencing data into the CIRCLE-seq pipeline facilitates streamlined interpretation and analysis of cleavage sites.

International Society for Cell & Gene Therapy Stem Cell Engineering Committee report on the current state of hematopoietic stem and progenitor cell-based genomic therapies and the challenges faced

Genetic manipulation of hematopoietic stem cells (HSCs) is being developed as a therapeutic strategy for several inherited disorders. This field is rapidly evolving with several novel tools and techniques being employed to achieve desired genetic changes. While commercial products are now available for sickle cell disease, transfusion-dependent β-thalassemia, metachromatic leukodystrophy and adrenoleukodystrophy, several challenges remain in patient selection, HSC mobilization and collection, genetic manipulation of stem cells, conditioning, hematologic recovery and post-transplant complications, financial issues, equity of access and institutional and global preparedness. In this report, we explore the current state of development of these therapies and provide a comprehensive assessment of the challenges these therapies face as well as potential solutions.

A millifluidic bioreactor allows the long term culture of primary lymphocytes or CD34+ hematopoietic cells while allowing the detection of tumorigenic expansion

Long-term culture of primary lymphocytes and hematopoietic stem and progenitor cells (HSPCs) is pivotal to their expansion and study. Furthermore, genetic engineering of the above-mentioned primary human cells has several safety needs, including the requirement of efficient in vitro assays for unwanted tumorigenic events. In this work, we tested and optimized the Miniaturized Optically Accessible Bioreactor (MOAB) platform. The MOAB consists of a millifluidic cell culture device with three optically-accessible culture chambers. Inside the MOAB, we inserted a silk-based framework that resembles some properties of the bone marrow environment and cultivated in this device either CD4+ T lymphocytes isolated from healthy donor buffy coat or cord blood-derived hematopoietic CD34+ cells. A fraction of these cells is viable for up to 3 months. Next, we tested the capability of the MOAB to detect tumorigenic events. Serial dilutions of engineered fluorescent tumor cells were mixed with either CD4+ or CD34+ primary cells, and their growth was followed. By this approach, we successfully detected as little as 100 tumorigenic cells mixed with 100,000 primary cells. We found that non-tumorigenic primary cells colonized the silk environment, whereas tumor cells, after an adaptation phase, expanded and entered the circulation. We conclude that the millifluidic platform allows the detection of rare tumorigenic events in the long-term culture of human cells.

The longitudinal kinetics of AAV5 vector integration profiles and evaluation of clonal expansion in mice

Adeno-associated virus (AAV)-based vectors are used clinically for gene transfer and persist as extrachromosomal episomes. A small fraction of vector genomes integrate into the host genome, but the theoretical risk of tumorigenesis depends on vector regulatory features. A mouse model was used to investigate integration profiles of an AAV serotype 5 (AAV5) vector produced using Sf and HEK293 cells that mimic key features of valoctocogene roxaparvovec (AAV5-hFVIII-SQ), a gene therapy for severe hemophilia A. The majority (95%) of vector genome reads were derived from episomes, and mean (± standard deviation) integration frequency was 2.70 ± 1.26 and 1.79 ± 0.86 integrations per 1,000 cells for Sf- and HEK293-produced vector. Longitudinal integration analysis suggested integrations occur primarily within 1 week, at low frequency, and their abundance was stable over time. Integration profiles were polyclonal and randomly distributed. No major differences in integration profiles were observed for either vector production platform, and no integrations were associated with clonal expansion. Integrations were enriched near transcription start sites of genes highly expressed in the liver (p = 1 × 10-4) and less enriched for genes of lower expression. We found no evidence of tumorigenesis or fibrosis caused by the vector integrations.

The Current Landscape of Secondary Malignancies after CAR T-Cell Therapies: How Could Malignancies Be Prevented?

Chimeric antigen receptor (CAR) T-cell therapies have revolutionised the field of haematological malignancies by achieving impressive remission rates in patients with highly refractory haematological malignancies, improving overall survival. To date, six commercial anti-CD19 and anti-BCMA CAR T-cell products have been approved by the Food and Drug Administration (FDA) for the treatment of relapsed/refractory B-cell haematological malignancies and multiple myeloma. The indications for CAR T-cell therapies are gradually expanding, with these therapies being investigated in a variety of diseases, including non-malignant ones. Despite the great success, there are several challenges surrounding CAR T-cell therapies, such as non-durable responses and high-grade toxicities. In addition, a new safety concern was added by the FDA on 28 November 2023 following reports of T-cell malignancies in patients previously treated with either anti-CD19 or anti-BCMA autologous CAR T-cell therapies both in clinical trials and in the real-world setting. Since then, several reports have been published presenting the incidence and analysing the risks of other secondary malignancies after CAR T-cell therapies. In this opinion article, the current landscape of secondary malignancies after CAR T-cell therapies is presented, along with a proposed strategy for future research aiming at potentially diminishing or abrogating the risk of developing secondary malignancies after CAR T-cell therapies.

Adeno-Associated Virus Vectors-a Target of Cellular and Humoral Immunity-are Expanding Their Reach Toward Hematopoietic Stem Cell Modification and Immunotherapies

All current market-approved gene therapy medical products for in vivo gene therapy of monogenic diseases rely on adeno-associated virus (AAV) vectors. Advances in gene editing technologies and vector engineering have expanded the spectrum of target cells and, thus, diseases that can be addressed. Consequently, AAV vectors are now being explored to modify cells of the hematopoietic system, including hematopoietic stem and progenitor cells (HSPCs), to develop novel strategies to treat monogenic diseases, but also to generate cell- and vaccine-based immunotherapies. However, the cell types that represent important new targets for the AAV vector system are centrally involved in immune responses against the vector and its transgene product as discussed briefly in the first part of this review. In the second part, studies exploring AAV vectors for genetic engineering of HSPCs, T and B lymphocytes, and beyond are presented.

The menace of severe adverse events and deaths associated with viral gene therapy and its potential solution

Over the past decade, in vivo gene replacement therapy has significantly advanced, resulting in market approval of numerous therapeutics predominantly relying on adeno-associated viral vectors (AAV). While viral vectors have undeniably addressed several critical healthcare challenges, their clinical application has unveiled a range of limitations and safety concerns. This review highlights the emerging challenges in the field of gene therapy. At first, we discuss both the role of biological barriers in viral gene therapy with a focus on AAVs, and review current landscape of in vivo human gene therapy. We delineate advantages and disadvantages of AAVs as gene delivery vehicles, mostly from the safety perspective (hepatotoxicity, cardiotoxicity, neurotoxicity, inflammatory responses etc.), and outline the mechanisms of adverse events in response to AAV. Contribution of every aspect of AAV vectors (genomic structure, capsid proteins) and host responses to injected AAV is considered and substantiated by basic, translational and clinical studies. The updated evaluation of recent AAV clinical trials and current medical experience clearly shows the risks of AAVs that sometimes overshadow the hopes for curing a hereditary disease. At last, a set of established and new molecular and nanotechnology tools and approaches are provided as potential solutions for mitigating or eliminating side effects. The increasing number of severe adverse reactions and, sadly deaths, demands decisive actions to resolve the issue of immune responses and extremely high doses of viral vectors used for gene therapy. In response to these challenges, various strategies are under development, including approaches aimed at augmenting characteristics of viral vectors and others focused on creating secure and efficacious non-viral vectors. This comprehensive review offers an overarching perspective on the present state of gene therapy utilizing both viral and non-viral vectors.

Chemogenetic Tools and their Use in Studies of Neuropsychiatric Disorders

Chemogenetics is a newly developed set of tools that allow for selective manipulation of cell activity. They consist of a receptor mutated irresponsive to endogenous ligands and a synthetic ligand that does not interact with the wild-type receptors. Many different types of these receptors and their respective ligands for inhibiting or excitating neuronal subpopulations were designed in the past few decades. It has been mainly the G-protein coupled receptors (GPCRs) selectively responding to clozapine-N-oxide (CNO), namely Designer Receptors Exclusively Activated by Designer Drugs (DREADDs), that have been employed in research. Chemogenetics offers great possibilities since the activity of the receptors is reversible, inducible on demand by the ligand, and non-invasive. Also, specific groups or types of neurons can be selectively manipulated thanks to the delivery by viral vectors. The effect of the chemogenetic receptors on neurons lasts longer, and even chronic activation can be achieved. That can be useful for behavioral testing. The great advantage of chemogenetic tools is especially apparent in research on brain diseases since they can manipulate whole neuronal circuits and connections between different brain areas. Many psychiatric or other brain diseases revolve around the dysfunction of specific brain networks. Therefore, chemogenetics presents a powerful tool for investigating the underlying mechanisms causing the disease and revealing the link between the circuit dysfunction and the behavioral or cognitive symptoms observed in patients. It could also contribute to the development of more effective treatments.

Preclinical evidence in the assembly of mammalian SWI/SNF complexes: Epigenetic insights and clinical perspectives in human lung disease therapy

The SWI/SNF complex, also known as the BRG1/BRM-associated factor (BAF) complex, represents a critical regulator of chromatin remodeling mechanisms in mammals. It is alternatively referred to as mSWI/SNF and has been suggested to be imbalanced in human disease compared with human health. Three types of BAF assemblies associated with it have been described, including (1) canonical BAF (cBAF), (2) polybromo-associated BAF (PBAF), and (3) non-canonical BAF (ncBAF) complexes. Each of these BAF assemblies plays a role, either functional or dysfunctional, in governing gene expression patterns, cellular processes, epigenetic mechanisms, and biological processes. Recent evidence increasingly links the dysregulation of mSWI/SNF complexes to various human non-malignant lung chronic disorders and lung malignant diseases. This review aims to provide a comprehensive general state-of-the-art and a profound examination of the current understanding of mSWI/SNF assembly processes, as well as the structural and functional organization of mSWI/SNF complexes and their subunits. In addition, it explores their intricate functional connections with potentially dysregulated transcription factors, placing particular emphasis on molecular and cellular pathogenic processes in lung diseases. These processes are reflected in human epigenome aberrations that impact clinical and therapeutic levels, suggesting novel perspectives on the diagnosis and molecular therapies for human respiratory diseases.

Atavistic strategy for the treatment of hyperuricemia via ionizable liposomal mRNA

Hyperuricemia is associated with an increased risk of gout, hypertension, diabetes, and cardiovascular diseases. Most mammals maintain normal serum uric acid (SUA) via urate oxidase (Uox), an enzyme that metabolizes poorly-soluble UA to highly-soluble allantoin. In contrast, Uox became a pseudogene in humans and apes over the long course of evolution. Here we demonstrate an atavistic strategy for treating hyperuricemia based on endogenous expression of Uox in hepatocytes mediated by mRNA (mUox) loaded with an ionizable lipid nanoparticle termed iLAND. mUox@iLAND allows effective transfection and protein expression in vitro. A single dose of mUox@iLAND lowers SUA levels for several weeks in two female murine models, including a novel long-lasting model, which is also confirmed by metabolomics analysis. Together with the excellent safety profiles observed in vivo, the proposed mRNA agent demonstrates substantial potential for hyperuricemia therapy and the prevention of associated conditions.

Accelerating Diverse Cell-Based Therapies Through Scalable Design

Augmenting cells with novel, genetically encoded functions will support therapies that expand beyond natural capacity for immune surveillance and tissue regeneration. However, engineering cells at scale with transgenic cargoes remains a challenge in realizing the potential of cell-based therapies. In this review, we introduce a range of applications for engineering primary cells and stem cells for cell-based therapies. We highlight tools and advances that have launched mammalian cell engineering from bioproduction to precision editing of therapeutically relevant cells. Additionally, we examine how transgenesis methods and genetic cargo designs can be tailored for performance. Altogether, we offer a vision for accelerating the translation of innovative cell-based therapies by harnessing diverse cell types, integrating the expanding array of synthetic biology tools, and building cellular tools through advanced genome writing techniques.

Gene therapy for the leukodystrophies: From preclinical animal studies to clinical trials

Leukodystrophies are progressive single gene disorders affecting the white matter of the brain. Several gene therapy trials are in progress to address the urgent unmet need for this patient population. We performed a comprehensive literature review of all gene therapy clinical trials listed in www.clinicaltrials.gov through August 2024, and the relevant preclinical studies that enabled clinical translation. Of the approximately 50 leukodystrophies described to date, only eight have existing gene therapy clinical trials: metachromatic leukodystrophy, X-linked adrenoleukodystrophy, globoid cell leukodystrophy, Canavan disease, giant axonal neuropathy, GM2 gangliosidoses, Alexander disease and Pelizaeus-Merzbacher disease. What led to the emergence of gene therapy trials for these specific disorders? What preclinical data or disease context was enabling? For each of these eight disorders, we first describe its pathophysiology and clinical presentation. We discuss the impact of gene therapy delivery route, targeted cell type, delivery modality, dosage, and timing on therapeutic efficacy. We note that use of allogeneic hematopoietic stem cell transplantation in some leukodystrophies allowed for an accelerated path to clinic even in the absence of available animal models. In other leukodystrophies, small and large animal model studies enabled clinical translation of experimental gene therapies. Human clinical trials for the leukodystrophies include ex vivo lentiviral gene delivery, in vivo AAV-mediated gene delivery, and intrathecal antisense oligonucleotide approaches. We outline adverse events associated with each modality focusing specifically on genotoxicity and immunotoxicity. We review monitoring and management of events related to insertional mutagenesis and immune responses. The data presented in this review show that gene therapy, while promising, requires systematic monitoring to account for the precarious disease biology and the adverse events associated with new technology.

Gene therapy in pediatrics - Clinical studies and approved drugs (as of 2023)

Gene therapy in pediatrics represents a cutting-edge therapeutic strategy for treating a range of genetic disorders that manifest in childhood. Gene therapy involves the modification or correction of a mutated gene or the introduction of a functional gene into a patient's cells. In general, it is implemented through two main modalities namely ex vivo gene therapy and in vivo gene therapy. Currently, a noteworthy array of gene therapy products has received valid market authorization, with several others in various stages of the approval process. Additionally, a multitude of clinical trials are actively underway, underscoring the dynamic progress within this field. Pediatric genetic disorders in the fields of hematology, oncology, vision and hearing loss, immunodeficiencies, neurological, and metabolic disorders are areas for gene therapy interventions. This review provides a comprehensive overview of the evolution and current progress of gene therapy-based treatments in the clinic for pediatric patients. It navigates the historical milestones of gene therapies, currently approved gene therapy products by the U.S. Food and Drug Administration (FDA) and/or European Medicines Agency (EMA) for children, and the promising future for genetic disorders. By providing a thorough compilation of approved gene therapy drugs and published results of completed or ongoing clinical trials, this review serves as a guide for pediatric clinicians to get a quick overview of the situation of clinical studies and approved gene therapy products as of 2023.

The Fate(s) of CAR T-Cell Therapy: Navigating the Risks of CAR+ T-Cell Malignancy

The introduction of chimeric antigen receptor (CAR) T-cell therapy represents a landmark advancement in treating resistant forms of cancer such as leukemia, lymphoma, and myeloma. However, concerns about long-term safety have emerged following an FDA investigation into reports of second primary malignancies (SPM) after CAR-T cell treatment. This review offers a thorough examination of how genetically modified T cells might transform into CAR+ SPM. It explores genetic and molecular pathways leading to T-cell lymphomagenesis, the balance between CAR T-cell persistence, stemness, and oncogenic risk, and the trade-off of T-cell exhaustion, which may limit therapy efficacy but potentially reduce lymphomagenesis risk. Significance: An FDA probe into 22 cases of second primary T-cell malignancies following CAR T-cell therapy stresses the need to investigate their origins. Few may arise from preexisting genetic and epigenetic alterations and those introduced during therapeutic engineering. Technological advances, regulatory oversight, and patient monitoring are essential to mitigate potential risks.

Nanoplatform-Based In Vivo Gene Delivery Systems for Cancer Therapy

Gene therapy uses modern molecular biology methods to repair disease-causing genes. As a burgeoning therapeutic, it has been widely applied for cancer therapy. Since 1989, there have been numerous clinical gene therapy cases worldwide. However, a few are successful. The main challenge of clinical gene therapy is the lack of efficient and safe vectors. Although viral vectors show high transfection efficiency, their application is still limited by immune rejection and packaging capacity. Therefore, the development of non-viral vectors is overwhelming. Nanoplatform-based non-viral vectors become a hotspot in gene therapy. The reasons are mainly as follows. 1) Non-viral vectors can be engineered to be uptaken by specific types of cells or tissues, providing effective targeting capability. 2) Non-viral vectors can protect goods that need to be delivered from degradation. 3) Nanoparticles can transport large-sized cargo such as CRISPR/Cas9 plasmids and nucleoprotein complexes. 4) Nanoparticles are highly biosafe, and they are not mutagenic in themselves compared to viral vectors. 5) Nanoparticles are easy to scale preparation, which is conducive to clinical conversion and application. Here, an overview of the categories of nanoplatform-based non-viral gene vectors, the limitations on their development, and their applications in cancer therapy.

Engineering strategies to safely drive CAR T-cells into the future

Chimeric antigen receptor (CAR) T-cell therapy has proven a breakthrough in cancer treatment in the last decade, giving unprecedented results against hematological malignancies. All approved CAR T-cell products, as well as many being assessed in clinical trials, are generated using viral vectors to deploy the exogenous genetic material into T-cells. Viral vectors have a long-standing clinical history in gene delivery, and thus underwent iterations of optimization to improve their efficiency and safety. Nonetheless, their capacity to integrate semi-randomly into the host genome makes them potentially oncogenic via insertional mutagenesis and dysregulation of key cellular genes. Secondary cancers following CAR T-cell administration appear to be a rare adverse event. However several cases documented in the last few years put the spotlight on this issue, which might have been underestimated so far, given the relatively recent deployment of CAR T-cell therapies. Furthermore, the initial successes obtained in hematological malignancies have not yet been replicated in solid tumors. It is now clear that further enhancements are needed to allow CAR T-cells to increase long-term persistence, overcome exhaustion and cope with the immunosuppressive tumor microenvironment. To this aim, a variety of genomic engineering strategies are under evaluation, most relying on CRISPR/Cas9 or other gene editing technologies. These approaches are liable to introduce unintended, irreversible genomic alterations in the product cells. In the first part of this review, we will discuss the viral and non-viral approaches used for the generation of CAR T-cells, whereas in the second part we will focus on gene editing and non-gene editing T-cell engineering, with particular regard to advantages, limitations, and safety. Finally, we will critically analyze the different gene deployment and genomic engineering combinations, delineating strategies with a superior safety profile for the production of next-generation CAR T-cell.

Nanoinjection: A Platform for Innovation in Ex Vivo Cell Engineering

In human cells, intracellular access and therapeutic cargo transport, including gene-editing tools (e.g., CRISPR-Cas9 and transposons), nucleic acids (e.g., DNA, mRNA, and siRNA), peptides, and proteins (e.g., enzymes and antibodies), are tightly constrained to ensure healthy cell function and behavior. This principle is exemplified in the delivery mechanisms of chimeric antigen receptor (CAR)-T cells for ex-vivo immunotherapy. In particular, the clinical success of CAR-T cells has established a new standard of care by curing previously incurable blood cancers. The approach involves the delivery, typically via the use of electroporation (EP) and lentivirus, of therapeutic CAR genes into a patient's own T cells, which are then engineered to express CARs that target and combat their blood cancer. But the key difficulty lies in genetically manipulating these cells without causing irreversible damage or loss of function─all the while minimizing complexities of manufacturing, safety concerns, and costs, and ensuring the efficacy of the final CAR-T cell product.Nanoinjection─the process of intracellular delivery using nanoneedles (NNs)─is an emerging physical delivery route that efficiently negotiates the plasma membrane of many cell types, including primary human T cells. It occurs with minimal perturbation, invasiveness, and toxicity, with high efficiency and throughput at high spatial and temporal resolutions. Nanoinjection promises greatly improved delivery of a broad range of therapeutic cargos with little or no damage to those cargos. A nanoinjection platform allows these cargos to function in the intracellular space as desired. The adaptability of nanoinjection platforms is now bringing major advantages in immunomodulation, mechanotransduction, sampling of cell states (nanobiopsy), controlled intracellular interrogation, and the primary focus of this account─intracellular delivery and its applications in ex vivo cell engineering. Mechanical nanoinjection typically exerts direct mechanical force on the cell membrane, offering a straightforward route to improve membrane perturbation by the NNs and subsequent transport of genetic cargo into targeted cell type (adherent or suspension cells). By contrast, electroactive nanoinjection is controlled by coupling NNs with an electric field─a new route for activating electroporation (EP) at the nanoscale─allowing a dramatic reduction of the applied voltage to a cell and so minimizing post-EP damage to cells and cargo, and overcoming many of the limitations of conventional bulk EP. Nanoinjection transcends mere technique; it is an approach to cell engineering ex vivo, offering the potential to endow cells with new, powerful features such as generating chimeric antigen receptor (CAR)-T cells for future CAR-T cell technologies. We first discuss the manufacturing of NN devices (Section 2), then delve into nanoinjection-mediated cell engineering (Section 3), nanoinjection mechanisms and interfacing methodologies (Section 4), and emerging applications in using nanoinjection to create functional CAR-T cells (Section 5).

Mechanisms Underlying the Development of Murine T-Cell Lymphoblastic Lymphoma/Leukemia Induced by Total-Body Irradiation

Exposure to ionizing radiation is associated with an increased risk of hematologic malignancies in myeloid and lymphoid lineages in humans and experimental mice. Given that substantial evidence links radiation exposure with the risk of hematologic malignancies, it is imperative to deeply understand the mechanisms underlying cellular and molecular changes during the latency period between radiation exposure and the emergence of fully transformed malignant cells. One experimental model widely used in the field of radiation and cancer biology to study hematologic malignancies induced by radiation exposure is mouse models of radiation-induced thymic lymphoma. Murine radiation-induced thymic lymphoma is primarily driven by aberrant activation of Notch signaling, which occurs frequently in human precursor T-cell lymphoblastic lymphoma (T-LBL) and T-cell lymphoblastic leukemia (T-ALL). Here, we summarize the literature elucidating cell-autonomous and non-cell-autonomous mechanisms underlying cancer initiation, progression, and malignant transformation in the thymus following total-body irradiation (TBI) in mice.