CAR T Cells Generated UsingSleeping BeautyTransposon Vectors and Expanded with an EBV-Transformed Lymphoblastoid Cell Line Display Antitumor ActivityIn VitroandIn Vivo

Survival advantage of native and engineered T cells is acquired by mitochondrial transfer from mesenchymal stem cells

BACKGROUND

Apoptosis, a form of programmed cell death, is critical for the development and homeostasis of the immune system. Chimeric antigen receptor T (CAR-T) cell therapy, approved for hematologic cancers, retains several limitations and challenges associated with ex vivo manipulation, including CAR T-cell susceptibility to apoptosis. Therefore, strategies to improve T-cell survival and persistence are required. Mesenchymal stem/stromal cells (MSCs) exhibit immunoregulatory and tissue-restoring potential. We have previously shown that the transfer of umbilical cord MSC (UC-MSC)-derived mitochondrial (MitoT) prompts the genetic reprogramming of CD3+ T cells towards a Treg cell lineage. The potency of T cells plays an important role in effective immunotherapy, underscoring the need for improving their metabolic fitness. In the present work, we evaluate the effect of MitoT on apoptotis of native T lymphocytes and engineered CAR-T cells.

METHODS

We used a cell-free approach using artificial MitoT (Mitoception) of UC-MSC derived MT to peripheral blood mononuclear cells (PBMCs) followed by RNA-seq analysis of CD3+ MitoTpos and MitoTneg sorted cells. Target cell apoptosis was induced with Staurosporine (STS), and cell viability was evaluated with Annexin V/7AAD and TUNEL assays. Changes in apoptotic regulators were assessed by flow cytometry, western blot, and qRT-PCR. The effect of MitoT on 19BBz CAR T-cell apoptosis in response to electroporation with a non-viral transposon-based vector was assessed with Annexin V/7AAD.

RESULTS

Gene expression related to apoptosis, cell death and/or responses to different stimuli was modified in CD3+ T cells after Mitoception. CD3+MitoTpos cells were resistant to STS-induced apoptosis compared to MitoTneg cells, showing a decreased percentage in apoptotic T cells as well as in TUNEL+ cells. Additionally, MitoT prevented the STS-induced collapse of the mitochondrial membrane potential (MMP) levels, decreased caspase-3 cleavage, increased BCL2 transcript levels and BCL-2-related BARD1 expression in FACS-sorted CD3+ T cells. Furthermore, UC-MSC-derived MitoT reduced both early and late apoptosis in CAR-T cells following electroporation, and exhibited an increasing trend in cytotoxic activity levels.

CONCLUSIONS

Artificial MitoT prevents STS-induced apoptosis of human CD3+ T cells by interfering with the caspase pathway. Furthermore, we observed that MitoT confers protection to apoptosis induced by electroporation in MitoTpos CAR T-engineered cells, potentially improving their metabolic fitness and resistance to environmental stress. These results widen the physiological perspective of organelle-based therapies in immune conditions while offering potential avenues to enhance CAR-T treatment outcomes where their viability is compromised.

Evolution of the clinical-stage hyperactive TcBuster transposase as a platform for robust non-viral production of adoptive cellular therapies

Cellular therapies for the treatment of human diseases, such as chimeric antigen receptor (CAR) T and natural killer (NK) cells have shown remarkable clinical efficacy in treating hematological malignancies; however, current methods mainly utilize viral vectors that are limited by their cargo size capacities, high cost, and long timelines for production of clinical reagent. Delivery of genetic cargo via DNA transposon engineering is a more timely and cost-effective approach, yet has been held back by less efficient integration rates. Here, we report the development of a novel hyperactive TcBuster (TcB-M) transposase engineered through structure-guided and in vitro evolution approaches that achieves high-efficiency integration of large, multicistronic CAR-expression cassettes in primary human cells. Our proof-of-principle TcB-M engineering of CAR-NK and CAR-T cells shows low integrated vector copy number, a safe insertion site profile, robust in vitro function, and improves survival in a Burkitt lymphoma xenograft model in vivo. Overall, TcB-M is a versatile, safe, efficient and open-source option for the rapid manufacture and preclinical testing of primary human immune cell therapies through delivery of multicistronic large cargo via transposition.

Immunotherapy guided precision medicine in solid tumors

Cancer is no longer recognized as a single disease but a collection of diseases each with its defining characteristics and behavior. Even within the same cancer type, there can be substantial heterogeneity at the molecular level. Cancer cells often accumulate various genetic mutations and epigenetic alterations over time, leading to a coexistence of distinct subpopulations of cells within the tumor. This tumor heterogeneity arises not only due to clonal outgrowth of cells with genetic mutations, but also due to interactions of tumor cells with the tumor microenvironment (TME). The latter is a dynamic ecosystem that includes cancer cells, immune cells, fibroblasts, endothelial cells, stromal cells, blood vessels, and extracellular matrix components, tumor-associated macrophages and secreted molecules. The complex interplay between tumor heterogeneity and the TME makes it difficult to develop one-size-fits-all treatments and is often the cause of therapeutic failure and resistance in solid cancers. Technological advances in the post-genomic era have given us cues regarding spatial and temporal tumor heterogeneity. Armed with this knowledge, oncologists are trying to target the unique genomic, epigenetic, and molecular landscape in the tumor cell that causes its oncogenic transformation in a particular patient. This has ushered in the era of personalized precision medicine (PPM). Immunotherapy, on the other hand, involves leveraging the body's immune system to recognize and attack cancer cells and spare healthy cells from the damage induced by radiation and chemotherapy. Combining PPM and immunotherapy represents a paradigm shift in cancer treatment and has emerged as a promising treatment modality for several solid cancers. In this chapter, we summarise major types of cancer immunotherapy and discuss how they are being used for precision medicine in different solid tumors.

AAV-mediated delivery of a Sleeping Beauty transposon and an mRNA-encoded transposase for the engineering of therapeutic immune cells

Engineering cells for adoptive therapy requires overcoming limitations in cell viability and, in the efficiency of transgene delivery, the duration of transgene expression and the stability of genomic integration. Here we report a gene-delivery system consisting of a Sleeping Beauty (SB) transposase encoded into a messenger RNA delivered by an adeno-associated virus (AAV) encoding an SB transposon that includes the desired transgene, for mediating the permanent integration of the transgene. Compared with lentiviral vectors and with the electroporation of plasmids of transposon DNA or minicircle DNA, the gene-delivery system, which we named MAJESTIC (for 'mRNA AAV-SB joint engineering of stable therapeutic immune cells'), offers prolonged transgene expression, as well as higher transgene expression, therapeutic-cell yield and cell viability. MAJESTIC can deliver chimeric antigen receptors (CARs) into T cells (which we show lead to strong anti-tumour activity in vivo) and also transduce natural killer cells, myeloid cells and induced pluripotent stem cells with bi-specific CARs, kill-switch CARs and synthetic T-cell receptors.

Biomaterials for chimeric antigen receptor T cell engineering

Chimeric antigen receptor T (CAR-T) cells have achieved breakthrough efficacies against hematological malignancies, but their unsatisfactory efficacies in solid tumors limit their applications. The prohibitively high prices further restrict their access to broader populations. Novel strategies are urgently needed to address these challenges, and engineering biomaterials can be one promising approach. The established process for manufacturing CAR-T cells involves multiple steps, and biomaterials can help simplify or improve several of them. In this review, we cover recent progress in engineering biomaterials for producing or stimulating CAR-T cells. We focus on the engineering of non-viral gene delivery nanoparticles for transducing CAR into T cells ex vivo/in vitro or in vivo. We also dive into the engineering of nano-/microparticles or implantable scaffolds for local delivery or stimulation of CAR-T cells. These biomaterial-based strategies can potentially change the way CAR-T cells are manufactured, significantly reducing their cost. Modulating the tumor microenvironment with the biomaterials can also considerably enhance the efficacy of CAR-T cells in solid tumors. We pay special attention to progress made in the past five years, and perspectives on future challenges and opportunities are also discussed. STATEMENT OF SIGNIFICANCE: Chimeric antigen receptor T (CAR-T) cell therapies have revolutionized the field of cancer immunotherapy with genetically engineered tumor recognition. They are also promising for treating many other diseases. However, the widespread application of CAR-T cell therapy has been hampered by the high manufacturing cost. Poor penetration of CAR-T cells into solid tissues further restricted their use. While biological strategies have been explored to improve CAR-T cell therapies, such as identifying new cancer targets or integrating smart CARs, biomaterial engineering provides alternative strategies toward better CAR-T cells. In this review, we summarize recent advances in engineering biomaterials for CAR-T cell improvement. Biomaterials ranging from nano-, micro-, and macro-scales have been developed to assist CAR-T cell manufacturing and formulation.

Therapeutic immune cell engineering with an mRNA : AAV- Sleeping Beauty composite system

Adoptive cell therapy has shown clinical success in patients with hematological malignancies. Immune cell engineering is critical for production, research, and development of cell therapy; however, current approaches for generation of therapeutic immune cells face various limitations. Here, we establish a composite gene delivery system for the highly efficient engineering of therapeutic immune cells. This system, termed MAJESTIC ( m RNA A AV-Sleeping-Beauty J oint E ngineering of S table T herapeutic I mmune C ells), combines the merits of mRNA, AAV vector, and transposon into one composite system. In MAJESTIC, the transient mRNA component encodes a transposase that mediates permanent genomic integration of the Sleeping Beauty (SB) transposon, which carries the gene-of-interest and is embedded within the AAV vector. This system can transduce diverse immune cell types with low cellular toxicity and achieve highly efficient and stable therapeutic cargo delivery. Compared with conventional gene delivery systems, such as lentiviral vector, DNA transposon plasmid, or minicircle electroporation, MAJESTIC shows higher cell viability, chimeric antigen receptor (CAR) transgene expression, therapeutic cell yield, as well as prolonged transgene expression. CAR-T cells generated by MAJESTIC are functional and have strong anti-tumor activity in vivo . This system also demonstrates versatility for engineering different cell therapy constructs such as canonical CAR, bi-specific CAR, kill switch CAR, and synthetic TCR; and for CAR delivery into various immune cells, including T cells, natural killer cells, myeloid cells, and induced pluripotent stem cells.

Therapeutic approaches to Epstein-Barr virus cancers

Epstein-Barr virus (EBV) establishes a lifelong latent infection that can be a causal agent for a diverse spectrum of cancers and autoimmune disease. A complex and dynamic viral lifecycle evades eradication by the host immune system and confounds antiviral therapeutic strategies. To date, there are no clinically approved vaccines or therapies that selectively target EBV as the underlying cause of EBV-associated disease. Here, we review the challenges and recent advances in the development of EBV-specific therapeutics for treatment of EBV-associated cancers.

Chimeric Antigen Receptor T-Cells: An Overview of Concepts, Applications, Limitations, and Proposed Solutions

Adaptive immunity, orchestrated by B-cells and T-cells, plays a crucial role in protecting the body from pathogenic invaders and can be used as tools to enhance the body's defense mechanisms against cancer by genetically engineering these immune cells. Several strategies have been identified for cancer treatment and evaluated for their efficacy against other diseases such as autoimmune and infectious diseases. One of the most advanced technologies is chimeric antigen receptor (CAR) T-cell therapy, a pioneering therapy in the oncology field. Successful clinical trials have resulted in the approval of six CAR-T cell products by the Food and Drug Administration for the treatment of hematological malignancies. However, there have been various obstacles that limit the use of CAR T-cell therapy as the first line of defense mechanism against cancer. Various innovative CAR-T cell therapeutic designs have been evaluated in preclinical and clinical trial settings and have demonstrated much potential for development. Such trials testing the suitability of CARs against solid tumors and HIV are showing promising results. In addition, new solutions have been proposed to overcome the limitations of this therapy. This review provides an overview of the current knowledge regarding this novel technology, including CAR T-cell structure, different applications, limitations, and proposed solutions.

Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular Consensus on genetically modified cells. VII. Present and future of technologies for production of CAR cell therapies

Chimeric Antigen Receptor T (CAR-T) cells are certainly an important therapy for patients with relapsed and/or refractory hematologic malignancies. Currently, there are five CAR-T cell products approved by the FDA but several research groups and/or biopharmaceutical companies are encouraged to develop new products based on CAR cells using T or other cell types. Production of CAR cells requires intensive work from the basic, pre-clinical to translational levels, aiming to overcome technical difficulties and failure in the production. At least five key common steps are needed for the manipulation of T-lymphocytes (or other cells), such as: cell type selection, activation, gene delivery, cell expansion and final product formulation. However, reproducible manufacturing of high-quality clinical-grade CAR cell products is still required to apply this technology to a greater number of patients. This chapter will discuss the present and future development of new CAR designs that are safer and more effective to improve this therapy, achieving more selective killing of malignant cells and less toxicity to be applied in the clinical setting.

Cytometric analysis of T cell phenotype using cytokine profiling for improved manufacturing of an EBV-specific T cell therapy

Adoptive immunotherapy using Epstein–Barr Virus (EBV)‐specific T cells is a potentially curative treatment for patients with EBV‐related malignancies where other clinical options have proved ineffective. We describe improved good manufacturing practice (GMP)‐compliant culture and analysis processes for conventional lymphoblastoid cell line (LCL)‐driven EBV‐specific T cell manufacture, and describe an improved phenotyping approach for analysing T cell products. We optimized the current LCL‐mediated clinical manufacture of EBV‐specific T cells to establish an improved process using xenoprotein‐free GMP‐compliant reagents throughout, and compared resulting products with our previous banked T cell clinical therapy. We assessed effects of changes to LCL:T cell ratio in T cell expansion, and developed a robust flow cytometric marker panel covering T cell memory, activation, differentiation and intracellular cytokine release to characterize T cells more effectively. These data were analysed using a t‐stochastic neighbour embedding (t‐SNE) algorithm. The optimized GMP‐compliant process resulted in reduced cell processing time and improved retention and expansion of central memory T cells. Multi‐parameter flow cytometry determined the optimal protocol for LCL stimulation and expansion of T cells and demonstrated that cytokine profiling using interleukin (IL)‐2, tumour necrosis factor (TNF)‐α and interferon (IFN)‐γ was able to determine the differentiation status of T cells throughout culture and in the final product. We show that fully GMP‐compliant closed‐process culture of LCL‐mediated EBV‐specific T cells is feasible, and profiling of T cells through cytokine expression gives improved characterization of start material, in‐process culture conditions and final product. Visualization of the complex multi‐parameter flow cytometric data can be simplified using t‐SNE analysis.

CARTmath-A Mathematical Model of CAR-T Immunotherapy in Preclinical Studies of Hematological Cancers

Immunotherapy has gained great momentum with chimeric antigen receptor T cell (CAR-T) therapy, in which patient's T lymphocytes are genetically manipulated to recognize tumor-specific antigens, increasing tumor elimination efficiency. In recent years, CAR-T cell immunotherapy for hematological malignancies achieved a great response rate in patients and is a very promising therapy for several other malignancies. Each new CAR design requires a preclinical proof-of-concept experiment using immunodeficient mouse models. The absence of a functional immune system in these mice makes them simple and suitable for use as mathematical models. In this work, we develop a three-population mathematical model to describe tumor response to CAR-T cell immunotherapy in immunodeficient mouse models, encompassing interactions between a non-solid tumor and CAR-T cells (effector and long-term memory). We account for several phenomena, such as tumor-induced immunosuppression, memory pool formation, and conversion of memory into effector CAR-T cells in the presence of new tumor cells. Individual donor and tumor specificities are considered uncertainties in the model parameters. Our model is able to reproduce several CAR-T cell immunotherapy scenarios, with different CAR receptors and tumor targets reported in the literature. We found that therapy effectiveness mostly depends on specific parameters such as the differentiation of effector to memory CAR-T cells, CAR-T cytotoxic capacity, tumor growth rate, and tumor-induced immunosuppression. In summary, our model can contribute to reducing and optimizing the number of in vivo experiments with in silico tests to select specific scenarios that could be tested in experimental research. Such an in silico laboratory is an easy-to-run open-source simulator, built on a Shiny R-based platform called CARTmath. It contains the results of this manuscript as examples and documentation. The developed model together with the CARTmath platform have potential use in assessing different CAR-T cell immunotherapy protocols and its associated efficacy, becoming an accessory for in silico trials.

Could Changing the DNA Methylation Landscape Promote the Destruction of Epstein-Barr Virus-Associated Cancers?

DNA methylation at CpG motifs provides an epigenetic route to regulate gene expression. In general, an inverse correlation between DNA hypermethylation at CpG motifs and gene expression is observed. Epstein Barr-virus (EBV) infects people and the EBV genome resides in the nucleus where either its replication cycle initiates or it enters a long-term latency state where the viral genome becomes hypermethylated at CpG motifs. Viral gene expression shows a largely inverse correlation with DNA hypermethylation. DNA methylation occurs through the action of DNA methyl transferase enzymes: writer DNA methyl transferases add methyl groups to specific regions of unmethylated DNA; maintenance DNA methyl transferases reproduce the pattern of DNA methylation during genome replication. The impact of DNA methylation is achieved through the association of various proteins specifically with methylated DNA and their influence on gene regulation. DNA methylation can be changed through altering DNA methyl transferase activity or through the action of enzymes that further modify methylated CpG motifs. Azacytidine prodrugs that are incorporated into CpG motifs during DNA replication are recognized by DNA methyl transferases and block their function resulting in hypomethylation of DNA. EBV-associated cancers have hypermethylated viral genomes and many carcinomas also have highly hypermethylated cellular genomes. Decitabine, a member of the azacytidine prodrug family, reactivates viral gene expression and promotes the recognition of lymphoma cells by virus-specific cytotoxic T-cells. For EBV-associated cancers, the impact of decitabine on the cellular genome and the prospect of combining decitabine with other therapeutic approaches is currently unknown but exciting.

CAR-T cells: Early successes in blood cancer and challenges in solid tumors

New approaches to cancer immunotherapy have been developed, showing the ability to harness the immune system to treat and eliminate cancer. For many solid tumors, therapy with checkpoint inhibitors has shown promise. For hematologic malignancies, adoptive and engineered cell therapies are being widely developed, using cells such as T lymphocytes, as well as natural killer (NK) cells, dendritic cells, and potentially others. Among these adoptive cell therapies, the most active and advanced therapy involves chimeric antigen receptor (CAR)-T cells, which are T cells in which a chimeric antigen receptor is used to redirect specificity and allow T cell recognition, activation and killing of cancers, such as leukemia and lymphoma. Two autologous CAR-T products have been approved by several health authorities, starting with the U.S. Food and Drug Administration (FDA) in 2017. These products have shown powerful, inducing, long-lasting effects against B cell cancers in many cases. In distinction to the results seen in hematologic malignancies, the field of using CAR-T products against solid tumors is in its infancy. Targeting solid tumors and trafficking CAR-T cells into an immunosuppressive microenvironment are both significant challenges. The goal of this review is to summarize some of the most recent aspects of CAR-T cell design and manufacturing that have led to successes in hematological malignancies, allowing the reader to appreciate the barriers that must be overcome to extend CAR-T therapies to solid tumors successfully.

CAR T-Cell Production Using Nonviral Approaches

Chimeric antigen receptor T-cells (CAR T-cells) represent a novel and promising approach in cancer immunotherapy. According to the World Health Organization (WHO), the number of oncological patients is steadily growing in developed countries despite immense progress in oncological treatments, and the prognosis of individual patients is still relatively poor. Exceptional results have been recorded for CAR T-cell therapy in patients suffering from B-cell malignancies. This success opens up the possibility of using the same approach for other types of cancers. To date, the most common method for CAR T-cell generation is the use of viral vectors. However, dealing with virus-derived vectors brings possible obstacles in the CAR T-cell manufacturing process owing to strict regulations and high cost demands. Alternative approaches may facilitate further development and the transfer of the method to clinical practice. The most promising substitutes for virus-derived vectors are transposon-derived vectors, most commonly sleeping beauty, which offer great coding capability and a safe integration profile while maintaining a relatively low production cost. This review is aimed at summarizing the state of the art of nonviral approaches in CAR T-cell generation, with a unique perspective on the conditions in clinical applications and current Good Manufacturing Practice. If CAR T-cell therapy is to be routinely used in medical practice, the manufacturing cost and complexity need to be as low as possible, and transposon-based vectors seem to meet these criteria better than viral-based vectors.

Genetic engineering of T cells for immunotherapy

Genetically engineered T cell immunotherapies have provided remarkable clinical success to treat B cell acute lymphoblastic leukaemia by harnessing a patient's own T cells to kill cancer, and these approaches have the potential to provide therapeutic benefit for numerous other cancers, infectious diseases and autoimmunity. By introduction of either a transgenic T cell receptor or a chimeric antigen receptor, T cells can be programmed to target cancer cells. However, initial studies have made it clear that the field will need to implement more complex levels of genetic regulation of engineered T cells to ensure both safety and efficacy. Here, we review the principles by which our knowledge of genetics and genome engineering will drive the next generation of adoptive T cell therapies.

Chimeric antigen receptor-natural killer cells: Novel insight into immunotherapy for solid tumors (Review)

The chimeric antigen receptor (CAR) is an artificially modified fusion protein consisting of an extracellular antigen-binding domain, transmembrane domain and intracellular signalling domain. CAR-T therapy has demonstrated remarkable clinical efficacy in hematological malignancies. However, cytokine release syndrome and other side effects have hindered its application in solid tumors. CAR-natural killer (NK) cells have attracted broad attention due to their safety in clinical applications, their mechanism in recognising cancer cells and the abundance of its clinical specimens. Preclinical and clinical trials of human primary NK cells and NK-92 cell lines demonstrated that CAR-NK cells are able to fight haematological malignancies and solid tumors. However, the implication of CAR-NK cell therapy also has certain challenges, including the expansion and activation of primary NK cells in vitro, selection of CAR targets, survival time of CAR-NK cells in vivo, storage and transportation of NK cells, and efficiency of NK cell transduction. This review focuses on the latest progress of CAR-NK cells in the treatment of solid tumors.

Genetic and epigenetic modification of human primary NK cells for enhanced antitumor activity

Cancer immunotherapy using genetically modified immune cells such as those expressing chimeric antigen receptors has shown dramatic outcomes in patients with refractory and relapsed malignancies. Natural killer (NK) cells as a member of the innate immune system, possessing both anticancer (cytotoxic) and proinflammatory (cytokine) responses to cancers and rare off-target toxicities have great potential for a wide range of cancer therapeutic settings. Therefore, improving NK cell antitumor activity through genetic modification is of high interest in the field of cancer immunotherapy. However, gene manipulation in primary NK cells has been challenging because of broad resistance to many genetic modification methods that work well in T cells. Here we review recent successful approaches for genetic and epigenetic modification of NK cells including epigenetic remodeling, transposons, mRNA-mediated gene delivery, lentiviruses, and CRISPR gene targeting.

A comprehensive analysis of the fatal toxic effects associated with CD19 CAR-T cell therapy

To determine the incidence, spectrum, timing, and clinical features of CD19 Chimeric antigen receptor (CAR-T) cell therapy-associated fatal toxic effects. We initiated a comprehensive analysis. First, we retrospectively queried the real-world data from a World Health Organization (WHO) pharmacovigilance database (Vigilyze). Furthermore, we performed a meta-analysis of published trials of CD19 CAR-T cell therapy. From screening the WHO database, we identified 1200 patients: 499 received Kymriah therapy, and 701 received Yescarta therapy. We compared the adverse reactions of the two drugs. We evaluated all published clinical trials, comprising 19 trials and 890 patients. Our meta-analysis showed that the incidence of fatal toxic effects associated with death was 5.4%. Infections and infestations appeared to present the highest risk of death. The toxic effect specific median time to death was 30, 30, and 68 days for total, cytokine release syndrome (CRS), and nervous system disorders (NSD), respectively. We observed a high mortality rate for some toxic effects and an early onset of death with varied causes, indicating the need for clinicians to pay more attention to the monitoring and treatment of these fatal toxic effects when using CD19 CAR-T cell therapy, especially for infections and infestations.

Development of CAR-T cell therapy for B-ALL using a point-of-care approach

Recently approved by the FDA and European Medicines Agency, CAR-T cell therapy is a new treatment option for B-cell malignancies. Currently, CAR-T cells are manufactured in centralized facilities and face bottlenecks like complex scaling up, high costs, and logistic operations. These difficulties are mainly related to the use of viral vectors and the requirement to expand CAR-T cells to reach the therapeutic dose. In this paper, by using Sleeping Beauty-mediated genetic modification delivered by electroporation, we show that CAR-T cells can be generated and used without the need for ex vivo activation and expansion, consistent with a point-of-care (POC) approach. Our results show that minimally manipulated CAR-T cells are effective in vivo against RS4;11 leukemia cells engrafted in NSG mice even when inoculated after only 4 h of gene transfer. In an effort to better characterize the infused CAR-T cells, we show that 19BBz T lymphocytes infused after 24 h of electroporation (where CAR expression is already detectable) can improve the overall survival and reduce tumor burden in organs of mice engrafted with RS4;11 or Nalm-6 B cell leukemia. A side-by-side comparison of POC approach with a conventional 8-day expansion protocol using Transact beads demonstrated that both approaches have equivalent antitumor activity in vivo. Our data suggest that POC approach is a viable alternative for the generation and use of CAR-T cells, overcoming the limitations of current manufacturing protocols. Its use has the potential to expand CAR immunotherapy to a higher number of patients, especially in the context of low-income countries.

PD-1 disrupted CAR-T cells in the treatment of solid tumors: Promises and challenges

Unprecedented efficacy of chimeric antigen receptor (CAR) T cell therapy in the treatment of hematologic malignancies brings new hope for patients with many cancer types including solid tumors. However, the challenges for CAR-T cell therapy in eradicating solid tumors are immense. To overcome these seemingly intractable hurdles, more "powerful" CAR-T cells with enhanced antitumor efficacy are required. Emerging data support that the anti-tumor activity of CAR-T cells can be enhanced significantly without evident toxicity through simultaneous PD-1 disruption by genome editing. This review focuses on the current progress of PD-1 gene disrupted CAR-T cells in cancer therapy. Here we discuss key rationales for this new combination strategy and summarize the available pre-clinical studies. An update is provided on human clinical studies and available registered cancer clinical trials using CAR-T cells with PD-1 disruption. Future prospects and challenges are also discussed.