Universal allogeneic CAR T cells engineered with Sleeping Beauty transposons and CRISPR-CAS9 for cancer immunotherapy

PELI2 regulates early B-cell progenitor differentiation and related leukemia via the IL-7R expression

Little is known about the transition mechanisms that govern early lymphoid lineage progenitors from common lymphoid progenitors (CLP). Pellino2 (PELI2) is a newly discovered E3 ubiquitin ligase, which plays important roles in inflammation and the immune system. However, the physiological and molecular roles of PELI2 in the differentiation of immune cells are largely unknown. Here, by using a conditional knockout mouse model, we demonstrated that PELI2 is required for early B-cell development and stressed hematopoiesis. PELI2 interacted with and stabilized PU.1 via K63-polyubiquitination to regulate IL-7R expression. The defects of B-cell development induced by PELI2 deletion were restored by overexpression of PU.1. Similarly, PELI2 promoted TCF3 protein stability via K63-polyubiquitination to regulate IL-7R expression, which is required for the proliferation of B-cell precursor acute lymphoblastic leukemia (BCP-ALL) cells. These results underscore the significance of PELI2 in both normal B lymphopoiesis and malignant B-cell acute lymphoblastic leukemia via the regulation of IL-7R expression, providing a potential therapeutic approach for BCP-ALL.

BCMA/CD47-directed universal CAR-T cells exhibit excellent antitumor activity in multiple myeloma

BACKGROUND

BCMA-directed autologous chimeric antigen receptor T (CAR-T) cells have shown excellent clinical efficacy in relapsed or refractory multiple myeloma (RRMM), however, the current preparation process for autologous CAR-T cells is complicated and costly. Moreover, the upregulation of CD47 expression has been observed in multiple myeloma, and anti-CD47 antibodies have shown remarkable results in clinical trials. Therefore, we focus on the development of BCMA/CD47-directed universal CAR-T (UCAR-T) cells to improve these limitations.

METHODS

In this study, we employed phage display technology to screen nanobodies against BCMA and CD47 protein, and determined the characterization of nanobodies. Furthermore, we simultaneously disrupted the endogenous TRAC and B2M genes of T cells using CRISPR/Cas9 system to generate TCR and HLA double knock-out T cells, and developed BCMA/CD47-directed UCAR-T cells and detected the antitumor activity in vitro and in vivo.

RESULTS

We obtained fourteen and one specific nanobodies against BCMA and CD47 protein from the immunized VHH library, respectively. BCMA/CD47-directed UCAR-T cells exhibited superior CAR expression (89.13-98.03%), and effectively killing primary human MM cells and MM cell lines. BCMA/CD47-directed UCAR-T cells demonstrated excellent antitumor activity against MM and prolonged the survival of tumor-engrafted NCG mice in vivo.

CONCLUSIONS

This work demonstrated that BCMA/CD47-directed UCAR-T cells exhibited potent antitumor activity against MM in vitro and in vivo, which provides a potential strategy for the development of a novel "off-the-shelf" cellular immunotherapies for the treatment of multiple myeloma.

Novel insights into TCR-T cell therapy in solid neoplasms: optimizing adoptive immunotherapy

Adoptive immunotherapy in the T cell landscape exhibits efficacy in cancer treatment. Over the past few decades, genetically modified T cells, particularly chimeric antigen receptor T cells, have enabled remarkable strides in the treatment of hematological malignancies. Besides, extensive exploration of multiple antigens for the treatment of solid tumors has led to clinical interest in the potential of T cells expressing the engineered T cell receptor (TCR). TCR-T cells possess the capacity to recognize intracellular antigen families and maintain the intrinsic properties of TCRs in terms of affinity to target epitopes and signal transduction. Recent research has provided critical insight into their capability and therapeutic targets for multiple refractory solid tumors, but also exposes some challenges for durable efficacy. In this review, we describe the screening and identification of available tumor antigens, and the acquisition and optimization of TCRs for TCR-T cell therapy. Furthermore, we summarize the complete flow from  laboratory to clinical applications of TCR-T cells. Last, we emerge future prospects for improving therapeutic efficacy in cancer world with combination therapies or TCR-T derived products. In conclusion, this review depicts our current understanding of TCR-T cell therapy in solid neoplasms, and provides new perspectives for expanding its clinical applications and improving therapeutic efficacy.

In Situ Reprogramming of Immune Cells Using Synthetic Nanomaterials

In the past decade, adoptive cell therapy with chimeric antigen receptor-T (CAR-T) cells has revolutionized cancer treatment. However, the complexity and high costs involved in manufacturing current adoptive cell therapy greatly inhibit its widespread availability and access. To address this, in situ cell therapy, which directly reprograms immune cells inside the body, has recently been developed as a promising alternative. Here, an overview of the recent progress in the development of synthetic nanomaterials is provided to deliver plasmid DNA or mRNA for in situ reprogramming of T cells and macrophages, focusing especially on in situ CAR therapies. Also, the main challenges for in situ immune cell reprogramming are discussed and some approaches to overcome these barriers to fulfill the clinical applications are proposed.

Delivery of CD47-SIRPα checkpoint blocker by BCMA-directed UCAR-T cells enhances antitumor efficacy in multiple myeloma

In the treatment of relapsed or refractory multiple myeloma patients, BCMA-directed autologous CAR-T cells have showed excellent anti-tumor activity. However, their widespread application is limited due to the arguably cost and time-consuming. Multiple myeloma cells highly expressed CD47 molecule and interact with the SIRPα ligand on the surface of macrophages, in which evade the clearance of macrophages through the activation of "don't eat me" signal. In this study, a BCMA-directed universal CAR-T cells, BC404-UCART, secreting a CD47-SIRPα blocker was developed using CRISPR/Cas9 gene-editing system. BC404-UCART cells significantly inhibited tumor growth and prolonged the survival of mice in the xenograft model. The anti-tumor activity of BC404-UCART cells was achieved via two mechanisms, on the one hand, the UCAR-T cells directly killed tumor cells, on the other hand, the BC404-UCART cells enhanced the phagocytosis of macrophages by secreting anti-CD47 nanobody hu404-hfc fusion that blocked the "don't eat me" signal between macrophages and tumor cells, which provides a potential strategy for the development of novel "off-the-shelf" cellular immunotherapies for the treatment of multiple myeloma.

Sánchez E, Ivanova M, Pastora K, Alcántara-Sánchez C, García-Martínez J, Martín-Antonio B, Ramírez M, González-Murillo Á. Choosing T-cell sources determines CAR-T cell activity in neuroblastoma

Introduction

The clinical success of chimeric antigen receptor-modified T cells (CAR-T cells) for hematological malignancies has not been reproduced for solid tumors, partly due to the lack of cancer-type specific antigens. In this work, we used a novel combinatorial approach consisting of a versatile anti-FITC CAR-T effector cells plus an FITC-conjugated neuroblastoma (NB)-targeting linker, an FITC-conjugated monoclonal antibody (Dinutuximab) that recognizes GD2.

Methods

We compared cord blood (CB), and CD45RA-enriched peripheral blood leukapheresis product (45RA) as allogeneic sources of T cells, using peripheral blood (PB) as a control to choose the best condition for anti-FITC CAR-T production. Cells were manufactured under two cytokine conditions (IL-2 versus IL-7+IL-15+IL-21) with or without CD3/CD28 stimulation. Immune phenotype, vector copy number, and genomic integrity of the final products were determined for cell characterization and quality control assessment. Functionality and antitumor capacity of CB/45RA-derived anti-FITC CAR-T cells were analyzed in co-culture with different anti-GD2-FITC labeled NB cell lines.

Results

The IL-7+IL-15+IL-21 cocktail, in addition to co-stimulation signals, resulted in a favorable cell proliferation rate and maintained less differentiated immune phenotypes in both CB and 45RA T cells. Therefore, it was used for CAR-T cell manufacturing and further characterization. CB and CD45RA-derived anti-FITC CAR-T cells cultured with IL-7+IL-15+IL-21 retained a predominantly naïve phenotype compared with controls. In the presence of the NB-FITC targeting, CD4+ CB-derived anti-FITC CAR-T cells showed the highest values of co-stimulatory receptors OX40 and 4-1BB, and CD8+ CAR-T cells exhibited high levels of PD-1 and 4-1BB and low levels of TIM3 and OX40, compared with CAR-T cells form the other sources studied. CB-derived anti-FITC CAR-T cells released the highest amounts of cytokines (IFN-γ and TNF-α) into co-culture supernatants. The viability of NB target cells decreased to 30% when co-cultured with CB-derived CAR-T cells during 48h.

Conclusion

CB and 45RA-derived T cells may be used as allogeneic sources of T cells to produce CAR-T cells. Moreover, ex vivo culture with IL-7+IL-15+IL-21 could favor CAR-T products with a longer persistence in the host. Our strategy may complement the current use of Dinutuximab in treating NB through its combination with a targeted CAR-T cell approach.

Advanced strategies in improving the immunotherapeutic effect of CAR-T cell therapy

Chimeric antigen receptor (CAR-T) cell therapy is a newly developed immunotherapy strategy and has achieved satisfactory outcomes in the treatment of hematological malignancies. However, some adverse effects related to CAR-T cell therapy have to be resolved before it is widely used in clinics as a cancer treatment. Furthermore, the application of CAR-T cell therapy in the treatment of solid tumors has been hampered by numerous limitations. Therefore, it is essential to explore novel strategies to improve the therapeutic effect of CAR-T cell therapy. In this review, we summarized the recently developed strategies aimed at optimizing the generation of CAR-T cells and improving the anti-tumor efficiency of CAR-T cell therapy. Furthermore, the discovery of new targets for CAR-T cell therapy and the combined treatment strategies of CAR-T cell therapy with chemotherapy, radiotherapy, cancer vaccines and nanomaterials are highlighted.

Antibiotic-Free Gene Vectors: A 25-Year Journey to Clinical Trials

Until very recently, the major use, for gene therapy, specifically of linear or circular DNA, such as plasmids, was as ancillary products for viral vectors' production or as a genetic template for mRNA production. Thanks to targeted and more efficient physical or chemical delivery techniques and to the refinement of their structure, non-viral plasmid DNA are now under intensive consideration as pharmaceutical drugs. Plasmids traditionally carry an antibiotic resistance gene for providing the selection pressure necessary for maintenance in a bacterial host. Nearly a dozen different antibiotic-free gene vectors have now been developed and are currently assessed in preclinical assays and phase I/II clinical trials. Their reduced size leads to increased transfection efficiency and prolonged transgene expression. In addition, associating non-viral gene vectors and DNA transposons, which mediate transgene integration into the host genome, circumvents plasmid dilution in dividing eukaryotic cells which generate a loss of the therapeutic gene. Combining these novel molecular tools allowed a significantly higher yield of genetically engineered T and Natural Killer cells for adoptive immunotherapies due to a reduced cytotoxicity and increased transposition rate. This review describes the main progresses accomplished for safer, more efficient and cost-effective gene and cell therapies using non-viral approaches and antibiotic-free gene vectors.

Are we ready for personalized CAR-T therapy?

The future of chimeric antigen receptor T (CAR-T) therapy remains unclear. New studies are constantly being published confirming the efficacy and favorable safety profile of its innovative enhancements. Currently approved CAR-T drugs are manufactured exclusively for a specific patient from the recipient's own cells. This does not close the door to further modifications with subsequent personalization and better adaptation to the individual needs. Bringing such a drug to market would involve raising the already high costs, so it is necessary to lower the existing ones. On the other hand, so-called universal CAR-T are also getting closer to the patient's bed, but its implementation may struggle with multiple challenges, including development of graft-versus-host disease (GvHD) and alloimmunity. However, that off-the-shelf therapy could prove useful as a quick solution for patients in very poor condition or excluded from current therapy due to manufacturing limitations. The introduction of currently tested solutions may undoubtedly change the current paradigm of treatment.

Uncertainty quantification for gene delivery methods: A roadmap for pDNA manufacturing from phase I clinical trials to commercialization

The fast-growing interest in cell and gene therapy (C>) products has led to a growing demand for the production of plasmid DNA (pDNA) and viral vectors for clinical and commercial use. Manufacturers, regulators, and suppliers need to develop strategies for establishing robust and agile supply chains in the otherwise empirical field of C>. A model-based methodology that has great potential to support the wider adoption of C> is presented, by ensuring efficient timelines, scalability, and cost-effectiveness in the production of key raw materials. Specifically, key process and economic parameters are identified for (1) the production of pDNA for the forward-looking scenario of non-viral-based Chimeric Antigen Receptor (CAR) T-cell therapies from clinical (200 doses) to commercial (40,000 doses) scale and (2) the commercial (40,000 doses) production of pDNA and lentiviral vectors for the current state-of-the-art viral vector-based CAR T-cell therapies. By applying a systematic global sensitivity analysis, we quantify uncertainty in the manufacturing process and apportion it to key process and economic parameters, highlighting cost drivers and limitations that steer decision-making. The results underline the cost-efficiency and operational flexibility of non-viral-based therapies in the overall C> supply chain, as well as the importance of economies-of-scale in the production of pDNA.

Advancements in CRISPR screens for the development of cancer immunotherapy strategies

CRISPR screen technology enables systematic and scalable interrogation of gene function by using the CRISPR-Cas9 system to perturb gene expression. In the field of cancer immunotherapy, this technology has empowered the discovery of genes, biomarkers, and pathways that regulate tumor development and progression, immune reactivity, and the effectiveness of immunotherapeutic interventions. By conducting large-scale genetic screens, researchers have successfully identified novel targets to impede tumor growth, enhance anti-tumor immune responses, and surmount immunosuppression within the tumor microenvironment (TME). Here, we present an overview of CRISPR screens conducted in tumor cells for the purpose of identifying novel therapeutic targets. We also explore the application of CRISPR screens in immune cells to propel the advancement of cell-based therapies, encompassing T cells, natural killer cells, dendritic cells, and macrophages. Furthermore, we outline the crucial components necessary for the successful implementation of immune-specific CRISPR screens and explore potential directions for future research.

Advancing CART therapy for acute myeloid leukemia: recent breakthroughs and strategies for future development

Chimeric antigen receptor (CAR) T therapies are being developed for acute myeloid leukemia (AML) on the basis of the results obtained for other haematological malignancies and the need of new treatments for relapsed and refractory AML. The biggest challenge of CART therapy for AML is to identify a specific target antigen, since antigens expressed in AML cells are usually shared with healthy haematopoietic stem cells (HSC). The concomitant expression of the target antigen on both tumour and HSC may lead to on-target/off-tumour toxicity. In this review, we guide researchers to design, develop, and translate to the clinic CART therapies for the treatment of AML. Specifically, we describe what issues have to be considered to design these therapies; what in vitro and in vivo assays can be used to prove their efficacy and safety; and what expertise and facilities are needed to treat and manage patients at the hospital.

Applications of CRISPR technology in cellular immunotherapy

CRISPR technology has transformed multiple fields, including cancer and immunology. CRISPR-based gene editing and screening empowers direct genomic manipulation of immune cells, opening doors to unbiased functional genetic screens. These screens aid in the discovery of novel factors that regulate and reprogram immune responses, offering novel drug targets. The engineering of immune cells using CRISPR has sparked a transformation in the cellular immunotherapy field, resulting in a multitude of ongoing clinical trials. In this review, we discuss the development and applications of CRISPR and related gene editing technologies in immune cells, focusing on functional genomics screening, gene editing-based cell therapies, as well as future directions in this rapidly advancing field.

Optimization of universal allogeneic CAR-T cells combining CRISPR and transposon-based technologies for treatment of acute myeloid leukemia

Despite the potential of CAR-T therapies for hematological malignancies, their efficacy in patients with relapse and refractory Acute Myeloid Leukemia has been limited. The aim of our study has been to develop and manufacture a CAR-T cell product that addresses some of the current limitations. We initially compared the phenotype of T cells from AML patients and healthy young and elderly controls. This analysis showed that T cells from AML patients displayed a predominantly effector phenotype, with increased expression of activation (CD69 and HLA-DR) and exhaustion markers (PD1 and LAG3), in contrast to the enriched memory phenotype observed in healthy donors. This differentiated and more exhausted phenotype was also observed, and corroborated by transcriptomic analyses, in CAR-T cells from AML patients engineered with an optimized CAR construct targeting CD33, resulting in a decreased in vivo antitumoral efficacy evaluated in xenograft AML models. To overcome some of these limitations we have combined CRISPR-based genome editing technologies with virus-free gene-transfer strategies using Sleeping Beauty transposons, to generate CAR-T cells depleted of HLA-I and TCR complexes (HLA-IKO/TCRKO CAR-T cells) for allogeneic approaches. Our optimized protocol allows one-step generation of edited CAR-T cells that show a similar phenotypic profile to non-edited CAR-T cells, with equivalent in vitro and in vivo antitumoral efficacy. Moreover, genomic analysis of edited CAR-T cells revealed a safe integration profile of the vector, with no preferences for specific genomic regions, with highly specific editing of the HLA-I and TCR, without significant off-target sites. Finally, the production of edited CAR-T cells at a larger scale allowed the generation and selection of enough HLA-IKO/TCRKO CAR-T cells that would be compatible with clinical applications. In summary, our results demonstrate that CAR-T cells from AML patients, although functional, present phenotypic and functional features that could compromise their antitumoral efficacy, compared to CAR-T cells from healthy donors. The combination of CRISPR technologies with transposon-based delivery strategies allows the generation of HLA-IKO/TCRKO CAR-T cells, compatible with allogeneic approaches, that would represent a promising option for AML treatment.

Targeted delivery of a PD-1-blocking scFv by CD133-specific CAR-T cells using nonviral Sleeping Beauty transposition shows enhanced antitumour efficacy for advanced hepatocellular carcinoma

BACKGROUND

CD133 is considered a marker for cancer stem cells (CSCs) in several types of tumours, including hepatocellular carcinoma (HCC). Chimeric antigen receptor-specific T (CAR-T) cells targeting CD133-positive CSCs have emerged as a tool for the clinical treatment of HCC, but immunogenicity, the high cost of clinical-grade recombinant viral vectors and potential insertional mutagenesis limit their clinical application.

METHODS

CD133-specific CAR-T cells secreting PD-1 blocking scFv (CD133 CAR-T and PD-1 s cells) were constructed using a sleeping beauty transposon system from minicircle technology, and the antitumour efficacy of CD133 CAR-T and PD-1 s cells was analysed in vitro and in vivo.

RESULTS

A univariate analysis showed that CD133 expression in male patients at the late stage (II and III) was significantly associated with worse progression-free survival (PFS) (P = 0.0057) and overall survival (OS) (P = 0.015), and a multivariate analysis showed a trend toward worse OS (P = 0.041). Male patients with advanced HCC exhibited an approximately 20-fold higher PD-L1 combined positive score (CPS) compared with those with HCC at an early stage. We successfully generated CD133 CAR-T and PD-1 s cells that could secrete PD-1 blocking scFv based on a sleeping beauty system involving minicircle vectors. CD133 CAR-T and PD-1 s cells exhibited significant antitumour activity against HCC in vitro and in xenograft mouse models. Thus, CD133 CAR-T and PD-1 s cells may be a therapeutically tractable strategy for targeting CD133-positive CSCs in male patients with advanced HCC.

CONCLUSIONS

Our study provides a nonviral strategy for constructing CAR-T cells that could also secrete checkpoint blockade inhibitors based on a Sleeping Beauty system from minicircle vectors and revealed a potential benefit of this strategy for male patients with advanced HCC and high CD133 expression (median immunohistochemistry score > 2.284).

Current approaches to develop "off-the-shelf" chimeric antigen receptor (CAR)-T cells for cancer treatment: a systematic review

Chimeric antigen receptor (CAR)-T cell therapy is one of the most promising advances in cancer treatment. It is based on genetically modified T cells to express a CAR, which enables the recognition of the specific tumour antigen of interest. To date, CAR-T cell therapies approved for commercialisation are designed to treat haematological malignancies, showing impressive clinical efficacy in patients with relapsed or refractory advanced-stage tumours. However, since they all use the patient´s own T cells as starting material (i.e. autologous use), they have important limitations, including manufacturing delays, high production costs, difficulties in standardising the preparation process, and production failures due to patient T cell dysfunction. Therefore, many efforts are currently being devoted to contribute to the development of safe and effective therapies for allogeneic use, which should be designed to overcome the most important risks they entail: immune rejection and graft-versus-host disease (GvHD). This systematic review brings together the wide range of different approaches that have been studied to achieve the production of allogeneic CAR-T cell therapies and discuss the advantages and disadvantages of every strategy. The methods were classified in two major categories: those involving extra genetic modifications, in addition to CAR integration, and those relying on the selection of alternative cell sources/subpopulations for allogeneic CAR-T cell production (i.e. γδ T cells, induced pluripotent stem cells (iPSCs), umbilical cord blood T cells, memory T cells subpopulations, virus-specific T cells and cytokine-induced killer cells). We have observed that, although genetic modification of T cells is the most widely used approach, new approaches combining both methods have emerged. However, more preclinical and clinical research is needed to determine the most appropriate strategy to bring this promising antitumour therapy to the clinical setting.

Chimeric antigen receptor engineered natural killer cells for cancer therapy

Natural killer (NK) cells, a unique component of the innate immune system, are inherent killers of stressed and transformed cells. Based on their potent capacity to kill cancer cells and good tolerance of healthy cells, NK cells have been successfully employed in adoptive cell therapy to treat cancer patients. In recent years, the clinical success of chimeric antigen receptor (CAR)-T cells has proven the vast potential of gene-manipulated immune cells as the main force to fight cancer. Following the lessons learned from mature gene-transfer technologies and advanced strategies in CAR-T therapy, NK cells have been rapidly explored as a promising candidate for CAR-based therapy. An exponentially growing number of studies have employed multiple sources of CAR-NK cells to target a wide range of cancer-related antigens, showing remarkable outcomes and encouraging safety profiles. Clinical trials of CAR-NK cells have also shown their impressive therapeutic efficacy in the treatment of hematological tumors, but CAR-NK cell therapy for solid tumors is still in the initial stages. In this review, we present the favorable profile of NK cells as a potential platform for CAR-based engineering and then summarize the outcomes and strategies of CAR-NK therapies in up-to-date preclinical and clinical investigations. Finally, we evaluate the challenges remaining in CAR-NK therapy and describe existing strategies that can assist us in devising future prospective solutions.

Recent advances in therapeutic CRISPR-Cas9 genome editing: mechanisms and applications

Recently, clustered regularly interspaced palindromic repeats (CRISPR)-Cas9 derived editing tools had significantly improved our ability to make desired changes in the genome. Wild-type Cas9 protein recognizes the target genomic loci and induced local double strand breaks (DSBs) in the guidance of small RNA molecule. In mammalian cells, the DSBs are mainly repaired by endogenous non-homologous end joining (NHEJ) pathway, which is error prone and results in the formation of indels. The indels can be harnessed to interrupt gene coding sequences or regulation elements. The DSBs can also be fixed by homology directed repair (HDR) pathway to introduce desired changes, such as base substitution and fragment insertion, when proper donor templates are provided, albeit in a less efficient manner. Besides making DSBs, Cas9 protein can be mutated to serve as a DNA binding platform to recruit functional modulators to the target loci, performing local transcriptional regulation, epigenetic remolding, base editing or prime editing. These Cas9 derived editing tools, especially base editors and prime editors, can introduce precise changes into the target loci at a single-base resolution and in an efficient and irreversible manner. Such features make these editing tools very promising for therapeutic applications. This review focuses on the evolution and mechanisms of CRISPR-Cas9 derived editing tools and their applications in the field of gene therapy.

Cellular and humoral immunotherapy in children, adolescents and young adults with non-Hodgkin lymphoma

The prognosis is dismal (2-year overall survival less than 25%) for childhood, adolescent, and young adult (CAYA) with relapsed and/or refractory (R/R) non-Hodgkin lymphoma (NHL). Novel targeted therapies are desperately needed for this poor-risk population. CD19, CD20, CD22, CD79a, CD38, CD30, LMP1 and LMP2 are attractive targets for immunotherapy in CAYA patients with R/R NHL. Novel anti-CD20 monoclonal antibodies, anti-CD38 monoclonal antibody, antibody drug conjugates and T and natural killer (NK)-cell bispecific and trispecific engagers are being investigated in the R/R setting and are changing the landscape of NHL therapy. A variety of cellular immunotherapies such as viral activated cytotoxic T-lymphocyte, chimeric antigen receptor (CAR) T-cells, NK and CAR NK-cells have been investigated and provide alternative options for CAYA patients with R/R NHL. Here, we provide an update and clinical practice guidance of utilizing these cellular and humoral immunotherapies in CAYA patients with R/R NHL.

Explorations of CRISPR/Cas9 for improving the long-term efficacy of universal CAR-T cells in tumor immunotherapy

Chimeric antigen receptor (CAR) T therapy has shown remarkable success in discovering novel CAR-T cell products for treating malignancies. Despite of successful results from clinical trials, CAR-T cell therapy is ineffective for long-term disease progression. Numerous challenges of CAR-T cell immunotherapy such as cell dysfunction, cytokine-related toxicities, TGF-β resistance, GvHD risks, antigen escape, restricted trafficking, and tumor cell infiltration still exist that hamper the safety and efficacy of CAR-T cells for malignancies. The accumulated data revealed that these challenges could be overcome with the advanced CRISPR genome editing technology, which is the most promising tool to knockout TRAC and HLA genes, inhibiting the effects of dominant negative receptors (PD-1, TGF-β, and B2M), lowering the risks of cytokine release syndrome (CRS), and regulating CAR-T cell function in the tumor microenvironment (TME). CRISPR technology employs DSB-free genome editing methods that robustly allow efficient and controllable genetic modification. The present review explored the innovative aspects of CRISPR/Cas9 technology for developing next-generation/universal allogeneic CAR-T cells. The present manuscript addressed the ongoing status of clinical trials of CRISPR/Cas9-engineered CAR-T cells against cancer and pointed out the off-target effects associated with CRISPR/Cas9 genome editing. It is concluded that CAR-T cells modified by CRISPR/Cas9 significantly improved antitumor efficacy in a cost-effective manner that provides opportunities for novel cancer immunotherapies.

Application of CRISPR/Cas9 Technology in Cancer Treatment: A Future Direction

Gene editing, especially with clustered regularly interspaced short palindromic repeats associated protein 9 (CRISPR-Cas9), has advanced gene function science. Gene editing's rapid advancement has increased its medical/clinical value. Due to its great specificity and efficiency, CRISPR/Cas9 can accurately and swiftly screen the whole genome. This simplifies disease-specific gene therapy. To study tumor origins, development, and metastasis, CRISPR/Cas9 can change genomes. In recent years, tumor treatment research has increasingly employed this method. CRISPR/Cas9 can treat cancer by removing genes or correcting mutations. Numerous preliminary tumor treatment studies have been conducted in relevant fields. CRISPR/Cas9 may treat gene-level tumors. CRISPR/Cas9-based personalized and targeted medicines may shape tumor treatment. This review examines CRISPR/Cas9 for tumor therapy research, which will be helpful in providing references for future studies on the pathogenesis of malignancy and its treatment.

Molecular and therapeutic effect of CRISPR in treating cancer

Cancer has become one of the common causes of mortality around the globe due to mutations in the genome which allows rapid growth of cells uncontrollably without repairing DNA errors. Cancers could arise due alterations in DNA repair mechanisms (errors in mismatch repair genes), activation of oncogenes and inactivation of tumor suppressor genes. Each cancer type is different and each individual has a unique genetic change which leads them to cancer. Studying genetic and epigenetic alterations in the genome leads to understanding the underlying features. CAR T therapy over other immunotherapies such as monoclonal antibodies, immune checkpoint inhibitors, cancer vaccines and adoptive cell therapies has been widely used to treat cancer in recent days and gene editing has now become one of the promising treatments for many genetic diseases. This tool allows scientists to change the genome by adding, removing or altering genetic material of an organism. Due to advance in genetics and novel molecular techniques such as CRISPR, TALEN these genes can be edited in such a way that their original function could be replaced which in turn improved the treatment possibilities and can be used against malignancies and even cure cancer in future along with CAR T cell therapy due to the specific recognition and attacking of tumor.

Efficacy and safety of universal (TCRKO) ARI-0001 CAR-T cells for the treatment of B-cell lymphoma

Autologous T cells expressing the Chimeric Antigen Receptor (CAR) have been approved as advanced therapy medicinal products (ATMPs) against several hematological malignancies. However, the generation of patient-specific CAR-T products delays treatment and precludes standardization. Allogeneic off-the-shelf CAR-T cells are an alternative to simplify this complex and time-consuming process. Here we investigated safety and efficacy of knocking out the TCR molecule in ARI-0001 CAR-T cells, a second generation αCD19 CAR approved by the Spanish Agency of Medicines and Medical Devices (AEMPS) under the Hospital Exemption for treatment of patients older than 25 years with Relapsed/Refractory acute B cell lymphoblastic leukemia (B-ALL). We first analyzed the efficacy and safety issues that arise during disruption of the TCR gene using CRISPR/Cas9. We have shown that edition of TRAC locus in T cells using CRISPR as ribonuleorproteins allows a highly efficient TCR disruption (over 80%) without significant alterations on T cells phenotype and with an increased percentage of energetic mitochondria. However, we also found that efficient TCRKO can lead to on-target large and medium size deletions, indicating a potential safety risk of this procedure that needs monitoring. Importantly, TCR edition of ARI-0001 efficiently prevented allogeneic responses and did not detectably alter their phenotype, while maintaining a similar anti-tumor activity ex vivo and in vivo compared to unedited ARI-0001 CAR-T cells. In summary, we showed here that, although there are still some risks of genotoxicity due to genome editing, disruption of the TCR is a feasible strategy for the generation of functional allogeneic ARI-0001 CAR-T cells. We propose to further validate this protocol for the treatment of patients that do not fit the requirements for standard autologous CAR-T cells administration.

CAR-T cell potency: from structural elements to vector backbone components

Chimeric antigen receptor (CAR) T cell therapy, in which a patient’s own T lymphocytes are engineered to recognize and kill cancer cells, has achieved remarkable success in some hematological malignancies in preclinical and clinical trials, resulting in six FDA-approved CAR-T products currently available in the market. Once equipped with a CAR construct, T cells act as living drugs and recognize and eliminate the target tumor cells in an MHC-independent manner. In this review, we first described all structural modular of CAR in detail, focusing on more recent findings. We then pointed out behind-the-scene elements contributing to CAR expression and reviewed how CAR expression can be drastically affected by the elements embedded in the viral vector backbone.