CRISPR-Cas9-mediated disruption of PD-1 on human T cells for adoptive cellular therapies of EBV positive gastric cancer

The paths toward non-viral CAR-T cell manufacturing: A comprehensive review of state-of-the-art methods

Although CAR-T cell therapy has emerged as a game-changer in cancer immunotherapy several bottlenecks limit its widespread use as a front-line therapy. Current protocols for the production of CAR-T cells rely mainly on the use of lentiviral/retroviral vectors. Nevertheless, according to the safety concerns around the use of viral vectors, there are several regulatory hurdles to their clinical use. Large-scale production of viral vectors under "Current Good Manufacturing Practice" (cGMP) involves rigorous quality control assessments and regulatory requirements that impose exorbitant costs on suppliers and as a result, lead to a significant increase in the cost of treatment. Pursuing an efficient non-viral method for genetic modification of immune cells is a hot topic in cell-based gene therapy. This study aims to investigate the current state-of-the-art in non-viral methods of CAR-T cell manufacturing. In the first part of this study, after reviewing the advantages and disadvantages of the clinical use of viral vectors, different non-viral vectors and the path of their clinical translation are discussed. These vectors include transposons (sleeping beauty, piggyBac, Tol2, and Tc Buster), programmable nucleases (ZFNs, TALENs, and CRISPR/Cas9), mRNA, plasmids, minicircles, and nanoplasmids. Afterward, various methods for efficient delivery of non-viral vectors into the cells are reviewed.

Liposome-based in situ antigen-modification strategy for "universal" T-cell-receptor engineered T cell in cancer immunotherapy

T-cell receptor (TCR) engineered T-cell therapy, unlike chimeric antigen receptor T-cell therapy, relies on the inherent ability of TCRs to detect a wider variety of antigenic epitopes, such as protein fragments found internally or externally on cells. Hence, TCR-T-cell therapy offers broader possibilities for treating solid tumors. However, because of the complicated process of identifying specific antigenic peptides, their clinical application still encounters significant challenges. Thus, we aimed to establish a novel "universal" TCR-T "artificial antigen expression" technique that involves the delivery of the antigen to tumor cells using DSPE-PEG-NY-ESO-1157-165 liposomes (NY-ESO-1 Lips) to express TCR-T-cell-specific recognition targets. In vitro as well as in vivo studies revealed that they could accumulate efficiently in the tumor area and deliver target antigens to activate the tumor-specific cytotoxic T-cell immune response. NY-ESO-1 TCR-T therapy, when used in combination, dramatically curbed tumor progression and extended the longevity of mice. Additionally, PD-1 blockage enhanced the therapeutic effect of the aforementioned therapy. In conclusion, NY-ESO-1 Lips "cursed" tumor cells by enabling antigenic target expression on their surface. This innovative technique presents a groundbreaking approach for the widespread utilization of TCR-T in solid tumor treatment.

Low-dose radiation therapy mobilizes antitumor immunity: New findings and future perspectives

Radiotherapy has unique immunostimulatory and immunosuppressive effects. Although high-dose radiotherapy has been found to have systemic antitumor effects, clinically significant abscopal effects were uncommon on the basis of irradiating single lesion. Low-dose radiation therapy (LDRT) emerges as a novel approach to enhance the antitumor immune response due to its role as a leverage to reshape the tumor immune microenvironment (TIME). In this article, from bench to bedside, we reviewed the possible immunomodulatory role of LDRT on TIME and systemic tumor immune environment, and outlined preclinical evidence and clinical application. We also discussed the current challenges when LDRT is used as a combination therapy, including the optimal dose, fraction, frequency, and combination of drugs. The advantage of low toxicity makes LDRT potential to be applied in multiple lesions to amplify antitumor immune response in polymetastatic disease, and its intersection with other disciplines might also make it a direction for radiotherapy-combined modalities.

GMP-manufactured CRISPR/Cas9 technology as an advantageous tool to support cancer immunotherapy

BACKGROUND

CRISPR/Cas9 system to treat human-related diseases has achieved significant results and, even if its potential application in cancer research is improving, the application of this approach in clinical practice is still a nascent technology.

MAIN BODY

CRISPR/Cas9 technology is not yet used as a single therapy to treat tumors but it can be combined with traditional treatment strategies to provide personalized gene therapy for patients. The combination with chemotherapy, radiation and immunotherapy has been proven to be a powerful means of screening, identifying, validating and correcting tumor targets. Recently, CRISPR/Cas9 technology and CAR T-cell therapies have been integrated to open novel opportunities for the production of more efficient CAR T-cells for all patients. GMP-compatible equipment and reagents are already available for several clinical-grade systems at present, creating the basis and framework for the accelerated development of novel treatment methods.

CONCLUSION

Here we will provide a comprehensive collection of the actual GMP-grade CRISPR/Cas9-mediated approaches used to support cancer therapy highlighting how this technology is opening new opportunities for treating tumors.

CRISPR Advancements for Human Health

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) has emerged as a powerful gene editing technology that is revolutionizing biomedical research and clinical medicine. The CRISPR system allows scientists to rewrite the genetic code in virtually any organism. This review provides a comprehensive overview of CRISPR and its clinical applications. We first introduce the CRISPR system and explain how it works as a gene editing tool. We then highlight current and potential clinical uses of CRISPR in areas such as genetic disorders, infectious diseases, cancer, and regenerative medicine. Challenges that need to be addressed for the successful translation of CRISPR to the clinic are also discussed. Overall, CRISPR holds great promise to advance precision medicine, but ongoing research is still required to optimize delivery, efficacy, and safety.

Polymer-mediated nanoformulations: a promising strategy for cancer immunotherapy

Engineering polymer-based nano-systems have attracted many researchers owing to their unique qualities like shape, size, porosity, mechanical strength, biocompatibility, and biodegradability. Both natural and synthetic polymers can be tuned to get desired surface chemistry and functionalization to improve the efficacy of cancer therapy by promoting targeted delivery to the tumor site. Recent advancements in cancer immunoediting have been able to manage both primary tumor and metastatic lesions via activation of the immune system. The combinations of nano-biotechnology and immunotherapeutic agents have provided positive outcomes by enhancing the host immune response in cancer therapy. The nanoparticles have been functionalized using antibodies, targeted antigens, small molecule ligands, and other novel agents that can interact with biological systems at nanoscale levels. Several polymers, such as polyethylene glycol (PEG), poly(lactic-co-glycolic acid) (PLGA), poly(ε-caprolactone) (PCL), and chitosan, have been approved by the Food and Drug Administration for clinical use in biomedicine. The polymeric nanoformulations such as polymers-antibody/antigen conjugates and polymeric drug conjugates are currently being explored as nanomedicines that can target cancer cells directly or target immune cells to promote anti-cancer immunotherapy. In this review, we focus on scientific developments and advancements on engineered polymeric nano-systems in conjugation with immunotherapeutic agents targeting the tumor microenvironment to improve their efficacy and the safety for better clinical outcomes.

Silencing of PD-1 combined with EBV-specific killer T cells for the treatment of EBV-associated B lymphoma

Epstein-Barr Virus (EBV) infection is closely associated with the development of lymphoma, as it plays a significant role in the malignant transformation of lymphocytes. The expression of programmed death-1 (PD-1), which binds to PD-L1 in tumor cells, can lead to immune evasion by lymphoma cells and promote tumor progression. In this study, immortalized B lymphoblastoid cell lines (B-LCLs) positive for EBV-specific proteins were established from human peripheral mononuclear cells (PBMCs) using EBV induction along with CpG-ODN 2006 and cyclosporin A. EBV-specific T cells (EBVST) were generated by multiple immunizations of CD3+ T lymphocytes using irradiated B-LCLs. Flow cytometry analysis confirmed the activation of EBVST through the detection of CD3+, CD4+, and CD8+ markers. Co-incubation of EBVST with EBV-positive B lymphocyte cell lines resulted in the secretion of perforin by EBVST, leading to granzyme B-mediated cell death and an increase in LDH levels. Silencing PD-1 in EBVST cells enhanced perforin production, increased granzyme B release, and upregulated cell death in co-incubated B lymphocytes. In a nude mice tumor transplantation model, silencing PD-1 in combination with EBV-specific killer T cells exhibited the maximum inhibition of B-lymphoblastoma. This treatment upregulated the expression of proteins associated with apoptosis and immune response, while inhibiting anti-apoptotic protein expression in tumor tissues. Silencing PD-1 also increased the infiltration of EBV-specific killer T cells in the tumor tissues. Overall, PD-1 silencing enhanced the tumor targeting effect of EBV-specific killer T cells on EBV-infected B lymphocytes and attenuated the immune escape effect mediated by the PD-1 pathway.

CRISPR-Cas9: A Potent Gene-editing Tool for the Treatment of Cancer

The prokaryotic adaptive immune system has clustered regularly interspaced short palindromic repeat. CRISPR-associated protein (CRISPR-Cas) genome editing systems have been harnessed. A robust programmed technique for efficient and accurate genome editing and gene targeting has been developed. Engineered cell therapy, in vivo gene therapy, animal modeling, and cancer diagnosis and treatment are all possible applications of this ground-breaking approach. Multiple genetic and epigenetic changes in cancer cells induce malignant cell growth and provide chemoresistance. The capacity to repair or ablate such mutations has enormous potential in the fight against cancer. The CRISPR-Cas9 genome editing method has recently become popular in cancer treatment research due to its excellent efficiency and accuracy. The preceding study has shown therapeutic potential in expanding our anticancer treatments by using CRISPR-Cas9 to directly target cancer cell genomic DNA in cellular and animal cancer models. In addition, CRISPR-Cas9 can combat oncogenic infections and test anticancer medicines. It may design immune cells and oncolytic viruses for cancer immunotherapeutic applications. In this review, these preclinical CRISPRCas9- based cancer therapeutic techniques are summarised, along with the hurdles and advancements in converting therapeutic CRISPR-Cas9 into clinical use. It will increase their applicability in cancer research.

Precision Genome Editing Techniques in Gene Therapy: Current State and Future Prospects

Precision genome editing is a rapidly evolving field in gene therapy, allowing for the precise modification of genetic material. The CRISPR and Cas systems, particularly the CRISPRCas9 system, have revolutionized genetic research and therapeutic development by enabling precise changes like single-nucleotide substitutions, insertions, and deletions. This technology has the potential to correct disease-causing mutations at their source, allowing for the treatment of various genetic diseases. Programmable nucleases like CRISPR-Cas9, transcription activator-like effector nucleases (TALENs), and zinc finger nucleases (ZFNs) can be used to restore normal gene function, paving the way for novel therapeutic interventions. However, challenges, such as off-target effects, unintended modifications, and ethical concerns surrounding germline editing, require careful consideration and mitigation strategies. Researchers are exploring innovative solutions, such as enhanced nucleases, refined delivery methods, and improved bioinformatics tools for predicting and minimizing off-target effects. The prospects of precision genome editing in gene therapy are promising, with continued research and innovation expected to refine existing techniques and uncover new therapeutic applications.

Expanded Alternatives of CRISPR-Cas9 Applications in Immunotherapy of Colorectal Cancer

Immunotherapy for colorectal cancer (CRC) is limited to patients with advanced disease who have already undergone first-line chemotherapy and whose tumors exhibit microsatellite instability. Novel technical strategies are required to enhance therapeutic options and achieve a more robust immunological response. Therefore, exploring gene analysis and manipulation at the molecular level can further accelerate the development of advanced technologies to address these challenges. The emergence of advanced genome editing technology, particularly of clustered, regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein (Cas) 9, holds promise in expanding the boundaries of cancer immunotherapy. In this manuscript, we provide a comprehensive review of the applications and perspectives of CRISPR technology in improving the design, generation, and efficiency of current immunotherapies, focusing on solid tumors such as colorectal cancer, where these approaches have not been as successful as in hematological conditions.

CRISPR/Cas9 system: recent applications in immuno-oncology and cancer immunotherapy

Clustered regulatory interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) is essentially an adaptive immunity weapon in prokaryotes against foreign DNA. This system inspires the development of genome-editing technology in eukaryotes. In biomedicine research, CRISPR has offered a powerful platform to establish tumor-bearing models and screen potential targets in the immuno-oncology field, broadening our insights into cancer genomics. In translational medicine, the versatile CRISPR/Cas9 system exhibits immense potential to break the current limitations of cancer immunotherapy, thereby expanding the feasibility of adoptive cell therapy (ACT) in treating solid tumors. Herein, we first explain the principles of CRISPR/Cas9 genome editing technology and introduce CRISPR as a tool in tumor modeling. We next focus on the CRISPR screening for target discovery that reveals tumorigenesis, immune evasion, and drug resistance mechanisms. Moreover, we discuss the recent breakthroughs of genetically modified ACT using CRISPR/Cas9. Finally, we present potential challenges and perspectives in basic research and clinical translation of CRISPR/Cas9. This review provides a comprehensive overview of CRISPR/Cas9 applications that advance our insights into tumor-immune interaction and lay the foundation to optimize cancer immunotherapy.

Innovative Strategies of Reprogramming Immune System Cells by Targeting CRISPR/Cas9-Based Genome-Editing Tools: A New Era of Cancer Management

The recent developments in the study of clustered regularly interspaced short palindromic repeats/associated protein 9 (CRISPR/Cas9) system have revolutionized the art of genome-editing and its applications for cellular differentiation and immune response behavior. This technology has further helped in understanding the mysteries of cancer progression and possible designing of novel antitumor immunotherapies. CRISPR/Cas9-based genome-editing is now often used to engineer universal T-cells, equipped with recombinant T-cell receptor (TCR) or chimeric antigen receptor (CAR). In addition, this technology is used in cytokine stimulation, antibody designing, natural killer (NK) cell transfer, and to overcome immune checkpoints. The innovative potential of CRISPR/Cas9 in preparing the building blocks of adoptive cell transfer (ACT) immunotherapy has opened a new window of antitumor immunotherapy and some of them have gained FDA approval. The manipulation of immunogenetic regulators has opened a new interface for designing, implementation and interpretation of CRISPR/Cas9-based screening in immuno-oncology. Several cancers like lymphoma, melanoma, lung, and liver malignancies have been treated with this strategy, once thought to be impossible. The safe and efficient delivery of CRISPR/Cas9 system within the immune cells for the genome-editing strategy is a challenging task which needs to be sorted out for efficient immunotherapy. Several targeting approaches like virus-mediated, electroporation, microinjection and nanoformulation-based methods have been used, but each procedure offers some limitations. Here, we elaborate the recent updates of cancer management through immunotherapy in partnership with CRISPR/Cas9 technology. Further, some innovative methods of targeting this genome-editing system within the immune system cells for reprogramming them, as a novel strategy of anticancer immunotherapy is elaborated. In addition, future prospects and clinical trials are also discussed.

The role of microbiota in the development and treatment of gastric cancer

The stomach was once considered a sterile organ until the discovery of Helicobacter pylori (HP). With the application of high-throughput sequencing technology and macrogenomics, researchers have identified fungi and fivemajor bacterial phyla within the stomachs of healthy individuals. These microbial communities exert regulatory influence over various physiological functions, including energy metabolism and immune responses. HP is a well-recognized risk factor for gastric cancer, significantly altering the stomach's native microecology. Currently, numerous studies are centered on the mechanisms by which HP contributes to gastric cancer development, primarily involving the CagA oncoprotein. However, aside from exogenous infections such as HP and EBV, certain endogenous dysbiosis can also lead to gastric cancer through multiple mechanisms. Additionally, gut microbiota and its metabolites significantly impact the development of gastric cancer. The role of microbial therapies, including diet, phages, probiotics and fecal microbiota transplantation, in treating gastric cancer should not be underestimated. This review aims to study the mechanisms involved in the roles of exogenous pathogen infection and endogenous microbiota dysbiosis in the development of gastric cancer. Also, we describe the application of microbiota therapy in the treatment and prognosis of gastric cancer.

Reversing T Cell Exhaustion by Converting Membrane PD-1 to Its Soluble form in Jurkat Cells; Applying The CRISPR/Cas9 Exon Skipping Strategy

OBJECTIVE

T-cells express two functional forms of the programmed cell death protein 1 (PD-1): membrane (mPD-1) and soluble (sPD-1). The binding of mPD-1 and its ligand (PD-L1) on tumor cells could lead activated lymphocytes toward exhaustion. Selective deletion of the transmembrane domain via alternative splicing of exon-3 in PD-1 mRNA could generate sPD-1. Overexpression of sPD-1 could disrupt the mPD-1/PD-L1 interaction in tumor-specific T cells. We investigated the effect of secreted sPD-1 from pooled engineered and non-engineered T cell supernatant on survival and proliferation of lymphocytes in the tumor microenvironment (TME).

MATERIALS AND METHODS

In this experimental study, we designed two sgRNA sequences upstream and downstream of exon-3 in the PDCD1 gene. The lentiCRISPRv2 puro vector was used to clone the dual sgRNAs and produce lentiviral particles to transduce Jurkat T cells. Analysis assays were used to clarify the change in PD-1 expression pattern in the pooled (engineered and non-engineered) Jurkat cells. Co-culture conditions were established with PD-L1+ cancer cells and lymphocytes.

RESULTS

CRISPR/Cas9 could delete exon-3 of the PDCD1 gene in the engineered cells based on the tracking of indels by decomposition (TIDE) and interference of CRISPR edit (ICE) sequencing analysis reports. Our results showed a 12% reduction in mPD-1 positive cell population after CRISPR manipulation and increment in sPD-1 concentration in the supernatant. The increased sPD-1 confirmed its positive effect on proliferation of lymphocytes co-cultured with PDL1+ cancer cells. The survival percent of lymphocytes co-cultured with the pooled cells supernatant was 12.5% more than the control.

CONCLUSION

The CRISPR/Cas9 exon skipping approach could be used in adoptive cell immunotherapies to change PD-1 expression patterns and overcome exhaustion.

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.

Recent Advances and Therapeutic Strategies Using CRISPR Genome Editing Technique for the Treatment of Cancer

CRISPR genome editing technique has the potential to target cancer cells in a precise manner. The latest advancements have helped to address one of the prominent concerns about this strategy which is the off-target integrations observed with dsDNA and have resulted in more studies being carried out for potentially safer and more targeted gene therapy, so as to make it available for the clinical trials in order to effectively treat cancer. CRISPR screens offer great potential for the high throughput investigation of the gene functionality in various tumors. It extends its capability to identify the tumor growth essential genes, therapeutic resistant genes, and immunotherapeutic responses. CRISPR screens are mostly performed in in vitro models, but latest advancements focus on developing in vivo models to view cancer progression in animal models. It also allows the detection of factors responsible for tumorigenesis. In CRISPR screens key parameters are optimized in order to meet proficient gene targeting efficiencies. It also detects various molecular effectors required for gene regulation in different cancers, essential pathways which modulate cytotoxicity to immunotherapy in cancer cells, important genes which contribute to cancer cell survival in hypoxic states and modulate cancer long non-coding RNAs. The current review focuses on the recent developments in the therapeutic application of CRISPR technology for cancer therapy. Furthermore, the associated challenges and safety concerns along with the various strategies that can be implemented to overcome these drawbacks has been discussed.

Natural Killer Cell-Based Immunotherapy against Glioblastoma

Glioblastoma (GBM) is the most aggressive and malignant primary brain tumor in adults. Despite multimodality treatment involving surgical resection, radiation therapy, chemotherapy, and tumor-treating fields, the median overall survival (OS) after diagnosis is approximately 2 years and the 5-year OS is poor. Considering the poor prognosis, novel treatment strategies are needed, such as immunotherapies, which include chimeric antigen receptor T-cell therapy, immune checkpoint inhibitors, vaccine therapy, and oncolytic virus therapy. However, these therapies have not achieved satisfactory outcomes. One reason for this is that these therapies are mainly based on activating T cells and controlling GBM progression. Natural killer (NK) cell-based immunotherapy involves the new feature of recognizing GBM via differing mechanisms from that of T cell-based immunotherapy. In this review, we focused on NK cell-based immunotherapy as a novel GBM treatment strategy.

CRISPR/Cas9 therapeutics: progress and prospects

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene-editing technology is the ideal tool of the future for treating diseases by permanently correcting deleterious base mutations or disrupting disease-causing genes with great precision and efficiency. A variety of efficient Cas9 variants and derivatives have been developed to cope with the complex genomic changes that occur during diseases. However, strategies to effectively deliver the CRISPR system to diseased cells in vivo are currently lacking, and nonviral vectors with target recognition functions may be the focus of future research. Pathological and physiological changes resulting from disease onset are expected to serve as identifying factors for targeted delivery or targets for gene editing. Diseases are both varied and complex, and the choice of appropriate gene-editing methods and delivery vectors for different diseases is important. Meanwhile, there are still many potential challenges identified when targeting delivery of CRISPR/Cas9 technology for disease treatment. This paper reviews the current developments in three aspects, namely, gene-editing type, delivery vector, and disease characteristics. Additionally, this paper summarizes successful examples of clinical trials and finally describes possible problems associated with current CRISPR applications.

Influence of the Microbiome Metagenomics and Epigenomics on Gastric Cancer

Gastric cancer (GC) is one of the major causes of cancer deaths worldwide. The disease is seldomly detected early and this limits treatment options. Because of its heterogeneous and complex nature, the disease remains poorly understood. The literature supports the contribution of the gut microbiome in the carcinogenesis and chemoresistance of GC. Drug resistance is the major challenge in GC therapy, occurring as a result of rewired metabolism. Metabolic rewiring stems from recurring genetic and epigenetic factors affecting cell development. The gut microbiome consists of pathogens such as H. pylori, which can foster both epigenetic alterations and mutagenesis on the host genome. Most of the bacteria implicated in GC development are Gram-negative, which makes it challenging to eradicate the disease. Gram-negative bacterium co-infections with viruses such as EBV are known as risk factors for GC. In this review, we discuss the role of microbiome-induced GC carcinogenesis. The disease risk factors associated with the presence of microorganisms and microbial dysbiosis are also discussed. In doing so, we aim to emphasize the critical role of the microbiome on cancer pathological phenotypes, and how microbiomics could serve as a potential breakthrough in determining effective GC therapeutic targets. Additionally, consideration of microbial dysbiosis in the GC classification system might aid in diagnosis and treatment decision-making, taking the specific pathogen/s involved into account.

Identification of Malassezia globosa as a Gastric Fungus Associated with PD-L1 Expression and Overall Survival of Patients with Gastric Cancer

BACKGROUND

Microbiotas affected the prognosis of cancer patients by regulating programmed death ligand-1 (PD-L1) expression. However, the relationship between gastric fungi and PD-L1 expression is still unclear in gastric cancer (GC). We aimed at exploring the association of gastric fungi with PD-L1 expression and overall survival in GC.

METHODS

A total of 61 GC patients were divided into the two groups based on the PD-L1 combined positive scores (CPS). Fungal profiling was performed by internal transcribed spacer rDNA sequencing, and the survival analyses were performed by Kaplan-Meier curves.

RESULTS

We observed a taxonomic difference of fungi between the PD-L1-High (CPS ≥ 10) and PD-L1-Low group (CPS < 10) by principal coordinates analysis (PCoA) (P = 0.014 for Bray-Curtis and P = 0.042 for Jaccard). Malassezia had a higher abundance in the PD-L1-High group compared to the PD-L1-Low group (P = 0.045). Malassezia globosa elevated significantly in the PD-L1-High group. GC patients with PD-L1 low expression and low abundance of Malassezia globosa had a longer overall survival (OS) than others (P = 0.047). Malassezia globosa was associated with PD-L1 expression (Odds Ratio = 3.509, 95% Confidence Interval: 1.056-11.656, P = 0.040). Malassezia globosa was associated with the tumor size (P = 0.031) and PD-L1 status (P = 0.024). GC patients with a high abundance of Malassezia globosa had shorter OS than others (P = 0.028). Malassezia globosa was an independent factor (Hazard Ratio = 3.080, 95% Confidence Interval: 1.140-8.323, P = 0.027) for OS after adjusting for tumor stage. Malassezia globosa was figured out to be associated with- fatty acid and lipid biosynthesis and degradation via LIPASYN pathway. Conclusions. Malassezia globosa was identified as a PD-L1 expression-associated gastric fungus and associated with OS of GC patients, which calls for more studies to further explore its potential in PD-L1/PD-1 targeted immunotherapy.

Lymphopenic condition enhanced the antitumor immunity of PD-1-knockout T cells mediated by CRISPR/Cas9 system in malignant melanoma

BACKGROUND

Adoptive transfer of PD-1 knockout T cells mediated by CRISPR/Cas9 technology has been used in various cancers and got satisfactory treatment effectiveness. However, the effectiveness was limited due to the low proliferation ability, antigen recognition ability and short lifetime of T cells in vivo.

METHOD

In this study, PD-1 knockout T cells mediated by CRISPR/Cas9 system were transferred into lymphopenic mice after sub-lethal dose of total body irradiation. The antitumor effects of PD-1 knockout T cells were comprehensively analyzed by flow cytometry. Moreover, PD-L1 knockout B16 cells were inoculated subcutaneously in lymphopenic mice receiving infusion of naïve T cells to value the role of PD-1/PD-L1 axis on lymphopenia-induced antitumor immunity RESULT: In this study, we found that the PD-1-knockout T cells underwent several rounds of homeostatic proliferation in vivo when they were transferred into lymphopenic mice. The number of IFN-γ-releasing CTL was significantly increased and the tumor growth was remarkably inhibited in lymphopenic mice receiving infusion of PD-1 knockout T cells. The expression of PD-L1 on tumor cells rose smartly in lymphopenic mice undergoing homeostatic proliferation. PD-L1 gene knockout on B16 melanoma cells could effectively enhance the antitumor immunity mediated by the homeostatic proliferation of T cells and significantly inhibited the growth of tumor CONCLUSION: These findings suggested that lymphopenic condition after total body irradiation might be able to create an environment to promote the PD-1 knockout T cells to recognize tumor antigen and undergo homeostatic proliferation, thus induced a more powerful antitumor immunity than adoptively transferring into immunocompetent hosts.

Research Progress on Radiotherapy Combined with Immunotherapy for Associated Pneumonitis During Treatment of Non-Small Cell Lung Cancer

Radiation pneumonitis is a common and serious complication of radiotherapy for thoracic tumours. Although radiotherapy technology is constantly improving, the incidence of radiation pneumonitis is still not low, and severe cases can be life-threatening. Once radiation pneumonitis develops into radiation fibrosis (RF), it will have irreversible consequences, so it is particularly important to prevent the occurrence and development of radiation pneumonitis. Immune checkpoint inhibitors (ICIs) have rapidly altered the treatment landscape for multiple tumour types, providing unprecedented survival in some patients, especially for the treatment of non-small cell lung cancer (NSCLC). However, in addition to its remarkable curative effect, ICls may cause immune-related adverse events. The incidence of checkpoint inhibitor pneumonitis (CIP) is 3% to 5%, and its mortality rate is 10% to 17%. In addition, the incidence of CIP in NSCLC is higher than in other tumour types, reaching 7%–13%. With the increasing use of immune checkpoint inhibitors (ICls) and thoracic radiotherapy in the treatment of patients with NSCLC, ICIs may induce delayed radiation pneumonitis in patients previously treated with radiation therapy, or radiation activation of the systemic immune system increases the toxicity of adverse reactions, which may lead to increased pulmonary toxicity and the incidence of pneumonitis. In this paper, the data about the occurrence of radiation pneumonitis, immune pneumonitis, and combined treatment and the latest related research results will be reviewed.

Viral infection in hematopoietic stem cell transplantation: an International Society for Cell & Gene Therapy Stem Cell Engineering Committee review on the role of cellular therapy in prevention and treatment

Despite recent advances in the field of HSCT, viral infections remain a frequent causeof morbidity and mortality among HSCT recipients. Adoptive transfer of viral specific T cells has been successfully used both as prophylaxis and treatment of viral infections in immunocompromised HSCT recipients. Increasingly, precise risk stratification of HSCT recipients with infectious complications should incorporate not only pretransplant clinical criteria, but milestones of immune reconstitution as well. These factors can better identify those at highest risk of morbidity and mortality and identify a population of HSCT recipients in whom adoptive therapy with viral specific T cells should be considered for either prophylaxis or second line treatment early after inadequate response to first line antiviral therapy. Broadening these approaches to improve outcomes for transplant recipients in countries with limited resources is a major challenge. While the principles of risk stratification can be applied, early detection of viral reactivation as well as treatment is challenging in regions where commercial PCR assays and antiviral agents are not readily available.

Effect of CRISPR/Cas9-Edited PD-1/PD-L1 on Tumor Immunity and Immunotherapy

Clustered regularly interspaced short palindromic repeats/CRISPR-associated nuclease9 (CRISPR/Cas9) gene editing technology implements precise programming of the human genome through RNA guidance. At present, it has been widely used in the construction of animal tumor models, the study of drug resistance regulation mechanisms, epigenetic control and innovation in cancer treatment. Tumor immunotherapy restores the normal antitumor immune response by restarting and maintaining the tumor-immune cycle. CRISPR/Cas9 technology has occupied a central position in further optimizing anti-programmed cell death 1(PD-1) tumor immunotherapy. In this review, we summarize the recent progress in exploring the regulatory mechanism of tumor immune PD-1 and programmed death ligand 1(PD-L1) based on CRISPR/Cas9 technology and its clinical application in different cancer types. In addition, CRISPR genome-wide screening identifies new drug targets and biomarkers to identify potentially sensitive populations for anti-PD-1/PD-L1 therapy and maximize antitumor effects. Finally, the strong potential and challenges of CRISPR/Cas9 for future clinical applications are discussed.

Challenges of CRISPR-Based Gene Editing in Primary T Cells

Adaptive T-cell immunotherapy holds great promise for the successful treatment of leukemia, as well as other types of cancers. More recently, it was also shown to be an effective treatment option for chronic virus infections in immunosuppressed patients. Autologous or allogeneic T cells used for immunotherapy are usually genetically modified to express novel T-cell or chimeric antigen receptors. The production of such cells was significantly simplified with the CRISPR/Cas system, allowing for the deletion or insertion of novel genes at specific locations within the genome. In this review, we describe recent methodological breakthroughs that were important for the conduction of these genetic modifications, summarize crucial points to be considered when conducting such experiments, and highlight the potential pitfalls of these approaches.

The Application of CRISPR/Cas9 Technology for Cancer Immunotherapy: Current Status and Problems

Cancer is one of the main causes of disease-related deaths in the world. Although cancer treatment strategies have been improved in recent years, the survival time of cancer patients is still far from satisfied. Cancer immunotherapy, such as Oncolytic virotherapy, Immune checkpoints inhibition, Chimeric antigen receptor T (CAR-T) cell therapy, Chimeric antigen receptor natural killer (CAR-NK) cell therapy and macrophages genomic modification, has emerged as an effective therapeutic strategy for different kinds of cancer. However, many patients do not respond to the cancer immunotherapy which warrants further investigation to optimize this strategy. The clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9 (CRISPR/Cas9), as a versatile genome engineering tool, has become popular in the biology research field and it was also applied to optimize tumor immunotherapy. Moreover, CRISPR-based high-throughput screening can be used in the study of immunomodulatory drug resistance mechanism. In this review, we summarized the development as well as the application of CRISPR/Cas9 technology in the cancer immunotherapy and discussed the potential problems that may be caused by this combination.

Gene editing to enhance the efficacy of cancer cell therapies

Adoptive T cell therapies have shown impressive signals of activity, but their clinical impact could be enhanced by technologies to increase T cell potency and diminish the cost and labor involved in manufacturing these products. Gene editing platforms are under study in this arena to (1) enhance immune cell potency by knocking out molecules that inhibit immune responses; (2) deliver genetic payloads into precise genomic locations and thereby enhance safety and/or improve the gene expression profile by leveraging physiologic promoters, enhancers, and repressors; and (3) enable off-the-shelf therapies by preventing alloreactivity and immune rejection. This review discusses gene editing approaches that have been the best studied in the context of human T cells and adoptive T cell therapies, summarizing their current status and near-term potential for translation.

Increased antitumor efficacy of PD-1-deficient melanoma-specific human lymphocytes

Background

Genome editing offers unique perspectives for optimizing the functional properties of T cells for adoptive cell transfer purposes. So far, PDCD1 editing has been successfully tested mainly in chimeric antigen receptor T (CAR-T) cells and human primary T cells. Nonetheless, for patients with solid tumors, the adoptive transfer of effector memory T cells specific for tumor antigens remains a relevant option, and the use of high avidity T cells deficient for programmed cell death-1 (PD-1) expression is susceptible to improve the therapeutic benefit of these treatments.

Methods

Here we used the transfection of CAS9/sgRNA ribonucleoproteic complexes to edit PDCD1 gene in human effector memory CD8⁺ T cells specific for the melanoma antigen Melan-A. We cloned edited T cell populations and validated PDCD1 editing through sequencing and cytometry in each T cell clone, together with T-cell receptor (TCR) chain’s sequencing. We also performed whole transcriptomic analyses on wild-type (WT) and edited T cell clones. Finally, we documented in vitro and in vivo through adoptive transfer in NOD scid gamma (NSG) mice, the antitumor properties of WT and PD-1KO T cell clones, expressing the same TCR.

Results

Here we demonstrated the feasibility to edit PDCD1 gene in human effector memory melanoma-specific T lymphocytes. We showed that PD-1 expression was dramatically reduced or totally absent on PDCD1-edited T cell clones. Extensive characterization of a panel of T cell clones expressing the same TCR and exhibiting similar functional avidity demonstrated superior antitumor reactivity against a PD-L1 expressing melanoma cell line. Transcriptomic analysis revealed a downregulation of genes involved in proliferation and DNA replication in PD-1-deficient T cell clones, whereas genes involved in metabolism and cell signaling were upregulated. Finally, we documented the superior ability of PD-1-deficient T cells to significantly delay the growth of a PD-L1 expressing human melanoma tumor in an NSG mouse model.

Conclusion

The use of such lymphocytes for adoptive cell transfer purposes, associated with other approaches modulating the tumor microenvironment, would be a promising alternative to improve immunotherapy efficacy in solid tumors.

Combination of CRISPR/Cas9 System and CAR-T Cell Therapy: A New Era for Refractory and Relapsed Hematological Malignancies

Chimeric antigen receptor T (CAR-T) cell therapy is the novel treatment strategy for hematological malignancies such as acute lymphoblastic leukemia (ALL), lymphoma and multiple myeloma. However, treatment-related toxicities such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) have become significant hurdles to CAR-T treatment. Multiple strategies were established to alter the CAR structure on the genomic level to improve efficacy and reduce toxicities. Recently, the innovative gene-editing technology-clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease9 (Cas9) system, which particularly exhibits preponderance in knock-in and knockout at specific sites, is widely utilized to manufacture CAR-T products. The application of CRISPR/Cas9 to CAR-T cell therapy has shown promising clinical results with minimal toxicity. In this review, we summarized the past achievements of CRISPR/Cas9 in CAR-T therapy and focused on the potential CAR-T targets.

CRISPR/Cas9 Gene-Editing in Cancer Immunotherapy: Promoting the Present Revolution in Cancer Therapy and Exploring More

In recent years, immunotherapy has showed fantastic promise in pioneering and accelerating the field of cancer therapy and embraces unprecedented breakthroughs in clinical practice. The clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein 9 (CRISPR-Cas9) system, as a versatile gene-editing technology, lays a robust foundation to efficiently innovate cancer research and cancer therapy. Here, we summarize recent approaches based on CRISPR/Cas9 system for construction of chimeric antigen receptor T (CAR-T) cells and T cell receptor T (TCR-T) cells. Besides, we review the applications of CRISPR/Cas9 in inhibiting immune checkpoint signaling pathways and highlight the feasibility of CRISPR/Cas9 based engineering strategies to screen novel cancer immunotherapy targets. Conclusively, we discuss the perspectives, potential challenges and possible solutions in this vivid growing field.

Post-transcriptional control of T-cell cytokine production: Implications for cancer therapy

As part of the adaptive immune system, T cells are vital for the eradication of infected and malignantly transformed cells. To perform their protective function, T cells produce effector molecules that are either directly cytotoxic, such as granzymes, perforin, interferon-γ and tumour necrosis factor α, or attract and stimulate (immune) cells, such as interleukin-2. As these molecules can also induce immunopathology, tight control of their production is required. Indeed, inflammatory cytokine production is regulated on multiple levels. Firstly, locus accessibility and transcription factor availability and activity determine the amount of mRNA produced. Secondly, post-transcriptional mechanisms, influencing mRNA splicing/codon usage, stability, decay, localization and translation rate subsequently determine the amount of protein that is produced. In the immune suppressive environments of tumours, T cells gradually lose the capacity to produce effector molecules, resulting in tumour immune escape. Recently, the role of post-transcriptional regulation in fine-tuning T-cell effector function has become more appreciated. Furthermore, several groups have shown that exhausted or dysfunctional T cells from cancer patients or murine models possess mRNA for inflammatory mediators, but fail to produce effector molecules, hinting that post-transcriptional events also play a role in hampering tumour-infiltrating lymphocyte effector function. Here, the post-transcriptional regulatory events governing T-cell cytokine production are reviewed, with a specific focus on the importance of post-transcriptional regulation in anti-tumour responses. Furthermore, potential approaches to circumvent tumour-mediated dampening of T-cell effector function through the (dis)engagement of post-transcriptional events are explored, such as CRISPR/Cas9-mediated genome editing or chimeric antigen receptors.

Delivery technologies for T cell gene editing: Applications in cancer immunotherapy

While initial approaches to adoptive T cell therapy relied on the identification and expansion of rare tumour-reactive T cells, genetic engineering has transformed cancer immunotherapy by enabling the modification of primary T cells to increase their therapeutic potential. Specifically, gene editing technologies have been utilized to create T cell populations with improved responses to antigens, lower rates of exhaustion, and potential for use in allogeneic applications. In this review, we provide an overview of T cell therapy gene editing strategies and the delivery technologies utilized to genetically engineer T cells. We also discuss recent investigations and clinical trials that have utilized gene editing to enhance the efficacy of T cells and broaden the application of cancer immunotherapies.

CRISPR/Cas: a Nobel Prize award-winning precise genome editing technology for gene therapy and crop improvement

Since it was first recognized in bacteria and archaea as a mechanism for innate viral immunity in the early 2010s, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) has rapidly been developed into a robust, multifunctional genome editing tool with many uses. Following the discovery of the initial CRISPR/Cas-based system, the technology has been advanced to facilitate a multitude of different functions. These include development as a base editor, prime editor, epigenetic editor, and CRISPR interference (CRISPRi) and CRISPR activator (CRISPRa) gene regulators. It can also be used for chromatin and RNA targeting and imaging. Its applications have proved revolutionary across numerous biological fields, especially in biomedical and agricultural improvement. As a diagnostic tool, CRISPR has been developed to aid the detection and screening of both human and plant diseases, and has even been applied during the current coronavirus disease 2019 (COVID-19) pandemic. CRISPR/Cas is also being trialed as a new form of gene therapy for treating various human diseases, including cancers, and has aided drug development. In terms of agricultural breeding, precise targeting of biological pathways via CRISPR/Cas has been key to regulating molecular biosynthesis and allowing modification of proteins, starch, oil, and other functional components for crop improvement. Adding to this, CRISPR/Cas has been shown capable of significantly enhancing both plant tolerance to environmental stresses and overall crop yield via the targeting of various agronomically important gene regulators. Looking to the future, increasing the efficiency and precision of CRISPR/Cas delivery systems and limiting off-target activity are two major challenges for wider application of the technology. This review provides an in-depth overview of current CRISPR development, including the advantages and disadvantages of the technology, recent applications, and future considerations.

Applications of CRISPR Genome Editing to Advance the Next Generation of Adoptive Cell Therapies for Cancer

Adoptive cell therapy (ACT) for cancer shows tremendous potential; however, several challenges preclude its widespread use. These include poor T-cell function in hostile tumor microenvironments, a lack of tumor-specific target antigens, and the high cost and poor scalability of cell therapy manufacturing. Creative genome-editing strategies are beginning to emerge to address each of these limitations, which has initiated the next generation of cell therapy products now entering clinical trials. CRISPR is at the forefront of this revolution, offering a simple and versatile platform for genetic engineering. This review provides a comprehensive overview of CRISPR applications that have advanced ACT. SIGNIFICANCE: The clinical impact of ACT for cancer can be expanded by implementing specific genetic modifications that enhance the potency, safety, and scalability of cellular products. Here we provide a detailed description of such genetic modifications, highlighting avenues to enhance the therapeutic efficacy and accessibility of ACT for cancer. Furthermore, we review high-throughput CRISPR genetic screens that have unveiled novel targets for cell therapy enhancement.

Using CRISPR to enhance T cell effector function for therapeutic applications

T cells are critical to fight pathogenic microbes and combat malignantly transformed cells in the fight against cancer. To exert their effector function, T cells produce effector molecules, such as the pro-inflammatory cytokines IFN-γ, TNF-α and IL-2. Tumors possess many inhibitory mechanisms that dampen T cell effector function, limiting the secretion of cytotoxic molecules. As a result, the control and elimination of tumors is impaired. Through recent advances in genomic editing, T cells can now be successfully modified via CRISPR/Cas9 technology. For instance, engaging (post-)transcriptional mechanisms to enhance T cell cytokine production, the retargeting of T cell antigen specificity or rendering T cells refractive to inhibitory receptor signaling can augment T cell effector function. Therefore, CRISPR/Cas9-mediated genome editing might provide novel strategies for cancer immunotherapy. Recently, the first-in-patient clinical trial was successfully performed with CRISPR/Cas9-modified human T cell therapy. In this review, a brief overview of currently available techniques is provided, and recent advances in T cell genomic engineering for the enhancement of T cell effector function for therapeutic purposes are discussed.

Mini review: genome and transcriptome editing using CRISPR-cas systems for haematological malignancy gene therapy

The recent introduction of clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR associated protein (Cas) systems, offer an array of genome and transcriptome editing tools for clinical repair strategies. These include Cas9, Cas12a, dCas9 and more recently Cas13 effectors. RNA targeting CRISPR-Cas13 complexes show unique characteristics with the capability to engineer transcriptomes and modify gene expression, providing a potential clinical cancer therapy tool across various tissue types. Cas13 effectors such as RNA base editing for A to I replacement allows for precise transcript modification. Further applications of Cas13a highlights its capability of producing rapid diagnostic results in a mobile platform. This review will focus on the adaptions of existing CRISPR-Cas systems, along with new Cas effectors for transcriptome or RNA modifications used in disease modelling and gene therapy for haematological malignancy. We also address the current diagnostic and therapeutic potential of CRISPR-Cas systems for personalised haematological malignancy.

Improving Cancer Immunotherapy with CRISPR-Based Technology

The rapidly evolving field of immunotherapy has attracted great attention in the field of cancer research and already revolutionized the clinical practice standard for treating cancer. Genetically engineered T cells expressing either T cell receptors or chimeric antigen receptors represent novel treatment modalities and are considered powerful weapons to fight cancer. The immune checkpoint blockade, which harnesses the negative control signaling behind the anti-tumor immune response with therapeutic antibodies by blocking cytotoxic T lymphocyte-associated protein 4 or the programmed cell death 1 pathways are another mainstream direction for cancer immunotherapy. In addition to cytotoxic T cells, other immune cell types such as nature killer cells and macrophages also possess the ability to eradicate cancer cells, which may serve as the basis to develop novel cancer immunotherapies. The advent of cutting-edge genome editing technology, especially clustered regularly interspaced palindromic repeats (CRISPR)-based tools, has greatly expedited many biomedical research areas, including cancer immunology and immunotherapy. In this review, the contribution of current CRISPR techniques to basic and translational cancer immunology research is discussed, and the future for cancer immunotherapy in the age of CRISPR is predicted.

Targeting TIM-3 in solid tumors: innovations in the preclinical and translational realm and therapeutic potential

INTRODUCTION

Immune checkpoint inhibitors (ICIs) have shown a great therapeutic efficacy in cancer patients. However, a significant proportion of cancer patients remain unresponsive or show limited response. T cell immunoglobulin and mucin-domain containing protein-3 (TIM-3) is a co-inhibitory receptor expressed on various cell types and is involved in the attenuation of immune responses. TIM-3 and its ligands are highly expressed in various solid malignancies and some studies have reported its association with worse disease outcomes. Thus, targeting TIM-3 could be a promising therapeutic approach to treat cancer patients.

AREAS COVERED

This review describes the role of TIM-3 and its ligands in regulating anti-tumor immunity and their contribution to cancer progression. Moreover, this review focuses on the preclinical models and translational data from important studies published in PubMed till October 2020, which demonstrate the therapeutic benefits of targeting TIM-3 signaling.

EXPERT OPINION

Despite the promising data obtained from targeting TIM-3 in preclinical models, precise mechanisms underlying the anti-tumor effects of TIM-3 inhibition are not fully elucidated. Therefore, mechanistic studies are required to provide better insights into the anti-tumor effects of targeting TIM-3, and clinical data are necessary to determine the safety profiles and therapeutic efficacy of TIM-3 inhibition in cancer patients.

Mutation of PD-1 immune receptor tyrosine-based switch motif (ITSM) enhances the antitumor activity of cytotoxic T cells

BACKGROUND

Programmed cell death protein 1 (PD-1), as an immune checkpoint cell membrane receptor, negatively regulates T cell activation via its immune receptor, the tyrosine-based switch motif (ITSM). The purpose of this research was to evaluate the antitumor activity T cells with the ITSM mutation of PD-1 on non-small cell lung cancer (NSCLC) in vitro and in vivo.

METHODS

In this study, the tyrosine of ITSM in cytotoxic T cells was mutated using the adenine base editor (ABE)-xCas9 system to evaluate its effect on the antitumor activity of T cells against NSCLC.

RESULTS

Results showed that the PD-1-deficient T cells enhanced the death of the cocultured NSCLC cells compared with the normal T cells and saline solution. PD-1-deficient T cells also changed the interleukin 2(IL-2), interferon γ (IFN-γ), tumor necrosis factor α (TNF-α), and granulocyte-macrophage colony-stimulating factor (GM-CSF) secretion of T cells compared with those of the normal T cells. The effectiveness of ITSM mutation in enhancing the antitumor activity of PD-1-deficient T cells was verified in vivo by using a mouse xenograft model. The xenografted mice treated with PD-1-deficient T cells demonstrated repressed tumor growth of the NSCLC cells compared with those treated with normal T cells and saline solution.

CONCLUSIONS

The mutation of ITSM in cytotoxic T cell via the ABE-xCas9 system can significantly enhance the antitumor activity of T cells.

CRISPR-Cas, a robust gene-editing technology in the era of modern cancer immunotherapy

Cancer immunotherapy has been emerged as a promising strategy for treatment of a broad spectrum of malignancies ranging from hematological to solid tumors. One of the principal approaches of cancer immunotherapy is transfer of natural or engineered tumor-specific T-cells into patients, a so called "adoptive cell transfer", or ACT, process. Construction of allogeneic T-cells is dependent on the employment of a gene-editing tool to modify donor-extracted T-cells and prepare them to specifically act against tumor cells with enhanced function and durability and least side-effects. In this context, CRISPR technology can be used to produce universal T-cells, equipped with recombinant T cell receptor (TCR) or chimeric antigen receptor (CAR), through multiplex genome engineering using Cas nucleases. The robust potential of CRISPR-Cas in preparing the building blocks of ACT immunotherapy has broaden the application of such therapies and some of them have gotten FDA approvals. Here, we have collected the last investigations in the field of immuno-oncology conducted in partnership with CRISPR technology. In addition, studies that have addressed the challenges in the path of CRISPR-mediated cancer immunotherapy, as well as pre-treatment applications of CRISPR-Cas have been mentioned in detail.

CRISPR/Cas systems to overcome challenges in developing the next generation of T cells for cancer therapy

Genetically engineered immune cells with chimeric antigen receptors (CAR) or modified T cell receptors (TCR) have demonstrated their potential as a potent class of new cancer therapeutic strategy. Despite the clinical success of autologous CD19 CAR T cells in hematological malignancies, allogeneic T cells exhibit many advantages over their autologous counterparts and have recently gathered widespread attention due to the emergence of multiplex genome editing techniques, particularly CRISPR/Cas systems. Furthermore, genetically engineered T cells face a host of major challenges in solid tumors that are not as significant for blood cancers such as T cell targeted delivery, target specificity, proliferation, persistence, and the immunosuppressive tumor microenvironment. We take this opportunity to analyze recent strategies to develop allogeneic T cells, specifically in consideration of CRISPR/Cas and its delivery systems for multiplex gene editing. Additionally, we discuss the current methods used to delivery CRISPR/Cas systems for immunotherapeutic applications, and the challenges to continued development of novel delivery systems. We also provide a comprehensive analysis of the major challenges that genetically engineered T cells face in solid tumors along with the most recent strategies to overcome these barriers, with an emphasis on CRISPR-based approaches. We illustrate the synergistic prospects for how the combination of synthetic biology and immune-oncology could pave the way for designing the next generation of precision cancer therapy.

Engineering CD4+ T Cells to Enhance Cancer Immunity

This review presents key advances in combining T cell receptor (TCR) gene transfer to redirect T-cell specificity with gene engineering in order to enhance cancer-protective immune function. We discuss how emerging insights might be applied to CD4+ T cells. Although much attention has been paid to the role of CD8+ cytotoxic T cells in tumour protection, we provide convincing evidence that CD4+ helper T cells play a critical role in cancer immune responses in animal models and also in patients. We demonstrate that genetic engineering technologies provide exciting opportunities to extend the specificity range of CD4+ T cells from MHC class-II-presented epitopes to include peptides presented by MHC class I molecules. Functional enhancement of tumour immunity can improve the sensitivity of T cells to cancer antigens, promote survival in a hostile tumour microenvironment, boost cancer-protective effector mechanisms and enable the formation of T-cell memory. Engineered cancer-specific CD4+ T cells may contribute to protective immunity by a direct pathway involving cancer cell killing, and by an indirect pathway that boosts the function, persistence and memory formation of CD8+ T cells.

Engineering Strategies to Enhance TCR-Based Adoptive T Cell Therapy

T cell receptor (TCR)-based adoptive T cell therapies (ACT) hold great promise for the treatment of cancer, as TCRs can cover a broad range of target antigens. Here we summarize basic, translational and clinical results that provide insight into the challenges and opportunities of TCR-based ACT. We review the characteristics of target antigens and conventional αβ-TCRs, and provide a summary of published clinical trials with TCR-transgenic T cell therapies. We discuss how synthetic biology and innovative engineering strategies are poised to provide solutions for overcoming current limitations, that include functional avidity, MHC restriction, and most importantly, the tumor microenvironment. We also highlight the impact of precision genome editing on the next iteration of TCR-transgenic T cell therapies, and the discovery of novel immune engineering targets. We are convinced that some of these innovations will enable the field to move TCR gene therapy to the next level.

Multi-layered control of PD-L1 expression in Epstein-Barr virus-associated gastric cancer

Gastric cancer (GC) is the fifth most common cancer worldwide. In approximately 10% of GC cases, cancer cells show ubiquitous and monoclonal Epstein-Barr virus (EBV) infection. A significant feature of EBV-associated GC (EBVaGC) is high lymphocytic infiltration and high expression of immune checkpoint proteins, including programmed death-ligand 1 (PD-L1). This highlights EBVaGC as a strong candidate for immune checkpoint blockade therapy. Indeed, several recent studies have shown that EBV positivity in GC correlates with positive response to programmed cell death protein 1 (PD-1)/PD-L1 blockade therapy. Understanding the mechanisms that control PD-L1 expression in EBVaGC can indicate new predictive biomarkers for immunotherapy, as well as therapeutic targets for combination therapy. Various mechanisms have been implicated in PD-L1 expression regulation, including structural variations, post-transcriptional control, oncogenic activation of intrinsic signaling pathways, and increased sensitivity to extrinsic signals. This review provides the most recent updates on the multilayered control of PD-L1 expression in EBVaGC.

Effect of Low-Dose Radiation Therapy on Abscopal Responses to Hypofractionated Radiation Therapy and Anti-PD1 in Mice and Patients With Non-Small Cell Lung Cancer

PURPOSE

Hypofractionated radiation therapy (HFRT) can induce antitumor T cell responses, particularly in combination with immune checkpoint inhibitors (ICI), but abscopal effects are often precluded by insufficient T cell infiltration of distant, nonirradiated tumors. Additional noncytotoxic, low-dose radiation therapy (LDRT) of distant tumors may enhance the abscopal response, but clinical evidence and preclinical studies for this scenario are lacking.

METHODS AND MATERIALS

We investigated whether triple treatment consisting of HFRT, ICI, and LDRT could achieve better systemic antitumor response in bilateral mouse tumor models and in patients with stage IV non-small cell lung cancer.

RESULTS

Our analyses of bilateral mouse tumor models show that HFRT treatment of the primary tumor combined with LDRT treatment of the abscopal tumor and anti-PD1 therapy enhances the abscopal response compared with HFRT/anti-PD1, HFRT/LDRT, or LDRT/anti-PD1 double treatments; complete cure was observed in more than half of the mice treated with triple therapy. The enhanced abscopal effect was associated with increased infiltration of CD8+ effector T cells and upregulated expression of T cell-attracting chemokines. Of 9 patients with metastatic non-small cell lung cancer who were treated with this triple therapy, 3 and 2 patients showed partial responses and stable disease, respectively. Among 9 relatively large (175.7 ± 42.3 cm³) LDRT lesions, 6 lesions decreased by 28% in size, on average.

CONCLUSIONS

Our study demonstrates preclinically that LDRT of established metastases significantly enhances the abscopal response to HFRT plus ICI. It also shows that additional LDRT was well tolerated by patients and that this treatment profile is effective and worth further study.

Update on gastric cancer treatments and gene therapies

Gastric cancer is an active topic of clinical and basic research due to high morbidity and mortality. To date, gastrectomy and chemotherapy are the only therapeutic options for gastric cancer patients, but drug resistance, either acquired or primary, is the main cause for treatment failure. Differences in development and response to cancer treatments have been observed among ethnically diverse GC patient populations. In spite of major incidence, GC Asian patients have a significantly better prognosis and response to treatments than Caucasian ones due to genetic discordances between the two populations. Gene therapy could be an alternative strategy to overcome such issues and especially CRISPR/Cas9 represents one of the most intriguing gene-editing system. Thus, in this review article, we want to provide an update on the currently used therapies for the treatment of advanced GC. Graphical abstract.

Sharpening the Molecular Scissors: Advances in Gene-Editing Technology

The ability to precisely modify human genes has been made possible by the development of tools such as meganucleases, zinc finger nucleases, TALENs, and CRISPR/Cas. These now make it possible to generate targeted deletions, insertions, gene knock outs, and point variants; to modulate gene expression by targeting transcription factors or epigenetic machineries to DNA; or to target and modify RNA. Endogenous repair mechanisms are used to make the modifications required in DNA; they include non-homologous end joining, homology-directed repair, homology-independent targeted integration, microhomology-mediated end joining, base-excision repair, and mismatch repair. Off-target effects can be monitored using in silico prediction and sequencing and minimized using Cas proteins with higher accuracy, such as high-fidelity Cas9, enhanced-specificity Cas9, and hyperaccurate Cas9. Alternatives to Cas9 have been identified, including Cpf1, Cas12a, Cas12b, and smaller Cas9 orthologs such as CjCas9. Delivery of gene-editing components is performed ex vivo using standard techniques or in vivo using AAV, lipid nanoparticles, or cell-penetrating peptides. Clinical development of gene-editing technology is progressing in several fields, including immunotherapy in cancer treatment, antiviral therapy for HIV infection, and treatment of genetic disorders such as β-thalassemia, sickle cell disease, lysosomal storage disorders, and retinal dystrophy. Here we review these technological advances and the challenges to their clinical implementation.