Sleeping Beauty-engineered CAR T cells achieve antileukemic activity without severe toxicities

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.

Prospects and challenges of CAR-T in the treatment of ovarian cancer

Ovarian cancer ranks as the seventh most prevalent cancer among women and is considered the most lethal gynecological malignancy on a global scale. The absence of reliable screening techniques, coupled with the insidious onset of nonspecific symptoms, often results in a delayed diagnosis, typically at an advanced stage characterized by peritoneal involvement. Management of advanced tumors typically involves a combination of chemotherapy and cytoreductive surgery. However, the therapeutic arsenal for ovarian cancer patients remains limited, highlighting the unmet need for precise, targeted, and sustained-release pharmacological agents. Genetically engineered T cells expressing chimeric antigen receptors (CARs) represent a promising novel therapeutic modality that selectively targets specific antigens, demonstrating robust and enduring antitumor responses in numerous patients. CAR T cell therapy has exhibited notable efficacy in hematological malignancies and is currently under investigation for its potential in treating various solid tumors, including ovarian cancer. Currently, numerous researchers are engaged in the development of novel CAR-T cells designed to target ovarian cancer, with subsequent evaluation of these candidate cells in preclinical studies. Given the ability of chimeric antigen receptor (CAR) expressing T cells to elicit potent and long-lasting anti-tumor effects, this therapeutic approach holds significant promise for the treatment of ovarian cancer. This review article examines the utilization of CAR-T cells in the context of ovarian cancer therapy.

INSPIRED Symposium Part 4B: Chimeric Antigen Receptor T Cell Correlative Studies-Established Findings and Future Priorities

Chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of B cell malignancies, with multiple CAR T cell products approved for numerous indications by regulatory agencies worldwide. However, significant work remains to be done to enhance these treatments. In March 2023, a group of experts in CAR T cell therapy assembled at the National Institutes of Health in Bethesda, Maryland at the Insights in Pediatric CAR T Cell Immunotherapy: Recent Advances and Future Directions (INSPIRED) Symposium to identify key areas for research for the coming years. In session 4B, correlative studies to be incorporated into future clinical trials and real-world settings were discussed. Active areas of research identified included (1) optimizing CAR T cell product manufacturing; (2) ensuring adequate lymphodepletion prior to CAR T cell administration; (3) overcoming immunoregulatory cells and tumor stroma present in the tumor microenvironment, particularly in solid tumors; (4) understanding tumor intrinsic properties that lead to CAR T cell immunotherapy resistance; and (5) uncovering biomarkers predictive of treatment resistance, treatment durability, or immune-related adverse events. Here we review the results of previously published clinical trials and real-world studies to summarize what is currently known about each of these topics. We then outline priorities for future research that we believe will be important for improving our understanding of CAR T cell therapy and ultimately leading to better outcomes for patients.

Optimization and validation of in vivo flow cytometry chimeric antigen receptor T cell detection method using CD19his indirect staining

CD19-targeted chimeric antigen receptor T (CAR-T) cell therapy has shown unprecedented results in patients with B cell relapsed/refractory acute lymphoblastic leukemia (R/R-ALL) and B cell non-Hodgkin lymphomas where no other curative options are available. In vivo monitoring of CAR-T cell kinetics is fundamental to understand the correlation between CAR-T cells expansion and persistence with treatment response and toxicity development. The aim of this study was to define a robust, sensitive, and universal method for CAR-T cell detection using flow cytometry. We set up and compared with each other three assays for CD19 CAR-T cell detection, all based on commercially available reagents. All methods used a recombinant human CD19 protein fragment recognized by the single-chain variable fragment of the CAR construct. The two indirect staining assays (CD19his + APC-conjugated antihistidine antibody and CD19bio + APC-conjugated antibiotin antibody) showed better sensitivity and specificity compared with the direct staining with CD19-FITC, and CD19his had a better cost-effective profile. We validated CAR detection with CD19his with parallel quantitative real-time polymerase chain reaction data and we could demonstrate a strong positive correlation. We also showed that CD19his staining can be easily included in a multicolor flow cytometry panel to achieve additional information about the cell phenotype of CAR-T cell positive subpopulations. Finally, this method can be used for different anti-CD19 CAR-T cell products and for different sample sources. These data demonstrate that detection of CAR-T cells by CD19his flow cytometry staining is a reliable, robust, and broadly applicable tool for in vivo monitoring of CAR-T cells.

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

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

Optimizing CAR-T cell therapy in adults with B-cell acute lymphoblastic leukemia

Chimeric antigen receptor T-cell (CAR-T) therapy has demonstrated unprecedented success in the treatment of various hematologic malignancies including relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). Currently, there are two FDA-approved CD19-directed CAR-T cell products for the treatment of adults with R/R B-ALL. Despite high remission rates following CD19 CAR-T cell therapy in R/R B-ALL, remission durability remains limited in most adult patients, with relapse observed frequently in the absence of additional consolidation therapy. Furthermore, the burden of CAR-T cell toxicity remains significant in adults with R/R B-ALL and further limits the wide utilization of this effective therapy. In this review, we discuss patient and disease factors that are linked to CAR-T cell therapy outcomes in R/R B-ALL and strategies to optimize durability of response to reduce relapse and mitigate toxicity in the adult population. We additionally discuss future approaches being explored to maximize the benefit of CAR-T in adults with B-ALL.

BCMA CAR-T cells in multiple myeloma-ready for take-off?

Although the approval of new drugs has improved the clinical outcome of multiple myeloma (MM), it was widely regarded as incurable over the past decades. However, recent advancements in groundbreaking immunotherapies, such as chimeric antigen receptor T cells (CAR-T), have yielded remarkable results in heavily pretreated relapse/refractory patients, instilling hope for a potential cure. CAR-T are genetically modified cells armed with a novel receptor to specifically recognize and kill tumor cells. Among the potential targets for MM, the B-cell maturation antigen (BCMA) stands out since it is highly and almost exclusively expressed on plasma cells. Here, we review the currently approved BCMA-directed CAR-T products and ongoing clinical trials in MM. Furthermore, we explore innovative approaches to enhance BCMA-directed CAR-T and overcome potential reasons for treatment failure. Additionally, we explore the side effects associated with these novel therapies and shed light on accessibility of CAR-T therapy around the world.

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.

Allogeneic CAR-T Therapy Technologies: Has the Promise Been Met?

This last decade, chimeric antigen receptor (CAR) T-cell therapy has become a real treatment option for patients with B-cell malignancies, while multiple efforts are being made to extend this therapy to other malignancies and broader patient populations. However, several limitations remain, including those associated with the time-consuming and highly personalized manufacturing of autologous CAR-Ts. Technologies to establish "off-the-shelf" allogeneic CAR-Ts with low alloreactivity are currently being developed, with a strong focus on gene-editing technologies. Although these technologies have many advantages, they have also strong limitations, including double-strand breaks in the DNA with multiple associated safety risks as well as the lack of modulation. As an alternative, non-gene-editing technologies provide an interesting approach to support the development of allogeneic CAR-Ts in the future, with possibilities of fine-tuning gene expression and easy development. Here, we will review the different ways allogeneic CAR-Ts can be manufactured and discuss which technologies are currently used. The biggest hurdles for successful therapy of allogeneic CAR-Ts will be summarized, and finally, an overview of the current clinical evidence for allogeneic CAR-Ts in comparison to its autologous counterpart will be given.

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.

The paths and challenges of "off-the-shelf" CAR-T cell therapy: An overview of clinical trials

The advent of chimeric antigen receptor T cells (CAR-T cells) has made a tremendous revolution in the era of cancer immunotherapy, so that since 2017 eight CAR-T cell products have been granted marketing authorization. All of these approved products are generated from autologous sources, but this strategy faces several challenges such as time-consuming and expensive manufacturing process and reduced anti-tumor potency of patients' T cells due to the disease or previous therapies. The use of an allogeneic source can overcome these issues and provide an industrial, scalable, and standardized manufacturing process that reduces costs and provides faster treatment for patients. Nevertheless, for using allogeneic CAR-T cells, we are faced with the challenge of overcoming two formidable impediments: severe life-threatening graft-versus-host-disease (GvHD) caused by allogeneic CAR-T cells, and allorejection of allogeneic CAR-T cells by host immune cells which is called "host versus graft" (HvG). In this study, we reviewed recent registered clinical trials of allogeneic CAR-T cell therapy to analyze different approaches to achieve a safe and efficacious "off-the-shelf" source for chimeric antigen receptor (CAR) based immunotherapy.

Microphysiological systems for solid tumor immunotherapy: opportunities and challenges

Immunotherapy remains more effective for hematologic tumors than for solid tumors. One of the main challenges to immunotherapy of solid tumors is the immunosuppressive microenvironment these tumors generate, which limits the cytotoxic capabilities of immune effector cells (e.g., cytotoxic T and natural killer cells). This microenvironment is characterized by hypoxia, nutrient starvation, accumulated waste products, and acidic pH. Tumor-hijacked cells, such as fibroblasts, macrophages, and T regulatory cells, also contribute to this inhospitable microenvironment for immune cells by secreting immunosuppressive cytokines that suppress the antitumor immune response and lead to immune evasion. Thus, there is a strong interest in developing new drugs and cell formulations that modulate the tumor microenvironment and reduce tumor cell immune evasion. Microphysiological systems (MPSs) are versatile tools that may accelerate the development and evaluation of these therapies, although specific examples showcasing the potential of MPSs remain rare. Advances in microtechnologies have led to the development of sophisticated microfluidic devices used to recapitulate tumor complexity. The resulting models, also known as microphysiological systems (MPSs), are versatile tools with which to decipher the molecular mechanisms driving immune cell antitumor cytotoxicity, immune cell exhaustion, and immune cell exclusion and to evaluate new targeted immunotherapies. Here, we review existing microphysiological platforms to study immuno-oncological applications and discuss challenges and opportunities in the field.

Electrotransfer for nucleic acid and protein delivery

Electrotransfer of nucleic acids and proteins has become crucial in biotechnology for gene augmentation and genome editing. This review explores the applications of electrotransfer in both ex vivo and in vivo scenarios, emphasizing biomedical uses. We provide insights into completed clinical trials and successful instances of nucleic acid and protein electrotransfer into therapeutically relevant cells such as immune cells and stem and progenitor cells. In addition, we delve into emerging areas of electrotransfer where nanotechnology and deep learning techniques overcome the limitations of traditional electroporation.

Breast cancer immunotherapy: a comprehensive review

Cancer remains a major health problem despite numerous new medical interventions that have been introduced in recent years. One of the major choices for cancer therapy is so-called adoptive cell therapy (ACT). ACT can be performed using both innate immune cells, including dendritic cells (DCs), natural killer (NK) cells, and γδ T cells and acquired immune T cells. It has become possible to utilize these cells in both their native and modified states in clinical studies. Because of considerable success in cancer treatment, ACT now plays a role in advanced therapy protocols. Genetic engineering of autologous and allogeneic immune cells (T lymphocytes, NK cells, macrophages, etc.) with chimeric antigen receptors (CAR) is a powerful new tool to target specific antigens on cancer cells. The Food and Drug Administration (FDA) in the US has approved certain CAR-T cells for hematologic malignancies and it is hoped that their use can be extended to incorporate a variety of cells, in particular NK cells. However, the ACT method has some limitations, such as the risk of rejection in allogeneic engrafts. Accordingly, numerous efforts are being made to eliminate or minimize this and other complications. In the present review, we have developed a guide to breast cancer (BC) therapy from conventional therapy, through to cell-based approaches, in particular novel technologies including CAR with emphasis on NK cells as a new and safer candidate in this field as well as the more recent aptamer technology, which can play a major role in BC immunotherapy.

CSPG4 CAR-redirected Cytokine Induced Killer lymphocytes (CIK) as effective cellular immunotherapy for HLA class I defective melanoma

BACKGROUND

Even acknowledging the game-changing results achieved in the treatment of metastatic melanoma with the use of immune checkpoint inhibitors (ICI), a large proportion of patients (40-60%) still fail to respond or relapse due to the development of resistance. Alterations in the expression of Human Leukocyte Antigen class I (HLA-I) molecules are considered to play a major role in clinical resistance to ICI. Cellular immunotherapy with HLA-independent CAR-redirected lymphocytes is a promising alternative in this challenging setting and dedicated translational models are needed.

METHODS

In this study, we propose an HLA-independent therapeutic strategy with Cytokine Induced Killer lymphocytes (CIK) genetically engineered with a Chimeric Antigen Receptor (CAR) targeting the tumor antigen CSPG4 as effector mechanism. We investigated the preclinical antitumor activity of CSPG4-CAR.CIK in vitro and in a xenograft murine model focusing on patient-derived melanoma cell lines (Mel) with defective expression of HLA-I molecules.

RESULTS

We successfully generated CSPG4-CAR.CIK from patients with metastatic melanoma and reported their intense activity in vitro against a panel of CSPG4-expressing patient-derived Mel. The melanoma killing activity was intense, even at very low effector to target ratios, and not influenced by the expression level (high, low, defective) of HLA-I molecules on target cells. Furthermore, CAR.CIK conditioned medium was capable of upregulating the expression of HLA-I molecules on melanoma cells. A comparable immunomodulatory effect was replicated by treatment of Mel cells with exogenous IFN-γ and IFN-α. The antimelanoma activity of CSPG4-CAR.CIK was successfully confirmed in vivo, obtaining a significant tumor growth inhibition of an HLA-defective Mel xenograft in immunodeficient mice.

CONCLUSIONS

In this study we reported the intense preclinical activity of CSPG4-CAR.CIK against melanoma, including those with low or defective HLA-I expression. Our findings support CSPG4 as a valuable CAR target in melanoma and provide translational rationale for clinical studies exploring CAR-CIK cellular immunotherapies within the challenging setting of patients not responsive or relapsing to immune checkpoint inhibitors.

Differences in efficacy and safety among CAR-Ts anti-CD19/CD22, anti-CD19, and anti-CD22, in adult patients with relapse/refractory B-cell acute lymphoblastic leukemia: a meta-analysis and systematic review

Relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) is a challenging disease with low rates of remission and survival in adult patients. Anti-CD19 Chimeric Antigen Receptor T-cells (CAR-Ts) therapies have been approved for these patients. Dual-target CAR-Ts against CD19 and CD22 have recently been developed to improve the efficacy of the single-target therapy; however, extent of the improvement using this dual-target therapy has yet to be determined. We performed a meta-analysis of the outcome and safety of CAR-Ts, comparing anti-CD19 vs anti-CD22 vs dual-target anti-CD19/CD22 CAR-Ts, to elucidate the differences and limitations of these therapies in adult patients with R/R B-ALL. Although the limitations of our study derived from heterogeneity in the included publications, our results suggest that anti-CD19/CD22 CAR-Ts generate lower incidence of relapse and neurotoxicity, but similar results were obtained regarding complete remission, minimal residual disease, overall survival, and cytokine release syndrome compared with single-target anti-CD19 and anti-CD22 CAR-Ts.

Incidence of CD19-negative relapse after CD19-targeted immunotherapy in R/R BCP acute lymphoblastic leukemia: a review

There are inconsistencies in the reporting of CD19 antigen status following treatment with CD19-targeted therapies. A majority of evidence comes from studies reporting small sample sizes. In this review, we systematically summarize published studies that have reported rates of CD19-negative relapse after treatment with either blinatumomab or CD19-directed CAR T-cell therapy and report the rates of CD19-negative relapse when evaluated in a standardized way across trials. CD19-negative relapse appears to occur more commonly in relapses following CAR T-cell therapy compared with blinatumomab, whether proportions are calculated among all treated patients (8.7% vs 4.5%) or among patients who relapse (30% vs 22.5%). The median (range) duration of follow-up was 29.3 (17.4-50.8) and 20.4 (6.9-49.0) months for publications on blinatumomab (n = 10) and CAR T-cell therapies (n = 23), respectively. There is a need for standardized reporting of CD19 antigen status in the setting of relapse following novel immunotherapies to inform clinical practice.

Anti-CD117 CAR T cells incorporating a safety switch eradicate human acute myeloid leukemia and hematopoietic stem cells

Discrimination between hematopoietic stem cells and leukemic stem cells remains a major challenge for acute myeloid leukemia immunotherapy. CAR T cells specific for the CD117 antigen can deplete malignant and healthy hematopoietic stem cells before consolidation with allogeneic hematopoietic stem cell transplantation in absence of cytotoxic conditioning. Here we exploit non-viral technology to achieve early termination of CAR T cell activity to prevent incoming graft rejection. Transient expression of an anti-CD117 CAR by mRNA conferred T cells the ability to eliminate CD117+ targets in vitro and in vivo. As an alternative approach, we used a Sleeping Beauty transposon vector for the generation of CAR T cells incorporating an inducible Caspase 9 safety switch. Stable CAR expression was associated with high proportion of T memory stem cells, low levels of exhaustion markers, and potent cellular cytotoxicity. Anti-CD117 CAR T cells mediated depletion of leukemic cells and healthy hematopoietic stem cells in NSG mice reconstituted with human leukemia or CD34+ cord blood cells, respectively, and could be terminated in vivo. The use of a non-viral technology to control CAR T cell pharmacokinetic properties is attractive for a first-in-human study in patients with acute myeloid leukemia prior to hematopoietic stem cell transplantation.

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).

How can Cytokine-induced killer cells overcome CAR-T cell limits

The successful treatment of patients affected by B-cell malignancies with Chimeric Antigen Receptor (CAR)-T cells represented a breakthrough in the field of adoptive cell therapy (ACT). However, CAR-T therapy is not an option for every patient, and several needs remain unmet. In particular, the production of CAR-T cells is expensive, labor-intensive and logistically challenging; additionally, the toxicities deriving from CAR-T cells infusion, such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), have been documented extensively. Alternative cellular therapy products such as Cytokine-induced killer (CIK) cells have the potential to overcome some of these obstacles. CIK cells are a heterogeneous population of polyclonal CD3+CD56+ T cells with phenotypic and functional properties of NK cells. CIK cell cytotoxicity is exerted in a major histocompatibility complex (MHC)-unrestricted manner through the engagement of natural killer group 2 member D (NKG2D) molecules, against a wide range of hematological and solid tumors without the need for prior antigen exposure or priming. The foremost potential of CIK cells lies in the very limited ability to induce graft-versus-host disease (GvHD) reactions in the allogeneic setting. CIK cells are produced with a simple and extremely efficient expansion protocol, which leads to a massive expansion of effector cells and requires a lower financial commitment compared to CAR-T cells. Indeed, CAR-T manufacturing involves the engineering with expensive GMP-grade viral vectors in centralized manufacturing facilities, whereas CIK cell production is successfully performed in local academic GMP facilities, and CIK cell treatment is now licensed in many countries. Moreover, the toxicities observed for CAR-T cells are not present in CIK cell-treated patients, thus further reducing the costs associated with hospitalization and post-infusion monitoring of patients, and ultimately encouraging the delivery of cell therapies in the outpatient setting. This review aims to give an overview of the limitations of CAR-T cell therapy and outline how the use of CIK cells could overcome such drawbacks thanks to their unique features. We highlight the undeniable advantages of using CIK cells as a therapeutic product, underlying the opportunity for further research on the topic.

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.

Homology-independent targeted insertion (HITI) enables guided CAR knock-in and efficient clinical scale CAR-T cell manufacturing

BACKGROUND

Chimeric Antigen Receptor (CAR) T cells are now standard of care (SOC) for some patients with B cell and plasma cell malignancies and could disrupt the therapeutic landscape of solid tumors. However, access to CAR-T cells is not adequate to meet clinical needs, in part due to high cost and long lead times for manufacturing clinical grade virus. Non-viral site directed CAR integration can be accomplished using CRISPR/Cas9 and double-stranded DNA (dsDNA) or single-stranded DNA (ssDNA) via homology-directed repair (HDR), however yields with this approach have been limiting for clinical application (dsDNA) or access to large yields sufficient to meet the manufacturing demands outside early phase clinical trials is limited (ssDNA).

METHODS

We applied homology-independent targeted insertion (HITI) or HDR using CRISPR/Cas9 and nanoplasmid DNA to insert an anti-GD2 CAR into the T cell receptor alpha constant (TRAC) locus and compared both targeted insertion strategies in our system. Next, we optimized post-HITI CRISPR EnrichMENT (CEMENT) to seamlessly integrate it into a 14-day process and compared our knock-in with viral transduced anti-GD2 CAR-T cells. Finally, we explored the off-target genomic toxicity of our genomic engineering approach.

RESULTS

Here, we show that site directed CAR integration utilizing nanoplasmid DNA delivered via HITI provides high cell yields and highly functional cells. CEMENT enriched CAR T cells to approximately 80% purity, resulting in therapeutically relevant dose ranges of 5.5 × 10⁸-3.6 × 10⁹ CAR + T cells. CRISPR knock-in CAR-T cells were functionally comparable with viral transduced anti-GD2 CAR-T cells and did not show any evidence of off-target genomic toxicity.

CONCLUSIONS

Our work provides a novel platform to perform guided CAR insertion into primary human T-cells using nanoplasmid DNA and holds the potential to increase access to CAR-T cell therapies.

Potency assays and biomarkers for cell-based advanced therapy medicinal products

Advanced Therapy Medicinal Products (ATMPs) based on somatic cells expanded in vitro, with or without genetic modification, is a rapidly growing area of drug development, even more so following the marketing approval of several such products. ATMPs are produced according to Good Manufacturing Practice (GMP) in authorized laboratories. Potency assays are a fundamental aspect of the quality control of the end cell products and ideally could become useful biomarkers of efficacy in vivo. Here we summarize the state of the art with regard to potency assays used for the assessment of the quality of the major ATMPs used clinic settings. We also review the data available on biomarkers that may substitute more complex functional potency tests and predict the efficacy in vivo of these cell-based drugs.

Safety and efficacy of CRISPR-based non-viral PD1 locus specifically integrated anti-CD19 CAR-T cells in patients with relapsed or refractory Non-Hodgkin's lymphoma: a first-in-human phase I study

Background

Thus far, all approved chimeric antigen receptor (CAR)-T products are manufactured using modified viruses, which increases the risk of tumorigenesis, costs and production time. We aimed to evaluate the safety and efficacy of a kind of virus-free CAR-T cells (PD1-19bbz), in which an anti-CD19 CAR sequence is specifically integrated at the PD1 locus using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9, in adults with relapsed/refractory (r/r) B cell non-Hodgkin's lymphoma (B-NHL).

Methods

This single-arm phase I dose-escalation clinical trial evaluated PD1-19bbz in adult patients with r/r B-NHL from May 3rd 2020 to August 10th 2021. The patients were recruited and treated at the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China. Patients underwent leukapheresis and lymphodepleting chemotherapy before PD1-19bbz infusion. After the dose-escalation phase including three cohorts: 2 × 10⁶/kg, 4 × 10⁶/kg, 6 × 10⁶/kg with three patients at each dose level, the optimal biological dose was determined to be 2 × 10⁶/kg, which was then applied to an extended cohort of nine patients. The primary endpoint was the incidence of dose-limiting toxicities (DLT). The secondary endpoint was the response and survival. This trial was registered at www.clinicaltrials.gov as #NCT04213469.

Findings

Twenty-one patients received PD1-19bbz infusion. Among all treated patients, 19 (90%) patients were diagnosed with stage III or IV disease. Meanwhile, 19 (90%) were stratified as intermediate risk or worse. Of note, four participants had >50% programmed death ligand-1 (PD-L1) expression in pre-treatment tumour sample, including two with extremely high levels (∼80%). There was no DLT identified. Fourteen patients had low-grade (1-2) cytokine release syndrome and two patients received tocilizumab. Four patients experienced immune effector cell-associated neurotoxicity syndrome of grade 1-2. The most common adverse events were hematologic toxicities, including anaemia (n = 6), lymphocyte count decreased (n = 19), neutrophil count decreased (n = 17), white blood cell count decreased (n = 10), and platelet count decreased (n = 2). All patients had objective response and 18 patients reached complete response. At a median follow-up of 19.2 months, nine patients remained in remission, and the estimated median progression-free survival duration was 19.5 months (95% confidence interval: 9.9-infinity), with the median overall survival not reached.

Interpretation

In this first-in-human study of non-viral specifically integrated CAR-T products, PD1-19bbz exhibited promising efficacy with a manageable toxicity profile. A phase I/II trial of PD1-19bbz in a larger patient cohort is underway.

Funding

National Key R&D Program of China, National Natural Science Foundation of China, Key Project of Science and Technology Department of Zhejiang Province, Shanghai Zhangjiang National Independent Innovation Demonstration Area, Key Projects of Special Development Funds.

The Black Hole: CAR T Cell Therapy in AML

Despite exhaustive studies, researchers have made little progress in the field of adoptive cellular therapies for relapsed/refractory acute myeloid leukemia (AML), unlike the notable uptake for B cell malignancies. Various single antigen-targeting chimeric antigen receptor (CAR) T cell Phase I trials have been established worldwide and have recruited approximately 100 patients. The high heterogeneity at the genetic and molecular levels within and between AML patients resembles a black hole: a great gravitational field that sucks in everything. One must consider the fact that only around 30% of patients show a response; there are, however, consequential off-tumor effects. It is obvious that a new point of view is needed to achieve more promising results. This review first introduces the unique therapeutic challenges of not only CAR T cells but also other adoptive cellular therapies in AML. Next, recent single-cell sequencing data for AML to assess somatically acquired alterations at the DNA, epigenetic, RNA, and protein levels are discussed to give a perspective on cellular heterogeneity, intercellular hierarchies, and the cellular ecosystem. Finally, promising novel strategies are summarized, including more sophisticated next-generation CAR T, TCR-T, and CAR NK therapies; the approaches with which to tailor the microenvironment and target neoantigens; and allogeneic approaches.

Intrathymic AAV delivery results in therapeutic site-specific integration at TCR loci in mice

Adeno-associated virus (AAV) vectors have been successfully exploited in gene therapy applications for the treatment of several genetic disorders. AAV is considered an episomal vector, but it has been shown to integrate within the host cell genome after the generation of double-strand DNA breaks or nicks. Although AAV integration raises some safety concerns, it can also provide therapeutic benefit; the direct intrathymic injection of an AAV harboring a therapeutic transgene results in integration in T-cell progenitors and long-term T-cell immunity. To assess the mechanisms of AAV integration, we retrieved and analyzed hundreds of AAV integration sites from lymph node-derived mature T cells and compared these with liver and brain tissue from treated mice. Notably, we found that although AAV integrations in the liver and brain were distributed across the entire mouse genome, >90% of the integrations in T cells were clustered within the T-cell receptor α, β, and γ genes. More precisely, the insertion mapped to DNA breaks created by the enzymatic activity of recombination activating genes (RAGs) during variable, diversity, and joining recombination. Our data indicate that RAG activity during T-cell receptor maturation induces a site-specific integration of AAV genomes and opens new therapeutic avenues for achieving long-term AAV-mediated gene transfer in dividing cells.

Harnessing novel strategies and cell types to overcome immune tolerance during adoptive cell therapy in cancer

Cell therapy encompasses an expanding spectrum of cell-based regimes for the treatment of human ailments, such as the use of immune cells, in particular T cells, for combating tumors and the modulation of inflammatory immune responses. In this review, we focus on cell therapy in the immuno-oncology space, which is largely driven by interests and demands from the clinics for better solutions to target various hard-to-treat cancers. We discuss recent advances in various types of cell therapies, including T cell receptor-T cells, chimeric antigen receptor (CAR)-T cells, tumor-infiltrating lymphocytes and natural killer cells. Particularly, the present review focuses on the strategies to improve therapeutic responses by either enhancing tumor recognition or the resilience of infused immune cells within tumor microenvironment. Finally, we discuss the potential of other innate or innate-like immune cell types currently being explored as promising CAR-cell alternatives that seek to address the limitations of conventional adoptive cell therapies.

Cellular Therapies in Chronic Lymphocytic Leukemia and Richter’s Transformation: Recent Developments in Chimeric Antigen Receptor T-Cells, Natural Killer Cells, and Allogeneic Stem Cell Transplant

Cellular therapies can be viewed as both the newest and oldest techniques for treating chronic lymphocytic leukemia (CLL) and Richter’s transformation (RT). On one hand, allogeneic hematopoietic stem cell transplantation (alloHSCT) has been available for decades, though its use is diminishing with the increasing availability of effective novel targeted agents, especially in CLL. Among newer techniques, chimeric antigen receptor T-cells (CAR-T) have demonstrated astounding efficacy in several hematologic malignancies, leading to FDA approval and use in clinical practice. However, though CLL is the earliest disease type for which CAR-T were studied, development has been slower and has yet to lead to regulatory approval. Owing partially to its rarity but also due to the aggressive behavior of RT, CAR-T in RT have only been minimally explored. Here, we will focus on the applications of cellular therapies in CLL and RT, specifically reviewing more recent data related to alloHSCT in the novel-agent era and CAR-T cell development in CLL/RT, focusing on safety and efficacy successes and limitations. We will review strategies to improve upon CAR-T efficacy and discuss ongoing trials utilizing CAR-T in CLL/RT, as well as emerging technologies, such as allogeneic CAR-T and natural killer CAR (CAR NK) cells.

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

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

Cellular Cancer Immunotherapy Development and Manufacturing in the Clinic

The transfusion of naturally derived or modified cellular therapies, referred to as adoptive cell therapy (ACT), has demonstrated clinical efficacy in the treatment of hematologic malignancies and metastatic melanoma. In addition, cellular vaccination, such as dendritic cell-based cancer vaccines, continues to be actively explored. The manufacturing of these therapies presents a considerable challenge to expanding the use of ACT as a viable treatment modality, particularly at academic production facilities. Furthermore, the expanding commercial interest in ACT presents new opportunities as well as strategic challenges for the future vision of cellular manufacturing in academic centers. Current trends in the production of ACT at tertiary care centers and prospects for improved manufacturing practices that will foster further clinical benefit are reviewed herein.

Optimal Use of Novel Immunotherapeutics in B-Cell Precursor ALL

Novel immune therapies are currently being used for patients with R/R ALL based on their ability to induce not only hematologic but also molecular remission. Despite promising results, specific clinical conditions, such as high tumor burden or extra medullary relapse, are still associated with a remarkably poor clinical outcome. Therefore, how to optimize the choice and the timing of such new treatments within different clinical settings remains a matter of debate. In addition, with the aim of increasing the rate and depth of molecular remission, clinical studies are currently evaluating the combination of these immunotherapies with chemotherapy in the contest of frontline treatment. The preliminary data suggest that this approach may increase the cure rate and perhaps reduce the use of allogeneic stem cell transplantation (alloHSCT) in first remission. In Ph-positive ALL, reproducible results are showing that frontline treatment programs, based on the combination of tyrosine kinase inhibitors and immunotherapy, can achieve unprecedented rates of hematologic and molecular remission as well as a long-term cure, even in the absence of chemotherapy and alloHSCT. The results from these studies have led to the development of potentially curative treatment modalities, even for older ALL patients who cannot be treated with conventional intensive chemotherapy. The present review examined the evidence for an appropriate use of the new immunotherapies in ALL patients and provided some appraisal of the current and future possible uses of these drugs for achieving further therapeutic improvement in the treatment of this disease.

Adoptive cellular immunotherapy for solid neoplasms beyond CAR-T

In recent decades, immune checkpoint blockade and chimeric antigen receptor T cell (CAR-T) therapy are two milestone achievements in clinical immunotherapy. However, both show limited efficacies in most solid neoplasms, which necessitates the exploration of new immunotherapeutic modalities. The failure of CAR-T and immune checkpoint blockade in several solid neoplasms is attributed to multiple factors, including low antigenicity of tumor cells, low infiltration of effector T cells, and diverse mechanisms of immunosuppression in the tumor microenvironment. New adoptive cell therapies have been attempted for solid neoplasms, including TCR-T, CAR-natural killer cells (CAR-NK), and CAR-macrophages (CAR-M). Compared to CAR-T, these new adoptive cell therapies have certain advantages in treating solid neoplasms. In this review, we summarized the 40-year evolution of adoptive cell therapies, then focused on the advances of TCR-T, CAR-NK, and CAR-M in solid neoplasms and discussed their potential clinical applications.

Weaponizing natural killer cells for solid cancer immunotherapy

Enhancing natural killer (NK) cell-based innate immunity has become a promising strategy for immunotherapy against hard-to-cure solid cancers. Monoclonal antibody (mAb) therapy has been used to activate NK-cell-mediated antibody-dependent cellular cytotoxicity (ADCC) towards solid cancers. Cancer cells, however, can subvert immunosurveillance using multiple immunosuppressive mechanisms, which may hamper NK cell ADCC. Mechanisms to safely enhance ADCC by NK cells, such as utilizing temporary inhibition of receptor endocytosis to increase antibody presentation from target to effector cells can now be used to enhance NK-cell-mediated ADCC against solid tumors. This review summarizes and discusses the recent advances in the field and highlights current and potential future use of immunotherapies to maximize the therapeutic efficacy of innate anticancer immunity.

BCMA-targeting chimeric antigen receptor T-cell therapy for multiple myeloma

Multiple myeloma (MM) remains an incurable hematologic malignancy, despite the development of numerous innovative therapies during the past two decades. Immunotherapies are changing the treatment paradigm of MM and have improved the overall response and survival of patients with relapsed/refractory (RR) MM. B cell maturation antigen (BCMA), selectively expressed in normal and malignant plasma cells, has been targeted by several immunotherapeutic modalities. Chimeric antigen receptor (CAR) T cells, the breakthrough in cancer immunotherapy, have revolutionized the treatment of B cell malignancies and remarkably improved the prognosis of RRMM. BCMA-targeting CAR T cell therapy is the most developed CAR T cell therapy for MM, and the US Food and Drug Administration has already approved idecabtagene vicleucel (Ide-cel) and ciltacabtagene autoleucel (Cilta-cel) for MM. However, the development of novel BCMA-targeting CAR T cell therapies remains in progress. This review focuses on BCMA-targeting CAR T cell therapy, covering all stages of investigational progress, including the innovative preclinical studies, the initial phase I clinical trials, and the more developed phase II clinical trials. It also discusses possible measures to improve the efficacy and safety of this therapy.

Current and future concepts for the generation and application of genetically engineered CAR-T and TCR-T cells

Adoptive cell therapy (ACT) has seen a steep rise of new therapeutic approaches in its immune-oncology pipeline over the last years. This is in great part due to the recent approvals of chimeric antigen receptor (CAR)-T cell therapies and their remarkable efficacy in certain soluble tumors. A big focus of ACT lies on T cells and how to genetically modify them to target and kill tumor cells. Genetically modified T cells that are currently utilized are either equipped with an engineered CAR or a T cell receptor (TCR) for this purpose. Both strategies have their advantages and limitations. While CAR-T cell therapies are already used in the clinic, these therapies face challenges when it comes to the treatment of solid tumors. New designs of next-generation CAR-T cells might be able to overcome these hurdles. Moreover, CARs are restricted to surface antigens. Genetically engineered TCR-T cells targeting intracellular antigens might provide necessary qualities for the treatment of solid tumors. In this review, we will summarize the major advancements of the CAR-T and TCR-T cell technology. Moreover, we will cover ongoing clinical trials, discuss current challenges, and provide an assessment of future directions within the field.

Full chimaeric CAR.CIK from patients engrafted after allogeneic haematopoietic cell transplant: Feasibility, anti-leukaemic potential and alloreactivity across major human leukocyte antigen barriers

Cytokine-induced killer lymphocytes (CIK) are a promising alternative to conventional donor lymphocyte infusion (DLI), following allogeneic haematopoietic cell transplantation (HCT), due to their intrinsic anti-tumour activity and reduced risk of graft-versus-host disease (GVHD). We explored the feasibility, anti-leukaemic activity and alloreactive risk of CIK generated from full-donor chimaeric (fc) patients and genetically redirected by a chimeric antigen receptor (CAR) (fcCAR.CIK) against the leukaemic target CD44v6. fcCAR.CIK were successfully ex-vivo expanded from leukaemic patients in complete remission after HCT confirming their intense preclinical anti-leukaemic activity without enhancing the alloreactivity across human leukocyte antigen (HLA) barriers. Our study provides translational bases to support clinical studies with fcCAR.CIK, a sort of biological bridge between the autologous and allogeneic sources, as alternative DLI following HCT.

CAR-T cell therapy in multiple myeloma: Current limitations and potential strategies

Over the last decade, the survival outcome of patients with multiple myeloma (MM) has been substantially improved with the emergence of novel therapeutic agents, such as proteasome inhibitors, immunomodulatory drugs, anti-CD38 monoclonal antibodies, selective inhibitors of nuclear export (SINEs), and T cell redirecting bispecific antibodies. However, MM remains an incurable neoplastic plasma cell disorder, and almost all MM patients inevitably relapse due to drug resistance. Encouragingly, B cell maturation antigen (BCMA)-targeted chimeric antigen receptor T (CAR-T) cell therapy has achieved impressive success in the treatment of relapsed/refractory (R/R) MM and brought new hopes for R/R MM patients in recent years. Due to antigen escape, the poor persistence of CAR-T cells, and the complicated tumor microenvironment, a significant population of MM patients still experience relapse after anti-BCMA CAR-T cell therapy. Additionally, the high manufacturing costs and time-consuming manufacturing processes caused by the personalized manufacturing procedures also limit the broad clinical application of CAR-T cell therapy. Therefore, in this review, we discuss current limitations of CAR-T cell therapy in MM, such as the resistance to CAR-T cell therapy and the limited accessibility of CAR-T cell therapy, and summarize some optimization strategies to overcome these challenges, including optimizing CAR structure, such as utilizing dual-targeted/multi-targeted CAR-T cells and armored CAR-T cells, optimizing manufacturing processes, combing CAR-T cell therapy with existing or emerging therapeutic approaches, and performing subsequent anti-myeloma therapy after CAR-T cell therapy as salvage therapy or maintenance/consolidation therapy.

Dose-response correlation for CAR-T cells: a systematic review of clinical studies

The potential of chimeric antigen receptor (CAR) T cells to successfully treat hematological cancers is widely recognized. Multiple CAR-T cell therapies are currently under clinical development, with most in early stage, during which dose selection is a key goal. The objective of this review is to address the question of dose-dependent effects on response and/or toxicity from available CAR-T cell clinical trial data. For that purpose, systematic literature review of studies published between January 2010 and May 2022 was performed on PubMed and Embase to search clinical studies that evaluated CAR-T cells for hematological cancers. Studies published in English were considered. Studies in children (age <18 years), solid tumors, bispecific CAR-T cells and CAR-T cell cocktails were excluded. As a result, a total of 74 studies met the inclusion criteria. Thirty-nine studies tested multiple dose levels of CAR-T cells with at least >1 patient at each dose level. Thirteen studies observed dose-related increase in disease response and 23 studies observed dose-related increase in toxicity across a median of three dose levels. Optimal clinical efficacy was seen at doses 50-100 million cells for anti-CD19 CAR-T cells and >100 million cells for anti-BCMA CAR-T cells in majority of studies. The findings suggest, for a given construct, there exists a dose at which a threshold of optimal efficacy occurs. Dose escalation may reveal increasing objective response rates (ORRs) until that threshold is reached. However, when ORR starts to plateau despite increasing dose, further dose escalation is unlikely to result in improved ORR but is likely to result in higher incidence and/or severity of mechanistically related adverse events.

ISAnalytics enables longitudinal and high-throughput clonal tracking studies in hematopoietic stem cell gene therapy applications

Longitudinal clonal tracking studies based on high-throughput sequencing technologies supported safety and long-term efficacy and unraveled hematopoietic reconstitution in many gene therapy applications with unprecedented resolution. However, monitoring patients over a decade-long follow-up entails a constant increase of large data volume with the emergence of critical computational challenges, unfortunately not addressed by currently available tools. Here we present ISAnalytics, a new R package for comprehensive and high-throughput clonal tracking studies using vector integration sites as markers of cellular identity. Once identified the clones externally from ISAnalytics and imported in the package, a wide range of implemented functionalities are available to users for assessing the safety and long-term efficacy of the treatment, here described in a clinical trial use case for Hurler disease, and for supporting hematopoietic stem cell biology in vivo with longitudinal analysis of clones over time, proliferation and differentiation. ISAnalytics is conceived to be metadata-driven, enabling users to focus on biological questions and hypotheses rather than on computational aspects. ISAnalytics can be fully integrated within laboratory workflows and standard procedures. Moreover, ISAnalytics is designed with efficient and scalable data structures, benchmarked with previous methods, and grants reproducibility and full analytical control through interactive web-reports and a module with Shiny interface. The implemented functionalities are flexible for all viral vector-based clonal tracking applications as well as genetic barcoding or cancer immunotherapies.

Current strategies employed in the manipulation of gene expression for clinical purposes

Abnormal gene expression level or expression of genes containing deleterious mutations are two of the main determinants which lead to genetic disease. To obtain a therapeutic effect and thus to cure genetic diseases, it is crucial to regulate the host's gene expression and restore it to physiological conditions. With this purpose, several molecular tools have been developed and are currently tested in clinical trials. Genome editing nucleases are a class of molecular tools routinely used in laboratories to rewire host's gene expression. Genome editing nucleases include different categories of enzymes: meganucleses (MNs), zinc finger nucleases (ZFNs), clustered regularly interspaced short palindromic repeats (CRISPR)- CRISPR associated protein (Cas) and transcription activator-like effector nuclease (TALENs). Transposable elements are also a category of molecular tools which includes different members, for example Sleeping Beauty (SB), PiggyBac (PB), Tol2 and TcBuster. Transposons have been used for genetic studies and can serve as gene delivery tools. Molecular tools to rewire host's gene expression also include episomes, which are divided into different categories depending on their molecular structure. Finally, RNA interference is commonly used to regulate gene expression through the administration of small interfering RNA (siRNA), short hairpin RNA (shRNA) and bi-functional shRNA molecules. In this review, we will describe the different molecular tools that can be used to regulate gene expression and discuss their potential for clinical applications. These molecular tools are delivered into the host's cells in the form of DNA, RNA or protein using vectors that can be grouped into physical or biochemical categories. In this review we will also illustrate the different types of payloads that can be used, and we will discuss recent developments in viral and non-viral vector technology.

Sleeping beauty generated CD19 CAR T-Cell therapy for advanced B-Cell hematological malignancies

Chimeric antigen receptor (CAR) T-cell therapy has emerged recently as a standard of care treatment for patients with relapsed or refractory acute lymphoblastic leukemia (ALL) and several subtypes of B-cell non-Hodgkin lymphoma (NHL). However, its use remains limited to highly specialized centers, given the complexity of its administration and its associated toxicities. We previously reported our experience in using a novel Sleeping Beauty (SB) CD19-specific CAR T-cell therapy in the peri-transplant setting, where it exhibited an excellent safety profile with encouraging survival outcomes. We have since modified the SB CD19 CAR construct to improve its efficacy and shorten its manufacturing time. We report here the phase 1 clinical trial safety results. Fourteen heavily treated patients with relapsed/refractory ALL and NHL were infused. Overall, no serious adverse events were directly attributed to the study treatment. Three patients developed grades 1-2 cytokine release syndrome and none of the study patients experienced neurotoxicity. All dose levels were well tolerated and no dose-limiting toxicities were reported. For efficacy, 3 of 8 (38%) patients with ALL achieved CR/CRi (complete remission with incomplete count recovery) and 1 (13%) patient had sustained molecular disease positivity. Of the 4 patients with DLBCL, 2 (50%) achieved CR. The SB-based CAR constructs allow manufacturing of targeted CAR T-cell therapies that are safe, cost-effective and with encouraging antitumor activity.

Natural killer cells in clinical development as non-engineered, engineered, and combination therapies

Natural killer (NK) cells are unique immune effectors able to kill cancer cells by direct recognition of surface ligands, without prior sensitization. Allogeneic NK transfer is a highly valuable treatment option for cancer and has recently emerged with hundreds of clinical trials paving the way to finally achieve market authorization. Advantages of NK cell therapies include the use of allogenic cell sources, off-the-shelf availability, and no risk of graft-versus-host disease (GvHD). Allogeneic NK cell therapies have reached the clinical stage as ex vivo expanded and differentiated non-engineered cells, as chimeric antigen receptor (CAR)-engineered or CD16-engineered products, or as combination therapies with antibodies, priming agents, and other drugs. This review summarizes the recent clinical status of allogeneic NK cell-based therapies for the treatment of hematological and solid tumors, discussing the main characteristics of the different cell sources used for NK product development, their use in cell manufacturing processes, the engineering methods and strategies adopted for genetically modified products, and the chosen approaches for combination therapies. A comparative analysis between NK-based non-engineered, engineered, and combination therapies is presented, examining the choices made by product developers regarding the NK cell source and the targeted tumor indications, for both solid and hematological cancers. Clinical trial outcomes are discussed and, when available, assessed in comparison with preclinical data. Regulatory challenges for product approval are reviewed, highlighting the lack of specificity of requirements and standardization between products. Additionally, the competitive landscape and business field is presented. This review offers a comprehensive overview of the effort driven by biotech and pharmaceutical companies and by academic centers to bring NK cell therapies to pivotal clinical trial stages and to market authorization.

Chimeric Antigen Receptor Immunotherapy for Solid Tumors: Choosing the Right Ingredients for the Perfect Recipe

Chimeric antigen receptor T cell therapies are revolutionizing the clinical practice of hematological tumors, whereas minimal progresses have been achieved in the solid tumor arena. Multiple reasons have been ascribed to this slower pace: The higher heterogeneity, the hurdles of defining reliable tumor antigens to target, and the broad repertoire of immune escape strategies developed by solid tumors are considered among the major ones. Currently, several CAR therapies are being investigated in preclinical and early clinical trials against solid tumors differing in the type of construct, the cells that are engineered, and the additional signals included with the CAR constructs to overcome solid tumor barriers. Additionally, novel approaches in development aim at overcoming some of the limitations that emerged with the approved therapies, such as large-scale manufacturing, duration of manufacturing, and logistical issues. In this review, we analyze the advantages and challenges of the different approaches under development, balancing the scientific evidences supporting specific choices with the manufacturing and regulatory issues that are essential for their further clinical development.

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

Allogeneic CD19-specific chimeric antigen receptor (CAR) T cells with inactivated donor T cell receptor (TCR) expression can be used as an "off-the-shelf" therapeutic modality for lymphoid malignancies, thus offering an attractive alternative to autologous, patient-derived T cells. Current approaches for T cell engineering mainly rely on the use of viral vectors. Here, we optimized and validated a non-viral genetic modification platform based on Sleeping Beauty (SB) transposons delivered with minicircles to express CD19-28z.CAR and CRISPR-Cas9 ribonucleoparticles to inactivate allogeneic TCRs. Efficient TCR gene disruption was achieved with minimal cytotoxicity and with attainment of robust and stable CD19-28z.CAR expression. The CAR T cells were responsive to CD19+ tumor cells with antitumor activities that induced complete tumor remission in NALM6 tumor-bearing mice while significantly reducing TCR alloreactivity and GvHD development. Single CAR signaling induced the similar T cell signaling signatures in TCR-disrupted CAR T cells and control CAR T cells. In contrast, TCR disruption inhibited T cell signaling/protein phosphorylation compared with the control CAR T cells during dual CAR/TCR signaling. This non-viral SB transposon-CRISPR-Cas9 combination strategy serves as an alternative for generating next-generation CD19-specific CAR T while reducing GvHD risk and easing potential manufacturing constraints intrinsic to viral vectors.

Clinical Strategies for Enhancing the Efficacy of CAR T-Cell Therapy for Hematological Malignancies

Chimeric antigen receptor (CAR) T cells have been successfully used for hematological malignancies, especially for relapsed/refractory B-cell acute lymphoblastic leukemia and non-Hodgkin’s lymphoma. Patients who have undergone conventional chemo-immunotherapy and have relapsed can achieve complete remission for several months with the infusion of CAR T-cells. However, side effects and short duration of response are still major barriers to further CAR T-cell therapy. To improve the efficacy, multiple targets, the discovery of new target antigens, and CAR T-cell optimization have been extensively studied. Nevertheless, the fact that the determination of the efficacy of CAR T-cell therapy is inseparable from the discussion of clinical application strategies has rarely been discussed. In this review, we will discuss some clinical application strategies, including lymphodepletion regimens, dosing strategies, combination treatment, and side effect management, which are closely related to augmenting and maximizing the efficacy of CAR T-cell therapy.

Donor-derived and off-the-shelf allogeneic anti-CD19 CAR T-cell therapy for R/R ALL and NHL: A systematic review and meta-analysis

Allogeneic anti-CD19 chimeric antigen receptor (CAR) T-cell therapy has the potential for extensive clinical applications. This study aimed to evaluate its efficacy and safety in treating relapsed or refractory (R/R) acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL). Four databases were searched for relevant studies. Among patients treated with donor-derived CAR T-cell therapy, ALL patients had a complete remission (CR) rate of 80 % and a 1-year overall survival rate of 51 %. The graft-versus-host disease (GvHD) rate was 4 %, cytokine release syndrome was 69 %, and immune effector cell-associated neurotoxicity syndrome was 8 %. For off-the-shelf CAR T-cell therapy, the CR rate for ALL was 70 %, and for NHL, it was 52 %. The objective response rate for NHL was 72 %. The pooled GvHD of off-the-shelf CAR T-cell therapy for ALL and NHL combined was 0 %. Allogeneic anti-CD19 CAR T-cell therapy are effective and safe for treating R/R ALL and NHL. AVAILABILITY OF DATA AND MATERIALS: All datasets generated in this study are included in the article/Supplementary Material.