Safety, efficacy and determinants of response of allogeneic CD19-specific CAR-NK cells in CD19+ B cell tumors: a phase 1/2 trial

Allogeneic chimeric antigen receptor cell therapies for cancer: progress made and remaining roadblocks

Chimeric antigen receptor (CAR) T cells are revolutionizing cancer therapy, particularly for haematological malignancies, conferring durable and sometimes curative responses in patients with advanced-stage disease. The CAR T cell products currently approved for clinical use are all autologous and are often effective; however, in patients who are lymphopenic and/or heavily pretreated with chemotherapy, autologous T cells can be difficult to harvest in sufficient numbers or have functional impairments that might ultimately render them less efficacious. Moreover, autologous products take several weeks to produce, and each product can be used in only one patient. By contrast, allogeneic CAR T cells can be produced for many patients using T cells from a single healthy donor, can be optimized for safety and efficacy, can be instantly available for 'off-the-shelf' use and, therefore, might also be more cost-effective. Despite these potential advantages, the development of allogeneic CAR T cells has lagged behind that of autologous products, owing to the additional challenges such as avoiding graft-versus-host disease and host-mediated graft rejection. Over the past few years, the development of advanced genome-editing techniques has facilitated the generation of novel allogeneic CAR T cell products. Furthermore, CAR cell products derived from other cell types such as induced pluripotent stem cells and natural killer cells are being investigated for clinical use. In this Review, we discuss the potential of allogeneic CAR cell products to expand life-saving immunotherapy to a much broader population of patients in the coming years, the progress made to date and strategies to overcome remaining hurdles.

Universal CAR cell therapy: Challenges and expanding applications

Chimeric Antigen Receptor (CAR) T cell therapy has gained success in adoptive cell therapy for hematological malignancies. Although most CAR cell therapies in clinical trials or markets remain autologous, their acceptance has been limited due to issues like lengthy manufacturing, poor cell quality, and demanding cost. Consequently, "Off-the-shelf", universal CAR (UCAR) cell therapy has emerged. Current concerns with UCAR therapies revolve around side effects such as graft versus host disease (GVHD) and host versus graft response (HVGR). Preclinical research on UCAR cell therapies aims to enhance efficacy and minimize these side effects. Common approaches involve gene editing techniques to knock out T cell receptor (TCR), human leukocyte antigen (HLA), and CD52 expression to mitigate GVHD and HVGR risks. However, these methods carry drawbacks including potential genotoxicity of the edited cells. Most recently, novel editing techniques, such as epigenetic editing and RNA writer systems, have been developed to reduce the risk of GVHD and HVGR, allowing for multiplex editing at different sites. Additionally, incorporating more cell types into UCAR cell therapies, like T-cell subtypes (DNT, γδT, virus-specific T cells) and NK cells, can efficiently target tumors without triggering side effects. In addition, the limited efficacy of T cells and NK cells against solid tumors is being addressed through CAR-Macrophages. In summary, CAR cell therapy has evolved to accommodate multiple cell types while expanding applications to various diseases, including hematologic malignancies and solid tumors, which holds tremendous growth potential and is promised to improve the lives of more patients in the future.

A bibliometric and knowledge-map study on the treatment of hematological malignancies with CAR-T cells from 2012 to 2023

Recently, CAR-T cell therapy in hematological malignancies has received extensive attention. The objective of this study is to gain a comprehensive understanding of the current research status, development trends, research hotspots, and emerging topics pertaining to CAR-T cells in the treatment of hematological malignancies. Articles pertaining to CAR-T cell therapy for hematological malignancies from the years 2012 to 2023 were obtained and assessed from the Web of Science Core Collection (WoSCC). A bibliometric approach was employed to conduct a scientific, comprehensive, and objective quantitative analysis, as well as a visual analysis, of this particular research domain. A comprehensive analysis was conducted on a corpus of 3643 articles, which were collaboratively authored by 72 countries and various research institutions. CAR-T cell research in treating hematological malignancies shows an increasing trend each year. Notably, the study identified the countries and institutions displaying the highest level of activity, the journals with the most citations and output, as well as the authors who garnered the highest frequency of citations and co-citations. Furthermore, the analysis successfully identified the research hotspots and highlighted six emerging topics within this domain. This study conducted a comprehensive exploration and analysis of the research status, development trends, research hotspots, and emerging topics about CAR-T cells in the treatment of hematological malignancies from 2012 to 2023. The findings of this study will serve as a valuable reference and guide for researchers seeking to delve deeper into this field and determine the future direction of their research.

CIMT 2024: Report on the 21st Annual Meeting of the Association for Cancer Immunotherapy

The 21st Association for Cancer Immunotherapy (CIMT) Annual Meeting took place from May 15th to May 17th in Mainz, Germany, and was attended by a total of 855 academic and clinical professionals hailing from 33 different countries. The conference served as a platform for these experts to convene and discuss the latest breakthroughs in cancer immunology and immunotherapy research. Dedicated sessions covering advancements in artificial intelligence tools for cancer immunotherapy research, as well as the landscape of cancer care and cancer immunotherapy trials on the African continent, prompted lively and informative discussions among the attendees. This report aims to provide an overview of the most noteworthy highlights and key takeaways from CIMT2024.

Chimeric antigen receptor-natural killer (CAR-NK) cell immunotherapy: A bibliometric analysis from 2004 to 2023

Chimeric antigen receptor-natural killer (CAR-NK) cells represent a breakthrough in cancer immunotherapy, making this a highly popular research area. However, comprehensive analyses of this field using bibliometric methods are rare. To our knowledge, this study has collected highest number of publications (1,259) on CAR-NK therapy from January 1, 2004, to December 31, 2023, and utilized CiteSpace and VOSviewer to analyze regions, institutions, journals, authors, and keywords to forecast the latest trends in CAR-NK therapy research. The United States and China, contributing over 60% of publications, are the primary drivers in this field. The Helmholtz Association and Harvard University are the most active institutions, with most publications appearing in Frontiers in Immunology. Winfried S. Wels is the most prolific author, while EL Liu is the most frequently co-cited author. "Immunotherapy," "T-cells," and "Cancer" are the most extensively covered topics in CAR-NK therapy research. Our study reveals current CAR-NK research trends, identifies potential research hotspots, and visualizes references through bibliometric methods, providing valuable guidance for future research in this field.

Bulk and single-cell transcriptomics identify gene signatures of stem cell-derived NK cell donors with superior cytolytic activity

Allogeneic natural killer (NK) cell therapies are a valuable treatment option for cancer, given their remarkable safety and favorable efficacy profile. Although the use of allogeneic donors allows for off-the-shelf and timely patient treatment, intrinsic interindividual differences put clinical efficacy at risk. The identification of donors with superior anti-tumor activity is essential to ensure the success of adoptive NK cell therapies. Here, we investigated the heterogeneity of 10 umbilical cord blood stem cell-derived NK cell batches. First, we evaluated the donors' cytotoxic potential against tumor cell lines from solid and hematological cancer indications, to distinguish a group of superior, "excellent" killers (4/10), compared with "good" killers (6/10). Next, bulk and single-cell RNA sequencing, performed at different stages of NK differentiation, revealed distinct transcriptomic features of the two groups. Excellent donors showed an enrichment in cytotoxicity pathways and a depletion of myeloid traits, linked to the presence of a larger population of effector-like NK cells early on during differentiation. Consequently, we defined a multi-factorial gene expression signature able to predict the donors' cytotoxic potential. Our study contributes to the identification of key traits of superior NK cell batches, supporting the development of efficacious NK therapeutics and the achievement of durable anti-tumor responses.

Anti-CD19 CAR T-cell therapy for primary and secondary CNS lymphomas

Central nervous system lymphomas (CNSL) are a heterogeneous group of generally aggressive tumors whose prognosis varies significantly, being more favorable in patients with primary disease and poorer in those with secondary lymphoma. Current treatments typically involve intensive chemotherapy followed by consolidation with autologous stem cell transplantation or whole-brain radiotherapy. However, if the disease relapses, there is no established standard of care. The recent approval of anti-CD19 chimeric antigen receptor (CAR) T-cell therapy for systemic B-cell lymphomas has shifted the treatment landscape for previously incurable patients. Even though this therapy was initially underexplored in the setting of CNSL due to safety and efficacy concerns, it could offer a new therapeutic avenue for these patients. In this review, we will provide a concise overview of the current treatment strategies for CNSL, highlighting their key limitations, including relapse rates and long-term toxicity. Following this, we will explore the most important studies and clinical trials on CNSL, focusing on recent advancements in anti-CD19 CAR T-cell therapy. This comprehensive analysis will offer insights into the successes and challenges of treating CNSL effectively.

CAR-NK cells derived from cord blood originate mainly from CD56-CD7+CD34-HLA-DR-Lin- NK progenitor cells

Cord blood (CB)-derived chimeric antigen receptor (CAR)-natural killer (NK) cells targeting CD19 have been shown to be effective against B cell malignancies. While human CD56+ NK cells can be expanded in vitro, NK cells can also be differentiated from hematopoietic progenitor cells. It is still unclear whether CAR-NK cells originate from mature NK cells or NK progenitor cells in CB. Here, we determined that CAR-NK cells were predominantly derived from CD56- NK progenitor cells. We first found that substantial numbers of CD19 CAR-NK cells were produced from CD56- CB mononuclear cells after in vitro culture for 2 weeks. Single-cell RNA sequencing analysis of CD56-CD3-CD14-CD19- CB mononuclear cells revealed that these cells could be subdivided into three subpopulations based on the expression of CD34 and human leukocyte antigen (HLA)-DR. NK cells originated primarily from CD34-HLA-DR- cells. In addition, among the CD34-HLA-DR- cells, only CD7+ cells could differentiate into NK cells. These results indicate that CD56-CD7+CD34-HLA-DR- lineage marker (Lin)- cells are the major origin of human CB-derived CAR-NK cells, indicating the importance of developing methods to enhance the quality and quantity of NK cells produced from these NK progenitor cells.

From tumor microenvironment to emerging biomarkers: the reshaping of the esophageal squamous cell carcinoma tumor microenvironment by neoadjuvant chemotherapy combined with immunotherapy

Esophageal squamous cell carcinoma is a cancer with high morbidity and mortality. The advent of immune checkpoint inhibitors has significantly increased complete response rates and postoperative R0 resection rates after neoadjuvant therapy. These drugs can largely reverse the suppression of the immune system caused by the tumor microenvironment, allowing the reactivation of anti-tumor immune infiltrating cells, significantly improving the patient's tumor microenvironment, and thus preventing tumor development. However, there are still some patients who respond poorly to neoadjuvant combined immunotherapy and cannot achieve the expected results. It is now found that exploring changes in the tumor microenvironment not only elucidates patient responsiveness to immunotherapy and identifies more reliable biomarkers, but also addresses the limitations of prediction with imaging examination such as CT and the instability of existing biomarkers. In light of these considerations, this review aims to delve into the alterations within the tumor microenvironment and identify potential predictive biomarkers ensuing from neoadjuvant immunotherapy in the context of esophageal squamous cell carcinoma.

The development and application of chimeric antigen receptor natural killer (CAR-NK) cells for cancer therapy: current state, challenges and emerging therapeutic advances

Immunotherapy has transformed the landscape of cancer treatment, with chimeric antigen receptor (CAR)-engineered T (CAR-T) cell therapy emerging as a front runner in addressing some hematological malignancies. Despite its considerable efficacy, the occurrence of severe adverse effects associated with CAR-T cell therapy has limited their scope and prompted the exploration of alternative therapeutic strategies. Natural killer (NK) cells, characterized by both their innate cytotoxicity and ability to lyse target cells without the constraint of peptide specificity conferred by a major histocompatibility complex (MHC), have similarly garnered attention as a viable immunotherapy. As such, another therapeutic approach has recently emerged that seeks to combine the continued success of CAR-T cell therapy with the flexibility of NK cells. Clinical trials involving CAR-engineered NK (CAR-NK) cell therapy have exhibited promising efficacy with fewer deleterious side effects. This review aims to provide a concise overview of the cellular and molecular basis of NK cell biology, facilitating a better understanding of advancements in CAR design and manufacturing. The focus is on current approaches and strategies employed in CAR-NK cell development, exploring at both preclinical and clinical settings. We will reflect upon the achievements, advantages, and challenges intrinsic to CAR-NK cell therapy. Anticipating the maturation of CAR-NK cell therapy technology, we foresee its encouraging prospects for a broader range of cancer patients and other conditions. It is our belief that this CAR-NK progress will bring us closer to making significant strides in the treatment of refractory and recurrent cancers, as well as other immune-mediated disorders.

Haploidentical hematopoietic cell transplantation as a platform for natural killer cell immunotherapy

An innovative approach is crucially needed to manage relapse after allogeneic hematopoietic cell transplantation (HCT) in patients with advanced hematological malignancies. This review explores key aspects of haploidentical HCT with post-transplant cyclophosphamide, highlighting the potential and suitability of this platform for natural killer (NK) cell immunotherapy. NK cells, known for their unique abilities to eliminate cancer cells, can also exhibit memory-like features and enhanced cytotoxicity when activated by cytokines. By discussing promising results from clinical trials, the review delves into the recent major advances: donor-derived NK cells can be expanded ex vivo in large numbers, cytokine activation may enhance NK cell persistence and efficacy in vivo, and post-HCT NK cell infusion can improve outcomes in high-risk and/or relapsed myeloid malignancies without increasing the risk of graft-versus-host disease, severe cytokine release syndrome, or neurotoxicity. Looking ahead, cytokine-activated NK cells can be synergized with immunomodulatory agents and/or genetically engineered to enhance their tumor-targeting specificity, cytotoxicity, and persistence while preventing exhaustion. The ongoing exploration of these strategies holds promising preliminary results and could be rapidly translated into clinical applications for the benefit of the patients.

Mesothelin CAR-engineered NK cells derived from human embryonic stem cells suppress the progression of human ovarian cancer in animals

CAR-NK cell therapy does not require HLA matching and has minimal side effects. However, traditional methods of engineering CARs into human tissue-derived NK cells exhibit heterogeneity, low transduction efficiency, and high manufacturing costs. Here, we provide a reliable approach for generating large-scale and cryopreserved mesothelin (MSLN) CAR-NK cells from human embryonic stem cells (hESCs) as an alternative cell source. We first constructed MSLN CAR-expressing hESCs to reduce CAR engineering costs and subsequently differentiated these stem cells into MSLN CAR-NK cells via an efficient organoid induction system. The MSLN CAR-NK cells exhibit the typical expression patterns of activating receptors, inhibitory receptors, and effector molecules of NK cells. In the presence of tumour cells, the MSLN CAR-NK cells show increased secretion of IFN-γ and TNF-α, as well as elevated CD107a expression level compared with induced NK cells. We cryopreserved the MSLN CAR-NK cells in liquid nitrogen using a clinical-grade freezing medium (CS10) for more than 6 months to mimic an off-the-shelf CAR-NK cell product. The thawed MSLN CAR-NK cells immediately recovered after 48-72-h culture and effectively eliminated ovarian tumour cells, including human primary ovarian tumour cells from patients. The thawed MSLN CAR-NK cells efficiently suppressed ovarian tumour development in vivo and prolonged the survival of tumour-bearing mice. Our study provides insights into the clinical translation of hESC-derived MSLN CAR-NK cells as a promising off-the-shelf cell product.

Advances in cell therapy: progress and challenges in hematological and solid tumors

Cell-based therapies harness the endogenous ability of the immune system to fight cancer and have shown promising results in the treatment of hematological malignancies. However, their clinical application beyond B cell malignancies is hampered by numerous hurdles, ranging from relapsed disease to a hostile tumor microenvironment (TME). Recent advances in cell engineering and TME modulation may expand the applicability of these therapies to a wider range of cancers, creating new treatment possibilities. Breakthroughs in advanced gene editing and sophisticated cell engineering, have also provided promising solutions to longstanding challenges. In this review, we examine the challenges and future directions of the most prominent cell-based therapies, including chimeric antigen receptor (CAR)-T cells, tumor-infiltrating lymphocytes (TILs), and natural killer (NK) cells, and emerging modalities. We provide a comprehensive analysis of emerging cell types and combination strategies translated into clinical trials, offering insights into the next generation of cell-based cancer treatments.

Breaking barriers: advancing cellular therapies in autoimmune disease management

Autoimmune diseases occur due to a dysregulation within the immune system, leading to an aberrant assault on the organism's own tissues. The pathogenesis of these conditions is multifactorial, encompassing intricate interplays among genetic predispositions, environmental determinants, and hormonal fluctuations. The spectrum of autoimmune diseases is broad, impacting a multitude of organ systems, with notable examples such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS), psoriasis, and vitiligo. Despite substantial progress in therapeutic interventions over recent years, a definitive cure for autoimmune diseases has yet to be realized, with existing modalities largely providing palliative care. Cellular therapy is considered the fourth pillar in the management of oncological disorders subsequent to surgical resection, radiotherapy, and chemotherapy. Cellular therapies have shown potential in augmenting immune competence and eliminating of targeted neoplastic cells in a spectrum of cancers. As targeting specific molecules on the surface of autoreactive B and T cells, such as CD19, BCMA, CD20, and CTLA-4, cellular therapies are emerging as promising approaches for the treatment of autoimmune diseases. This review delineates the advancements in the application of cellular therapies applied recently for autoimmune diseases and proposes considerations for the advancement of novel therapeutic strategies.

Hypoimmunogenic CD19 CAR-NK cells derived from embryonic stem cells suppress the progression of human B-cell malignancies in xenograft animals

Background

Chimeric antigen receptor (CAR) engineered natural killer (NK) cells exhibit advantages such as MHC-independent recognition and strong anti-tumor functions. However, allogeneic CAR-NK cells derived from human tissues are heterogeneous and susceptible to clearance by hosts.

Methods

We generated a B2M knockout, HLA-E and CD19 CAR ectopic expressing embryonic stem cell (ESC) line, which differentiated normally and gave rise to homogeneous CD19 CAR-NK (CD19 CAR-UiNK) cells using an organoid aggregate induction method. The CD19 CAR-UiNK were co-cultured with T cells or NK cells derived from peripheral blood mononuclear cells (PBMC) with the mismatched HLA to evaluate the immunogenicity of CD19 CAR-UiNK cells. We further assessed the therapeutic effects of CD19 CAR-UiNK cells on CD19+ tumor cells through in vitro cytotoxicity assays and in vivo animal models.

Results

The CD19 CAR-UiNK cells exhibited typical expression patterns of activating and inhibitory receptors, and crucial effector molecules of NK cells, similar to those of unmodified NK cells. In co-culture assays, the CD19 CAR-UiNK cells evaded allogeneic T cell response and suppressed allogeneic NK cell response. Functionally, the CD19 CAR-UiNK cells robustly secreted IFN-γ and TNF-α, and upregulated CD107a upon stimulation with Nalm-6 tumor cells. The CD19 CAR-UiNK cells effectively eliminated CD19+ tumor cells in vitro, including B-cell cancer cell lines and primary tumor cells from human B-cell leukemia and lymphoma. Further, the CD19 CAR-UiNK cells exhibited strong anti-tumor activity in xenograft animals.

Conclusion

We offer a strategy for deriving homogeneous and hypoimmunogenic CD19 CAR-iNK cells with robust anti-tumor effects from ESCs. Our study has significant implications for developing hypoimmunogenic CD19 CAR-NK cell therapy using human ESC as an unlimited cell source.

Efficacy of chimeric antigen receptor engineered natural killer cells in the treatment of hematologic malignancies: a systematic review and meta-analysis of preclinical studies

BACKGROUND

Chimeric antigen receptor (CAR) engineered NK cells (CAR-NK) are a novel approach to the immunotherapy of hematologic malignancies which seeks to overcome some of the challenges faced by CAR-T cells (CAR-T). With few published clinical studies, preclinical studies can identify strategies to accelerate clinical translation. We conducted a systematic review on the preclinical in vivo use of CAR-NK for the treatment of hematologic malignancies to assess these therapies in a holistic and unbiased manner.

METHODS

Our protocol was registered with PROSPERO (ID: CRD42023438375). We performed a search of OVID MEDLINE, OVID Embase, and Embase for animal studies employing human CAR-NK cells in the treatment of hematologic malignancies. Screening of studies for eligibility criteria was performed in duplicate. Our primary outcomes were survival and reduction in tumor volume. Data extraction from individual experiments was performed by one reviewer using DigitizeitTM software and verified by a second reviewer. Meta-analysis and subgroup analyses were performed using Comprehensive Meta-AnalysisTM software. Information for descriptive outcomes was extracted in duplicate by two independent reviewers. Risk of bias was assessed using the SYRCLE Risk of Bias Tool for Animal Studies.

RESULTS

A total of 34 papers met eligibility criteria. Overall, CD19 was the most common antigen targeted however there was substantial diversity in antigenic targets, source material for generating CAR-NK cells, and NK cell modifications. Mice treated with CAR-NK therapy survived significantly longer than untreated mice (median survival ratio of 1.18, 95% CI: 1.10-1.27, P < 0.001), and mice treated with nonengineered NK cells (median survival ratio 1.13, 95% CI: 1.03-1.23, P < 0.001). Similarly, treatment with CAR-NK significantly reduced the tumor burden when compared to untreated mice (ratio of mean tumor volume 0.23, 95% CI: 0.17-0.32, P < 0.001) or mice treated with nonengineered NK cells (ratio of mean tumor volume 0.37, 95% CI: 0.28-0.51, P < 0.001). Subgroup analysis showed that cotreatment with IL-15 reduced tumor volume but did not increase survival. In general, CAR-NK cell persistence was short but was increased by IL-15.

CONCLUSIONS

CAR-NK shows promise for the treatment of hematologic malignancies in preclinical models.

Epigenome Reprogramming Through H3K27 and H3K4 Trimethylation as a Resistance Mechanism to DNA Methylation Inhibition in BRAFV600E-Mutated Colorectal Cancer

PURPOSE

BRAFV600E-mutated colorectal cancer exhibits a strong correlation with DNA hypermethylation, suggesting that this subgroup of tumors presents unique epigenomic phenotypes. Nonetheless, 5-azacitidine, which inhibits DNA methyltransferase activity, is not efficacious in BRAFV600E colorectal cancer in vivo.

EXPERIMENTAL DESIGN

We randomized and treated mice implanted with patient-derived tumor xenografts harboring BRAFV600E mutation with control, 5-azacitidine, vemurafenib (BRAF inhibitor), or the combination. Comprehensive epigenomic profiling was conducted on control and 5-azacitidine-treated tumor samples, including DNA methylation, histone modifications, chromatin accessibility, and gene expression. Combinations of epigenetic agents were explored in preclinical BRAFV600E colorectal cancer models.

RESULTS

A profound reduction of DNA methylation levels upon 5-azacitidine treatment was confirmed, however, transcriptional repression was not relieved. This study unbiasedly explored the adaptive engagement of other epigenomic modifications upon 5-azacitidine treatment. A loss of histone acetylation and a gain of histone methylations, including H3K27 and H3K4 trimethylation, were observed around these hypomethylated regions, suggesting the involvement of polycomb repressive complex (PRC) activity around the genome with loss of DNA methylation, therefore maintaining the repression of key tumor-suppressor genes. Combined inhibition of PRC activity through EZH2 inhibition with 5-azacitidine treatment additively improved efficacies in BRAFV600E colorectal cancer cells.

CONCLUSIONS

In conclusion, DNA hypomethylation by 5-azacitidine exhibits a close association with H3K27me3 and PRC activity in BRAFV600E colorectal cancer, and simultaneous blockade of DNA methyltransferase and EZH2 holds promise as a potential therapeutic strategy for patients with BRAFV600E-mutated colorectal cancer.

Comprehensive snapshots of natural killer cells functions, signaling, molecular mechanisms and clinical utilization

Natural killer (NK) cells, initially identified for their rapid virus-infected and leukemia cell killing and tumor destruction, are pivotal in immunity. They exhibit multifaceted roles in cancer, viral infections, autoimmunity, pregnancy, wound healing, and more. Derived from a common lymphoid progenitor, they lack CD3, B-cell, or T-cell receptors but wield high cytotoxicity via perforin and granzymes. NK cells orchestrate immune responses, secreting inflammatory IFNγ or immunosuppressive TGFβ and IL-10. CD56dim and CD56bright NK cells execute cytotoxicity, while CD56bright cells also regulate immunity. However, beyond the CD56 dichotomy, detailed phenotypic diversity reveals many functional subsets that may not be optimal for cancer immunotherapy. In this review, we provide comprehensive and detailed snapshots of NK cells' functions and states of activation and inhibitions in cancer, autoimmunity, angiogenesis, wound healing, pregnancy and fertility, aging, and senescence mediated by complex signaling and ligand-receptor interactions, including the impact of the environment. As the use of engineered NK cells for cancer immunotherapy accelerates, often in the footsteps of T-cell-derived engineering, we examine the interactions of NK cells with other immune effectors and relevant signaling and the limitations in the tumor microenvironment, intending to understand how to enhance their cytolytic activities specifically for cancer immunotherapy.

A scalable, spin-free approach to generate enhanced induced pluripotent stem cell-derived natural killer cells for cancer immunotherapy

Natural killer (NK) cells play a vital role in innate immunity and show great promise in cancer immunotherapy. Traditional sources of NK cells, such as the peripheral blood, are limited by availability and donor variability. In addition, in vitro expansion can lead to functional exhaustion and gene editing challenges. This study aimed to harness induced pluripotent stem cell (iPSC) technology to provide a consistent and scalable source of NK cells, overcoming the limitations of traditional sources and enhancing the potential for cancer immunotherapy applications. We developed human placental-derived iPSC lines using reprogramming techniques. Subsequently, an optimized two-step differentiation protocol was introduced to generate high-purity NK cells. Initially, iPSCs were differentiated into hematopoietic-like stem cells using spin-free embryoid bodies (EBs). Subsequently, the EBs were transferred to ultra-low attachment plates to induce NK cell differentiation. iPSC-derived NK (iNK) cells expressed common NK cell markers (NKp46, NKp30, NKp44, CD16 and eomesodermin) at both RNA and protein levels. iNK cells demonstrated significant resilience to cryopreservation and exhibited enhanced cytotoxicity. The incorporation of a chimeric antigen receptor (CAR) construct further augmented their cytotoxic potential. This study exemplifies the feasibility of generating iNK cells with high purity and enhanced functional capabilities, their improved resilience to cryopreservation and the potential to have augmented cytotoxicity through CAR expression. Our findings offer a promising pathway for the development of potential cellular immunotherapies, highlighting the critical role of iPSC technology in overcoming challenges associated with traditional NK cell sources.

An Extended Flow Cytometry Evaluation of ex Vivo Expanded NK Cells Using K562.Clone1, a Feeder Cell Line Manufactured in Brazil

Natural killer (NK) cells play a crucial role in the immune system's response against cancer. However, the challenge of obtaining the required quantity of NK cells for effective therapeutic response necessitates the development of strategies for their ex vivo expansion. This study aimed to develop a novel feeder cell line, K562.Clone1, capable of promoting the ex vivo expansion of NK cells while preserving their cytotoxic potential. he K562 leukemic cell line was transduced with mbIL-21 and 4-1BBL proteins to generate K562.Clone1 cells. NK cells were then co-cultured with these feeder cells, and their expansion rate was monitored over 14 days. The cytotoxic potential of the expanded NK cells was evaluated against acute myeloid leukemia blasts and tumor cell lines of leukemia and glial origin. Statistical analysis was performed to determine the significance of the results. The K562.Clone1 co-cultured with peripheral NK showed a significant increase in cell count, with an approximate 94-fold expansion over 14 days. Expanded NK cells demonstrated cytotoxicity against the tested tumor cell lines, indicating preservation of their cytotoxic characteristics. Additionally, the CD56, CD16, inhibitory KIRs, and activation receptors were conserved and present in a well-balanced manner. The study successfully developed a feeder cell line, K562.Clone1, that effectively promotes the expansion of NK cells ex vivo while maintaining their cytotoxic potential. This development could significantly contribute to the advancement of NK cell therapy, especially in Brazil.

Genetically modified and unmodified cellular approaches to enhance graft versus leukemia effect, without increasing graft versus host disease: the use of allogeneic cytokine-induced killer cells

Although allogeneic hematopoietic cell transplantation (HCT) represents a curative approach for many patients with hematological diseases, post-transplantation relapse occurs in 20-50% of cases, representing the primary cause of treatment failure and mortality. Alloreactive donor T cells are responsible for the graft versus leukemia (GvL) effect, which represents the key mechanism for the long-term curative effect of HCT. However, the downside is represented by graft versus host disease (GvHD), largely contributing to transplant-related mortality (TRM). Multiple factors play a role in regulating the delicate balance between GvL and GvHD, such as the optimization of the donor HLA and KIR match, the type of graft source, and the adaptive use of post-transplant cellular therapy. In addition to the standard donor lymphocyte infusion (DLI), several attempts were made to favor the GvL effect without increasing the GvHD risk. Selected DLI, NK DLI, activated DLI and more sophisticated genetically engineered cells can be employed. In this scenario, cytokine-induced killer (CIK) cells represent a suitable tool to boost GvL while minimizing GvHD. CIK cells are T lymphocytes activated in culture in the presence of monoclonal antibodies against CD3 (OKT3), interferon-gamma (IFN-g), and interleukin-2 (IL-2), characterized by the expression of markers typical of NK cells and T cells (CD3+, CD56+, with a prevalent CD8+ phenotype). CIK cells can mediate cytotoxicity through both MHC and non-MHC restricted recognition, which is the so-called "dual-functional capability" and display minimum alloreactivity. Allogeneic CIK cells showed a favorable rate of response, especially in the setting of minimal residual disease, with a rate of GvHD not exceeding 25%. Finally, the CIK cell platform can be adapted for chimeric antigen receptor (CAR) cell strategy, showing promising results in both preclinical and clinical settings. In this review, we describe the main immunological basis for the development of the GvL and the possible cellular therapy approaches used to boost it, with a particular focus on the use of CIK cells.

Releasing our model T - chimeric antigen receptor (CAR) T-cells for autoimmune indications

PURPOSE OF REVIEW

This review provides an update on the rapidly growing field of engineered cellular therapies for autoimmune disorders, primarily focusing on clinical experience and correlative studies with chimeric antigen receptor (CAR) T-cells.

RECENT FINDINGS

To date, two case series describing treatment with CAR T-cell therapy for systemic lupus erythematosus (SLE) suggest that drug-free remission can be sustained in patients with previously treatment-refractory disease. The outcomes of these studies are similar, despite the use of different CAR constructs and lymphodepletion regimens. Although it is not yet clear whether the patients described have truly been cured, the majority of remissions have remained durable up to last follow-up at 1-2 years from treatment. Meanwhile, mechanistic studies are providing a window into how transient B-cell depletion mediates lasting benefit. With the encouraging data in SLE, CAR T-cells and other novel B-cell-depleting agents (e.g. bispecific T-cell engagers) are now being evaluated as treatment for other autoimmune conditions, with the goal of durable response.

SUMMARY

Recent reports highlight cellular therapies as a promising strategy for patients with treatment-refractory autoimmune conditions; however, there is still limited experience, and better insight into this therapeutic approach is expected to emerge rapidly.

Optimizing the procedure for manufacturing clinical-grade genetically manipulated natural killer cells for adoptive immunotherapy

BACKGROUND AIMS

Ex vivo-expanded natural killer (NK) cells hold significant potential as antitumor effector cells for adoptive immunotherapy. However, producing clinical-grade, genetically modified NK cells in sufficient quantities presents a considerable challenge.

METHODS

We tested RPMI 1640, KBM581, SCGM, NK MACS, X-VIVO 15 and AIM-V, each supplemented with fetal bovine serum, human AB serum, human platelet lysate or Immune Cell Serum Replacement (SR) combined with feeder cells, to produce cytotoxic NK cells. Subsequent analyses were conducted to assess cell viability, expansion folds, cytotoxicity, immunophenotype and transcriptome profile of NK cells under certain conditions. Furthermore, transfer plasmids varying in transgene size, promoter elements, backbones and packaging plasmids with different envelopes were used to transduce NK cells, and differences in transduction efficiency were compared. Nucleofection was performed every 2 days from day 0 to day 12 to determine the optimal time window for gene editing.

RESULTS

NK cells cultured in KBM581 medium supplemented with serum replacement exhibited the best expansion, achieving greater than 5000-fold increase within 2 weeks and exceeding 25 000-fold expansion within 3 weeks. In addition, NK cells cultured in KBM581 medium with human AB serum demonstrated the greatest cytolytic activities and exhibited greater expression of NKp30, 2B4, PRF1, granzyme B and IL2RG. Baboon envelope pseudotyped lentivirus outperformed baboon envelope-vesicular stomatitis virus type G hybrid envelope lentivirus, achieving robust NK-cell transduction. In addition, efficient gene knockout efficiency was achieved in NK cells on day 4 to day 6 post feeder cell activation using the LONZA DN-100 program, which can strike a balance between editing efficiency and cell expansion.

CONCLUSIONS

This research presents a Good Manufacturing Practice-compliant protocol using a feeder cell expansion system for the large-scale production of highly cytotoxic NK cells. The protocol facilitates genetic modification of these cells, positioning them as promising candidates for universal therapeutic applications in immunotherapy.

Tumor Biology Hides Novel Therapeutic Approaches to Diffuse Large B-Cell Lymphoma: A Narrative Review

Diffuse large B-cell lymphoma (DLBCL) is a malignancy of immense biological and clinical heterogeneity. Based on the transcriptomic or genomic approach, several different classification schemes have evolved over the years to subdivide DLBCL into clinically (prognostically) relevant subsets, but each leaves unclassified samples. Herein, we outline the DLBCL tumor biology behind the actual and potential drug targets and address the challenges and drawbacks coupled with their (potential) use. Therapeutic modalities are discussed, including small-molecule inhibitors, naked antibodies, antibody-drug conjugates, chimeric antigen receptors, bispecific antibodies and T-cell engagers, and immune checkpoint inhibitors. Candidate drugs explored in ongoing clinical trials are coupled with diverse toxicity issues and refractoriness to drugs. According to the literature on DLBCL, the promise for new therapeutic targets lies in epigenetic alterations, B-cell receptor and NF-κB pathways. Herein, we present putative targets hiding in lipid pathways, ferroptosis, and the gut microbiome that could be used in addition to immuno-chemotherapy to improve the general health status of DLBCL patients, thus increasing the chance of being cured. It may be time to devote more effort to exploring DLBCL metabolism to discover novel druggable targets. We also performed a bibliometric and knowledge-map analysis of the literature on DLBCL published from 2014-2023.

The future of genetic medicines delivered via targeted lipid nanoparticles to leukocytes

Genetic medicines hold vast therapeutic potential, offering the ability to silence or induce gene expression, knock out genes, and even edit DNA fragments. Applying these therapeutic modalities to leukocytes offers a promising path for treating various conditions yet overcoming the obstacles of specific and efficient delivery to leukocytes remains a major bottleneck in their clinical translation. Lipid nanoparticles (LNPs) have emerged as the leading delivery system for nucleic acids due to their remarkable versatility and ability to improve their in vivo stability, pharmacokinetics, and therapeutic benefits. Equipping LNPs with targeting moieties can promote their specific cellular uptake and internalization to leukocytes, making targeted LNPs (tLNPs) an inseparable part of developing leukocyte-targeted gene therapy. However, despite the significant advancements in research, genetic medicines for leukocytes using targeted delivery approaches have not been translated into the clinic yet. Herein, we discuss the important aspects of designing tLNPs and highlight the considerations for choosing an appropriate bioconjugation strategy and targeting moiety. Furthermore, we provide our insights on limiting challenges and identify key areas for further research to advance these exciting therapies for patient care.

Antitumor effects of intracranial injection of B7-H3-targeted Car-T and Car-Nk cells in a patient-derived glioblastoma xenograft model

BACKGROUND

Glioblastoma multiforme (GBM) is the most lethal primary brain tumor for which novel therapies are needed. Recently, chimeric antigen receptor (CAR) T cell therapy has been shown to be effective against GBM, but it is a personalized medicine and requires high cost and long time for the cell production. CAR-transduced natural killer (NK) cells can be used for "off-the-shelf" cellular immunotherapy because they do not induce graft-versus-host disease. Therefore, we aimed to analyze the anti-GBM effect of CAR-T or NK cells targeting B7-H3, which is known to be highly expressed in GBM.

METHODS

CAR-T cells targeting B7-H3 were generated using previously reported anti-B7-H3 scFv sequences. Cord blood (CB)-derived NK cells transduced with the B7-H3 CAR were also generated. Their anti-GBM effect was analyzed in vitro. The antitumor effect of intracranial injection of the B7-H3 CAR-T or NK cells was investigated in an in vivo xenograft model with patient-derived GBM cells.

RESULTS

Both B7-H3 CAR-T cells and CAR-NK cells exhibited marked cytotoxicity against patient-derived GBM cells in vitro. Furthermore, intracranial injection of CAR-T cells and CAR-NK cells targeting B7-H3 resulted in a significant antitumor effect against patient-derived GBM xenografts.

CONCLUSION

Not only CAR-T cells but also CB-derived CAR-NK cells targeting B7-H3 may have the potential to eliminate GBM cells.

CD28 Costimulation Augments CAR Signaling in NK Cells via the LCK/CD3ζ/ZAP70 Signaling Axis

Multiple factors in the design of a chimeric antigen receptor (CAR) influence CAR T-cell activity, with costimulatory signals being a key component. Yet, the impact of costimulatory domains on the downstream signaling and subsequent functionality of CAR-engineered natural killer (NK) cells remains largely unexplored. Here, we evaluated the impact of various costimulatory domains on CAR-NK cell activity, using a CD70-targeting CAR. We found that CD28, a costimulatory molecule not inherently present in mature NK cells, significantly enhanced the antitumor efficacy and long-term cytotoxicity of CAR-NK cells both in vitro and in multiple xenograft models of hematologic and solid tumors. Mechanistically, we showed that CD28 linked to CD3ζ creates a platform that recruits critical kinases, such as lymphocyte-specific protein tyrosine kinase (LCK) and zeta-chain-associated protein kinase 70 (ZAP70), initiating a signaling cascade that enhances CAR-NK cell function. Our study provides insights into how CD28 costimulation enhances CAR-NK cell function and supports its incorporation in NK-based CARs for cancer immunotherapy. Significance: We demonstrated that incorporation of the T-cell-centric costimulatory molecule CD28, which is normally absent in mature natural killer (NK) cells, into the chimeric antigen receptor (CAR) construct recruits key kinases including lymphocyte-specific protein tyrosine kinase and zeta-chain-associated protein kinase 70 and results in enhanced CAR-NK cell persistence and sustained antitumor cytotoxicity.

A structural, genetic and clinical comparison of CAR-T cells and CAR-NK cells: companions or competitors?

In recent years, following the groundbreaking achievements of chimeric antigen receptor (CAR) T cell therapy in hematological cancers, and advancements in cell engineering technologies, the exploration of other immune cells has garnered significant attention. CAR-Therapy extended beyond T cells to include CAR natural killer (NK) cells and CAR-macrophages, which are firmly established in the clinical trial landscape. Less conventional immune cells are also making their way into the scene, such as CAR mucosal-associated invariant T (MAIT) cells. This progress is advancing precision medicine and facilitating the development of ready-to-use biological treatments. However, in view of the unique features of natural killer cells, adoptive NK cell immunotherapy has emerged as a universal, allogenic, "off-the shelf" therapeutic strategy. CAR-NK cytotoxic cells present targeted tumor specificity but seem to be devoid of the side effects associated with CAR-T cells. CAR-NK cells appear to be potentially promising candidates for cancer immunotherapy. However, their application is hindered by significant challenges, particularly the limited persistence of CAR-NK cells in the body, which poses a hurdle to their sustained effectiveness in treating cancer. Based upon the foregoing, this review discusses the current status and applications of both CAR-T cells and CAR-NK cells in hematological cancers, and provides a comparative analysis of the structure, genetics, and clinical outcomes between these two types of genetically modified immune cells.

Advances in targeting tumor microenvironment for immunotherapy

The tumor microenvironment (TME) provides essential conditions for the occurrence, invasion, and spread of cancer cells. Initial research has uncovered immunosuppressive properties of the TME, which include low oxygen levels (hypoxia), acidic conditions (low pH), increased interstitial pressure, heightened permeability of tumor vasculature, and an inflammatory microenvironment. The presence of various immunosuppressive components leads to immune evasion and affects immunotherapy efficacy. This indicates the potential value of targeting the TME in cancer immunotherapy. Therefore, TME remodeling has become an effective method for enhancing host immune responses against tumors. In this study, we elaborate on the characteristics and composition of the TME and how it weakens immune surveillance and summarize targeted therapeutic strategies for regulating the TME.

CAR immunotherapy in autoimmune diseases: promises and challenges

In recent years, the use of chimeric antigen receptor (CAR)-T cells has emerged as a promising immunotherapy in multiple diseases. CAR-T cells are T cells genetically modified to express a surface receptor, known as CAR, for the targeting of cognate antigens on specific cells. The effectiveness of CAR-T cell therapy in hematologic malignancies including leukemia, myeloma, and non-Hodgkin's lymphoma has led to consider its use as a potential avenue of treatment for autoimmune diseases. However, broadening the use of CAR-T cell therapy to a large spectrum of autoimmune conditions is challenging particularly because of the possible development of side effects including cytokine release syndrome and neurotoxicity. The design of CAR therapy that include additional immune cells such as double-negative T cells, γδ T cells, T regulatory cells and natural killer cells has shown promising results in preclinical studies and clinical trials in oncology, suggesting a similar potential utility in the treatment of autoimmune diseases. This review examines the mechanisms, efficacy, and safety of CAR approaches with a focus on their use in autoimmune diseases including systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, multiple sclerosis, myasthenia gravis, lupus nephritis and other autoimmune diseases. Advantages and disadvantages as compared to CAR-T cell therapy will also be discussed.

CAR-T and CAR-NK as cellular cancer immunotherapy for solid tumors

In the past decade, chimeric antigen receptor (CAR)-T cell therapy has emerged as a promising immunotherapeutic approach for combating cancers, demonstrating remarkable efficacy in relapsed/refractory hematological malignancies in both pediatric and adult patients. CAR-natural killer (CAR-NK) cell complements CAR-T cell therapy by offering several distinct advantages. CAR-NK cells do not require HLA compatibility and exhibit low safety concerns. Moreover, CAR-NK cells are conducive to "off-the-shelf" therapeutics, providing significant logistic advantages over CAR-T cells. Both CAR-T and CAR-NK cells have shown consistent and promising results in hematological malignancies. However, their efficacy against solid tumors remains limited due to various obstacles including limited tumor trafficking and infiltration, as well as an immuno-suppressive tumor microenvironment. In this review, we discuss the recent advances and current challenges of CAR-T and CAR-NK cell immunotherapies, with a specific focus on the obstacles to their application in solid tumors. We also analyze in depth the advantages and drawbacks of CAR-NK cells compared to CAR-T cells and highlight CAR-NK CAR optimization. Finally, we explore future perspectives of these adoptive immunotherapies, highlighting the increasing contribution of cutting-edge biotechnological tools in shaping the next generation of cellular immunotherapy.

Tuning CAR T-cell therapies for efficacy and reduced toxicity

Chimeric antigen receptor (CAR) T-cell therapies are a standard of care for certain relapsed or refractory B-cell cancers. However, many patients do not respond to CAR T-cell therapy or relapse later, short- and long-term toxicities are common, and current CAR T-cell therapies have limited efficacy for solid cancers. The gene engineering inherent in CAR T-cell manufacture offers an unprecedented opportunity to control cellular characteristics and design products that may overcome these limitations. This review summarises available methods to "tune" CAR T-cells for optimal efficacy and safety. The components of a typical CAR, and the modifications that can influence CAR T-cell function are discussed. Methods of engineering passive, inducible or autonomous control mechanisms into CAR T-cells, allowing selective limitation or enhancement of CAR T-cell activity are reviewed. The impact of manufacturing processes on CAR T-cell function are considered, including methods of limiting CAR T-cell terminal differentiation and exhaustion, and the use of specific T-cell subsets as the CAR T starting material. We discuss the use of multicistronic transgenes and multiplexed gene editing. Finally, we highlight the need for innovative clinical trial designs if we are to make the most of the opportunities offered by CAR T-cell therapies.

Overview on Immunopathology of Chronic Lymphocytic Leukemia and Tumor-Associated Antigens with Therapeutic Applications

Chronic Lymphocytic Leukemia (CLL) is a clinically and biologically heterogeneous disease with a variable clinical course. The induction of a generalized state of immuno-suppression, leading to susceptibility to infections and the failure of anti-tumor immune responses, is a key feature of the clinical course of CLL. In addition to B-cell receptor (BCR) signaling in CLL, several receptor tyrosine kinases (RTKs) have been reported to be constitutively active in leukemic B cells, resulting in promoted survival and resistance to apoptosis induced by chemotherapy. Several treatment options are available for CLL, including a watch-and-wait strategy, chemotherapy, targeted therapies, immunotherapies such as adoptive cellular therapy (CAR T-Cell Therapy), stem cell transplantation (allogeneic transplantation), radiation therapy and surgery. The identification of Tumor-Associated Antigens (TAAs) is the bottleneck of tumor immunology and immunotherapy, serving as promising targets for precise diagnosis, monitoring, or therapeutic approaches. Numerous TAAs have been identified, and their application in immunotherapy holds promise for the treatment of CLL. Furthermore, extensive ongoing research aims to identify new cancer TAAs. In this review, our objective is to provide a comprehensive overview of CLL immunology and recent findings regarding advances in TAAs with therapeutic applications in CLL.

CRISPR/Cas9 editing of NKG2A improves the efficacy of primary CD33-directed chimeric antigen receptor natural killer cells

Chimeric antigen receptor (CAR)-modified natural killer (NK) cells show antileukemic activity against acute myeloid leukemia (AML) in vivo. However, NK cell-mediated tumor killing is often impaired by the interaction between human leukocyte antigen (HLA)-E and the inhibitory receptor, NKG2A. Here, we describe a strategy that overcomes CAR-NK cell inhibition mediated by the HLA-E-NKG2A immune checkpoint. We generate CD33-specific, AML-targeted CAR-NK cells (CAR33) combined with CRISPR/Cas9-based gene disruption of the NKG2A-encoding KLRC1 gene. Using single-cell multi-omics analyses, we identified transcriptional features of activation and maturation in CAR33-KLRC1ko-NK cells, which are preserved following exposure to AML cells. Moreover, CAR33-KLRC1ko-NK cells demonstrate potent antileukemic killing activity against AML cell lines and primary blasts in vitro and in vivo. We thus conclude that NKG2A-deficient CAR-NK cells have the potential to bypass immune suppression in AML.

Proteasome inhibition enhances the anti-leukemic efficacy of chimeric antigen receptor (CAR) expressing NK cells against acute myeloid leukemia

BACKGROUND

Relapsed and refractory acute myeloid leukemia (AML) carries a dismal prognosis. CAR T cells have shown limited efficacy in AML, partially due to dysfunctional autologous T cells and the extended time for generation of patient specific CAR T cells. Allogeneic NK cell therapy is a promising alternative, but strategies to enhance efficacy and persistence may be necessary. Proteasome inhibitors (PI) induce changes in the surface proteome which may render malignant cells more vulnerable to NK mediated cytotoxicity. Here, we investigated the potential benefit of combining PIs with CAR-expressing allogeneic NK cells against AML.

METHODS

We established the IC50 concentrations for Bortezomib and Carfilzomib against several AML cell lines. Surface expression of class-I HLA molecules and stress-associated proteins upon treatment with proteasome inhibitors was determined by multiparameter flow cytometry. Using functional in vitro assays, we explored the therapeutic synergy between pre-treatment with PIs and the anti-leukemic efficacy of NK cells with or without expression of AML-specific CAR constructs against AML cell lines and primary patient samples. Also, we investigated the tolerability and efficacy of a single PI application strategy followed by (CAR-) NK cell infusion in two different murine xenograft models of AML.

RESULTS

AML cell lines and primary AML patient samples were susceptible to Bortezomib and Carfilzomib mediated cytotoxicity. Conditioned resistance to Azacitidine/Venetoclax did not confer primary resistance to PIs. Treating AML cells with PIs reduced the surface expression of class-I HLA molecules on AML cells in a time-and-dose dependent manner. Stress-associated proteins were upregulated on the transcriptional level and on the cell surface. NK cell mediated killing of AML cells was enhanced in a synergistic manner. PI pre-treatment increased effector-target cell conjugate formation and Interferon-γ secretion, resulting in enhanced NK cell activity against AML cell lines and primary samples in vitro. Expression of CD33- and CD70-specific CARs further improved the antileukemic efficacy. In vivo, Bortezomib pre-treatment followed by CAR-NK cell infusion reduced AML growth, leading to prolonged overall survival.

CONCLUSIONS

PIs enhance the anti-leukemic efficacy of CAR-expressing allogeneic NK cells against AML in vitro and in vivo, warranting further exploration of this combinatorial treatment within early phase clinical trials.

Linker-specific monoclonal antibodies present a simple and reliable detection method for scFv-based CAR NK cells

Chimeric antigen receptor (CAR) T cell therapies have demonstrated significant successes in treating cancer. Currently, there are six approved CAR T cell products available on the market that target different malignancies of the B cell lineage. However, to overcome the limitations of CAR T cell therapies, other immune cells are being investigated for CAR-based cell therapies. CAR natural killer (NK) cells can be applied as allogeneic cell therapy, providing an economical, safe, and efficient alternative to autologous CAR T cells. To improve CAR research and future in-patient monitoring of cell therapeutics, a simple, reliable, and versatile CAR detection reagent is crucial. As most existing CARs contain a single-chain variable fragment (scFv) with either a Whitlow or a G4S linker site, linker-specific monoclonal antibodies (mAbs) can detect a broad range of CARs. This study demonstrates that these linker-specific mAbs can detect different CAR NK cells in vitro, spiked in whole blood, and within patient-derived tumor spheroids with high specificity and sensitivity, providing an effective and almost universal alternative for scFv-based CAR detection. Additionally, we confirm that linker-specific antibodies can be used for functional testing and enrichment of CAR NK cells, thereby providing a useful research tool to fast-track the development of novel CAR-based therapies.

Non-viral approaches in CAR-NK cell engineering: connecting natural killer cell biology and gene delivery

Natural Killer (NK) cells are exciting candidates for cancer immunotherapy with potent innate cytotoxicity and distinct advantages over T cells for Chimeric Antigen Receptor (CAR) therapy. Concerns regarding the safety, cost, and scalability of viral vectors has ignited research into non-viral alternatives for gene delivery. This review comprehensively analyses recent advancements and challenges with non-viral genetic modification of NK cells for allogeneic CAR-NK therapies. Non-viral alternatives including electroporation and multifunctional nanoparticles are interrogated with respect to CAR expression and translational responses. Crucially, the link between NK cell biology and design of drug delivery technologies are made, which is essential for development of future non-viral approaches. This review provides valuable insights into the current state of non-viral CAR-NK cell engineering, aimed at realising the full potential of NK cell-based immunotherapies.

Phase I study of safety and efficacy of allogeneic natural killer cell therapy in relapsed/refractory neuroblastomas post autologous hematopoietic stem cell transplantation

Despite low incidence, neuroblastoma, an immunologically cold tumor, is the most common extracranial solid neoplasm in pediatrics. In relapsed/refractory cases, the benefits of autologous hematopoietic stem cell transplantation (auto-HSCT) and other therapies are limited. Natural killer (NK) cells apply cytotoxicity against tumor cells independently of antigen-presenting cells and the adaptive immune system. The primary endpoint of this trial was to assess the safety of the injection of allogenic, ex vivo-expanded and primed NK cells in relapsed/refractory neuroblastoma patients after auto-HSCT. The secondary endpoint included the efficacy of this intervention in controlling tumors. NK cells were isolated and primed ex vivo (by adding interleukin [IL]-2, IL-15, and IL-21) in a GMP-compliant CliniMACS system and administered to four patients with relapsed/refractory MYCN-positive neuroblastoma. NK cell injections (1 and 5 × 107 cells/kg in the first and second injections, respectively) were safe, and no acute or sub-acute adverse events were observed. During the follow-up period, one complete response (CR) and one partial response (PR) were observed, while two cases exhibited progressive disease (PD). In follow-up evaluations, two died due to disease progression, including the case with a PR. The patient with CR had regular growth at the 31-month follow-up, and another patient with PD is still alive and receiving chemotherapies 20 months after therapy. This therapy is an appealing and feasible approach for managing refractory neuroblastomas post-HSCT. Further studies are needed to explore its efficacy with higher doses and more frequent administrations for high-risk neuroblastomas and other immunologically cold tumors.Trial registration number: irct.behdasht.gov.ir (Iranian Registry of Clinical Trials, No. IRCT20201202049568N1).

KIR2DS2+ NK cells in cancer patients demonstrate high activation in response to tumour-targeting antibodies

Strategies to mobilise natural killer (NK) cells against cancer include tumour-targeting antibodies, NK cell engagers (NKCEs) and the adoptive transfer of ex vivo expanded healthy donor-derived NK cells. Genetic and functional studies have revealed that expression of the activating killer immunoglobulin-like receptor KIR2DS2 is associated with enhanced function in NK cells from healthy donors and improved outcome in several different malignancies. The optimal strategy to leverage KIR2DS2+ NK cells therapeutically is however currently unclear. In this study, we therefore evaluated the response of KIR2DS2-expressing NK cells to activation against cancer with clinically relevant tumour-targeting antibodies and following ex vivo expansion. We identified that KIR2DS2high NK cells from patients with chronic lymphocytic leukaemia and hepatocellular carcinoma had enhanced activation in response to tumour-targeting antibodies compared to KIR2DS2- NK cells. However, the superior function of healthy donor derived KIR2DS2high NK cells was lost following ex vivo expansion which is required for adoptive transfer-based therapeutic strategies. These data provide evidence that targeting KIR2DS2 directly in cancer patients may allow for the utilisation of their enhanced effector function, however such activity may be lost following their ex vivo expansion.

CD22-targeted glyco-engineered natural killer cells offer a further treatment option for B-cell acute lymphoblastic leukemia

Not available.

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

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

Enhancing cellular immunotherapies in cancer by engineering selective therapeutic resistance

Adoptive cell therapies engineered to express chimeric antigen receptors (CARs) or transgenic T cell receptors (TCRs) to recognize and eliminate cancer cells have emerged as a promising approach for achieving long-term remissions in patients with cancer. To be effective, the engineered cells must persist at therapeutically relevant levels while avoiding off-tumour toxicities, which has been challenging to realize outside of B cell and plasma cell malignancies. This Review discusses concepts to enhance the efficacy, safety and accessibility of cellular immunotherapies by endowing cells with selective resistance to small-molecule drugs or antibody-based therapies to facilitate combination therapies with substances that would otherwise interfere with the functionality of the effector cells. We further explore the utility of engineering healthy haematopoietic stem cells to confer resistance to antigen-directed immunotherapies and small-molecule targeted therapies to expand the therapeutic index of said targeted anticancer agents as well as to facilitate in vivo selection of gene-edited haematopoietic stem cells for non-malignant applications. Lastly, we discuss approaches to evade immune rejection, which may be required in the setting of allogeneic cell therapies. Increasing confidence in the tools and outcomes of genetically modified cell therapy now paves the way for rational combinations that will open new therapeutic horizons.

Umbilical Cord Blood Hematopoietic Cells: From Biology to Hematopoietic Transplants and Cellular Therapies

Umbilical cord blood (UCB) is a rich source of hematopoietic stem and progenitor cells that are biologically superior to their adult counterparts. UCB cells can be stored for several years without compromising their numbers or function. Today, public and private UCB banks have been established in several countries around the world. After 35 years since the first UCB transplant (UCBT), more than 50,000 UCBTs have been performed worldwide. In pediatric patients, UCBT is comparable to or superior to bone marrow transplantation. In adult patients, UCB can be an alternative source of hematopoietic cells when an HLA-matched unrelated adult donor is not available and when a transplant is urgently needed. Delayed engraftment (due to reduced absolute numbers of hematopoietic cells) and higher costs have led many medical institutions not to consider UCB as a first-line cell source for hematopoietic transplants. As a result, the use of UCB as a source of hematopoietic stem and progenitor cells for transplantation has declined over the past decade. Several approaches are being investigated to make UCBTs more efficient, including improving the homing capabilities of primitive UCB cells and increasing the number of hematopoietic cells to be infused. Several of these approaches have already been applied in the clinic with promising results. UCB also contains immune effector cells, including monocytes and various lymphocyte subsets, which, together with stem and progenitor cells, are excellent candidates for the development of cellular therapies for hematological and non-hematological diseases.

Harnessing the Power of NK Cell Receptor Engineering as a New Prospect in Cancer Immunotherapy

Natural killer (NK) cells have recently gained popularity as an alternative for cancer immunotherapy. Adoptive cell transfer employing NK cells offers a safer therapeutic option compared to T-cell-based therapies, due to their significantly lower toxicity and the availability of diverse autologous and allogeneic NK cell sources. However, several challenges are associated with NK cell therapies, including limited in vivo persistence, the immunosuppressive and hostile tumor microenvironment (TME), and the lack of effective treatments for solid tumors. To address these limitations, the modification of NK cells to stably produce cytokines has been proposed as a strategy to enhance their persistence and proliferation. Additionally, the overexpression of activating receptors and the blockade of inhibitory receptors can restore the NK cell functions hindered by the TME. To further improve tumor infiltration and the elimination of solid tumors, innovative approaches focusing on the enhancement of NK cell chemotaxis through the overexpression of chemotactic receptors have been introduced. This review highlights the latest advancements in preclinical and clinical studies investigating the engineering of activating, inhibitory, and chemotactic NK cell receptors; discusses recent progress in cytokine manipulation; and explores the potential of combining the chimeric antigen receptor (CAR) technology with NK cell receptors engineering.

Measuring the impact of therapy-induced senescence on NK cell phenotypes in cancer

Cellular senescence is a damage-induced condition characterized by enduring cell cycle arrest and a heightened secretory profile known as the senescence-associated secretory phenotype (SASP). The SASP consists not only of release of inflammatory cytokines and chemokines that attract and activate a diverse repertoire of innate and adaptive immune cells, but also the upregulation of immunomodulatory cell surface molecules that promote immune clearance of senescent cells. Natural Killer (NK) cells are particularly adept at sensing and eliminating senescent cells. In the setting of cancer, commonly administered cytotoxic and cytostatic therapies can elicit senescence and in turn reactivate NK cell immune surveillance against tumors. Here, we detail a series of in vivo, ex vivo, and in vitro assays to assess the impact of therapy-induced senescence on NK cell phenotypes, including their activation, exhaustion, migration, and killing capacity in the context of pancreatic cancer. Importantly, this methodology can be adapted to investigate NK cell biology across various disease states and treatment modalities and help inform NK cell-based immunotherapies for cancer.

CAR-NK Cell Therapy: A Transformative Approach to Overcoming Oncological Challenges

The use of chimeric antigen receptor (CAR) in natural killer (NK) cells for cancer therapy is gaining momentum, marking a significant shift in cancer treatment. This review aims to explore the potential of CAR-NK cell therapy in cancer immunotherapy, providing a fresh perspective. It discusses the innovative approaches in CAR-NK cell design and engineering, particularly targeting refractory or recurrent cancers. By comparing CAR-NK cells with traditional therapies, the review highlights their unique ability to tackle tumor heterogeneity and immune system suppression. Additionally, it explains how novel cytokines and receptors can enhance CAR-NK cell efficacy, specificity, and functionality. This review underscores the advantages of CAR-NK cells, including reduced toxicity, lower cost, and broader accessibility compared to CAR-T cells, along with their potential in treating both blood cancers and solid tumors.

When playing the NK cell therapy card in glioblastoma, you can't beat interleukin-21

Glioblastoma is the most common brain cancer, with a 5-year survival rate of less than 10%. This grim prognosis highlights the urgent need for novel therapeutic approaches. In this issue of Cancer Cell, Shanley et al.1 report an innovative engineering strategy to supercharge NK cell immunity against glioblastoma.

Interleukin-21 engineering enhances NK cell activity against glioblastoma via CEBPD

Glioblastoma (GBM) is an aggressive brain cancer with limited therapeutic options. Natural killer (NK) cells are innate immune cells with strong anti-tumor activity and may offer a promising treatment strategy for GBM. We compared the anti-GBM activity of NK cells engineered to express interleukin (IL)-15 or IL-21. Using multiple in vivo models, IL-21 NK cells were superior to IL-15 NK cells both in terms of safety and long-term anti-tumor activity, with locoregionally administered IL-15 NK cells proving toxic and ineffective at tumor control. IL-21 NK cells displayed a unique chromatin accessibility signature, with CCAAT/enhancer-binding proteins (C/EBP), especially CEBPD, serving as key transcription factors regulating their enhanced function. Deletion of CEBPD resulted in loss of IL-21 NK cell potency while its overexpression increased NK cell long-term cytotoxicity and metabolic fitness. These results suggest that IL-21, through C/EBP transcription factors, drives epigenetic reprogramming of NK cells, enhancing their anti-tumor efficacy against GBM.

Beyond CAR-T: The rise of CAR-NK cell therapy in asthma immunotherapy

Asthma poses a major public health burden. While existing asthma drugs manage symptoms for many, some patients remain resistant. The lack of a cure, especially for severe asthma, compels exploration of novel therapies. Cancer immunotherapy successes with CAR-T cells suggest its potential for asthma treatment. Researchers are exploring various approaches for allergic diseases including membrane-bound IgE, IL-5, PD-L2, and CTLA-4 for asthma, and Dectin-1 for fungal asthma. NK cells offer several advantages over T cells for CAR-based immunotherapy. They offer key benefits: (1) HLA compatibility, meaning they can be used in a wider range of patients without the need for matching tissue types. (2) Minimal side effects (CRS and GVHD) due to their limited persistence and cytokine profile. (3) Scalability for "off-the-shelf" production from various sources. Several strategies have been introduced that highlight the superiority and challenges of CAR-NK cell therapy for asthma treatment including IL-10, IFN-γ, ADCC, perforin-granzyme, FASL, KIR, NCRs (NKP46), DAP, DNAM-1, TGF-β, TNF-α, CCL, NKG2A, TF, and EGFR. Furthermore, we advocate for incorporating AI for CAR design optimization and CRISPR-Cas9 gene editing technology for precise gene manipulation to generate highly effective CAR constructs. This review will delve into the evolution and production of CAR designs, explore pre-clinical and clinical studies of CAR-based therapies in asthma, analyze strategies to optimize CAR-NK cell function, conduct a comparative analysis of CAR-T and CAR-NK cell therapy with their respective challenges, and finally present established novel CAR designs with promising potential for asthma treatment.