Tethered IL-15 augments antitumor activity and promotes a stem-cell memory subset in tumor-specific T cells

T cell dysfunction and therapeutic intervention in cancer

Recent advances in immunotherapy have affirmed the curative potential of T cell-based approaches for treating relapsed and refractory cancers. However, the therapeutic efficacy is limited in part owing to the ability of cancers to evade immunosurveillance and adapt to immunological pressure. In this Review, we provide a brief overview of cancer-mediated immunosuppressive mechanisms with a specific focus on the repression of the surveillance and effector function of T cells. We discuss CD8+ T cell exhaustion and functional heterogeneity and describe strategies for targeting the molecular checkpoints that restrict T cell differentiation and effector function to bolster immunotherapeutic effects. We also delineate the emerging contributions of the tumor microenvironment to T cell metabolism and conclude by highlighting discovery-based approaches for developing future cellular therapies. Continued exploration of T cell biology and engineering hold great promise for advancing therapeutic interventions for cancer.

CAR T-cell therapy: a potential treatment strategy for pediatric midline gliomas

Pediatric brain tumors are the primary cause of death in children with cancer. Diffuse midline glioma (DMG) and diffuse intrinsic pontine glioma (DIPG) are frequently unresectable due to their difficult access location, and 5-year survival remains less than 20%. Despite significant advances in tumor biology and genetics, treatment options remain limited and ineffective. Immunotherapy using T cells with a chimeric antigen receptor (CAR) that has been genetically engineered is quickly emerging as a new treatment option for these patients. High levels of expression were detected for both disialoganglioside (GD2) and B7-H3 in pediatric DMG/DIPG. Numerous studies have been conducted in recent years employing various generations of GD2-CAR T cells. The two most prevalent adverse effects found with this therapy are cytokine release syndrome, which varies in severity from mild constitutional symptoms to a high-grade disease associated with potentially fatal multi-organ failure, and neurotoxicity, known as CAR T-cell-related encephalopathy syndrome. During the acute phase of anticancer action, peri-tumoral neuro-inflammation might cause deadly hydrocephalus. The initial results of clinical trials show that the outcomes are not highly encouraging as B cell malignancies and myelomas. In vivo research on CAR T-cell therapy for DIPG has yielded encouraging results, but in human trials, the early results have shown potentially fatal side effects and very modest, but fleeting improvements. Solid tumors present a hindrance to CAR T-cell therapy because of the antigenic dilemma and the strong immune-suppressing tumor microenvironment.

Generation of CAR-TSCM: CAR-T with super clutch

CAR-T therapy has demonstrated effectiveness in hematological malignancies and is now striding into solid tumor areas. One of the main roadblocks of CAR-T therapy is T cell exhaustion normally aroused by T cell terminal differentiation due to persistent contact with antigen in vivo or in vitro manufacturing process. TSCM positions as the first, and pivotal step of naïve T cell differentiation to downstream memory and effector stages. Researchers highly seek to restrain CAR-T cells at the TSCM stage during manufacture as TSCM percentage in CAR-T products is strongly associated with better treatment response. We reviewed the recent strategies regarding CAR-TSCM generation from aspects of starting source, manufacturing process, CAR assembly, transcription factor and metabolism regulation, etc.

Harnessing the tumor microenvironment to boost adoptive T cell therapy with engineered lymphocytes for solid tumors

Adoptive cell therapy (ACT) using Chimeric Antigen Receptor (CAR) and T Cell Receptor (TCR) engineered T cells represents an innovative therapeutic approach for the treatment of hematological malignancies, yet its application for solid tumors is still suboptimal. The tumor microenvironment (TME) places several challenges to overcome for a satisfactory therapeutic effect, such as physical barriers (fibrotic capsule and stroma), and inhibitory signals impeding T cell function. Some of these obstacles can be faced by combining ACT with other anti-tumor approaches, such as chemo/radiotherapy and checkpoint inhibitors. On the other hand, cutting edge technological tools offer the opportunity to overcome and, in some cases, take advantage of TME intrinsic characteristics to boost ACT efficacy. These include: the exploitation of chemokine gradients and integrin expression for preferential T-cell homing and extravasation; metabolic changes that have direct or indirect effects on TCR-T and CAR-T cells by increasing antigen presentation and reshaping T cell phenotype; introduction of additional synthetic receptors on TCR-T and CAR-T cells with the aim of increasing T cells survival and fitness.

Targeting cytokine and chemokine signaling pathways for cancer therapy

Cytokines are critical in regulating immune responses and cellular behavior, playing dual roles in both normal physiology and the pathology of diseases such as cancer. These molecules, including interleukins, interferons, tumor necrosis factors, chemokines, and growth factors like TGF-β, VEGF, and EGF, can promote or inhibit tumor growth, influence the tumor microenvironment, and impact the efficacy of cancer treatments. Recent advances in targeting these pathways have shown promising therapeutic potential, offering new strategies to modulate the immune system, inhibit tumor progression, and overcome resistance to conventional therapies. In this review, we summarized the current understanding and therapeutic implications of targeting cytokine and chemokine signaling pathways in cancer. By exploring the roles of these molecules in tumor biology and the immune response, we highlighted the development of novel therapeutic agents aimed at modulating these pathways to combat cancer. The review elaborated on the dual nature of cytokines as both promoters and suppressors of tumorigenesis, depending on the context, and discussed the challenges and opportunities this presents for therapeutic intervention. We also examined the latest advancements in targeted therapies, including monoclonal antibodies, bispecific antibodies, receptor inhibitors, fusion proteins, engineered cytokine variants, and their impact on tumor growth, metastasis, and the tumor microenvironment. Additionally, we evaluated the potential of combining these targeted therapies with other treatment modalities to overcome resistance and improve patient outcomes. Besides, we also focused on the ongoing research and clinical trials that are pivotal in advancing our understanding and application of cytokine- and chemokine-targeted therapies for cancer patients.

Tethered IL15-IL15Rα augments antitumor activity of CD19 CAR-T cells but displays long-term toxicity in an immunocompetent lymphoma mouse model

BACKGROUND

Adoptive cell therapy using genetically modified T cells to express chimeric antigen receptors (CAR-T) has shown encouraging results, particularly in certain blood cancers. Nevertheless, over 40% of B cell malignancy patients experience a relapse after CAR-T therapy, likely due to inadequate persistence of the modified T cells in the body. IL15, known for its pro-survival and proliferative properties, has been suggested for incorporation into the fourth generation of CAR-T cells to enhance their persistence. However, the potential systemic toxicity associated with this cytokine warrants further evaluation.

METHODS

We analyzed the persistence, antitumor efficacy and potential toxicity of anti-mouse CD19 CAR-T cells which express a membrane-bound IL15-IL15Rα chimeric protein (CD19/mbIL15q CAR-T), in BALB/c mice challenged with A20 tumor cells as well as in NSG mice.

RESULTS

Conventional CD19 CAR-T cells showed low persistence and poor efficacy in BALB/c mice treated with mild lymphodepletion regimens (total body irradiation (TBI) of 1 Gy). CD19/mbIL15q CAR-T exhibits prolonged persistence and enhanced in vivo efficacy, effectively eliminating established A20 B cell lymphoma. However, this CD19/mbIL15q CAR-T displays important long-term toxicities, with marked splenomegaly, weight loss, transaminase elevations, and significant inflammatory findings in some tissues. Mice survival is highly compromised after CD19/mbIL15q CAR-T cell transfer, particularly if a high TBI regimen is applied before CAR-T cell transfer.

CONCLUSION

Tethered IL15-IL15Rα augments the antitumor activity of CD19 CAR-T cells but displays long-term toxicity in immunocompetent mice. Inducible systems to regulate IL15-IL15Rα expression could be considered to control this toxicity.

Immunometabolism of CD8+ T cell differentiation in cancer

CD8+ cytotoxic T lymphocytes (CTLs) are central mediators of tumor immunity and immunotherapies. Upon tumor antigen recognition, CTLs differentiate from naive/memory-like toward terminally exhausted populations with more limited function against tumors. Such differentiation is regulated by both immune signals, including T cell receptors (TCRs), co-stimulation, and cytokines, and metabolism-associated processes. These immune signals shape the metabolic landscape via signaling, transcriptional and post-transcriptional mechanisms, while metabolic processes in turn exert spatiotemporal effects to modulate the strength and duration of immune signaling. Here, we review the bidirectional regulation between immune signals and metabolic processes, including nutrient uptake and intracellular metabolic pathways, in shaping CTL differentiation and exhaustion. We also discuss the mechanisms underlying how specific nutrient sources and metabolite-mediated signaling events orchestrate CTL biology. Understanding how metabolic programs and their interplay with immune signals instruct CTL differentiation and exhaustion is crucial to uncover tumor-immune interactions and design novel immunotherapies.

CAR-T cell manufacturing landscape-Lessons from the past decade and considerations for early clinical development

CAR-T cell therapies have consolidated their position over the last decade as an effective alternative to conventional chemotherapies for the treatment of a number of hematological malignancies. With an exponential increase in the number of commercial therapies and hundreds of phase 1 trials exploring CAR-T cell efficacy in different settings (including autoimmunity and solid tumors), demand for manufacturing capabilities in recent years has considerably increased. In this review, we explore the current landscape of CAR-T cell manufacturing and discuss some of the challenges limiting production capacity worldwide. We describe the latest technical developments in GMP production platform design to facilitate the delivery of a range of increasingly complex CAR-T cell products, and the challenges associated with translation of new scientific developments into clinical products for patients. We explore all aspects of the manufacturing process, namely early development, manufacturing technology, quality control, and the requirements for industrial scaling. Finally, we discuss the challenges faced as a small academic team, responsible for the delivery of a high number of innovative products to patients. We describe our experience in the setup of an effective bench-to-clinic pipeline, with a streamlined workflow, for implementation of a diverse portfolio of phase 1 trials.

Precision in Action: The Role of Clustered Regularly Interspaced Short Palindromic Repeats/Cas in Gene Therapies

Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)-associated enzyme-CAS holds great promise for treating many uncured human diseases and illnesses by precisely correcting harmful point mutations and disrupting disease-causing genes. The recent Food and Drug Association (FDA) approval of the first CRISPR-based gene therapy for sickle cell anemia marks the beginning of a new era in gene editing. However, delivering CRISPR specifically into diseased cells in vivo is a significant challenge and an area of intense research. The identification of new CRISPR/Cas variants, particularly ultra-compact CAS systems with robust gene editing activities, paves the way for the low-capacity delivery vectors to be used in gene therapies. CRISPR/Cas technology has evolved beyond editing DNA to cover a wide spectrum of functionalities, including RNA targeting, disease diagnosis, transcriptional/epigenetic regulation, chromatin imaging, high-throughput screening, and new disease modeling. CRISPR/Cas can be used to engineer B-cells to produce potent antibodies for more effective vaccines and enhance CAR T-cells for the more precise and efficient targeting of tumor cells. However, CRISPR/Cas technology has challenges, including off-target effects, toxicity, immune responses, and inadequate tissue-specific delivery. Overcoming these challenges necessitates the development of a more effective and specific CRISPR/Cas delivery system. This entails strategically utilizing specific gRNAs in conjunction with robust CRISPR/Cas variants to mitigate off-target effects. This review seeks to delve into the intricacies of the CRISPR/Cas mechanism, explore progress in gene therapies, evaluate gene delivery systems, highlight limitations, outline necessary precautions, and scrutinize the ethical considerations associated with its application.

Human anti-PSCA CAR macrophages possess potent antitumor activity against pancreatic cancer

Due to the limitations of autologous chimeric antigen receptor (CAR)-T cells, alternative sources of cellular immunotherapy, including CAR macrophages, are emerging for solid tumors. Human induced pluripotent stem cells (iPSCs) offer an unlimited source for immune cell generation. Here, we develop human iPSC-derived CAR macrophages targeting prostate stem cell antigen (PSCA) (CAR-iMacs), which express membrane-bound interleukin (IL)-15 and truncated epidermal growth factor receptor (EGFR) for immune cell activation and a suicide switch, respectively. These allogeneic CAR-iMacs exhibit strong antitumor activity against human pancreatic solid tumors in vitro and in vivo, leading to reduced tumor burden and improved survival in a pancreatic cancer mouse model. CAR-iMacs appear safe and do not exhibit signs of cytokine release syndrome or other in vivo toxicities. We optimized the cryopreservation of CAR-iMac progenitors that remain functional upon thawing, providing an off-the-shelf, allogeneic cell product that can be developed into CAR-iMacs. Overall, our preclinical data strongly support the potential clinical translation of this human iPSC-derived platform for solid tumors, including pancreatic cancer.

Memory/Active T-Cell Activation Is Associated with Immunotherapeutic Response in Fumarate Hydratase-Deficient Renal Cell Carcinoma

PURPOSE

Fumarate hydratase-deficient renal cell carcinoma (FH-deficient RCC) is a rare and lethal subtype of kidney cancer. However, the optimal treatments and molecular correlates of benefits for FH-deficient RCC are currently lacking.

EXPERIMENTAL DESIGN

A total of 91 patients with FH-deficient RCC from 15 medical centers between 2009 and 2022 were enrolled in this study. Genomic and bulk RNA-sequencing (RNA-seq) were performed on 88 and 45 untreated FH-deficient RCCs, respectively. Single-cell RNA-seq was performed to identify biomarkers for treatment response. Main outcomes included disease-free survival (DFS) for localized patients, objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) for patients with metastasis.

RESULTS

In the localized setting, we found that a cell-cycle progression signature enabled to predict disease progression. In the metastatic setting, first-line immune checkpoint inhibitor plus tyrosine kinase inhibitor (ICI+TKI) combination therapy showed satisfactory safety and was associated with a higher ORR (43.2% vs. 5.6%), apparently superior PFS (median PFS, 17.3 vs. 9.6 months, P = 0.016) and OS (median OS, not reached vs. 25.7 months, P = 0.005) over TKI monotherapy. Bulk and single-cell RNA-seq data revealed an enrichment of memory and effect T cells in responders to ICI plus TKI combination therapy. Furthermore, we identified a signature of memory and effect T cells that was associated with the effectiveness of ICI plus TKI combination therapy.

CONCLUSIONS

ICI plus TKI combination therapy may represent a promising treatment option for metastatic FH-deficient RCC. A memory/active T-cell-derived signature is associated with the efficacy of ICI+TKI but necessitates further validation.

Chimeric antigen receptor T-cell therapy in childhood acute myeloid leukemia: how far are we from a clinical application?

Recurrent and/or refractory (R/R) pediatric acute myeloid leukemia (AML) remains a recalcitrant disease with poor outcomes. Cell therapy with genetically modified immune effector cells holds the promise to improve outcomes for R/R AML since it relies on cytotoxic mechanisms that are distinct from chemotherapeutic agents. While T cells expressing chimeric antigen receptors (CAR T cells) showed significant anti-AML activity in preclinical models, early phase clinical studies have demonstrated limited activity, irrespective of the targeted AML antigen. Lack of efficacy is most likely multifactorial, including: (i) a limited array of AML-specific targets and target antigen heterogeneity; (ii) the aggressive nature of R/R AML and heavy pretreatment of patients; (iii) T-cell product manufacturing, and (iv) limited expansion and persistence of the CAR T cells, which is in part driven by the immunosuppressive AML microenvironment. Here we review the results of early phase clinical studies with AML-specific CAR T cells, and avenues investigators are exploring to improve their effector function.

Challenges and opportunities for cancer stem cell-targeted immunotherapies include immune checkpoint inhibitor, cancer stem cell-dendritic cell vaccine, chimeric antigen receptor immune cells, and modified exosomes

Cancer stem cells (CSCs) are associated with the tumor microenvironment (TME). CSCs induce tumorigenesis, tumor recurrence and progression, and resistance to standard therapies. Indeed, CSCs pose an increasing challenge to current cancer therapy due to their stemness or self-renewal properties. The molecular and cellular interactions between heterogeneous CSCs and surrounding TME components and tumor-supporting immune cells show synergistic effects toward treatment failure. In the immunosuppressive TME, CSCs express various immunoregulatory proteins, growth factors, metabolites and cytokines, and also produce exosomes, a type of extracellular vesicles, to protect themselves from host immune surveillance. Among these, the identification and application of CSC-derived exosomes could be considered for the development of therapeutic approaches to eliminate CSCs or cancer, in addition to targeting the modulators that remodel the composition of the TME, as reviewed in this study. Here, we introduce the role of CSCs and how their interaction with TME complicates immunotherapies, and then present the CSC-based immunotherapy and the limitation of these therapies. We describe the biology and role of tumor/CSC-derived exosomes that induce immune suppression in the TME, and finally, introduce their potentials for the development of CSC-based targeted immunotherapy in the future.

Engineering Improved CAR T Cell Products with A Multi-Cytokine Particle Platform for Hematologic and Solid Tumors

Despite the remarkable clinical efficacy of chimeric antigen receptor (CAR) T cells in hematological malignancies, only a subset of patients achieves a durable complete response (dCR). DCR has been correlated with CAR T cell products enriched with T cells memory phenotypes. Therefore, reagents that consistently promote memory phenotypes during the manufacturing of CAR T cells have the potential to significantly improve clinical outcomes. A novel modular multi-cytokine particle (MCP) platform is developed that combines the signals necessary for activation, costimulation, and cytokine support into a single "all-in-one" stimulation reagent for CAR T cell manufacturing. This platform allows for the assembly and screening of compositionally diverse MCP libraries to identify formulations tailored to promote specific phenotypes with a high degree of flexibility. The approach is leveraged to identify unique MCP formulations that manufacture CAR T cell products from diffuse large B cell patients   with increased proportions of memory-like phenotypes MCP-manufactured CAR T cells demonstrate superior anti-tumor efficacy in mouse models of lymphoma and ovarian cancer through enhanced persistence. These findings serve as a proof-of-principle of the powerful utility of the MCP platform to identify "all-in-one" stimulation reagents that can improve the effectiveness of cell therapy products through optimal manufacturing.

Lyophilized lymph nodes for improved delivery of chimeric antigen receptor T cells

Lymph nodes are crucial organs of the adaptive immune system, orchestrating T cell priming, activation and tolerance. T cell activity and function are highly regulated by lymph nodes, which have a unique structure harbouring distinct cells that work together to detect and respond to pathogen-derived antigens. Here we show that implanted patient-derived freeze-dried lymph nodes loaded with chimeric antigen receptor T cells improve delivery to solid tumours and inhibit tumour recurrence after surgery. Chimeric antigen receptor T cells can be effectively loaded into lyophilized lymph nodes, whose unaltered meshwork and cytokine and chemokine contents promote chimeric antigen receptor T cell viability and activation. In mouse models of cell-line-derived human cervical cancer and patient-derived pancreatic cancer, delivery of chimeric antigen receptor T cells targeting mesothelin via the freeze-dried lymph nodes is more effective in preventing tumour recurrence when compared to hydrogels containing T-cell-supporting cytokines. This tissue-mediated cell delivery strategy holds promise for controlled release of various cells and therapeutics with long-term activity and augmented function.

Development of a chimeric cytokine receptor that captures IL-6 and enhances the antitumor response of CAR-T cells

The efficacy of chimeric antigen receptor (CAR)-engineered T cell therapy is suboptimal in most cancers, necessitating further improvement in their therapeutic actions. However, enhancing antitumor T cell response inevitably confers an increased risk of cytokine release syndrome associated with monocyte-derived interleukin-6 (IL-6). Thus, an approach to simultaneously enhance therapeutic efficacy and safety is warranted. Here, we develop a chimeric cytokine receptor composed of the extracellular domains of GP130 and IL6RA linked to the transmembrane and cytoplasmic domain of IL-7R mutant that constitutively activates the JAK-STAT pathway (G6/7R or G6/7R-M452L). CAR-T cells with G6/7R efficiently absorb and degrade monocyte-derived IL-6 in vitro. The G6/7R-expressing CAR-T cells show superior expansion and persistence in vivo, resulting in durable antitumor response in both liquid and solid tumor mouse models. Our strategy can be widely applicable to CAR-T cell therapy to enhance its efficacy and safety, irrespective of the target antigen.

State of the art and perspectives of chimeric antigen receptor T cells cell therapy for neuroblastoma

Neuroblastoma (NB) is a solid, neuroendocrine pediatric solid tumor with divergent clinical behavior. Patients with high-risk diseases have poor prognoses despite complex multimodal therapy, which requires the search for new therapeutic approaches. Chimeric antigen receptor T cells (CAR-T) have led to dramatic improvements in the survival of cancer patients, most notably those with hematologic malignancies. Early-phase clinical trials of CAR-T cell therapy for NB have proven safe and feasible, but limited clinical efficacy. At the same time, multiple experimental and preclinical studies have shown that the most common in clinical trials single 2nd or 3rd generation CAR structure is not sufficient for a complete response in solid tumors. Here, we review the recent advances and future perspectives associated with engineered receptors, including several antigens binding, armored CAR-T of 4th and 5th generation and CAR-T cell combination strategies with other immunotherapy. We also summarize the results and shortcomings of ongoing clinical trials of CAR-T therapy for NB.

Generation of allogeneic CAR-NKT cells from hematopoietic stem and progenitor cells using a clinically guided culture method

Cancer immunotherapy with autologous chimeric antigen receptor (CAR) T cells faces challenges in manufacturing and patient selection that could be avoided by using 'off-the-shelf' products, such as allogeneic CAR natural killer T (AlloCAR-NKT) cells. Previously, we reported a system for differentiating human hematopoietic stem and progenitor cells into AlloCAR-NKT cells, but the use of three-dimensional culture and xenogeneic feeders precluded its clinical application. Here we describe a clinically guided method to differentiate and expand IL-15-enhanced AlloCAR-NKT cells with high yield and purity. We generated AlloCAR-NKT cells targeting seven cancers and, in a multiple myeloma model, demonstrated their antitumor efficacy, expansion and persistence. The cells also selectively depleted immunosuppressive cells in the tumor microenviroment and antagonized tumor immune evasion via triple targeting of CAR, TCR and NK receptors. They exhibited a stable hypoimmunogenic phenotype associated with epigenetic and signaling regulation and did not induce detectable graft versus host disease or cytokine release syndrome. These properties of AlloCAR-NKT cells support their potential for clinical translation.

Synthetic Cells and Molecules in Cellular Immunotherapy

Cellular immunotherapy has emerged as an exciting strategy for cancer treatment, as it aims to enhance the body's immune response to tumor cells by engineering immune cells and designing synthetic molecules from scratch. Because of the cytotoxic nature, abundance in peripheral blood, and maturation of genetic engineering techniques, T cells have become the most commonly engineered immune cells to date. Represented by chimeric antigen receptor (CAR)-T therapy, T cell-based immunotherapy has revolutionized the clinical treatment of hematological malignancies. However, serious side effects and limited efficacy in solid tumors have hindered the clinical application of cellular immunotherapy. To address these limitations, various innovative strategies regarding synthetic cells and molecules have been developed. On one hand, some cytotoxic immune cells other than T cells have been engineered to explore the potential of targeted elimination of tumor cells, while some adjuvant cells have also been engineered to enhance the therapeutic effect. On the other hand, diverse synthetic cellular components and molecules are added to engineered immune cells to regulate their functions, promoting cytotoxic activity and restricting side effects. Moreover, novel bioactive materials such as hydrogels facilitating the delivery of therapeutic immune cells have also been applied to improve the efficacy of cellular immunotherapy. This review summarizes the innovative strategies of synthetic cells and molecules currently available in cellular immunotherapies, discusses the limitations, and provides insights into the next generation of cellular immunotherapies.

The TOPK Inhibitor HI-TOPK-032 Enhances CAR T-cell Therapy of Hepatocellular Carcinoma by Upregulating Memory T Cells

Chimeric antigen receptor (CAR) T cells are emerging as an effective antitumoral therapy. However, their therapeutic effects on solid tumors are limited because of their short survival time and the immunosuppressive tumor microenvironment. Memory T cells respond more vigorously and persist longer than their naïve/effector counterparts. Therefore, promoting CAR T-cell development into memory T cells could further enhance their antitumoral effects. HI-TOPK-032 is a T-LAK cell-originated protein kinase (TOPK)-specific inhibitor that moderately represses some types of tumors. However, it is unknown whether HI-TOPK-032 works on hepatocellular carcinoma (HCC) and whether it impacts antitumoral immunity. Using both subcutaneous and orthotopic xenograft tumor models of two human HCC cell lines, Huh-7 and HepG2, we found that HI-TOPK-032 significantly improved proliferation/persistence of CD8+ CAR T cells, as evidenced by an increase in CAR T-cell counts or frequency of Ki-67+CD8+ cells and a decrease in PD-1+LAG-3+TIM-3+CD8+ CAR T cells in vivo. Although HI-TOPK-032 did not significantly suppress HCC growth, it enhanced the capacity of CAR T cells to inhibit tumor growth. Moreover, HI-TOPK-032 augmented central memory CD8+ T cell (TCM) frequency while increasing eomesodermin expression in CD8+ CAR T cells in tumor-bearing mice. Moreover, it augmented CD8+ CAR TCM cells in vitro and reduced their expression of immune checkpoint molecules. Finally, HI-TOPK-032 inhibited mTOR activation in CAR T cells in vitro and in tumors, whereas overactivation of mTOR reversed the effects of HI-TOPK-032 on CD8+ TCM cells and tumor growth. Thus, our studies have revealed mechanisms underlying the antitumoral effects of HI-TOPK-032 while advancing CAR T-cell immunotherapy.

High-Dimensional Analyses Reveal IL15 Enhances Activation of Sipuleucel-T Lymphocyte Subsets and Reverses Immunoresistance

Sipuleucel-T (sip-T) is the only FDA-approved autologous cellular immunotherapy for metastatic castration-resistant prostate cancer (mCRPC). To elucidate parameters of the response profile to this therapy, we report high-dimensional analyses of sip-T using cytometry by time of flight (CyTOF) and show a lymphoid predominance, with CD3+ T cells constituting the highest proportion (median ∼60%) of sip-T, followed by B cells, and natural killer (NK) and NKT cells. We hypothesized that treatment of sip-T with homeostatic cytokines known to activate/expand effector lymphocytes could augment efficacy against prostate tumors. Of the cytokines tested, IL15 was the most effective at enhancing activation and proliferation of effector lymphocytes, as well as augmenting tumor cytotoxicity in vitro. Co-culture of sip-T with IL15 and control or prostate-relevant antigens showed substantial activation and expansion of CD8+ T cells and NKT cells in an antigen-specific manner. Adoptive transfer of IL15-treated sip-T into NSG mice resulted in more potent prostate tumor growth inhibition compared with control sip-T. Evaluation of tumor-infiltrating lymphocytes revealed a 2- to 14-fold higher influx of sip-T and a significant increase in IFNγ producing CD8+ T cells and NKT cells within the tumor microenvironment in the IL15 group. In conclusion, we put forward evidence that IL15 treatment can enhance the functional antitumor immunity of sip-T, providing rationale for combining IL15 or IL15 agonists with sip-T to treat patients with mCRPC.

FOXO1 enhances CAR T cell stemness, metabolic fitness and efficacy

Chimeric antigen receptor (CAR) T cell therapy has transformed the treatment of haematological malignancies such as acute lymphoblastic leukaemia, B cell lymphoma and multiple myeloma1-4, but the efficacy of CAR T cell therapy in solid tumours has been limited5. This is owing to a number of factors, including the immunosuppressive tumour microenvironment that gives rise to poorly persisting and metabolically dysfunctional T cells. Analysis of anti-CD19 CAR T cells used clinically has shown that positive treatment outcomes are associated with a more 'stem-like' phenotype and increased mitochondrial mass6-8. We therefore sought to identify transcription factors that could enhance CAR T cell fitness and efficacy against solid tumours. Here we show that overexpression of FOXO1 promotes a stem-like phenotype in CAR T cells derived from either healthy human donors or patients, which correlates with improved mitochondrial fitness, persistence and therapeutic efficacy in vivo. This work thus reveals an engineering approach to genetically enforce a favourable metabolic phenotype that has high translational potential to improve the efficacy of CAR T cells against solid tumours.

Principles and therapeutic applications of adaptive immunity

Adaptive immunity provides protection against infectious and malignant diseases. These effects are mediated by lymphocytes that sense and respond with targeted precision to perturbations induced by pathogens and tissue damage. Here, we review key principles underlying adaptive immunity orchestrated by distinct T cell and B cell populations and their extensions to disease therapies. We discuss the intracellular and intercellular processes shaping antigen specificity and recognition in immune activation and lymphocyte functions in mediating effector and memory responses. We also describe how lymphocytes balance protective immunity against autoimmunity and immunopathology, including during immune tolerance, response to chronic antigen stimulation, and adaptation to non-lymphoid tissues in coordinating tissue immunity and homeostasis. Finally, we discuss extracellular signals and cell-intrinsic programs underpinning adaptive immunity and conclude by summarizing key advances in vaccination and engineering adaptive immune responses for therapeutic interventions. A deeper understanding of these principles holds promise for uncovering new means to improve human health.

Regulatory T cells suppress myeloma-specific immunity during autologous stem cell mobilization and transplantation

ABSTRACT

Autologous stem cell transplantation (ASCT) is the standard of care consolidation therapy for eligible patients with myeloma but most patients eventually progress, an event associated with features of immune escape. Novel approaches to enhance antimyeloma immunity after ASCT represent a major unmet need. Here, we demonstrate that patient-mobilized stem cell grafts contain high numbers of effector CD8 T cells and immunosuppressive regulatory T cells (Tregs). We showed that bone marrow (BM)-residing T cells are efficiently mobilized during stem cell mobilization (SCM) and hypothesized that mobilized and highly suppressive BM-derived Tregs might limit antimyeloma immunity during SCM. Thus, we performed ASCT in a preclinical myeloma model with or without stringent Treg depletion during SCM. Treg depletion generated SCM grafts containing polyfunctional CD8 T effector memory cells, which dramatically enhanced myeloma control after ASCT. Thus, we explored clinically tractable translational approaches to mimic this scenario. Antibody-based approaches resulted in only partial Treg depletion and were inadequate to recapitulate this effect. In contrast, a synthetic interleukin-2 (IL-2)/IL-15 mimetic that stimulates the IL-2 receptor on CD8 T cells without binding to the high-affinity IL-2Ra used by Tregs efficiently expanded polyfunctional CD8 T cells in mobilized grafts and protected recipients from myeloma progression after ASCT. We confirmed that Treg depletion during stem cell mobilization can mitigate constraints on tumor immunity and result in profound myeloma control after ASCT. Direct and selective cytokine signaling of CD8 T cells can recapitulate this effect and represent a clinically testable strategy to improve responses after ASCT.

Genome editing iPSC to purposing enhancement of induce CD8 killer T cell function for regenerative immunotherapy

In recent years, immunotherapy has become a standard cancer therapy, joining surgery, chemotherapy, and radiation therapy. This therapeutic approach involves the use of patient-derived antigen-specific T cells or genetically modified T cells engineered with chimeric antigen receptors (CAR) or T cell receptors (TCR) that specifically target cancer antigens. However, T cells require ex vivo stimulation for proliferation when used in therapy, and the resulting "exhaustion," which is characterized by a diminished proliferation capacity and anti-tumor activity, poses a significant challenge. As a solution, we reported "rejuvenated" CD8 + T cells that possess high proliferation capacity from induced pluripotent stem cells (iPSCs) in 2013. This review discusses the status and future developments in immunotherapy using iPSC-derived T cells, drawing insights from our research to overcome the exhaustion associated with antigen-specific T cell therapy.

Current challenges and therapeutic advances of CAR-T cell therapy for solid tumors

The application of chimeric antigen receptor (CAR) T cells in the management of hematological malignancies has emerged as a noteworthy therapeutic breakthrough. Nevertheless, the utilization and effectiveness of CAR-T cell therapy in solid tumors are still limited primarily because of the absence of tumor-specific target antigen, the existence of immunosuppressive tumor microenvironment, restricted T cell invasion and proliferation, and the occurrence of severe toxicity. This review explored the history of CAR-T and its latest advancements in the management of solid tumors. According to recent studies, optimizing the design of CAR-T cells, implementing logic-gated CAR-T cells and refining the delivery methods of therapeutic agents can all enhance the efficacy of CAR-T cell therapy. Furthermore, combination therapy shows promise as a way to improve the effectiveness of CAR-T cell therapy. At present, numerous clinical trials involving CAR-T cells for solid tumors are actively in progress. In conclusion, CAR-T cell therapy has both potential and challenges when it comes to treating solid tumors. As CAR-T cell therapy continues to evolve, further innovations will be devised to surmount the challenges associated with this treatment modality, ultimately leading to enhanced therapeutic response for patients suffered solid tumors.

Cooperative Armoring of CAR and TCR T Cells by T Cell-Restricted IL15 and IL21 Universally Enhances Solid Tumor Efficacy

PURPOSE

Chimeric antigen receptor (CAR) and T-cell receptor (TCR) T-cell therapies are effective in a subset of patients with solid tumors, but new approaches are needed to universally improve patient outcomes. Here, we developed a technology to leverage the cooperative effects of IL15 and IL21, two common cytokine-receptor gamma chain family members with distinct, pleiotropic effects on T cells and other lymphocytes, to enhance the efficacy of adoptive T cells.

EXPERIMENTAL DESIGN

We designed vectors that induce the constitutive expression of either membrane-tethered IL15, IL21, or IL15/IL21. We used clinically relevant preclinical models of transgenic CARs and TCRs against pediatric and adult solid tumors to determine the effect of the membrane-tethered cytokines on engineered T cells for human administration.

RESULTS

We found that self-delivery of these cytokines by CAR or TCR T cells prevents functional exhaustion by repeated stimulation and limits the emergence of dysfunctional natural killer (NK)-like T cells. Across different preclinical murine solid tumor models, we observed enhanced regression with each individual cytokine but the greatest antitumor efficacy when T cells were armored with both.

CONCLUSIONS

The coexpression of membrane-tethered IL15 and IL21 represents a technology to enhance the resilience and function of engineered T cells against solid tumors and could be applicable to multiple therapy platforms and diseases. See related commentary by Ruffin et al., p. 1431.

CAR products from novel sources: a new avenue for the breakthrough in cancer immunotherapy

Chimeric antigen receptor (CAR) T cell therapy has transformed cancer immunotherapy. However, significant challenges limit its application beyond B cell-driven malignancies, including limited clinical efficacy, high toxicity, and complex autologous cell product manufacturing. Despite efforts to improve CAR T cell therapy outcomes, there is a growing interest in utilizing alternative immune cells to develop CAR cells. These immune cells offer several advantages, such as major histocompatibility complex (MHC)-independent function, tumor microenvironment (TME) modulation, and increased tissue infiltration capabilities. Currently, CAR products from various T cell subtypes, innate immune cells, hematopoietic progenitor cells, and even exosomes are being explored. These CAR products often show enhanced antitumor efficacy, diminished toxicity, and superior tumor penetration. With these benefits in mind, numerous clinical trials are underway to access the potential of these innovative CAR cells. This review aims to thoroughly examine the advantages, challenges, and existing insights on these new CAR products in cancer treatment.

Immunometabolic Adaptation of CD19-Targeted CAR T Cells in the Central Nervous System Microenvironment of Patients Promotes Memory Development

Metabolic reprogramming is a hallmark of T-cell activation, and metabolic fitness is fundamental for T-cell-mediated antitumor immunity. Insights into the metabolic plasticity of chimeric antigen receptor (CAR) T cells in patients could help identify approaches to improve their efficacy in treating cancer. Here, we investigated the spatiotemporal immunometabolic adaptation of CD19-targeted CAR T cells using clinical samples from CAR T-cell-treated patients. Context-dependent immunometabolic adaptation of CAR T cells demonstrated the link between their metabolism, activation, differentiation, function, and local microenvironment. Specifically, compared with the peripheral blood, low lipid availability, high IL15, and low TGFβ in the central nervous system microenvironment promoted immunometabolic adaptation of CAR T cells, including upregulation of a lipolytic signature and memory properties. Pharmacologic inhibition of lipolysis in cerebrospinal fluid led to decreased CAR T-cell survival. Furthermore, manufacturing CAR T cells in cerebrospinal fluid enhanced their metabolic fitness and antileukemic activity. Overall, this study elucidates spatiotemporal immunometabolic rewiring of CAR T cells in patients and demonstrates that these adaptations can be exploited to maximize the therapeutic efficacy of CAR T cells.

SIGNIFICANCE

The spatiotemporal immunometabolic landscape of CD19-targeted CAR T cells from patients reveals metabolic adaptations in specific microenvironments that can be exploited to maximize the therapeutic efficacy of CAR T cells.

Adoptive cell therapy for solid tumors beyond CAR-T: Current challenges and emerging therapeutic advances

Adoptive cellular immunotherapy using immune cells expressing chimeric antigen receptors (CARs) is a highly specific anti-tumor immunotherapy that has shown promise in the treatment of hematological malignancies. However, there has been a slow progress toward the treatment of solid tumors owing to the complex tumor microenvironment that affects the localization and killing ability of the CAR cells. Solid tumors with a strong immunosuppressive microenvironment and complex vascular system are unaffected by CAR cell infiltration and attack. To improve their efficacy toward solid tumors, CAR cells have been modified and upgraded by "decorating" and "pruning". This review focuses on the structure and function of CARs, the immune cells that can be engineered by CARs and the transformation strategies to overcome solid tumors, with a view to broadening ideas for the better application of CAR cell therapy for the treatment of solid tumors.

Modular chimeric cytokine receptors with leucine zippers enhance the antitumour activity of CAR T cells via JAK/STAT signalling

The limited availability of cytokines in solid tumours hinders maintenance of the antitumour activity of chimeric antigen receptor (CAR) T cells. Cytokine receptor signalling pathways in CAR T cells can be activated by transgenic expression or injection of cytokines in the tumour, or by engineering the activation of cognate cytokine receptors. However, these strategies are constrained by toxicity arising from the activation of bystander cells, by the suboptimal biodistribution of the cytokines and by downregulation of the cognate receptor. Here we show that replacement of the extracellular domains of heterodimeric cytokine receptors in T cells with two leucine zipper motifs provides optimal Janus kinase/signal transducer and activator of transcription signalling. Such chimeric cytokine receptors, which can be generated for common γ-chain receptors, interleukin-10 and -12 receptors, enabled T cells to survive cytokine starvation without induction of autonomous cell growth, and augmented the effector function of CAR T cells in vitro in the setting of chronic antigen exposure and in human tumour xenografts in mice. As a modular design, leucine zippers can be used to generate constitutively active cytokine receptors in effector immune cells.

From complexity to clarity: unravelling tumor heterogeneity through the lens of tumor microenvironment for innovative cancer therapy

Despite the tremendous clinical successes recorded in the landscape of cancer therapy, tumor heterogeneity remains a formidable challenge to successful cancer treatment. In recent years, the emergence of high-throughput technologies has advanced our understanding of the variables influencing tumor heterogeneity beyond intrinsic tumor characteristics. Emerging knowledge shows that drivers of tumor heterogeneity are not only intrinsic to cancer cells but can also emanate from their microenvironment, which significantly favors tumor progression and impairs therapeutic response. Although much has been explored to understand the fundamentals of the influence of innate tumor factors on cancer diversity, the roles of the tumor microenvironment (TME) are often undervalued. It is therefore imperative that a clear understanding of the interactions between the TME and other tumor intrinsic factors underlying the plastic molecular behaviors of cancers be identified to develop patient-specific treatment strategies. This review highlights the roles of the TME as an emerging factor in tumor heterogeneity. More particularly, we discuss the role of the TME in the context of tumor heterogeneity and explore the cutting-edge diagnostic and therapeutic approaches that could be used to resolve this recurring clinical conundrum. We conclude by speculating on exciting research questions that can advance our understanding of tumor heterogeneity with the goal of developing customized therapeutic solutions.

Cytokine signaling in chimeric antigen receptor T-cell therapy

Adoptive immunotherapy using chimeric antigen-receptor (CAR)-engineered T cells can induce robust antitumor responses against hematologic malignancies. However, its efficacy is not durable in the majority of the patients, warranting further improvement of T-cell functions. Cytokine signaling is one of the key cascades regulating T-cell survival and effector functions. In addition to cytokines that use the common γ chain as a receptor subunit, multiple cytokines regulate T-cell functions directly or indirectly. Modulating cytokine signaling in CAR-T cells by genetic engineering is one promising strategy to augment their therapeutic efficacy. These strategies include ectopic expression of cytokines, cytokine receptors, and synthetic molecules that mimic endogenous cytokine signaling. Alternatively, autocrine IL-2 signaling can be augmented through reprogramming of CAR-T cell properties through transcriptional and epigenetic modification. On the other hand, cytokine production by CAR-T cells triggers systemic inflammatory responses, which mainly manifest as adverse events such as cytokine-release syndrome (CRS) and neurotoxicity. In addition to inhibiting direct inflammatory mediators such as IL-6 and IL-1 released from activated macrophages, suppression of T-cell-derived cytokines associated with the priming of macrophages can be accomplished through genetic modification of CAR-T cells. In this review, I will outline recently developed synthetic biology approaches to exploit cytokine signaling to enhance CAR-T cell functions. I will also discuss therapeutic target molecules to prevent or alleviate CAR-T cell-related toxicities.

Lymph Node-Targeted Vaccine Boosting of TCR T-cell Therapy Enhances Antitumor Function and Eradicates Solid Tumors

T-cell receptor (TCR)-modified T-cell therapies have shown promise against solid tumors, but overall therapeutic benefits have been modest due in part to suboptimal T-cell persistence and activation in vivo, alongside potential tumor antigen escape. In this study, we demonstrate an approach to enhance the in vivo persistence and function of TCR T cells through combination with Amphiphile (AMP) vaccination including cognate TCR T peptides. AMP modification improves lymph node targeting of conjugated tumor immunogens and adjuvants, thereby coordinating a robust T cell-activating endogenous immune response. AMP vaccine combination with TCR T-cell therapy led to complete eradication and durable responses against established murine solid tumors refractory to TCR T-cell monotherapy. Enhanced antitumor efficacy was correlated with simultaneous in vivo invigoration of adoptively transferred TCR T cells and in situ expansion of the endogenous antitumor T-cell repertoire. Long-term protection against tumor recurrence in AMP-vaccinated mice was associated with antigen spreading to additional tumor-associated antigens not targeted by vaccination. AMP vaccination further correlated with pro-inflammatory lymph node transcriptional reprogramming and increased antigen presenting-cell maturation, resulting in TCR T-cell expansion and functional enhancement in lymph nodes and solid tumor parenchyma without lymphodepletion. In vitro evaluation of AMP peptides with matched human TCR T cells targeting NY-ESO-1, mutant KRAS, and HPV16 E7 illustrated the clinical potential of AMP vaccination to enhance human TCR T-cell proliferation, activation, and antitumor activity. Taken together, these studies provide rationale and evidence to support clinical evaluation of combining AMP vaccination with TCR T-cell therapies to augment antitumor activity.

IL-15 in T-Cell Responses and Immunopathogenesis

IL-15 belongs to the common gamma chain cytokine family and has pleiotropic immunological functions. IL-15 is a homeostatic cytokine essential for the development and maintenance of NK cells and memory CD8+ T cells. In addition, IL-15 plays a critical role in the activation, effector functions, tissue residency, and senescence of CD8+ T cells. IL-15 also activates virtual memory T cells, mucosal-associated invariant T cells and γδ T cells. Recently, IL-15 has been highlighted as a major trigger of TCR-independent activation of T cells. This mechanism is involved in T cell-mediated immunopathogenesis in diverse diseases, including viral infections and chronic inflammatory diseases. Deeper understanding of IL-15-mediated T-cell responses and their underlying mechanisms could optimize therapeutic strategies to ameliorate host injury by T cell-mediated immunopathogenesis. This review highlights recent advancements in comprehending the role of IL-15 in relation to T cell responses and immunopathogenesis under various host conditions.

Elevating the potential of CAR-T cell therapy in solid tumors: exploiting biomaterials-based delivery techniques

Chimeric antigen receptor (CAR) T cells exhibit promising progress in addressing hematologic malignancies. However, CAR-T therapy for solid tumors remains limited, with no FDA-approved CAR-T products available for clinical use at present. Primary reasons include insufficient infiltration, accumulation, tumor immunosuppression of the microenvironment, and related side effects. Single utilization of CAR-T cannot effectively overcome these unfavorable obstacles. A probable effective pathway to achieve a better CAR-T therapy effect would be to combine the benefits of biomaterials-based technology. In this article, comprehensive biomaterials strategies to break through these obstacles of CAR-T cell therapy at the tumor sites are summarized, encompassing the following aspects: 1) generating orthotopic CAR-T cells; 2) facilitating CAR-T cell trafficking; 3) stimulating CAR-T cell expansion and infiltration; 4) improving CAR-T cell activity and persistence; 5) reprogramming the immunosuppressive microenvironments. Additionally, future requirements for the development of this field, with a specific emphasis on promoting innovation and facilitating clinical translation, are thoroughly discussed.

Engineering Challenges and Opportunities in Autologous Cellular Cancer Immunotherapy

The use of a patient's own immune or tumor cells, manipulated ex vivo, enables Ag- or patient-specific immunotherapy. Despite some clinical successes, there remain significant barriers to efficacy, broad patient population applicability, and safety. Immunotherapies that target specific tumor Ags, such as chimeric Ag receptor T cells and some dendritic cell vaccines, can mount robust immune responses against immunodominant Ags, but evolving tumor heterogeneity and antigenic downregulation can drive resistance. In contrast, whole tumor cell vaccines and tumor lysate-loaded dendritic cell vaccines target the patient's unique tumor antigenic repertoire without prior neoantigen selection; however, efficacy can be weak when lower-affinity clones dominate the T cell pool. Chimeric Ag receptor T cell and tumor-infiltrating lymphocyte therapies additionally face challenges related to genetic modification, T cell exhaustion, and immunotoxicity. In this review, we highlight some engineering approaches and opportunities to these challenges among four classes of autologous cell therapies.

IL-10-expressing CAR T cells resist dysfunction and mediate durable clearance of solid tumors and metastases

The success of chimeric antigen receptor (CAR) T cell therapy in treating several hematopoietic malignancies has been difficult to replicate in solid tumors, in part because of T cell exhaustion and eventually dysfunction. To counter T cell dysfunction in the tumor microenvironment, we metabolically armored CAR T cells by engineering them to secrete interleukin-10 (IL-10). We show that IL-10 CAR T cells preserve intact mitochondrial structure and function in the tumor microenvironment and increase oxidative phosphorylation in a mitochondrial pyruvate carrier-dependent manner. IL-10 secretion promoted proliferation and effector function of CAR T cells, leading to complete regression of established solid tumors and metastatic cancers across several cancer types in syngeneic and xenograft mouse models, including colon cancer, breast cancer, melanoma and pancreatic cancer. IL-10 CAR T cells also induced stem cell-like memory responses in lymphoid organs that imparted durable protection against tumor rechallenge. Our results establish a generalizable approach to counter CAR T cell dysfunction through metabolic armoring, leading to solid tumor eradication and long-lasting immune protection.

The Progress and Prospects of Immune Cell Therapy for the Treatment of Cancer

Immune cell therapy as a revolutionary treatment modality, significantly transformed cancer care. It is a specialized form of immunotherapy that utilizes living immune cells as therapeutic reagents for the treatment of cancer. Unlike traditional drugs, cell therapies are considered "living drugs," and these products are currently customized and require advanced manufacturing techniques. Although chimeric antigen receptor (CAR)-T cell therapies have received tremendous attention in the industry regarding the treatment of hematologic malignancies, their effectiveness in treating solid tumors is often restricted, leading to the emergence of alternative immune cell therapies. Tumor-infiltrating lymphocytes (TIL) cell therapy, cytokine-induced killer (CIK) cell therapy, dendritic cell (DC) vaccines, and DC/CIK cell therapy are designed to use the body's natural defense mechanisms to target and eliminate cancer cells, and usually have fewer side effects or risks. On the other hand, cell therapies, such as chimeric antigen receptor-T (CAR-T) cell, T cell receptor (TCR)-T, chimeric antigen receptor-natural killer (CAR-NK), or CAR-macrophages (CAR-M) typically utilize either autologous stem cells, allogeneic or xenogeneic cells, or genetically modified cells, which require higher levels of manipulation and are considered high risk. These high-risk cell therapies typically hold special characteristics in tumor targeting and signal transduction, triggering new anti-tumor immune responses. Recently, significant advances have been achieved in both basic and clinical researches on anti-tumor mechanisms, cell therapy product designs, and technological innovations. With swift technological integration and a high innovation landscape, key future development directions have emerged. To meet the demands of cell therapy technological advancements in treating cancer, we comprehensively and systematically investigate the technological innovation and clinical progress of immune cell therapies in this study. Based on the therapeutic mechanisms and methodological features of immune cell therapies, we analyzed the main technical advantages and clinical transformation risks associated with these therapies. We also analyzed and forecasted the application prospects, providing references for relevant enterprises with the necessary information to make informed decisions regarding their R&D direction selection.

Evolving CAR-T-Cell Therapy for Cancer Treatment: From Scientific Discovery to Cures

In recent years, chimeric antigen receptor (CAR)-T-cell therapy has emerged as the most promising immunotherapy for cancer that typically uses patients' T cells and genetically engineered them to target cancer cells. Although recent improvements in CAR-T-cell therapy have shown remarkable success for treating hematological malignancies, the heterogeneity in tumor antigens and the immunosuppressive nature of the tumor microenvironment (TME) limits its efficacy in solid tumors. Despite the enormous efforts that have been made to make CAR-T-cell therapy more effective and have minimal side effects for treating hematological malignancies, more research needs to be conducted regarding its use in the clinic for treating various other types of cancer. The main concern for CAR-T-cell therapy is severe toxicities due to the cytokine release syndrome, whereas the other challenges are associated with complexity and immune-suppressing TME, tumor antigen heterogeneity, the difficulty of cell trafficking, CAR-T-cell exhaustion, and reduced cytotoxicity in the tumor site. This review discussed the latest discoveries in CAR-T-cell therapy strategies and combination therapies, as well as their effectiveness in different cancers. It also encompasses ongoing clinical trials; current challenges regarding the therapeutic use of CAR-T-cell therapy, especially for solid tumors; and evolving treatment strategies to improve the therapeutic application of CAR-T-cell therapy.

Genome Engineering for Next-Generation Cellular Immunotherapies

Over the past decade, cellular immunotherapies such as CAR-T, TCR-T, and NK cell therapies have achieved tremendous success in cancer treatment. However, various challenges and obstacles remain, including antigen escape, immunosuppression in the tumor microenvironment, toxicities, and on-target off-tumor effects. Recent strategies for overcoming these roadblocks have included the use of genome engineering. Multiplexed CRISPR-Cas and synthetic biology approaches facilitate the development of cell therapies with higher potency and sophisticated modular control; they also offer a toolkit for allogeneic therapy development. Engineering approaches have targeted genetic modifications to enhance long-term persistence through cytokine modulation, knockout of genes mediating immunosuppressive signals, and genes such as the endogenous TCR and MHC-I that elicit adverse host-graft interactions in an allogeneic context. Genome engineering approaches for other immune cell types are also being explored, such as CAR macrophages and CAR-NK cells. Future therapeutic development of cellular immunotherapies may also be guided by novel target discovery through unbiased CRISPR genetic screening approaches.

New insights into the stemness of adoptively transferred T cells by γc family cytokines

T cell-based adoptive cell therapy (ACT) has exhibited excellent antitumoral efficacy exemplified by the clinical breakthrough of chimeric antigen receptor therapy (CAR-T) in hematologic malignancies. It relies on the pool of functional T cells to retain the developmental potential to serially kill targeted cells. However, failure in the continuous supply and persistence of functional T cells has been recognized as a critical barrier to sustainable responses. Conferring stemness on infused T cells, yielding stem cell-like memory T cells (TSCM) characterized by constant self-renewal and multilineage differentiation similar to pluripotent stem cells, is indeed necessary and promising for enhancing T cell function and sustaining antitumor immunity. Therefore, it is crucial to identify TSCM cell induction regulators and acquire more TSCM cells as resource cells during production and after infusion to improve antitumoral efficacy. Recently, four common cytokine receptor γ chain (γc) family cytokines, encompassing interleukin-2 (IL-2), IL-7, IL-15, and IL-21, have been widely used in the development of long-lived adoptively transferred TSCM in vitro. However, challenges, including their non-specific toxicities and off-target effects, have led to substantial efforts for the development of engineered versions to unleash their full potential in the induction and maintenance of T cell stemness in ACT. In this review, we summarize the roles of the four γc family cytokines in the orchestration of adoptively transferred T cell stemness, introduce their engineered versions that modulate TSCM cell formation and demonstrate the potential of their various combinations. Video Abstract.

Engineering strategies to optimise adoptive cell therapy in ovarian cancer

Ovarian cancer is amongst the ten most common cancer types in women, and it is one of the leading causes of death. Despite the promising results of targeted therapies, including anti-angiogenic agents and poly (ADP-ribose) polymerase inhibitors (PARPi), the majority of patients will relapse and develop treatment resistance, implying that novel therapeutic strategies are required. Adoptive cell therapy (ACT) refers to the process by which autologous immune cells are used to eliminate cancer. Examples include tumour infiltrating lymphocytes (TILs), T cells genetically engineered with T cell receptors (TCR), or chimeric antigen receptor (CAR)-T cells. Recently, ACT has revealed promising results in the treatment of haematological malignancies, however, its application to solid tumours is still limited due to lack of functionality and persistence of T cells, prevalence of an exhausted phenotype and impaired trafficking towards the tumour microenvironment (TME). In this review we explore the potential of ACT for the treatment of ovarian cancer and strategies to overcome its principal limitations.

Empowering gene delivery with protein engineering platforms

The repertoire of therapeutic proteins has been substantially augmented by molecular engineering approaches, which have seen remarkable advancement in recent years. In particular, advances in directed evolution technologies have empowered the development of custom-designed proteins with novel and disease-relevant functions. Whereas engineered proteins have typically been administered through systemic injection of the purified molecule, exciting progress in gene delivery affords the opportunity to elicit sustained production of the engineered proteins by targeted cells in the host organism. Combining developments at the leading edge of protein engineering and gene delivery has catapulted a new wave of molecular and cellular therapy approaches, which harbor great promise for personalized and precision medicine. This mini-review outlines currently used display platforms for protein evolution and describes recent examples of how the resulting engineered proteins have been incorporated into DNA- and cell-based therapeutic platforms, both in vitro and in vivo. Collectively, the strategies detailed herein provide a framework for synthesizing molecular engineering workflows with gene therapy systems for a breadth of applications in research and medicine.

DIALing-up the preclinical characterization of gene-modified adoptive cellular immunotherapies

The preclinical characterization of gene modified adoptive cellular immunotherapy candidates for clinical development often requires the use of mouse models. Gene-modified lymphocytes (GML) incorporating chimeric antigen receptors (CAR) and T-cell receptors (TCR) into immune effector cells require in vivo characterization of biological activity, mechanism of action, and preclinical safety. Typically, this characterization involves the assessment of dose-dependent, on-target, on-tumor activity in severely immunocompromised mice. While suitable for the purpose of evaluating T cell-expressed transgene function in a living host, this approach falls short in translating cellular therapy efficacy, safety, and persistence from preclinical models to humans. To comprehensively characterize cell therapy products in mice, we have developed a framework called "DIAL". This framework aims to enable an end-to-end understanding of genetically engineered cellular immunotherapies in vivo, from infusion to tumor clearance and long-term immunosurveillance. The acronym DIAL stands for Distribution, Infiltration, Accumulation, and Longevity, compartmentalizing the systemic attributes of gene-modified cellular therapy and providing a platform for optimization with the ultimate goal of improving therapeutic efficacy. This review will discuss both existent and emerging examples of DIAL characterization in mouse models, as well as opportunities for future development and optimization.

FOXO1 is a master regulator of CAR T memory programming

Poor CAR T persistence limits CAR T cell therapies for B cell malignancies and solid tumors1,2. The expression of memory-associated genes such as TCF7 (protein name TCF1) is linked to response and long-term persistence in patients3-7, thereby implicating memory programs in therapeutic efficacy. Here, we demonstrate that the pioneer transcription factor, FOXO1, is responsible for promoting memory programs and restraining exhaustion in human CAR T cells. Pharmacologic inhibition or gene editing of endogenous FOXO1 in human CAR T cells diminished the expression of memory-associated genes, promoted an exhaustion-like phenotype, and impaired antitumor activity in vitro and in vivo. FOXO1 overexpression induced a gene expression program consistent with T cell memory and increased chromatin accessibility at FOXO1 binding motifs. FOXO1-overexpressing cells retained function, memory potential, and metabolic fitness during settings of chronic stimulation and exhibited enhanced persistence and antitumor activity in vivo. In contrast, TCF1 overexpression failed to enforce canonical memory programs or enhance CAR T cell potency. Importantly, endogenous FOXO1 activity correlated with CAR T and TIL responses in patients, underscoring its clinical relevance in cancer immunotherapy. Our results demonstrate that memory reprogramming through FOXO1 can enhance the persistence and potency of human CAR T cells and highlights the utility of pioneer factors, which bind condensed chromatin and induce local epigenetic remodeling, for optimizing therapeutic T cell states.

The shifting roles and toxicities of cellular therapies in B-cell malignancies

Cellular therapies provide a curative-intent option for patients with relapsedand refractory lymphomas. Current options including high dose chemotherapyfollowed by autologous or allogeneic hematopoietic stem cell transplantation or CD19 chimericantigen receptor T-cell (CART) therapy. The indication varies according to lymphoma sub-type and line oftherapy. The sequencing of these therapies and their use in second-line orlater settings to manage these diseases is undergoing significant changes, withCD19 CAR T becoming a preferred option for relapsed aggressive B-cell lymphoma.The mechanism of both therapies causes significant yet distinctlymphodepletion, infectious, and inflammatory toxicities. The resulting patternand timing of immune reconstitution helps guide risk-mitigating strategies,revaccination, and infectious prophylaxis. In this review, we discuss theindication, efficacy, toxicity and immune reconstitution of autologoushematopoietic stem cell transplantation and CAR T therapy for use in thetreatment of lymphoma.

Coengineering specificity, safety, and function into T cells for cancer immunotherapy

Adoptive T-cell transfer (ACT) therapies, including of tumor infiltrating lymphocytes (TILs) and T cells gene-modified to express either a T cell receptor (TCR) or a chimeric antigen receptor (CAR), have demonstrated clinical efficacy for a proportion of patients and cancer-types. The field of ACT has been driven forward by the clinical success of CD19-CAR therapy against various advanced B-cell malignancies, including curative responses for some leukemia patients. However, relapse remains problematic, in particular for lymphoma. Moreover, for a variety of reasons, relative limited efficacy has been demonstrated for ACT of non-hematological solid tumors. Indeed, in addition to pre-infusion challenges including lymphocyte collection and manufacturing, ACT failure can be attributed to several biological processes post-transfer including, (i) inefficient tumor trafficking, infiltration, expansion and retention, (ii) chronic antigen exposure coupled with insufficient costimulation resulting in T-cell exhaustion, (iii) a range of barriers in the tumor microenvironment (TME) mediated by both tumor cells and suppressive immune infiltrate, (iv) tumor antigen heterogeneity and loss, or down-regulation of antigen presentation machinery, (v) gain of tumor intrinsic mechanisms of resistance such as to apoptosis, and (vi) various forms of toxicity and other adverse events in patients. Affinity-optimized TCRs can improve T-cell function and innovative CAR designs as well as gene-modification strategies can be used to coengineer specificity, safety, and function into T cells. Coengineering strategies can be designed not only to directly support the transferred T cells, but also to block suppressive barriers in the TME and harness endogenous innate and adaptive immunity. Here, we review a selection of the remarkable T-cell coengineering strategies, including of tools, receptors, and gene-cargo, that have been developed in recent years to augment tumor control by ACT, more and more of which are advancing to the clinic.

Synthetic manipulation of the cancer-immunity cycle: CAR-T cell therapy

Synthetic immunity to cancer has been pioneered by the application of chimeric antigen receptor (CAR) engineering into autologous T cells. CAR T cell therapy is highly amenable to molecular engineering to bypass barriers of the cancer immunity cycle, such as endogenous antigen presentation, immune priming, and natural checkpoints that constrain immune responses. Here, we review CAR T cell design and the mechanisms that drive sustained CAR T cell effector activity and anti-tumor function. We discuss engineering approaches aimed at improving anti-tumor function through a variety of mechanistic interventions for both hematologic and solid tumors. The ability to engineer T cells in such a variety of ways, including by modifying their trafficking, antigen recognition, costimulation, and addition of synthetic genes, circuits, knockouts and base edits to finely tune complex functions, is arguably the most powerful way to manipulate the cancer immunity cycle in patients.

Clinical development of chimeric antigen receptor-T cell therapy for hematological malignancies

ABSTRACT

Cellular therapies have revolutionized the treatment of hematological malignancies since their conception and rapid development. Chimeric antigen receptor (CAR)-T cell therapy is the most widely applied cellular therapy. Since the Food and Drug Administration approved two CD19-CAR-T products for clinical treatment of relapsed/refractory acute lymphoblastic leukemia and diffuse large B cell lymphoma in 2017, five more CAR-T cell products were subsequently approved for treating multiple myeloma or B cell malignancies. Moreover, clinical trials of CAR-T cell therapy for treating other hematological malignancies are ongoing. Both China and the United States have contributed significantly to the development of clinical trials. However, CAR-T cell therapy has many limitations such as a high relapse rate, adverse side effects, and restricted availability. Various methods are being implemented in clinical trials to address these issues, some of which have demonstrated promising breakthroughs. This review summarizes developments in CAR-T cell trials and advances in CAR-T cell therapy.