Reprogramming antitumor immunity

ICI-induced cardiovascular toxicity: mechanisms and immune reprogramming therapeutic strategies

The advent of immune checkpoint inhibitors (ICIs) has revolutionized cancer treatment, offering life-saving benefits to tumor patients. However, the utilize of ICI agents is often accompanied by immune-related adverse events (irAEs), among which cardiovascular toxicities have attracted more and more attention. ICI induced cardiovascular toxicities predominantly present as acute myocarditis and chronic atherosclerosis, both of which are driven by excessive immune activation. Reprogramming of T cells and macrophages has been demonstrated as a pivotal factor in the pathogenesis of these complications. Therapeutic strategies targeting glycolysis, fatty acid oxidation, reactive oxygen species (ROS) production and some other key signaling have shown promise in mitigating immune hyperactivation and inflammation. In this review, we explored the intricate mechanisms underlying ICI-induced cardiovascular toxicities and highlighted the protective potential of immune reprogramming. We emphasize the roles of T cell and macrophage reprogramming in the heart and vasculature, showcasing their contributions to both short-term and long-term regulation of cardiovascular health. Ultimately, a deeper understanding of these processes will not only enhance the safety of ICIs but also pave the way for innovative strategies to manage immune-related toxicities in cancers therapy.

Therapeutic potential of tumor-infiltrating lymphocytes in non-small cell lung cancer

Lung cancer is the leading cause of cancer-related death worldwide, with poor outcomes even for those diagnosed at early stages. Current standard-of-care for most non-small cell lung cancer (NSCLC) patients involves an array of chemotherapy, radiotherapy, immunotherapy, targeted therapy, and surgical resection depending on the stage and location of the cancer. While patient outcomes have certainly improved, advances in highly personalized care remain limited. However, there is growing excitement around harnessing the power of tumor-infiltrating lymphocytes (TILs) through the use of adoptive cell transfer (ACT) therapy. These TILs are naturally occurring, may already recognize tumor-specific antigens, and can have direct anti-cancer effect. In this review, we highlight comparisons of various ACTs, including a brief TIL history, show current advances and successes of TIL therapy in NSCLC, discuss the potential roles for epigenetics in T cell expansion, and highlight challenges and future directions of the field to combat NSCLC in a personalized manner.

Strategies for Reducing Toxicity and Enhancing Efficacy of Chimeric Antigen Receptor T Cell Therapy in Hematological Malignancies

Chimeric antigen receptor T cell (CAR-T) therapy in hematologic malignancies has made great progress, but there are still some problems. First, T cells from tumor patients show an exhaustion phenotype; thus, the persistence and function of the CAR-Ts are poor, and achieving a satisfactory curative effect is difficult. Second, some patients initially respond well but quickly develop antigen-negative tumor recurrence. Thirdly, CAR-T treatment is not effective in some patients and is accompanied by severe side effects, such as cytokine release syndrome (CRS) and neurotoxicity. The solution to these problems is to reduce the toxicity and enhance the efficacy of CAR-T therapy. In this paper, we describe various strategies for reducing the toxicity and enhancing the efficacy of CAR-T therapy in hematological malignancies. In the first section, strategies for modifying CAR-Ts using gene-editing technologies or combining them with other anti-tumor drugs to enhance the efficacy of CAR-T therapy are introduced. The second section describes some methods in which the design and construction of CAR-Ts differ from the conventional process. The aim of these methods is to enhance the anti-tumor activity of CAR-Ts and prevent tumor recurrence. The third section describes modifying the CAR structure or installing safety switches to radically reduce CAR-T toxicity or regulating inflammatory cytokines to control the symptoms of CAR-T-associated toxicity. Together, the knowledge summarized herein will aid in designing better-suited and safer CAR-T treatment strategies.

Carbon Monoxide Activates PERK-Regulated Autophagy to Induce Immunometabolic Reprogramming and Boost Antitumor T-cell Function

Mitochondria and endoplasmic reticulum (ER) share structural and functional networks and activate well-orchestrated signaling processes to shape cells' fate and function. While persistent ER stress (ERS) response leads to mitochondrial collapse, moderate ERS promotes mitochondrial function. Strategies to boost antitumor T-cell function by targeting ER-mitochondria cross-talk have not yet been exploited. Here, we used carbon monoxide (CO), a short-lived gaseous molecule, to test whether engaging moderate ERS conditions can improve mitochondrial and antitumor functions in T cells. In melanoma antigen-specific T cells, CO-induced transient activation of ERS sensor protein kinase R-like endoplasmic reticulum kinase (PERK) significantly increased antitumor T-cell function. Furthermore, CO-induced PERK activation temporarily halted protein translation and induced protective autophagy, including mitophagy. The use of LC3-GFP enabled differentiation between the cells that prepare themselves to undergo active autophagy (LC3-GFPpos) and those that fail to enter the process (LC3-GFPneg). LC3-GFPpos T cells showed strong antitumor potential, whereas LC3-GFPneg cells exhibited a T regulatory-like phenotype, harbored dysfunctional mitochondria, and accumulated abnormal metabolite content. These anomalous ratios of metabolites rendered the cells with a hypermethylated state and distinct epigenetic profile, limiting their antitumor activity. Overall, this study shows that ERS-activated autophagy pathways modify the mitochondrial function and epigenetically reprogram T cells toward a superior antitumor phenotype to achieve robust tumor control.

SIGNIFICANCE

Transient activation of ER stress with carbon monoxide drives mitochondrial biogenesis and protective autophagy that elicits superior antitumor T-cell function, revealing an approach to improving adoptive cell efficacy therapy.

TCR-T Immunotherapy: The Challenges and Solutions

T cell receptor-engineered T cell (TCR-T) therapy is free from the limit of surface antigen expression of the target cells, which is a potential cellular immunotherapy for cancer treatment. Significant advances in the treatment of hematologic malignancies with cellular immunotherapy have aroused the interest of researchers in the treatment of solid tumors. Nevertheless, the overall efficacy of TCR-T cell immunotherapy in solid tumors was not significantly high when compared with hematological malignancies. In this article, we pay attention to the barriers of TCR-T cell immunotherapy for solid tumors, as well as the strategies affecting the efficacy of TCR-T cell immunotherapy. To provide some reference for researchers to better overcome the impact of TCR-T cell efficiency in solid tumors.

Deciphering the molecular mechanism of the cancer formation by chromosome structural dynamics

Cancer reflects the dysregulation of the underlying gene network, which is strongly related to the 3D genome organization. Numerous efforts have been spent on experimental characterizations of the structural alterations in cancer genomes. However, there is still a lack of genomic structural-level understanding of the temporal dynamics for cancer initiation and progression. Here, we use a landscape-switching model to investigate the chromosome structural transition during the cancerization and reversion processes. We find that the chromosome undergoes a non-monotonic structural shape-changing pathway with initial expansion followed by compaction during both of these processes. Furthermore, our analysis reveals that the chromosome with a more expanding structure than those at both the normal and cancer cell during cancerization exhibits a sparse contact pattern, which shows significant structural similarity to the one at the embryonic stem cell in many aspects, including the trend of contact probability declining with the genomic distance, the global structural shape geometry and the spatial distribution of loci on the chromosome. In light of the intimate structure-function relationship at the chromosomal level, we further describe the cell state transition processes by the chromosome structural changes, suggesting an elevated cell stemness during the formation of the cancer cells. We show that cell cancerization and reversion are highly irreversible processes in terms of the chromosome structural transition pathways, spatial repositioning of chromosomal loci and hysteresis loop of contact evolution analysis. Our model draws a molecular-scale picture of cell cancerization from the chromosome structural perspective. The process contains initial reprogramming towards the stem cell followed by the differentiation towards the cancer cell, accompanied by an initial increase and subsequent decrease of the cell stemness.

A Correlation Between Differentiation Phenotypes of Infused T Cells and Anti-Cancer Immunotherapy

T-cell therapy, usually with ex-vivo expansion, is very promising to treat cancer. Differentiation status of infused T cells is a crucial parameter for their persistence and antitumor immunity. Key phenotypic molecules are effective and efficient to analyze differentiation status. Differentiation status is crucial for T cell exhaustion, in-vivo lifespan, antitumor immunity, and even antitumor pharmacological interventions. Strategies including cytokines, Akt, Wnt and Notch signaling, epigenetics, and metabolites have been developed to produce less differentiated T cells. Clinical trials have shown better clinical outcomes from infusion of T cells with less differentiated phenotypes. CD27+, CCR7+ and CD62L+ have been the most clinically relevant phenotypic molecules, while Tscm and Tcm the most clinically relevant subtypes. Currently, CD27+, CD62L+ and CCR7+ are recommended in the differentiation phenotype to evaluate strategies of enhancing stemness. Future studies may discover highly clinically relevant differentiation phenotypes for specific T-cell production methods or specific subtypes of cancer patients, with the advantages of precision medicine.

First-in-human phase 1 trial of induced regulatory T cells for graft-versus-host disease prophylaxis in HLA-matched siblings

Human CD4+25- T cells cultured in interleukin 2 (IL-2), rapamycin, and transforming growth factor β (TGFβ) along with anti-CD3 monoclonal antibody-loaded artificial antigen-presenting cells generate FoxP3+ induced regulatory T cells (iTregs) with potent suppressive function. We performed a phase 1, single-center, dose-escalation study to determine the safety profile of iTregs in adults with high-risk malignancy treated with reduced-intensity conditioning and mobilized peripheral blood stem cells (PBSCs) from HLA-identical sibling donors. Sixteen patients were enrolled and 14 were treated (2 productions failed to meet desired doses). One patient each received 3.0 × 106/kg, 3.0 × 107/kg, and 3.0 × 108/kg iTregs with corresponding T-conventional-to-iTreg ratios of 86:1, 8:1, and 1:2. After 3 patients received 3.0 × 108/kg in the presence of cyclosporine (CSA) and mycophenolate mofetil (MMF) with no dose-limiting toxicities, subsequent patients were to receive iTregs in the presence of sirolimus/MMF that favors Foxp3 stability based on preclinical modeling. However, 2 of 2 developed grade 3 acute graft-versus-host disease (GVHD), resulting in suspension of the sirolimus/MMF. An additional 7 patients received 3.0 × 108/kg iTregs with CSA/MMF. In the 14 patients treated with iTregs and CSA/MMF, there were no severe infusional toxicities with all achieving neutrophil recovery (median, day 13). Of 10 patients who received 3.0 × 108/kg iTregs and CSA/MMF, 7 had no aGVHD, 2 had grade 2, and 1 had grade 3. Circulating Foxp3+ iTregs were detectable through day 14. In summary, iTregs in the context of CSA/MMF can be delivered safely at doses as high as 3 × 108/kg. This trial was registered at www.clinicaltrials.gov as #NCT01634217.

Neoantigen Specific T Cells Derived From T Cell-Derived Induced Pluripotent Stem Cells for the Treatment of Hepatocellular Carcinoma: Potential and Challenges

Immunotherapy has become an indispensable part of the comprehensive treatment of hepatocellular carcinoma (HCC). Immunotherapy has proven effective in patients with early HCC, advanced HCC, or HCC recurrence after liver transplantation. Clinically, the most commonly used immunotherapy is immune checkpoint inhibition using monoclonal antibodies, such as CTLA-4 and PD-1. However, it cannot fundamentally solve the problems of a weakened immune system and inactivation of immune cells involved in killing tumor cells. T cells can express tumor antigen-recognizing T cell receptors (TCRs) or chimeric antigen receptors (CARs) on the cell surface through gene editing to improve the specificity and responsiveness of immune cells. According to previous studies, TCR-T cell therapy is significantly better than CAR-T cell therapy in the treatment of solid tumors and is one of the most promising immune cell therapies for solid tumors so far. However, its application in the treatment of HCC is still being researched. Technological advancements in induction and redifferentiation of induced pluripotent stem cells (iPSCs) allow us to use T cells to induce T cell-derived iPSCs (T-iPSCs) and then differentiate them into TCR-T cells. This has allowed a convenient strategy to study HCC models and explore optimal treatment strategies. This review gives an overview of the major advances in the development of protocols to generate neoantigen-specific TCR-T cells from T-iPSCs. We will also discuss their potential and challenges in the treatment of HCC.

Conventional Treatment for Multiple Myeloma Drives Premature Aging Phenotypes and Metabolic Dysfunction in T Cells

New diagnoses of multiple myeloma (MM) tend to occur after the age of 60, by which time thymic output is severely reduced. As a consequence, lymphocyte recovery after lymphopenia-inducing anti-MM therapies relies on homeostatic proliferation of peripheral T cells rather than replenishment by new thymic emigrants. To assess lymphocyte recovery and phenotype in patients with newly diagnosed MM (NDMM) and relapsed/refractory MM (RRMM), we tracked CD4+ and CD8+ T cell populations at serial time points throughout treatment and compared them to age-matched healthy donors (HD). Anti-MM therapies and autologous stem cell transplant (ASCT) caused a permanent reduction in the CD4:8 ratio, a decrease in naïve CD4+ T cells, and an increase in effector memory T cells and PD1-expressing CD4+ T cells. Transcriptional profiling highlighted that genes associated with fatty acid β-oxidation were upregulated in T cells in RRMM, suggesting increased reliance on mitochondrial respiration. High mitochondrial mass was seen in all T cell subsets in RRMM but with relatively suppressed reactive oxygen species and mitochondrial membrane potential, indicating mitochondrial dysfunction. These findings highlight that anti-MM and ASCT therapies perturb the composition of the T cell compartment and drive substantial metabolic remodeling, which may affect the fitness of T cells for immunotherapies. This is particularly pertinent to chimeric antigen receptor (CAR)-T therapy, which might be more efficacious if T cells were stored prior to ASCT rather than at relapse.

Hematopoietic Reprogramming Entangles with Hematopoiesis

Hematopoiesis generally refers to hematopoietic development in fetuses and adults, as well as to hematopoietic stem cell differentiation into progeny lineages. The multiple processes that generate diverse hematopoietic cells have been considered to be unidirectional. However, many reports have recently demonstrated that these processes are not only reversible but also interconvertible via cell reprogramming. The cell reprogramming that occurs in hematopoietic cells is termed hematopoietic reprogramming. We focus on both autogenous and artificial hematopoietic reprogramming under physiological and pathological conditions that is mainly directed by the actions of transcription factors (TFs), chemical compounds, or extracellular cytokines. A comprehensive understanding of hematopoietic reprogramming will help us not only to generate desirable cells for cell therapy but also to further analyze normal and malignant hematopoiesis.

Understanding and Modulating Immunity With Cell Reprogramming

Cell reprogramming concepts have been classically developed in the fields of developmental and stem cell biology and are currently being explored for regenerative medicine, given its potential to generate desired cell types for replacement therapy. Cell fate can be experimentally reversed or modified by enforced expression of lineage specific transcription factors leading to pluripotency or attainment of another somatic cell type identity. The possibility to reprogram fibroblasts into induced dendritic cells (DC) competent for antigen presentation creates a paradigm shift for understanding and modulating the immune system with direct cell reprogramming. PU.1, IRF8, and BATF3 were identified as sufficient and necessary to impose DC fate in unrelated cell types, taking advantage of Clec9a, a C-type lectin receptor with restricted expression in conventional DC type 1. The identification of such minimal gene regulatory networks helps to elucidate the molecular mechanisms governing development and lineage heterogeneity along the hematopoietic hierarchy. Furthermore, the generation of patient-tailored reprogrammed immune cells provides new and exciting tools for the expanding field of cancer immunotherapy. Here, we summarize cell reprogramming concepts and experimental approaches, review current knowledge at the intersection of cell reprogramming with hematopoiesis, and propose how cell fate engineering can be merged to immunology, opening new opportunities to understand the immune system in health and disease.

A Three-dimensional Thymic Culture System to Generate Murine Induced Pluripotent Stem Cell-derived Tumor Antigen-specific Thymic Emigrants

The inheritance of pre-rearranged T cell receptors (TCRs) and their epigenetic rejuvenation make induced pluripotent stem cell (iPSC)-derived T cells a promising source for adoptive T cell therapy (ACT). However, classical in vitro methods for producing regenerated T cells from iPSC result in either innate-like or terminally differentiated T cells, which are phenotypically and functionally distinct from naïve T cells. Recently, a novel three-dimensional (3D) thymic culture system was developed to generate a homogenous subset of CD8αβ⁺ antigen-specific T cells with a naïve T cell-like functional phenotype, including the capacity for proliferation, memory formation, and tumor suppression in vivo. This protocol avoids aberrant developmental fates, allowing for the generation of clinically relevant iPSC-derived T cells, designated as iPSC-derived thymic emigrants (iTE), while also providing a potent tool to elucidate the subsequent functions necessary for T cell maturation after thymic selection.

Hepatitis C Virus as a Unique Human Model Disease to Define Differences in the Transcriptional Landscape of T Cells in Acute versus Chronic Infection

The hepatitis C virus is unique among chronic viral infections in that an acute outcome with complete viral elimination is observed in a minority of infected patients. This unique feature allows direct comparison of successful immune responses with those that fail in the setting of the same human infection. Here we review how this scenario can be used to achieve better understanding of transcriptional regulation of T-cell differentiation. Specifically, we discuss results from a study comparing transcriptional profiles of hepatitis C virus (HCV)-specific CD8 T-cells during early HCV infection between patients that do and do not control and eliminate HCV. Identification of early gene expression differences in key T-cell differentiation molecules as well as clearly distinct transcriptional networks related to cell metabolism and nucleosomal regulation reveal novel insights into the development of exhausted and memory T-cells. With additional transcriptional studies of HCV-specific CD4 and CD8 T-cells in different stages of infection currently underway, we expect HCV infection to become a valuable model disease to study human immunity to viruses.

Approaches for generation of anti-leukemia specific T cells

As three decades ago, it was reported that adoptive T cell immunotherapy by infusion of autologous tumor infiltrating lymphocytes (TILs) mediated objective cancer regression in patients with metastatic melanoma. A new era of T cell immunotherapy arose since the improvement and clinical use of anti-CD19 chimeric antigen receptor T cells (CAR-T) for the treatment of refractory and relapsed B lymphocyte leukemia. However, several challenges and difficulties remain on the way to reach generic and effective T cell immunotherapy, including lacking a generic method for generating anti-leukemia-specific T cells from every patient. Here, we summarize the current methods of generating anti-leukemia-specific T cells, and the promising approaches in the future.

T cell senescence and CAR-T cell exhaustion in hematological malignancies

T cell senescence has been recognized to play an immunosuppressive role in the aging population and cancer patients. Strategies dedicated to preventing or reversing replicative and premature T cell senescence are required to increase the lifespan of human beings and to reduce the morbidity from cancer. In addition, overcoming the T cell terminal differentiation or senescence from lymphoma and leukemia patients is a promising approach to enhance the effectiveness of adoptive cellular immunotherapy (ACT). Chimeric antigen receptor T (CAR-T) cell and T cell receptor-engineered T (TCR-T) cell therapy highly rely on functionally active T cells. However, the mechanisms which drive T cell senescence remain unclear and controversial. In this review, we describe recent progress for restoration of T cell homeostasis from age-related senescence as well as recovery of T cell activation in hematological malignancies.

Epigenetic control of CD8+ T cell differentiation

Upon stimulation, small numbers of naive CD8+ T cells proliferate and differentiate into a variety of memory and effector cell types. CD8+ T cells can persist for years and kill tumour cells and virally infected cells. The functional and phenotypic changes that occur during CD8+ T cell differentiation are well characterized, but the epigenetic states that underlie these changes are incompletely understood. Here, we review the epigenetic processes that direct CD8+ T cell differentiation and function. We focus on epigenetic modification of DNA and associated histones at genes and their regulatory elements. We also describe structural changes in chromatin organization that affect gene expression. Finally, we examine the translational potential of epigenetic interventions to improve CD8+ T cell function in individuals with chronic infections and cancer.

Generation of Tumor Antigen-Specific iPSC-Derived Thymic Emigrants Using a 3D Thymic Culture System

Induced pluripotent stem cell (iPSC)-derived T cells may provide future therapies for cancer patients, but those generated by current methods, such as the OP9/DLL1 system, have shown abnormalities that pose major barriers for clinical translation. Our data indicate that these iPSC-derived CD8 single-positive T cells are more like CD4+CD8+ double-positive T cells than mature naive T cells because they display phenotypic markers of developmental arrest and an innate-like phenotype after stimulation. We developed a 3D thymic culture system to avoid these aberrant developmental fates, generating a homogeneous subset of CD8αβ+ antigen-specific T cells, designated iPSC-derived thymic emigrants (iTEs). iTEs exhibit phenotypic and functional similarities to naive T cells both in vitro and in vivo, including the capacity for expansion, memory formation, and tumor suppression. These data illustrate the limitations of current methods and provide a tool to develop the next generation of iPSC-based antigen-specific immunotherapies.

CD38-NAD+Axis Regulates Immunotherapeutic Anti-Tumor T Cell Response

Heightened effector function and prolonged persistence, the key attributes of Th1 and Th17 cells, respectively, are key features of potent anti-tumor T cells. Here, we established ex vivo culture conditions to generate hybrid Th1/17 cells, which persisted long-term in vivo while maintaining their effector function. Using transcriptomics and metabolic profiling approaches, we showed that the enhanced anti-tumor property of Th1/17 cells was dependent on the increased NAD⁺-dependent activity of the histone deacetylase Sirt1. Pharmacological or genetic inhibition of Sirt1 activity impaired the anti-tumor potential of Th1/17 cells. Importantly, T cells with reduced surface expression of the NADase CD38 exhibited intrinsically higher NAD⁺, enhanced oxidative phosphorylation, higher glutaminolysis, and altered mitochondrial dynamics that vastly improved tumor control. Lastly, blocking CD38 expression improved tumor control even when using Th0 anti-tumor T cells. Thus, strategies targeting the CD38-NAD⁺ axis could increase the efficacy of anti-tumor adoptive T cell therapy.

Bringing Induced Pluripotent Stem Cell Technology to the Bedside

Induced pluripotent stem cells (iPSCs) describe somatic cells that have been reprogrammed to the pluripotent state. From a scientific perspective, their discovery has provided a molecular roadmap for turning on and off cell identities, effectively allowing any cell type to have its identity changed into any other cell type. They also act as a human model for understanding the development of every cell and organ in the body. In addition, because they can be prepared from patients, iPSCs offer a unique human model for studying disease development, including many diseases that are generally diagnosed at a late stage of their development. These models have provided new insights on the pathogenesis and new targets to prevent or reverse the disease development process. Indeed, clinical studies on compounds based on drug screening hits in human iPSC disease models have begun. Because of their proliferation and differentiation capacity, iPSCs can also be used to prepare cells for transplantations, and related clinical studies using iPSC-based cell therapies are ongoing. The combination of iPSCs with other technologies or therapeutic strategies is expected to expand their medical benefits. In this review, we consider medical accomplishments based on iPSC research and future ones that can be anticipated.

Optimization of cGMP purification and expansion of umbilical cord blood-derived T-regulatory cells in support of first-in-human clinical trials

BACKGROUND AIMS

Thymic-derived regulatory T cells (tTreg) are critical regulators of the immune system. Adoptive tTreg transfer is a curative therapy for murine models of autoimmunity, graft rejection, and graft-versus-host disease (GVHD). We previously completed a "first-in-human" clinical trial using in vitro expanded umbilical cord blood (UCB)-derived tTreg to prevent GVHD in patients undergoing UCB hematopoietic stem cell transplantation (HSCT). tTreg were safe and demonstrated clinical efficacy, but low yield prevented further dose escalation.

METHODS

To optimize yield, we investigated the use of KT64/86 artificial antigen presenting cells (aAPCs) to expand tTreg and incorporated a single re-stimulation after day 12 in expansion culture.

RESULTS

aAPCs increased UCB tTreg expansion greater than eightfold over CD3/28 stimulation. Re-stimulation with aAPCs increased UCB tTreg expansion an additional 20- to 30-fold. Re-stimulated human UCB tTreg ameliorated GVHD disease in a xenogeneic model. Following current Good Manufacturing Practice (cGMP) validation, a trial was conducted with tTreg. tTreg doses up to >30-fold higher compared with that obtained with anti-CD3/28 mAb coated-bead expansion and Foxp3 expression was stable during in vitro expansion and following transfer to patients. Increased expansion did not result in a senescent phenotype and GVHD was significantly reduced.

DISCUSSION

Expansion culture with cGMP aAPCs and re-stimulation reproducibly generates sufficient numbers of UCB tTreg that exceeds the numbers of T effector cells in an UCB graft. The methodology supports future tTreg banking and is adaptable to tTreg expansion from HSC sources. Furthermore, because human leukocyte antigen matching is not required, allogeneic UCB tTreg may be a useful strategy for prevention of organ rejection and autoimmune disease.

Targeted Programming of the Lymph Node Environment Causes Evolution of Local and Systemic Immunity

Biomaterial vaccines offer cargo protection, targeting, and co-delivery of signals to immune organs such as lymph nodes (LNs), tissues that coordinate adaptive immunity. Understanding how individual vaccine components impact immune response has been difficult owing to the systemic nature of delivery. Direct intra-lymph node (i.LN.) injection offers a unique opportunity to dissect how the doses, kinetics, and combinations of signals reaching LNs influence the LN environment. Here, i.LN. injection was used as a tool to study the local and systemic responses to vaccines comprised of soluble antigen and degradable polymer particles encapsulating toll-like receptor agonists as adjuvants. Microparticle vaccines increased antigen presenting cells and lymphocytes in LNs, enhancing activation of these cells. Enumeration of antigen-specific CD8⁺ T cells in blood revealed expansion over 7 days, followed by a contraction period over 1 month as memory developed. Extending this strategy to conserved mouse and human tumor antigens resulted in tumor antigen-specific primary and recall responses by CD8⁺ T cells. During challenge with an aggressive metastatic melanoma model, i.LN. delivery of depots slowed tumor growth more than a potent human vaccine adjuvant, demonstrating local treatment of a target immunological site can promote responses that are potent, systemic, and antigen-specific.

Transient exposure to proteins SOX2, Oct-4, and NANOG immortalizes exhausted tumor-infiltrating CTLs

Adoptive cell transfer therapy (ACT) is one of the most promising immunotherapies against cancer, using tumor-infiltrating lymphocytes (TILs) expanded in vitro. Tumor-infiltrating cytotoxic T lymphocytes (TICTLs) play a prominent role in cancer control. TILs terminally differentiate in response to immunosuppressive environments within tumors, and thus are slow to expand and challenging to maintain both in vitro and in patients. To reverse this exhaustion, we utilize a nuclear protein delivery system that exposes TICTLs to the SOX2, Oct-4, and NANOG (SON) proteins. Unlike activated naïve CTLs (effector CTLs), TICTLs respond favorably to SON treatment, exhibiting steady proliferation and extended survivability independent of cytokine and antigen stimulation. Though TICTLs treated with SON (STICTLs) still express T cell receptors as well as other critical downstream components, they are unresponsive to antigen challenge, suggesting that SON treatment regresses TICTLs into a state similar to that of an early double negative T cell. Our findings indicate the TICTL response to SON proteins is unique when compared to effector CTLs, suggesting TICTLs may be sensitive to regulation by other lineage-specific transcription factors and opening a promising new avenue into cancer immunotherapy. To our knowledge, this is the first report on lineage reprogramming of TILs using protein stem cell transcription factors delivered directly to the nucleus.

Improving therapy of chronic lymphocytic leukemia with chimeric antigen receptor T cells

Adoptive cell immunotherapy for the treatment of chronic lymphocytic leukemia (CLL) has heralded a new era of synthetic biology. The infusion of genetically engineered, autologous chimeric antigen receptor (CAR) T cells directed against CD19 expressed by normal and malignant B cells represents a novel approach to cancer therapy. The results of recent clinical trials of CAR T cells in relapsed and refractory CLL have demonstrated long-term disease-free remissions, underscoring the power of harnessing and redirecting the immune system against cancer. This review will briefly summarize T-cell therapies in development for CLL disease. We discuss the role of T-cell function and phenotype, T-cell culture optimization, CAR design, and approaches to potentiate the survival and anti-tumor effects of infused lymphocytes. Future efforts will focus on improving the efficacy of CAR T cells for the treatment of CLL and incorporating adoptive cell immunotherapy into standard medical management of CLL.

Prospects for gene-engineered T cell immunotherapy for solid cancers

Adoptive transfer of receptor-engineered T cells has produced impressive results in treating patients with B cell leukemias and lymphomas. This success has captured public imagination and driven academic and industrial researchers to develop similar 'off-the-shelf' receptors targeting shared antigens on epithelial cancers, the leading cause of cancer-related deaths. However, the successful treatment of large numbers of people with solid cancers using this strategy is unlikely to be straightforward. Receptor-engineered T cells have the potential to cause lethal toxicity from on-target recognition of normal tissues, and there is a paucity of truly tumor-specific antigens shared across tumor types. Here we offer our perspective on how expanding the use of genetically redirected T cells to treat the majority of patients with solid cancers will require major technical, manufacturing and regulatory innovations centered around the development of autologous gene therapies targeting private somatic mutations.

Mechanistic insights into the oncolytic activity of vesicular stomatitis virus in cancer immunotherapy

Immunotherapy and oncolytic virotherapy have both shown anticancer efficacy in the clinic as monotherapies but the greatest promise lies in therapies that combine these approaches. Vesicular stomatitis virus is a prominent oncolytic virus with several features that promise synergy between oncolytic virotherapy and immunotherapy. This review will address the cytotoxicity of vesicular stomatitis virus in transformed cells and what this means for antitumor immunity and the virus’ immunogenicity, as well as how it facilitates the breaking of tolerance within the tumor, and finally, we will outline how these features can be incorporated into the rational design of new treatment strategies in combination with immunotherapy.

T cell exhaustion during persistent viral infections

Although robust and highly effective anti-viral T cells contribute to the clearance of many acute infections, viral persistence is associated with the development of functionally inferior, exhausted, T cell responses. Exhaustion develops in a step-wise and progressive manner, ranges in severity, and can culminate in the deletion of the anti-viral T cells. This disarming of the response is consequential as it compromises viral control and potentially serves to dampen immune-mediated damage. Exhausted T cells are unable to elaborate typical anti-viral effector functions. They are characterized by the sustained upregulation of inhibitory receptors and display a gene expression profile that distinguishes them from prototypic effector and memory T cell populations. In this review we discuss the properties of exhausted T cells; the virological and immunological conditions that favor their development; the cellular and molecular signals that sustain the exhausted state; and strategies for preventing and reversing exhaustion to favor viral control.

The efficacy of cetuximab in a tissue-engineered three-dimensional in vitro model of colorectal cancer

The preclinical development process of chemotherapeutic drugs is often carried out in two-dimensional monolayer cultures. However, a considerable amount of evidence demonstrates that two-dimensional cell culture does not accurately reflect the three-dimensional in vivo tumour microenvironment, specifically with regard to gene expression profiles, oxygen and nutrient gradients and pharmacokinetics. With this objective in mind, we have developed and established a physiologically relevant three-dimensional in vitro model of colorectal cancer based on the removal of interstitial fluid from collagen type I hydrogels. We employed the RAFT™ (Real Architecture For 3D Tissue) system for producing three-dimensional cultures to create a controlled reproducible, multiwell testing platform. Using the HT29 and HCT116 cell lines to model epidermal growth factor receptor expressing colorectal cancers, we characterized three-dimensional cell growth and morphology in addition to the anti-proliferative effects of the anti–epidermal growth factor receptor chemotherapeutic agent cetuximab in comparison to two-dimensional monolayer cultures. Cells proliferated well for 14 days in three-dimensional culture and formed well-defined cellular aggregates within the concentrated collagen matrix. Epidermal growth factor receptor expression levels revealed a twofold and threefold increase in three-dimensional cultures for both HT29 and HCT116 cells in comparison to two-dimensional monolayers, respectively (p < 0.05; p < 0.01). Cetuximab efficacy was significantly lower in HT29 three-dimensional cultures in comparison to two-dimensional monolayers, whereas HCT116 cells in both two-dimension and three-dimension were non-responsive to treatment in agreement with their KRAS mutant status. In summary, these results confirm the use of a three-dimensional in vitro cancer model as a suitable drug-screening platform for in vitro pharmacological testing.

A novel cohort of cancer-testis biomarker genes revealed through meta-analysis of clinical data sets

The identification of cancer-specific biomolecules is of fundamental importance to the development of diagnostic and/or prognostic markers, which may also serve as therapeutic targets. Some antigenic proteins are only normally present in male gametogenic tissues in the testis and not in normal somatic cells. When these proteins are aberrantly produced in cancer they are referred to as cancer/testis (CT) antigens (CTAs). Some CTA genes have been proven to encode immunogenic proteins that have been used as successful immunotherapy targets for various forms of cancer and have been implicated as drug targets. Here, a targeted in silico analysis of cancer expressed sequence tag (EST) data sets resulted in the identification of a significant number of novel CT genes. The expression profiles of these genes were validated in a range of normal and cancerous cell types. Subsequent meta-analysis of gene expression microarray data sets demonstrates that these genes are clinically relevant as cancer-specific biomarkers, which could pave the way for the discovery of new therapies and/or diagnostic/prognostic monitoring technologies.