Cancer regression and neurological toxicity following anti-MAGE-A3 TCR gene therapy

Harnessing the Anti-Tumor Mediators in Mast Cells as a New Strategy for Adoptive Cell Transfer for Cancer

The emergence of cancer immunotherapies utilizing adoptive cell transfer (ACT) continues to be one of the most promising strategies for cancer treatment. Mast cells (MCs) which occur throughout vascularized tissues, are most commonly associated with Type I hypersensitivity, bind immunoglobin E (IgE) with high affinity, produce anti-cancer mediators such as tumor necrosis factor alpha (TNF-α) and granulocyte macrophage colony-stimulating factor (GM-CSF), and generally populate the tumor microenvironments. Yet, the role of MCs in cancer pathologies remains controversial with evidence for both anti-tumor and pro-tumor effects. Here, we review the studies examining the role of MCs in multiple forms of cancer, provide an alternative, MC-based hypothesis underlying the mechanism of therapeutic tumor IgE efficacy in clinical trials, and propose a novel strategy for using tumor-targeted, IgE-sensitized MCs as a platform for developing new cellular cancer immunotherapies. This autologous MC cancer immunotherapy could have several advantages over current cell-based cancer immunotherapies and provide new mechanistic strategies for cancer therapeutics alone or in combination with current approaches.

Safety and efficacy of mutant neoantigen-specific T-cell treatment combined anti-PD-1 therapy in stage IV solid tumors

Aims: This trial explored the safety and efficacy of neoantigen-specific T cells (Nas-Ts) combined with anti-PD-1 (Nas-T + anti-PD-1). Patients & methods: This non-randomized trial recruited participants with solid tumors treated with at least two prior systemic treatment lines. For comparison, 1:1-matched controls who received anti-PD-1 alone were recruited. The primary end point was safety. Results: 15 participants were enrolled in the Nas-T + anti-PD-1 group, the objective response rate was 33.3%, and the disease control rate was 93.3%. The median progression-free survival was significantly different between the Nas-T + anti-PD-1 and control groups (13.8 vs 4.2 months; p = 0.024), but no difference in overall survival was found (p = 0.126). The most common adverse events were maculopapular skin reaction (53.3%), rash (53.3%), hepatotoxicity (53.3%) and fever (53.3%) in the Nas-T + anti-PD-1 group. No serious safety issues were experienced. Conclusion: Nas-Ts combined with anti-PD-1 could be more effective than anti-PD-1 alone in prolonging progression-free survival, with good safety.

Influence of Linker Orientation and Regulative Factor(s) in Liposomal Gene Delivery: A Molecular Level Investigation

Molecular level understanding of liposome-gene interaction is immensely important for the research progress and technological advancement of gene delivery, which is highly significant due to a wide range of applications of gene therapy. The liposomal gene delivery method is one of the most promising techniques due to its efficacy to easily fuse with the cell membrane and its lower toxicity. In vivo gene delivery using liposomes is reported to be extremely successful. However, the success of gene delivery depends on various factors including the chemical nature of the structural unit of the liposome. To explore the regulative factor(s) for liposomal gene delivery, we systematically analyze the linker orientation effect on the gene delivery efficiency of liposomes through a density functional theory (DFT) study. Interestingly, it is observed that the liposome-gene interaction is not the regulating factor for successful gene delivery. The success depends on the gel to liquid melting temperature of the liposome.

Cancer Neoantigens: Challenges and Future Directions for Prediction, Prioritization, and Validation

Prioritization of immunogenic neoantigens is key to enhancing cancer immunotherapy through the development of personalized vaccines, adoptive T cell therapy, and the prediction of response to immune checkpoint inhibition. Neoantigens are tumor-specific proteins that allow the immune system to recognize and destroy a tumor. Cancer immunotherapies, such as personalized cancer vaccines, adoptive T cell therapy, and immune checkpoint inhibition, rely on an understanding of the patient-specific neoantigen profile in order to guide personalized therapeutic strategies. Genomic approaches to predicting and prioritizing immunogenic neoantigens are rapidly expanding, raising new opportunities to advance these tools and enhance their clinical relevance. Predicting neoantigens requires acquisition of high-quality samples and sequencing data, followed by variant calling and variant annotation. Subsequently, prioritizing which of these neoantigens may elicit a tumor-specific immune response requires application and integration of tools to predict the expression, processing, binding, and recognition potentials of the neoantigen. Finally, improvement of the computational tools is held in constant tension with the availability of datasets with validated immunogenic neoantigens. The goal of this review article is to summarize the current knowledge and limitations in neoantigen prediction, prioritization, and validation and propose future directions that will improve personalized cancer treatment.

Genetic Modification of T Cells for the Immunotherapy of Cancer

Immunotherapy is a beneficial treatment approach for multiple cancers, however, current therapies are effective only in a small subset of patients. Adoptive cell transfer (ACT) is a facet of immunotherapy where T cells targeting the tumor cells are transferred to the patient with several primary forms, utilizing unmodified or modified T cells: tumor-infiltrating lymphocytes (TIL), genetically modified T cell receptor transduced T cells, and chimeric antigen receptor (CAR) transduced T cells. Many clinical trials are underway investigating the efficacy and safety of these different subsets of ACT, as well as trials that combine one of these subsets with another type of immunotherapy. The main challenges existing with ACT are improving clinical responses and decreasing adverse events. Current research focuses on identifying novel tumor targeting T cell receptors, improving safety and efficacy, and investigating ACT in combination with other immunotherapies.

When Onco-Immunotherapy Meets Cold Atmospheric Plasma: Implications on CAR-T Therapies

T cells engineered with chimeric antigen receptors (CAR) have demonstrated its widespread efficacy as a targeted immunotherapeutic modality. Yet, concerns on its specificity, efficacy and generalization prevented it from being established into a first-line approach against cancers. By reviewing challenges limiting its clinical application, ongoing efforts trying to resolve them, and opportunities that emerging oncotherapeutic modalities may bring to temper these challenges, we conclude that careful CAR design should be done to avoid the off-tumor effect, enhance the efficacy of solid tumor treatment, improve product comparability, and resolve problems such as differential efficacies of co-stimulatory molecules, cytokine storm, tumor lysis syndrome, myelosuppression and severe hepatotoxicity. As a promising solution, we propose potential synergies between CAR-T therapies and cold atmospheric plasma, an emerging onco-therapeutic strategy relying on reactive species, towards improved therapeutic efficacies and enhanced safety that deserve extensive investigations.

Glioma Immunotherapy: Advances and Challenges for Spinal Cord Gliomas

Spinal cord gliomas are rare entities that often have limited surgical options. Immunotherapy has shown promise in intracranial gliomas with some research suggesting benefit for spinal cord gliomas. A focused review of immunotherapies that have been investigated in spinal cord gliomas was performed. The primary methods of immunotherapy investigated in spinal cord gliomas include immune checkpoint inhibitors, adoptive T-cell therapies, and vaccine strategies. There are innumerable challenges that must be overcome to effectively apply immunotherapeutic strategies to the spinal cord gliomas including low incidence, few antigenic targets, the blood spinal cord barrier, the immunosuppressive tumor microenvironment and neurotoxic treatment effects. Nonetheless, research has suggested ways to overcome these challenges and treatments have been effective in case reports for metastatic non-small cell lung cancer, melanoma, midline glioma and glioblastoma. Current therapies for spinal cord gliomas are markedly limited. Further research is needed to determine if the success of immunotherapy for intracranial gliomas can be effectively applied to these unique tumors.

CRISPR-based gene disruption and integration of high-avidity, WT1-specific T cell receptors improve antitumor T cell function

T cell receptor (TCR)-based therapy has the potential to induce durable clinical responses in patients with cancer by targeting intracellular tumor antigens with high sensitivity and by promoting T cell survival. However, the need for TCRs specific for shared oncogenic antigens and the need for manufacturing protocols able to redirect T cell specificity while preserving T cell fitness remain limiting factors. By longitudinal monitoring of T cell functionality and dynamics in 15 healthy donors, we isolated 19 TCRs specific for Wilms' tumor antigen 1 (WT1), which is overexpressed by several tumor types. TCRs recognized several peptides restricted by common human leukocyte antigen (HLA) alleles and displayed a wide range of functional avidities. We selected five high-avidity HLA-A*02:01-restricted TCRs, three that were specific to the less explored immunodominant WT1_37-45 and two that were specific to the noncanonical WT1_-78-64 epitopes, both naturally processed by primary acute myeloid leukemia (AML) blasts. With CRISPR-Cas9 genome editing tools, we combined TCR-targeted integration into the TCR α constant (TRAC) locus with TCR β constant (TRBC) knockout, thus avoiding TCRαβ mispairing and maximizing TCR expression and function. The engineered lymphocytes were enriched in memory stem T cells. A unique WT1_37-45-specific TCR showed antigen-specific responses and efficiently killed AML blasts, acute lymphoblastic leukemia blasts, and glioblastoma cells in vitro and in vivo in the absence of off-tumor toxicity. T cells engineered to express this receptor are being advanced into clinical development for AML immunotherapy and represent a candidate therapy for other WT1-expressing tumors.

TCR signal strength defines distinct mechanisms of T cell dysfunction and cancer evasion

T cell receptor (TCR) signal strength is a key determinant of T cell responses. We developed a cancer mouse model in which tumor-specific CD8 T cells (TST cells) encounter tumor antigens with varying TCR signal strength. High-signal-strength interactions caused TST cells to up-regulate inhibitory receptors (IRs), lose effector function, and establish a dysfunction-associated molecular program. TST cells undergoing low-signal-strength interactions also up-regulated IRs, including PD1, but retained a cell-intrinsic functional state. Surprisingly, neither high- nor low-signal-strength interactions led to tumor control in vivo, revealing two distinct mechanisms by which PD1hi TST cells permit tumor escape; high signal strength drives dysfunction, while low signal strength results in functional inertness, where the signal strength is too low to mediate effective cancer cell killing by functional TST cells. CRISPR-Cas9-mediated fine-tuning of signal strength to an intermediate range improved anti-tumor activity in vivo. Our study defines the role of TCR signal strength in TST cell function, with important implications for T cell-based cancer immunotherapies.

Criteria to make animal studies more relevant to treating human cancer

Certain aspects of experimental tumor models in mice most accurately reflect the biology and immunology of cancer in patients. A survey of experimental cancer immunotherapy papers published in 2020 shows most do not achieve cancer shrinkage although treatment is initiated at an early time point after cancer cell injection, which does not reflect cancer immunotherapy in patients. Even then, few current experimental approaches eradicate the injected malignant cells, most only delay outgrowth. The value of targeting mutation-encoded tumor-specific antigens becomes increasingly evident while problems of finding normal gene-encoded tumor-associated antigens as safe, effective targets persist. It might be time to refocus on realistic experimental settings and truly cancer-specific targets. These antigens are associated with the least risk of side effects.

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.

Strategies for Improving the Efficacy of CAR T Cells in Solid Cancers

Simple Summary

Cell therapy with genetically retargeted T cells shows strong clinical efficacy against leukaemia and lymphoma. To make this therapy efficient against solid cancers, a series of hurdles must be addressed. This includes the need to enable the T cells to survive long term in patients and to overcome immunosuppressive mechanisms in the tumour. Further, it is essential to prevent tumour cells from escaping by losing the protein that is recognised by the infused cells. The present article provides an overview of the key strategies that are currently being investigated to overcome these hurdles. A series of approaches have been described in preclinical models, but these remain untested in patients. The further progress of the field will depend on evaluating more strategies in a proper clinical setting.

Abstract

Therapy with T cells equipped with chimeric antigen receptors (CARs) shows strong efficacy against leukaemia and lymphoma, but not yet against solid cancers. This has been attributed to insufficient T cell persistence, tumour heterogeneity and an immunosuppressive tumour microenvironment. The present article provides an overview of key strategies that are currently investigated to overcome these hurdles. Basic aspects of CAR design are revisited, relevant for tuning the stimulatory signal to the requirements of solid tumours. Novel approaches for enhancing T cell persistence are highlighted, based on epigenetic or post-translational modifications. Further, the article describes CAR T strategies that are being developed for overcoming tumour heterogeneity and the escape of cancer stem cells, as well as for countering prevalent mechanisms of immune suppression in solid cancers. In general, personalised medicine is faced with a lack of drugs matching the patient’s profile. The advances and flexibility of modern gene engineering may allow for the filling of some of these gaps with tailored CAR T approaches addressing mechanisms identified as important in the individual patient. At this point, however, CAR T cell therapy remains unproved in solid cancers. The further progress of the field will depend on bringing novel strategies into clinical evaluation, while maintaining safety.

Immunomodulatory potential of natural products from herbal medicines as immune checkpoints inhibitors: Helping to fight against cancer via multiple targets

Immunotherapy sheds new light to cancer treatment and is satisfied by cancer patients. However, immunotoxicity, single‐source antibodies, and single‐targeting stratege are potential challenges to the success of cancer immunotherapy. A huge number of promising lead compounds for cancer treatment are of natural origin from herbal medicines. The application of natural products from herbal medicines that have immunomodulatory properties could alter the landscape of immunotherapy drastically. The present study summarizes current medication for cancer immunotherapy and discusses the potential chemicals from herbal medicines as immune checkpoint inhibitors that have a broad range of immunomodulatory effects. Therefore, this review provides valuable insights into the efficacy and mechanism of actions of cancer immunotherapies, including natural products and combined treatment with immune checkpoint inhibitors, which could confer an improved clinical outcome for cancer treatment.

Advances in Allogeneic Cancer Cell Therapy and Future Perspectives on “Off-the-Shelf” T Cell Therapy Using iPSC Technology and Gene Editing

The concept of allogeneic cell therapy was first presented over 60 years ago with hematopoietic stem cell transplantation. However, complications such as graft versus host disease (GVHD) and regimen-related toxicities remained as major obstacles. To maximize the effect of graft versus leukemia, while minimizing the effect of GVHD, donor lymphocyte infusion was utilized. This idea, which was used against viral infections, postulated that adoptive transfer of virus-specific cytotoxic T lymphocytes could reconstitute specific immunity and eliminate virus infected cells and led to the idea of banking third party cytotoxic T cells (CTLs). T cell exhaustion sometimes became a problem and difficulty arose in creating robust CTLs. However, the introduction of induced pluripotent stem cells (iPSCs) lessens such problems, and by using iPSC technology, unlimited numbers of allogeneic rejuvenated CTLs with robust and proliferative cytotoxic activity can be created. Despite this revolutionary concept, several concerns still exist, such as immunorejection by recipient cells and safety issues of gene editing. In this review, we describe approaches to a feasible “off-the-shelf” therapy that can be distributed rapidly worldwide. We also offer perspectives on the future of allogeneic cell cancer immunotherapy.

Combined overexpression of four transcription factors promotes effector T cell dedifferentiation toward early phenotypes

Effector T cells, which are abundant but are short-lived after reinfusion into the body, are generally used for T-cell therapy, and antitumor immunity is typically not maintained over the long term. Genetic modification by early differentiated T cells and reinfusion has been shown to enhance antitumor immunity in vivo. This study overexpressed the characteristic transcription factors of differentiated early T cells by transfecting effector T cells with transcription factor recombinant lentivirus (S6 group: BCL6, EOMES, FOXP1, LEF1, TCF7, KLF7; S1 group: BCL6, EOMES, FOXP1, KLF7; S3 group: BCL6, EOMES, FOXP1, LEF1) to induce a sufficient number of effector T cells to dedifferentiate and optimize the transcription factor system. The results revealed that overexpression of early characteristic transcription factors in effector T cells upregulated the expression of early T cell differentiation markers (CCR7 and CD62L), with the S1 group having the highest expression level, while the rising trend of late differentiation marker (CD45RO) expression was suppressed. Moreover, the expression of early differentiation-related genes (ACTN1, CERS6, BCL2) was significantly increased, while the expression of late differentiation-related genes (KLRG-1) and effector function-related genes (GNLY, GZMB, PRF1) was significantly decreased; this difference in expression was more significant in the S1 group than in the other two experimental groups. The antiapoptotic ability of each experimental group was significantly enhanced, while the secretion ability of TNF-α and IFN-γ was weakened, with the effector cytokine secretion ability of the S1 group being the weakest. Transcriptomic analysis showed that the gene expression profile of each experimental group was significantly different from that of the control group, with differences in the gene expression pattern and number of differentially expressed genes in the S1 group compared with the other two experimental groups. The differentially expressed gene enrichment pathways were basically related to the cell cycle, cell division, and immune function. In conclusion, overexpression of early characteristic transcription factors in effector T cells induces their dedifferentiation, and induction of dedifferentiation by the S1 group may be more effective.

GPC2-CAR T cells tuned for low antigen density mediate potent activity against neuroblastoma without toxicity

Pediatric cancers often mimic fetal tissues and express proteins normally silenced postnatally that could serve as immune targets. We developed T cells expressing chimeric antigen receptors (CARs) targeting glypican-2 (GPC2), a fetal antigen expressed on neuroblastoma (NB) and several other solid tumors. CARs engineered using standard designs control NBs with transgenic GPC2 overexpression, but not those expressing clinically relevant GPC2 site density (∼5,000 molecules/cell, range 1-6 × 10³). Iterative engineering of transmembrane (TM) and co-stimulatory domains plus overexpression of c-Jun lowered the GPC2-CAR antigen density threshold, enabling potent and durable eradication of NBs expressing clinically relevant GPC2 antigen density, without toxicity. These studies highlight the critical interplay between CAR design and antigen density threshold, demonstrate potent efficacy and safety of a lead GPC2-CAR candidate suitable for clinical testing, and credential oncofetal antigens as a promising class of targets for CAR T cell therapy of solid tumors.

MAGEA6 positively regulates MSMO1 and promotes the migration and invasion of oesophageal cancer cells

The melanoma antigen gene family A (MAGEA) family of proteins comprises of cancer-testis antigens that are highly expressed in a number of tumours but are minimally expressed in normal cells. Due to its expression characteristics, this protein family has become a popular target for anti-cancer drugs and immunotherapy research over recent years. Although, elevated expression levels of MAGEA6 has been found in different types of tumours, there remains to be insufficient information on the function of MAGEA6 and its associated gene regulation pathways. The present study used Transwell, Cell Counting Kit-8 and wound healing assays to analyse the effects of MAGEA6 on Eca109 cell invasion, migration and proliferation. The main functions and pathways involved in MAGEA6 were predicted by Illumina Hiseq screening for mutually regulated genes and core genes. Eca109 cell line with a high expression of MAGEA6 was a stable cell line obtained by transfection in the early stage, and this cell line was used in subsequent experiments. Transcriptome sequencing was performed on this cell line and the Eca109 cell line that normally expressed MAGEA6. It was revealed that a high expression of MAGEA6 conferred a significant stimulating effect on cell proliferation whilst also significantly increasing cell invasion and migration. Transcriptomic analysis identified 14 differentially expressed genes and 13 core regulatory genes closely associated with MAGEA6 expression regulation, such as methylsterol monooxygenase 1 (MSMO1). The present study suggest that MAGEA6 positively regulated MSMO1 expression, which may serve an oncogenic role in cells through this regulatory effect. Overall, this provided a novel route of investigation for an in-depth study of the regulatory function of MAGEA6.

A Review of Cancer Immunotherapy Toxicity II: Adoptive Cellular Therapies, Kinase Inhibitors, Monoclonal Antibodies, and Oncolytic Viruses

Immunotherapy for cancer has undergone a rapid expansion in classes, agents, and indications. By utilizing aspects of the body's innate immune system, immunotherapy has improved life expectancy and quality of life for patients with several types of cancer. Adoptive cellular therapies, including chimeric antigen receptor T (CAR T) cell therapy, involve the genetic engineering of patient T cells to allow for targeting of neoplastic cells. Monitoring of patients during the lymphodepletion prior to therapy and following CAR T cell infusion is necessary to detect toxicity of therapy. Specific toxicities include cytokine release syndrome and neurologic toxicity, both of which may be life-threatening. Tocilizumab and/or corticosteroids should be considered for moderate to severe toxicity. Kinase inhibitor toxicity can occur as "on target" effects or "off target" effects to multiple organ systems due to shared protein epitopes. Treatments are organ-specific. Infusion reactions are common during treatment with monoclonal antibodies and treatment is largely supportive. Clinical experience with oncolytic viruses is limited, but local reactions including cellulitis as well as systemic influenza-like syndromes have been seen but are typically mild. Although clinical experience with adverse effects due to newer immunotherapy agents is growing, an up-to-date understanding of their mechanisms and potential toxicities is critical.

Sensitive identification of neoantigens and cognate TCRs in human solid tumors

The identification of patient-specific tumor antigens is complicated by the low frequency of T cells specific for each tumor antigen. Here we describe NeoScreen, a method that enables the sensitive identification of rare tumor (neo)antigens and of cognate T cell receptors (TCRs) expressed by tumor-infiltrating lymphocytes. T cells transduced with tumor antigen-specific TCRs identified by NeoScreen mediate regression of established tumors in patient-derived xenograft mice.

The current landscape of immunotherapy for pediatric brain tumors

Pediatric central nervous system tumors are the most common solid malignancies in childhood, and aggressive therapy often leads to long-term sequelae in survivors, making these tumors challenging to treat. Immunotherapy has revolutionized prospects for many cancer types in adults, but the intrinsic complexity of treating pediatric patients and the scarcity of clinical studies of children to inform effective approaches have hampered the development of effective immunotherapies in pediatric settings. Here, we review recent advances and ongoing challenges in pediatric brain cancer immunotherapy, as well as considerations for efficient clinical translation of efficacious immunotherapies into pediatric settings.

T cells targeted to TdT kill leukemic lymphoblasts while sparing normal lymphocytes

Unlike chimeric antigen receptors, T-cell receptors (TCRs) can recognize intracellular targets presented on human leukocyte antigen (HLA) molecules. Here we demonstrate that T cells expressing TCRs specific for peptides from the intracellular lymphoid-specific enzyme terminal deoxynucleotidyl transferase (TdT), presented in the context of HLA-A*02:01, specifically eliminate primary acute lymphoblastic leukemia (ALL) cells of T- and B-cell origin in vitro and in three mouse models of disseminated B-ALL. By contrast, the treatment spares normal peripheral T- and B-cell repertoires and normal myeloid cells in vitro, and in vivo in humanized mice. TdT is an attractive cancer target as it is highly and homogeneously expressed in 80-94% of B- and T-ALLs, but only transiently expressed during normal lymphoid differentiation, limiting on-target toxicity of TdT-specific T cells. TCR-modified T cells targeting TdT may be a promising immunotherapy for B-ALL and T-ALL that preserves normal lymphocytes.

[T cell-based immunotherapies in solid tumors]

In solid tumors, adoptive T cell therapies based on ex vivo amplification of antitumor T cell are represented by three main complementary approaches : (i) tumor infiltrating lymphocytes (TILs) which are amplified in vitro before reinjection to the patient, (ii) chimeric antigen receptor (CAR) engineered T cells and (iii) T cell receptor (TCR) engineered T cells. Despite encouraging results, some obstacles remain, such as optimal target selection and tumor microenvironment. In this Review, we discuss pros and cons of these different therapeutic strategies that may open new perspectives in the treatment of solid tumors.

Humanization of T cell-mediated immunity in mice

[Figure: see text].

Novel TCR-like CAR-T cells targeting an HLA∗0201-restricted SSX2 epitope display strong activity against acute myeloid leukemia

The synovial sarcoma X breakpoint 2 (SSX2) belongs to a multigene family of cancer-testis antigens and can be found overexpressed in multiple malignancies. Its restricted expression in immune-privileged normal tissues suggest that SSX2 may be a relevant target antigen for chimeric antigen receptor (CAR) therapy. We have developed a T cell receptor (TCR)-like antibody (Fab/3) that binds SSX2 peptide 41-49 (KASEKIFYV) in the context of HLA-A∗-0201. The sequence of Fab/3 was utilized to engineer a CAR with the CD3 zeta intra-cellular domain along with either a CD28 or 4-1BB costimulatory endodomain. Human T cells from HLA-A2⁺ donors were transduced to mediate anti-tumor activity against acute myeloid leukemia (AML) tumor cells. Upon challenge with HLA-A2⁺/SSX2⁺ AML tumor cells, CAR-expressing T cells released interferon-γ and eliminated the tumor cells in a long-term co-culture assay. Using the HLA-A2⁺ T2 cell line, we demonstrated a strong specificity of the single-chain variable fragment (scFv) for SSX2 p41-49 and the closely related SSX3 p41-49, with no response against the others SSX-homologous peptides or unrelated homologous peptides. Since SSX3 has not been observed in tumor cells and expression cannot be induced by pharmacological intervention, SSX2_41-49 represents an attractive target for CAR-based cellular therapy to treat multiple types of cancer.

Immunotherapy of cancer in the era of checkpoint inhibitor

Application of immunotherapy has revolutionized treatment of number of malignancies. We present a review of immunotherapy approaches, early-phase data of number of new immunotherapeutic targets in melanoma, cutaneous squamous cell carcinoma, Merkel cell cancer, and non-small cell lung cancer.

Genetically Modified T Cells for Esophageal Cancer Therapy: A Promising Clinical Application

Esophageal cancer is an exceedingly aggressive and malignant cancer that imposes a substantial burden on patients and their families. It is usually treated with surgery, chemotherapy, radiotherapy, and molecular-targeted therapy. Immunotherapy is a novel treatment modality for esophageal cancer wherein genetically engineered adoptive cell therapy is utilized, which modifies immune cells to attack cancer cells. Using chimeric antigen receptor (CAR) or T cell receptor (TCR) modified T cells yielded demonstrably encouraging efficacy in patients. CAR-T cell therapy has shown robust clinical results for malignant hematological diseases, particularly in B cell-derived malignancies. Natural killer (NK) cells could serve as another reliable and safe CAR engineering platform, and CAR-NK cell therapy could be a more generalized approach for cancer immunotherapy because NK cells are histocompatibility-independent. TCR-T cells can detect a broad range of targeted antigens within subcellular compartments and hold great potential for use in cancer therapy. Numerous studies have been conducted to evaluate the efficacy and feasibility of CAR and TCR based adoptive cell therapies (ACT). A comprehensive understanding of genetically-modified T cell technologies can facilitate the clinical translation of these adoptive cell-based immunotherapies. Here, we systematically review the state-of-the-art knowledge on genetically-modified T-cell therapy and provide a summary of preclinical and clinical trials of CAR and TCR-transgenic ACT.

Neoantigen-Reactive T Cells: The Driving Force behind Successful Melanoma Immunotherapy

Simple Summary

Cancer immunotherapy is a revolutionary type of cancer therapy. It uses the patient’s own immune system to fight and potentially cure cancer. The first major breakthrough of immunotherapy came from successful clinical trials for melanoma treatments. Since then, researchers have focused on understanding the science behind immunotherapy, so that patients with other types of cancer may also benefit. One of the major findings is that the T cells in melanoma patients may recognize a specific type of tumor antigen, called neoantigens, and then kill tumor cells that present these neoantigens. The neoantigens mainly arise from the DNA mutations found in tumor cells. These mutations are translated into mutated proteins that are then distinguished by T cells. In this article, we discuss the critical role of T cells in immunotherapy, as well as the clinical trials that shaped the treatments for melanoma.

Abstract

Patients with metastatic cutaneous melanoma have experienced significant clinical responses after checkpoint blockade immunotherapy or adoptive cell therapy. Neoantigens are mutated proteins that arise from tumor-specific mutations. It is hypothesized that the neoantigen recognition by T cells is the critical step for T-cell-mediated anti-tumor responses and subsequent tumor regressions. In addition to describing neoantigens, we review the sentinel and ongoing clinical trials that are helping to shape the current treatments for patients with cutaneous melanoma. We also present the existing evidence that establishes the correlations between neoantigen-reactive T cells and clinical responses in melanoma immunotherapy.

Cancer immunotherapy: Challenges and limitations

Although cancer immunotherapy has taken center stage in mainstream oncology inducing complete and long-lasting tumor regression, only a subset of patients receiving treatment respond and others relapse after an initial response. Different tumor types respond differently, and even in cancer types that respond (hot tumors), we still observe tumors that are unresponsive (cold tumors), suggesting the presence of resistance. Hence, the development of intrinsic or acquired resistance is a big challenge for the cancer immunotherapy field. Resistance to immunotherapy, including checkpoint inhibitors, CAR-T cell therapy, oncolytic viruses, and recombinant cytokines arises due to cancer cells employing several mechanisms to evade immunosurveillance.

Cancer Vaccine in Solid Tumors: Where We Stand

Cancer immunotherapy has achieved landmark progress in the field of medical oncology in the era of personalized medicine. In the recent past, our knowledge has expanded regarding how tumor cells escape from the immune system, introducing immunosuppressive microenvironments, and developing tolerance. Therapeutic cancer vaccine leads to activation of immune memory that is long-lasting, safe, and effective; hence, it is becoming an attractive method of immunotherapy. Various cancer vaccine trials in the past have taught us the types of target selection, magnitude of immune response, and implementation of appropriate technologies for the development of new successful cancer vaccines. Tumor-associated antigens, cancer germline antigens, oncogenic viral antigens, and tumor-specific antigens, also known as neoantigens, are potential targets for designing therapeutic cancer vaccines. Cancer vaccine could be cell based, viral vector based, peptide based, and nucleic acid based (DNA/RNA). Several preclinical and clinical studies have demonstrated the mechanism of action, safety, efficacy, and toxicities of various types of cancer vaccines. In this article, we review the types of various tumor antigens and types of cancer vaccines tested in clinical trials and discuss the application and importance of this approach toward precision medicine in the field of immuno-oncology.

Engineered T-cell Receptor T Cells for Cancer Immunotherapy

Engineering immune cells to target cancer is a rapidly advancing technology. The first commercial products, chimeric-antigen receptor (CAR) T cells, are now approved for hematologic malignancies. However, solid tumors pose a greater challenge for cellular therapy, in part because suitable cancer-specific antigens are more difficult to identify and surrounding healthy tissues are harder to avoid. In addition, impaired trafficking of immune cells to solid tumors, the harsh immune-inhibitory microenvironment, and variable antigen density and presentation help tumors evade immune cells targeting cancer-specific antigens. To overcome these obstacles, T cells are being engineered to express defined T-cell receptors (TCR). Given that TCRs target intracellular peptides expressed on tumor MHC molecules, this provides an expanded pool of potential targetable tumor-specific antigens relative to the cell-surface antigens that are targeted by CAR T cells. The affinity of TCR T cells can be tuned to allow for better tumor recognition, even with varying levels of antigen presentation on the tumor and surrounding healthy tissue. Further enhancements to TCR T cells include improved platforms that enable more robust cell expansion and persistence; coadministration of small molecules that enhance tumor recognition and immune activation; and coexpression of cytokine-producing moieties, activating coreceptors, or mediators that relieve checkpoint blockade. Early-phase clinical trials pose logistical challenges involving production, large-scale manufacturing, and more. The challenges and obstacles to successful TCR T-cell therapy, and ways to overcome these and improve anticancer activity and efficacy, are discussed herein.

Cross-HLA targeting of intracellular oncoproteins with peptide-centric CARs

The majority of oncogenic drivers are intracellular proteins, thus constraining their immunotherapeutic targeting to mutated peptides (neoantigens) presented by individual human leukocyte antigen (HLA) allotypes1. However, most cancers have a modest mutational burden that is insufficient to generate responses using neoantigen-based therapies2,3. Neuroblastoma is a paediatric cancer that harbours few mutations and is instead driven by epigenetically deregulated transcriptional networks4. Here we show that the neuroblastoma immunopeptidome is enriched with peptides derived from proteins that are essential for tumourigenesis and focus on targeting the unmutated peptide QYNPIRTTF, discovered on HLA-A*24:02, which is derived from the neuroblastoma dependency gene and master transcriptional regulator PHOX2B. To target QYNPIRTTF, we developed peptide-centric chimeric antigen receptors (CARs) using a counter-panning strategy with predicted potentially cross-reactive peptides. We further hypothesized that peptide-centric CARs could recognize peptides on additional HLA allotypes when presented in a similar manner. Informed by computational modelling, we showed that PHOX2B peptide-centric CARs also recognize QYNPIRTTF presented by HLA-A*23:01 and the highly divergent HLA-B*14:02. Finally, we demonstrated potent and specific killing of neuroblastoma cells expressing these HLAs in vitro and complete tumour regression in mice. These data suggest that peptide-centric CARs have the potential to vastly expand the pool of immunotherapeutic targets to include non-immunogenic intracellular oncoproteins and widen the population of patients who would benefit from such therapy by breaking conventional HLA restriction.

KRAS Inhibitors- yes but what next? Direct targeting of KRAS- vaccines, adoptive T cell therapy and beyond

Kirsten rat sarcoma viral oncogene homolog (KRAS) is a proto-oncogene of the RAS-MAPK pathway. KRAS mutations are present in a variety of malignancies including lung, colorectal, and pancreatic cancer. Until the recent approval of sotorasib, a KRAS G12C inhibitor, lack of targeted therapy for KRAS has resulted in poor prognosis of patients with tumors harboring KRAS mutations. While the conditional approval of sotorasib was a major breakthrough for those patients harboring KRAS G12C mutations, G12C only accounts for a fraction of those with KRAS mutations and eventual resistance to G12C inhibitors are unavoidable. This comprehensive review on KRAS inhibitors covers accumulating evidence on not only the G12C inhibitors but also other therapeutic attempts to tackle KRAS including combination therapy as well as direct inhibition with vaccines, adoptive T cell therapy, proteolysis-targeted chimeras (PROTACs) and CRISPR/Cas9.

Biological Therapies in the Treatment of Cancer-Update and New Directions

Biological therapies have changed the face of oncology by targeting cancerous cells while reducing the effect on normal tissue. This publication focuses mainly on new therapies that have contributed to the advances in treatment of certain malignancies. Immunotherapy, which has repeatedly proven to be a breakthrough therapy in melanoma, as well as B-ALL therapy with CAR T cells, are of great merit in this progress. These therapies are currently being developed by modifying bispecific antibodies and CAR T cells to improve their efficiency and bioavailability. Work on improving the therapy with oncolytic viruses is also progressing, and efforts are being made to improve the immunogenicity and stability of cancer vaccines. Combining various biological therapies, immunotherapy with oncolytic viruses or cancer vaccines is gaining importance in cancer therapy. New therapeutic targets are intensively sought among neoantigens, which are not immunocompromised, or antigens associated with tumor stroma cells. An example is fibroblast activation protein α (FAPα), the overexpression of which is observed in the case of tumor progression. Universal therapeutic targets are also sought, such as the neurotrophic receptor tyrosine kinase (NTRK) gene fusion, a key genetic driver present in many types of cancer. This review also raises the problem of the tumor microenvironment. Stromal cells can protect tumor cells from chemotherapy and contribute to relapse and progression. This publication also addresses the problem of cancer stem cells resistance to treatment and presents attempts to avoid this phenomenon. This review focuses on the most important strategies used to improve the selectivity of biological therapies.

An HLA-A*11:01-Binding Neoantigen from Mutated NPM1 as Target for TCR Gene Therapy in AML

Simple Summary

Acute myeloid leukemia (AML) is an aggressive hematological malignancy with poor prognosis. For AML relapses after chemotherapy, new and effective therapies are needed. In 30–35% of AMLs, a frameshift mutation in the nucleophosmin 1 gene (dNPM1) creates potential neoantigens that are attractive targets for immunotherapy. We previously isolated a T-cell receptor (TCR) that targets an HLA-A*02:01-binding dNPM1 neoantigen on primary AML. Here, we investigated whether AVEEVSLRK is another dNPM1 neoantigen that can be targeted by TCR gene transfer. We isolated various T-cells, cloned the HLA-A*11:01-restricted TCR from one T-cell clone and, upon transfer to CD8 cells, demonstrated targeting of dNPM1 primary AMLs in vitro. However, the TCR failed to mediate an anti-tumor effect in immunodeficient mice engrafted with dNPM1 OCI-AML3 cells. Our results demonstrate that AVEEVSLRK is an HLA-A*11:01-binding neoantigen on dNPM1 AML. Whether the isolated TCR is of sufficient affinity to treat patients remains uncertain.

Abstract

Acute myeloid leukemia (AML) is a hematological malignancy caused by clonal expansion of myeloid progenitor cells. Most patients with AML respond to chemotherapy, but relapses often occur and infer a very poor prognosis. Thirty to thirty-five percent of AMLs carry a four base pair insertion in the nucleophosmin 1 gene (NPM1) with a C-terminal alternative reading frame of 11 amino acids. We previously identified various neopeptides from the alternative reading frame of mutant NPM1 (dNPM1) on primary AML and isolated an HLA-A*02:01-restricted T-cell receptor (TCR) that enables human T-cells to kill AML cells upon retroviral gene transfer. Here, we isolated T-cells recognizing the dNPM1 peptide AVEEVSLRK presented in HLA-A*11:01. The TCR cloned from a T-cell clone recognizing HLA-A*11:01+ primary AML cells conferred in vitro recognition and lysis of AML upon transfer to CD8 cells, but failed to induce an anti-tumor effect in immunodeficient NSG mice engrafted with dNPM1 OCI-AML3 cells. In conclusion, our data show that AVEEVSLRK is a dNPM1 neoantigen on HLA-A*11:01+ primary AMLs. CD8 cells transduced with an HLA-A*11:01-restricted TCR for dNPM1 were reactive against AML in vitro. The absence of reactivity in a preclinical mouse model requires further preclinical testing to predict the potential efficacy of this TCR in clinical development.

From Hematopoietic Stem Cell Transplantation to Chimeric Antigen Receptor Therapy: Advances, Limitations and Future Perspectives

Chimeric antigen receptor (CAR) T-cell therapy was envisioned as a mechanism to re-direct effector T-cells to eliminate tumor cells. CARs are composed of the variable region of an antibody that binds a native cancer antigen coupled to the signaling domain of a TCR and co-stimulatory molecules. Its success and approval by the U.S. Food and Drug Administration for the treatment of B-cell malignancies revolutionized the immunotherapy field, leading to extensive research on its possible application for other cancer types. In this review, we will focus on the evolution of CAR-T cell therapy outlining current technologies as well as major obstacles for its wide application. We will highlight achievements, the efforts to increase efficacy and to evolve into an off-the-shelf treatment, and as a possible future treatment for non-cancer related diseases.

Identification of tumor antigens with immunopeptidomics

The identification of actionable tumor antigens is indispensable for the development of several cancer immunotherapies, including T cell receptor-transduced T cells and patient-specific mRNA or peptide vaccines. Most known tumor antigens have been identified through extensive molecular characterization and are considered canonical if they derive from protein-coding regions of the genome. By eluting human leukocyte antigen-bound peptides from tumors and subjecting these to mass spectrometry analysis, the peptides can be identified by matching the resulting spectra against reference databases. Recently, mass-spectrometry-based immunopeptidomics has enabled the discovery of noncanonical antigens-antigens derived from sequences outside protein-coding regions or generated by noncanonical antigen-processing mechanisms. Coupled with transcriptomics and ribosome profiling, this method enables the identification of thousands of noncanonical peptides, of which a substantial fraction may be detected exclusively in tumors. Spectral matching against the immense noncanonical reference may generate false positives. However, sensitive mass spectrometry, analytical validation and advanced bioinformatics solutions are expected to uncover the full landscape of presented antigens and clinically relevant targets.

TCR gene-engineered cell therapy for solid tumors

The engineering of immune cells to target cancer cells (cellular immunotherapy) has been an exciting area of development in recent years. One type of cellular therapy, T cell receptor (TCR) gene engineered therapy, has shown particular promise in solid tumors. Through use of a heterodimer to recognize intracellular tumor antigens presented through the major histocompatibility complex (MHC), TCR T cells are able to evoke a cytotoxic response as well as a clinical response. In this review, we discuss the potential of TCR-based cellular therapies in solid tumors. While various challenges exist with this therapy, multiple clinical trials are ongoing, in attempt to mitigate these limitations.

Depletion of T cells via Inducible Caspase 9 Increases Safety of Adoptive T-Cell Therapy Against Chronic Hepatitis B

T-cell therapy with T cells that are re-directed to hepatitis B virus (HBV)-infected cells by virus-specific receptors is a promising therapeutic approach for treatment of chronic hepatitis B and HBV-associated cancer. Due to the high number of target cells, however, side effects such as cytokine release syndrome or hepatotoxicity may limit safety. A safeguard mechanism, which allows depletion of transferred T cells on demand, would thus be an interesting means to increase confidence in this approach. In this study, T cells were generated by retroviral transduction to express either an HBV-specific chimeric antigen receptor (S-CAR) or T-cell receptor (TCR), and in addition either inducible caspase 9 (iC9) or herpes simplex virus thymidine kinase (HSV-TK) as a safety switch. Real-time cytotoxicity assays using HBV-replicating hepatoma cells as targets revealed that activation of both safety switches stopped cytotoxicity of S-CAR- or TCR-transduced T cells within less than one hour. In vivo, induction of iC9 led to a strong and rapid reduction of transferred S-CAR T cells adoptively transferred into AAV-HBV-infected immune incompetent mice. One to six hours after injection of the iC9 dimerizer, over 90% reduction of S-CAR T cells in the blood and the spleen and of over 99% in the liver was observed, thereby limiting hepatotoxicity and stopping cytokine secretion. Simultaneously, however, the antiviral effect of S-CAR T cells was diminished because remaining S-CAR T cells were mostly non-functional and could not be restimulated with HBsAg. A second induction of iC9 was only able to deplete T cells in the liver. In conclusion, T cells co-expressing iC9 and HBV-specific receptors efficiently recognize and kill HBV-replicating cells. Induction of T-cell death via iC9 proved to be an efficient means to deplete transferred T cells in vitro and in vivo containing unwanted hepatotoxicity.

Potent, Selective CARs as Potential T-Cell Therapeutics for HPV-positive Cancers

Next-generation T-cell therapies will likely continue to utilize T-cell receptors (TCRs) and chimeric antigen receptors (CARs) because each receptor type has advantages. TCRs often possess exceptional properties even when tested unmodified from patients' T cells. CARs are generally less sensitive, possibly because their ligand-binding domains are grafted from antibodies selected for binding affinity or avidity and not broadly optimized for a functional response. Because of the disconnect between binding and function among these receptor types, the ultimate potential of CARs optimized for sensitivity and selectivity is not clear. Here, we focus on a thoroughly studied immuno-oncology target, the HLA-A*02/HPV-E629-38 complex, and show that CARs can be optimized by a combination of high-throughput binding screens and low-throughput functional assays to have comparable activity to clinical TCRs in acute assays in vitro. These results provide a case study for the challenges and opportunities of optimizing high-performing CARs, especially in the context of targets utilized naturally by TCRs.

The Impact of COVID-19 on Cancer

Since late December 2019, the 2019 coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its rapid international spread have posed a global health threat. The World Health Organization has declared the outbreak of COVID-19 as "public health emergency of international concern". COVID-19 not only brings tremendous pressure to the medical system but also brings new challenges to the global economy. The occurrence and development of cancer has always been an area of active research, and COVID-19 also has a long-lasting impact on the diagnosis, treatment, and research of cancer. In the context, we review the adverse effects of COVID-19 on the screening, diagnosis, treatment and prognosis of cancer patients and the countermeasures in this situation, and provide solutions for improving the quality of life of cancer patients in the normalized prevention and control of COVID-19.

Adoptive T-cell immunotherapy in digestive tract malignancies: Current challenges and future perspectives

Multiple systemic treatments are currently available for advanced cancers of the digestive tract, but none of them is curative. Adoptive T-cell immunotherapy refers to the extraction, modification and re-infusion of autologous or allogenic T lymphocytes for therapeutic purposes. A number of clinical trials have investigated either non-engineered T cells (i.e., lymphokine-activated killer cells, cytokine induced killer cells, or tumor-infiltrating lymphocytes) or engineered T cells (T cell receptor-redirected T cells or chimeric antigen receptor T cells) in patients with digestive tract malignancies over the past two decades, with variable degrees of success. While the majority of completed trials have been primarily aimed at assessing the safety of T-cell transfer strategies, a new generation of studies is being designed to formally evaluate the antitumor potential of adoptive T-cell immunotherapy in both the metastatic and adjuvant settings. In this review, we provide an overview of completed and ongoing clinical trials of passive T-cell immunotherapy in patients with cancers of the digestive tract, focusing on present obstacles and future strategies for achieving potential success.

Characterization and modulation of anti-αβTCR antibodies and their respective binding sites at the βTCR chain to enrich engineered T cells

T cell engineering strategies offer cures to patients and have entered clinical practice with chimeric antibody-based receptors; αβT cell receptor (αβTCR)-based strategies are, however, lagging behind. To allow a more rapid and successful translation to successful concepts also using αβTCRs for engineering, incorporating a method for the purification of genetically modified T cells, as well as engineered T cell deletion after transfer into patients, could be beneficial. This would allow increased efficacy, reduced potential side effects, and improved safety of newly to-be-tested lead structures. By characterizing the antigen-binding interface of a good manufacturing process (GMP)-grade anti-αβTCR antibody, usually used for depletion of αβT cells from stem cell transplantation products, we developed a strategy that allows for the purification of untouched αβTCR-engineered immune cells by changing 2 amino acids only in the TCRβ chain constant domain of introduced TCR chains. Alternatively, we engineered an antibody that targets an extended mutated interface of 9 amino acids in the TCRβ chain constant domain and provides the opportunity to further develop depletion strategies of engineered immune cells.

Evolution of CD8+ T Cell Receptor (TCR) Engineered Therapies for the Treatment of Cancer

Engineered T cell receptor T (TCR-T) cell therapy has facilitated the generation of increasingly reliable tumor antigen-specific adaptable cellular products for the treatment of human cancer. TCR-T cell therapies were initially focused on targeting shared tumor-associated peptide targets, including melanoma differentiation and cancer-testis antigens. With recent technological developments, it has become feasible to target neoantigens derived from tumor somatic mutations, which represents a highly personalized therapy, since most neoantigens are patient-specific and are rarely shared between patients. TCR-T therapies have been tested for clinical efficacy in treating solid tumors in many preclinical studies and clinical trials all over the world. However, the efficacy of TCR-T therapy for the treatment of solid tumors has been limited by a number of factors, including low TCR avidity, off-target toxicities, and target antigen loss leading to tumor escape. In this review, we discuss the process of deriving tumor antigen-specific TCRs, including the identification of appropriate tumor antigen targets, expansion of antigen-specific T cells, and TCR cloning and validation, including techniques and tools for TCR-T cell vector construction and expression. We highlight the achievements of recent clinical trials of engineered TCR-T cell therapies and discuss the current challenges and potential solutions for improving their safety and efficacy, insights that may help guide future TCR-T studies in cancer.

Molecular Markers and Targets in Melanoma

Melanoma develops as a result of several genetic alterations, with UV radiation often acting as a mutagenic risk factor. Deep knowledge of the molecular signaling pathways of different types of melanoma allows better characterization and provides tools for the development of therapies based on the intervention of signals promoted by these cascades. The latest World Health Organization classification acknowledged the specific genetic drivers leading to melanoma and classifies melanocytic lesions into nine distinct categories according to the associate cumulative sun damage (CSD), which correlates with the molecular alterations of tumors. The largest groups are melanomas associated with low-CSD or superficial spreading melanomas, characterized by frequent presentation of the BRAFV600 mutation. High-CSD melanomas include lentigo maligna type and desmoplastic melanomas, which often have a high mutation burden and can harbor NRAS, BRAFnon-V600E, or NF1 mutations. Non-CSD-associated melanomas encompass acral and mucosal melanomas that usually do not show BRAF, NRAS, or NF1 mutations (triple wild-type), but in a subset may have KIT or SF3B1 mutations. To improve survival, these driver alterations can be treated with targeted therapy achieving significant antitumor activity. In recent years, relevant improvement in the prognosis and survival of patients with melanoma has been achieved, since the introduction of BRAF/MEK tyrosine kinase inhibitors and immune checkpoint inhibitors. In this review, we describe the current knowledge of molecular pathways and discuss current and potential therapeutic targets in melanoma, focusing on their clinical relevance of development.

SAGE1: a Potential Target Antigen for Lung Cancer T-Cell Immunotherapy

A fundamental understanding of cancer-specific antigens is crucial for successful T-cell immunotherapy. Sarcoma antigen 1 (SAGE1) is a cancer/testis antigen that has not yet been verified for T-cell immunotherapy applications. Here, we examined SAGE1 RNA expression and carried out IHC analyses, revealing that SAGE1 is expressed in 50% of non-small cell lung-cancer samples (n = 40). To verify the immunogenicity of SAGE1, we discovered a novel HLA-A*24:02 (HLA-A24)-restricted SAGE1 epitope (SAGE1_597-606, VFSTAPPAFI) using mass spectrometry and identified SAGE1_597-606-specific T-cell clones and T-cell receptors (TCR) from peripheral bloods of HLA-A24⁺ donors. The highest affinity TCR VF3 (K_D = 4.3 μM) demonstrated the highest antitumor potency. Moreover, VF3-transduced T cells mediated the efficient killing of HLA-A24⁺/SAGE1⁺ tumor cells in vitro and effectively inhibited the growth of lung cancer xenografts in mice. Together, our data suggest that SAGE1 could be a target for T-cell immunotherapies against lung cancer, while its specific TCRs could be candidates for developing reagents to treat SAGE1⁺ tumors.

Extensive functional comparisons between chimeric antigen receptors and T cell receptors highlight fundamental similarities

Though TCRs have been subject to limited engineering in the context of therapeutic design and optimization, they are used largely as found in nature. On the other hand, CARs are artificial, composed of different segments of proteins that function in the immune system. This characteristic raises the possibility of altered response to immune regulatory stimuli. Here we describe a large-scale, systematic comparison of CARs and TCRs across 5 different pMHC targets, with a total of 19 constructs examined in vitro. These functional measurements include CAR- and TCR-mediated activation, proliferation, and cytotoxicity in both acute and chronic settings. Surprisingly, we find no consistent difference between CARs and TCRs as receptor classes with respect to their relative sensitivity to major regulators of T cell activation: PD-L1, CD80/86 and IL-2. Though TCRs often emerge from human blood directly as potent, selective receptors, CARs must be heavily optimized to attain these properties for pMHC targets. Nonetheless, when iteratively improved and compared head to head in functional tests, CARs appear remarkably similar to TCRs with respect to immune modulation.

Tracking the CAR-T Revolution: Analysis of Clinical Trials of CAR-T and TCR-T Therapies for the Treatment of Cancer (1997-2020)

Chimeric antigen receptor and T-cell receptor (CAR-T/TCR-T) cellular immunotherapies have shown remarkable success in the treatment of some refractory B-cell malignancies, with potential to provide durable clinical response for other types of cancer. In this paper, we look at all available FDA CAR-T/TCR-T clinical trials for the treatment of cancer, and analyze them with respect to different disease tissues, targeted antigens, products, and originator locations. We found that 627 of 1007 registered are currently active and of those 273 (44%) originated in China and 280 (45%) in the US. Our analysis suggests that the rapid increase in the number of clinical trials is driven by the development of different CAR-T products that use a similar therapeutic approach. We coin the term bioparallels to describe such products. Our results suggest that one feature of the CAR-T/TCR-T industry may be a robust response to success and failure of competitor products.