Immunotherapy of metastatic melanoma using genetically engineered GD2-specific T cells

Inhibition of glycosphingolipid synthesis with eliglustat in combination with immune checkpoint inhibitors in advanced cancers: preclinical evidence and phase I clinical trial

Glycosphingolipids (GSLs) are abundantly expressed in cancer cells. The effects of GSL-targeted immunotherapies are not fully understood. Here, we show that the inhibition of GSL synthesis with the UDP-glucose ceramide glucosyltransferase inhibitor eliglustat can increase the exposure of the major histocompatibility complex (MHC) and tumour antigen peptides, enhancing the antitumour response of CD8+ T cells in a range of tumour models. We therefore conducted a proof-of-concept phase I trial on the combination of eliglustat and an anti-PD-1 antibody for the treatment of advanced cancers (NCT04944888). The primary endpoints were safety and feasibility, and the secondary endpoint was antitumor activity. All prespecified endpoints were met. Among the 31 enrolled patients, only 1 patient experienced a grade 3 adverse event (AE), and no grade 4 AEs were observed. The objective response rate was 22.6% and the disease control rate reached 71%. Of the 8 patients with proficient mismatch repair/microsatellite stable (pMMR/MSS) colorectal cancer, one achieved complete response and two each had partial response and stable disease. In summary, inhibiting the synthesis of GSLs might represent an effective immunotherapy approach.

Protocol for assessing GD2 on formalin-fixed paraffin-embedded tissue sections using immunofluorescence staining

The detection of disialoganglioside GD2 on tumor biopsies, especially in paraffin-embedded tissues, has been challenging due to the glycolipid structure of GD2 and its membrane anchorage. Here, we present an immunofluorescence protocol for the reliable assessment of GD2 on formalin-fixed paraffin-embedded (FFPE) tissues. We describe steps for antigen retrieval with Tris-EDTA buffer and staining with unconjugated anti-GD2 antibody (clone 14.G2a) and horse radish peroxidase (HRP)-conjugated secondary antibody. We then detail procedures for signal amplification using the tyramide signal amplification technique. For complete details on the use and execution of this protocol, please refer to Fischer-Riepe et al.1.

Safety and biological outcomes following a phase 1 trial of GD2-specific CAR-T cells in patients with GD2-positive metastatic melanoma and other solid cancers

BACKGROUND

Chimeric antigen receptor (CAR) T cell therapies specific for the CD19 and B-cell maturation antigen have become an approved standard of care worldwide for relapsed and refractory B-cell malignancies. If CAR-T cell therapy for non-hematological malignancies is to achieve the same stage of clinical development, then iterative early-phase clinical testing can add value to the clinical development process for evaluating CAR-T cell products containing different CAR designs and manufactured under differing conditions.

METHODS

We conducted a phase 1 trial of third-generation GD2-specific CAR-T cell therapy, which has previously been tested in neuroblastoma patients. In this study, the GD2-CAR-T therapy was evaluated for the first time in metastatic melanoma patients in combination with BRAF/MEK inhibitor therapy, and as a monotherapy in patients with colorectal cancer and a patient with fibromyxoid sarcoma. Feasibility and safety were determined and persistence studies, multiplex cytokine arrays on sera and detailed immune phenotyping of the original CAR-T products, the circulating CAR-T cells, and, in select patients, the tumor-infiltrating CAR-T cells were performed.

RESULTS

We demonstrate the feasibility of manufacturing CAR-T products at point of care for patients with solid cancer and show that a single intravenous infusion was well tolerated with no dose-limiting toxicities or severe adverse events. In addition, we note significant improvements in CAR-T cell immune phenotype, and expansion when a modified manufacturing procedure was adopted for the latter 6 patients recruited to this 12-patient trial. We also show evidence of CAR-T cell-mediated immune activity and in some patients expanded subsets of circulating myeloid cells after CAR-T cell therapy.

CONCLUSIONS

This is the first report of third-generation GD2-targeting CAR-T cells in patients with metastatic melanoma and other solid cancers such as colorectal cancer, showing feasibility, safety and immune activity, but limited clinical effect.

TRIAL REGISTRATION NUMBER

ACTRN12613000198729.

The molecular perspective on the melanoma and genome engineering of T-cells in targeting therapy

Melanoma, an aggressive malignant tumor originating from melanocytes in humans, is on the rise globally, with limited non-surgical treatment options available. Recent advances in understanding the molecular and cellular mechanisms underlying immune escape, tumorigenesis, drug resistance, and cancer metastasis have paved the way for innovative therapeutic strategies. Combination therapy targeting multiple pathways simultaneously has been shown to be promising in treating melanoma, eliciting favorable responses in most melanoma patients. CAR T-cells, engineered to overcome the limitations of human leukocyte antigen (HLA)-dependent tumor cell detection associated with T-cell receptors, offer an alternative approach. By genetically modifying apheresis-collected allogeneic or autologous T-cells to express chimeric antigen receptors, CAR T-cells can appreciate antigens on cell surfaces independently of major histocompatibility complex (MHC), providing a significant cancer cell detection advantage. However, identifying the most effective target antigen is the initial step, as it helps mitigate the risk of toxicity due to "on-target, off-tumor" and establishes a targeted therapeutic strategy. Furthermore, evaluating signaling pathways and critical molecules involved in melanoma pathogenesis remains insufficient. This study emphasizes the novel approaches of CAR T-cell immunoediting and presents new insights into the molecular signaling pathways associated with melanoma.

CAR-T Cell Therapy: From the Shop to Cancer Therapy

Cancer is a worldwide health problem. Nevertheless, new technologies in the immunotherapy field have emerged. Chimeric antigen receptor (CAR) technology is a novel biological form to treat cancer; CAR-T cell genetic engineering has positively revolutionized cancer immunotherapy. In this paper, we review the latest developments in CAR-T in cancer treatment. We present the structure of the different generations and variants of CAR-T cells including TRUCK (T cells redirected for universal cytokine killing. We explain the approaches of the CAR-T cells manufactured ex vivo and in vivo. Moreover, we describe the limitations and areas of opportunity for this immunotherapy and the current challenges of treating hematological and solid cancer using CAR-T technology as well as its constraints and engineering approaches. We summarize other immune cells that have been using CAR technology, such as natural killer (NK), macrophages (M), and dendritic cells (DC). We conclude that CAR-T cells have the potential to treat not only cancer but other chronic diseases.

Revolutionizing cancer treatment: a comprehensive review of CAR-T cell therapy

Chimeric antigen receptor (CAR)-T cell therapy is a promising new treatment for cancer that involves genetically modifying a patient's T-cells to recognize and attack cancer cells. This review provides an overview of the latest discoveries and clinical trials related to CAR-T cell therapy, as well as the concept and applications of the therapy. The review also discusses the limitations and potential side effects of CAR-T cell therapy, including the high cost and the risk of cytokine release syndrome and neurotoxicity. While CAR-T cell therapy has shown promising results in the treatment of hematologic malignancies, ongoing research is needed to improve the efficacy and safety of the therapy and expand its use to solid tumors. With continued research and development, CAR-T cell therapy has the potential to revolutionize cancer treatment and improve outcomes for patients with cancer.

Emerging phagocytosis checkpoints in cancer immunotherapy

Cancer immunotherapy, mainly including immune checkpoints-targeted therapy and the adoptive transfer of engineered immune cells, has revolutionized the oncology landscape as it utilizes patients' own immune systems in combating the cancer cells. Cancer cells escape immune surveillance by hijacking the corresponding inhibitory pathways via overexpressing checkpoint genes. Phagocytosis checkpoints, such as CD47, CD24, MHC-I, PD-L1, STC-1 and GD2, have emerged as essential checkpoints for cancer immunotherapy by functioning as "don't eat me" signals or interacting with "eat me" signals to suppress immune responses. Phagocytosis checkpoints link innate immunity and adaptive immunity in cancer immunotherapy. Genetic ablation of these phagocytosis checkpoints, as well as blockade of their signaling pathways, robustly augments phagocytosis and reduces tumor size. Among all phagocytosis checkpoints, CD47 is the most thoroughly studied and has emerged as a rising star among targets for cancer treatment. CD47-targeting antibodies and inhibitors have been investigated in various preclinical and clinical trials. However, anemia and thrombocytopenia appear to be formidable challenges since CD47 is ubiquitously expressed on erythrocytes. Here, we review the reported phagocytosis checkpoints by discussing their mechanisms and functions in cancer immunotherapy, highlight clinical progress in targeting these checkpoints and discuss challenges and potential solutions to smooth the way for combination immunotherapeutic strategies that involve both innate and adaptive immune responses.

Melanoma antigens recognized by T cells and their use for immunotherapy

Melanoma has been a prototype for cancer immunology research, and the mechanisms of anti-tumor T-cell responses have been extensively investigated in patients treated with various immunotherapies. Individual differences in cancer-immune status are defined mainly by cancer cell characteristics such as DNA mutations generating immunogenic neo-antigens, and oncogene activation causing immunosuppression, but also by patients' genetic backgrounds such as HLA types and genetic polymorphisms of immune related molecules, and environmental and lifestyle factors such as UV rays, smoking, gut microbiota and concomitant medications; these factors have an influence on the efficacy of immunotherapy. Recent comparative studies on responders and non-responders in immune-checkpoint inhibitor therapy using various new technologies including multi-omics analyses on genomic DNA, mRNA, metabolites and microbiota and single cell analyses of various immune cells have led to the advance of human tumor immunology and the development of new immunotherapy. Based on the new findings from these investigations, personalized cancer immunotherapies along with appropriate biomarkers and therapeutic targets are being developed for patients with melanoma. Here, we will discuss one of the essential subjects in tumor immunology: identification of immunogenic tumor antigens and their effective use in various immunotherapies including cancer vaccines and adoptive T-cell therapy.

Immunotherapy in Melanoma: Recent Advances and Future Directions

The use of immunotherapy in the treatment of advanced and high-risk melanoma has led to a striking improvement in outcomes. Although the incidence of melanoma has continued to rise, median survival has improved from approximately 6 months to nearly 6 years for patients with advanced inoperable stage IV disease. Recent understanding of the tumor microenvironment and its interplay with the immune system has led to the explosive development of novel immunotherapy treatments. Since the approval of the therapeutic cytokines interleukin-2 and interferon alfa-2 in the 1990s, the development of novel immune checkpoint inhibitors (ICIs), oncolytic virus therapy, and modulators of the tumor microenvironment have given way to a new era in melanoma treatment. Monoclonal antibodies directed at programmed cell death protein 1 receptor (PD-1) and its ligand (PDL-1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), and lymphocyte-activation gene 3 (LAG-3) have provided robust activation of the adaptive immune system, restoring immune surveillance leading to host tumor recognition and destruction. Multiple other immunomodulatory therapeutics are under investigation to overcome resistance to ICI therapy, including the toll-like receptor-9 (TLR-9) and 7/8 (TLR-7/8) agonists, stimulator of interferon genes (STING) agonists, and fecal microbiota transplantation. In this review, we focus on the recent advances in immunotherapy for the treatment of melanoma and provide an update on novel therapies currently under investigation.

Carotenoids from Marine Microalgae as Antimelanoma Agents

Melanoma cells are highly invasive and metastatic tumor cells and commonly express molecular alterations that contribute to multidrug resistance (e.g., BRAF^V600E mutation). Conventional treatment is not effective in a long term, requiring an exhaustive search for new alternatives. Recently, carotenoids from microalgae have been investigated as adjuvant in antimelanoma therapy due to their safety and acceptable clinical tolerability. Many of them are currently used as food supplements. In this review, we have compiled several studies that show microalgal carotenoids inhibit cell proliferation, cell migration and invasion, as well as induced cell cycle arrest and apoptosis in various melanoma cell lines. MAPK and NF-ĸB pathway, MMP and apoptotic factors are frequently affected after exposure to microalgal carotenoids. Fucoxanthin, astaxanthin and zeaxanthin are the main carotenoids investigated, in both in vitro and in vivo experimental models. Preclinical data indicate these compounds exhibit direct antimelanoma effect but are also capable of restoring melanoma cells sensitivity to conventional chemotherapy (e.g., vemurafenib and dacarbazine).

Targeting Tumor Glycans for Cancer Therapy: Successes, Limitations, and Perspectives

Simple Summary

Aberrant glycosylation is a common feature of many cancers, and it plays crucial roles in tumor development and biology. Cancer progression can be regulated by several physiopathological processes controlled by glycosylation, such as cell–cell adhesion, cell–matrix interaction, epithelial-to-mesenchymal transition, tumor proliferation, invasion, and metastasis. Different mechanisms of aberrant glycosylation lead to the formation of tumor-associated carbohydrate antigens (TACAs), which are suitable for selective cancer targeting, as well as novel antitumor immunotherapy approaches. This review summarizes the strategies developed in cancer immunotherapy targeting TACAs, analyzing molecular and cellular mechanisms and state-of-the-art methods in clinical oncology.

Abstract

Aberrant glycosylation is a hallmark of cancer and can lead to changes that influence tumor behavior. Glycans can serve as a source of novel clinical biomarker developments, providing a set of specific targets for therapeutic intervention. Different mechanisms of aberrant glycosylation lead to the formation of tumor-associated carbohydrate antigens (TACAs) suitable for selective cancer-targeting therapy. The best characterized TACAs are truncated O-glycans (Tn, TF, and sialyl-Tn antigens), gangliosides (GD2, GD3, GM2, GM3, fucosyl-GM1), globo-serie glycans (Globo-H, SSEA-3, SSEA-4), Lewis antigens, and polysialic acid. In this review, we analyze strategies for cancer immunotherapy targeting TACAs, including different antibody developments, the production of vaccines, and the generation of CAR-T cells. Some approaches have been approved for clinical use, such as anti-GD2 antibodies. Moreover, in terms of the antitumor mechanisms against different TACAs, we show results of selected clinical trials, considering the horizons that have opened up as a result of recent developments in technologies used for cancer control.

Melanoma therapeutics: a literature review

Melanoma is a relentless type of skin cancer which involves myriad signaling pathways which regulate many cellular processes. This makes melanoma difficult to treat, especially when identified late. At present, therapeutics include chemotherapy, surgical resection, biochemotherapy, immunotherapy, photodynamic and targeted approaches. These interventions are usually administered as either a single-drug or in combination, based on tumor location, stage, and patients' overall health condition. However, treatment efficacy generally decreases as patients develop treatment resistance. Genetic profiling of melanocytes and the discovery of novel molecular factors involved in the pathogenesis of melanoma have helped to identify new therapeutic targets. In this literature review, we examine several newly approved therapies, and briefly describe several therapies being assessed for melanoma. The goal is to provide a comprehensive overview of recent developments and to consider future directions in the field of melanoma.

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.

Sphingolipid metabolism in the development and progression of cancer: one cancer's help is another's hindrance

Cancer development is a multistep process in which cells must overcome a series of obstacles before they can become fully developed tumors. First, cells must develop the ability to proliferate unchecked. Once this is accomplished, they must be able to invade the neighboring tissue, as well as provide themselves with oxygen and nutrients. Finally, they must acquire the ability to detach from the newly formed mass in order to spread to other tissues, all the while evading an immune system that is primed for their destruction. Furthermore, increased levels of inflammation have been shown to be linked to the development of cancer, with sites of chronic inflammation being a common component of tumorigenic microenvironments. In this Review, we give an overview of the impact of sphingolipid metabolism in cancers, from initiation to metastatic dissemination, as well as discussing immune responses and resistance to treatments. We explore how sphingolipids can either help or hinder the progression of cells from a healthy phenotype to a cancerous one.

Chimeric Antigen Receptors Expand the Repertoire of Antigenic Macromolecules for Cellular Immunity

T-cell therapies have made significant improvements in cancer treatment over the last decade. One cellular therapy utilizing T-cells involves the use of a chimeric MHC-independent antigen-recognition receptor, typically referred to as a chimeric antigen receptor (CAR). CAR molecules, while mostly limited to the recognition of antigens on the surface of tumor cells, can also be utilized to exploit the diverse repertoire of macromolecules targetable by antibodies, which are incorporated into the CAR design. Leaning into this expansion of target macromolecules will enhance the diversity of antigens T-cells can target and may improve the tumor-specificity of CAR T-cell therapy. This review explores the types of macromolecules targetable by T-cells through endogenous and synthetic antigen-specific receptors.

iPSC-Derived Neoantigen-Specific CTL Therapy for Ewing Sarcoma

The prognosis of Ewing sarcoma caused by EWS/FLI1 fusion is poor, especially after metastasis. Although therapy with CTLs targeted against altered EWS/FLI1 sequences at the gene break/fusion site may be effective, CTLs generated from peripheral blood are often exhausted because of continuous exposure to tumor antigens. We addressed this by generating induced pluripotent stem cell (iPSC)-derived functionally rejuvenated CTLs (rejT) directed against the neoantigen encoded by the EWS/FLI1 fusion gene. In this study, we examined the antitumor effects of EWS/FLI1-rejTs against Ewing sarcoma. The altered amino acid sequence at the break/fusion point of EWS/FLI1, when presented as a neoantigen, evokes an immune response that targets EWS/FLI1 ⁺ sarcoma. Although the frequency of generated EWS/FLI1-specific CTLs was only 0.003%, we successfully established CTL clones from a healthy donor. We established iPSCs from a EWS/FLI1-specific CTL clone and redifferentiated them into EWS/FLI1-specific rejTs. To evaluate cytotoxicity, we cocultured EWS/FLI1-rejTs with Ewing sarcoma cell lines. EWS/FLI1-rejTs rapidly and continuously suppressed the proliferation of Ewing sarcoma for >40 hours. Using a Ewing sarcoma xenograft mouse model, we verified the antitumor effect of EWS/FLI1-rejTs via imaging, and EWS/FLI1-rejTs conferred a statistically significant survival advantage. "Off-the-shelf" therapy is less destructive and disruptive than chemotherapy, and radiation is always desirable, particularly in adolescents, whom Ewing sarcoma most often affects. Thus, EWS/FLI1-rejTs targeting a Ewing sarcoma neoantigen could be a promising new therapeutic tool.

The Current and Future Role of Radiation Therapy in the Era of CAR T-cell Salvage

Radiation therapy has the potential to modulate the immune system in a variety of ways, and given the critical role of the immune system in cancer elimination, it is becoming increasingly important to understand how radiation can be strategically implemented in conjunction with approved immunotherapies to improve the cancer patient's chance of cure and/or quality of life. Current successful, approved cancer immunotherapies fall into two broad classes: antibodies and cellular therapies. Approved cellular therapies thus far consist of Chimeric Antigen Receptor (CAR) T-cells targeting CD19 for refractory non-Hodgkin lymphoma and relapsed or refractory acute lymphoblastic leukemia. Part of the ardor surrounding CAR T-cells stems from the fact that the survival curve of treated patients has a clear plateau, meaning that a number of patients with aggressive, disseminated disease who would have otherwise died rather rapidly appear to now be cured, commonly after just one dose. Despite an encouraging number of these durable remissions, the majority do still relapse. In this review, we discuss the potential for strategically utilizing radiation to further improve CAR T-cell patient outcomes. Given that there are currently over 750 cellular therapies in development, half of which are now in clinical trial, CAR T-cell usage will inevitably expand; as the field grows in importance and effectiveness, radiation oncology has the opportunity to coevolve symbiotically and steer these novel, exciting live therapies to new depths.

Chimeric Antigen Receptor (CAR) T Cell Therapy for Metastatic Melanoma: Challenges and Road Ahead

Metastatic melanoma is the most aggressive and difficult to treat type of skin cancer, with a survival rate of less than 10%. Metastatic melanoma has conventionally been considered very difficult to treat; however, recent progress in understanding the cellular and molecular mechanisms involved in the tumorigenesis, metastasis and immune escape have led to the introduction of new therapies. These include targeted molecular therapy and novel immune-based approaches such as immune checkpoint blockade (ICB), tumor-infiltrating lymphocytes (TILs), and genetically engineered T-lymphocytes such as chimeric antigen receptor (CAR) T cells. Among these, CAR T cell therapy has recently made promising strides towards the treatment of advanced hematological and solid cancers. Although CAR T cell therapy might offer new hope for melanoma patients, it is not without its shortcomings, which include off-target toxicity, and the emergence of resistance to therapy (e.g., due to antigen loss), leading to eventual relapse. The present review will not only describe the basic steps of melanoma metastasis, but also discuss how CAR T cells could treat metastatic melanoma. We will outline specific strategies including combination approaches that could be used to overcome some limitations of CAR T cell therapy for metastatic melanoma.

Tumor-Associated Glycans as Targets for Immunotherapy: The Wistar Institute Experience/Legacy

Tumor cells are characterized by the expression of tumor-specific carbohydrate structures that differ from their normal counterparts. Carbohydrates on tumor cells have phenotypical as well as functional implications, impacting the tumor progression process, from malignant transformation to metastasis formation. Importantly, carbohydrates are structures that play a role in receptor-ligand interaction and elicit the activity of growth factor receptors, integrins, lectins, and other type 1 transmembrane proteins. They have been recognized as biomarkers for cancer diagnosis, and evidence demonstrating their relevance as targets for anticancer therapeutic strategies, including immunotherapy, continues to accumulate. Different approaches targeting carbohydrates include monoclonal antibodies (mAbs), antibody (Ab)-drug conjugates, vaccines, and adhesion antagonists. Development of bispecific antibodies and chimeric antigen receptor (CAR)-modified T cells against tumor-associated carbohydrate antigens (TACAs) as promising cancer immunotherapeutic agents is rapidly evolving. As reviewed here, there are several cancer-associated glycan features that can be leveraged to design rational drug or immune system targets, applying multiple TACA structural and functional features to be targeted as the standard treatment paradigm. Many of the underlying targets were defined by researchers at the Wistar Institute in Philadelphia, Pennsylvania, which provide basis for different immunotherapy approaches.

Generating CAR T cells from tumor-infiltrating lymphocytes

Background: Tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR) T-cell therapies have demonstrated promising, though limited, efficacy against melanoma. Methods: We designed a model system to explore the efficacy of dual specific T cells derived from melanoma patient TILs by transduction with a Her2-specific CAR. Results: Metastatic melanoma cells in our biobank constitutively expressed Her2 antigen. CAR-TIL produced greater amounts of IFN compared with parental TIL, when co-cultured with Her2 expressing tumor lines, including autologous melanoma tumor lines, although no consistent increase in cytotoxicity by TIL was afforded by expression of a CAR. Results of an in vivo study in NSG mice demonstrated tumor shrinkage when CAR-TILs were used in an adoptive cell therapy protocol. Conclusion: Potential limitations of transduced TIL in our study included limited proliferative potential and a terminally differentiated phenotype, which would need addressing in further work before consideration of clinical translation.

Expression of Potential Targets for Cell-Based Therapies on Melanoma Cells

Tumor antigen-specific redirection of cytotoxic T cells (CTLs) or natural killer (NK) cells including chimeric antigen receptor (CAR-) and T cell receptor (TCR-) cell therapy is currently being evaluated in different tumor entities including melanoma. Expression of melanoma-specific antigen recognized by the respective CAR or TCR directly or presented by HLA molecules is an indispensable prerequisite for this innovative therapy. In this study, we investigated in 168 FFPE tumor specimens of patients with stage I-IV melanoma the protein expression of HER2, TRP2, ABCB5, gp100, p53, and GD2 by immunohistochemistry (IHC). These results were correlated with clinical parameters. Membrane expression of HER2 and GD2 was also investigated in ten melanoma cell lines by flow cytometry for which corresponding tumors were analyzed by IHC. Our results demonstrated that gp100 was the most frequently overexpressed protein (61%), followed by TRP2 (50%), GD2 (38%), p53 (37%), ABCB5 (17%), and HER2 (3%). TRP2 expression was higher in primary tumors compared to metastases (p = 0.005). Accordingly, TRP2 and ABCB5 expression was significantly associated with lower tumor thickness of the primary (p = 0.013 and p = 0.025). There was no association between protein expression levels and survival in advanced melanoma patients. Flow cytometric analysis revealed abundant surface expression of GD2 and HER2 in all melanoma cell lines. The discordant HER2 expression in situ and in vitro suggests a tissue culture associated induction. In summary, our data support the use of gp100 and GD2 as a potential target for developing engineered TCR- or CAR-cell therapies, respectively, against melanoma.

OX40 costimulation by a chimeric antigen receptor abrogates CD28 and IL-2 induced IL-10 secretion by redirected CD4(+) T cells

Adoptive therapy with chimeric antigen receptor (CAR) redirected T cells recently showed remarkable anti-tumor efficacy in early phase clinical trials; self-repression of the immune response by T-cell secreted cytokines, however, is still an issue raising interest to abrogate the secretion of repressive cytokines while preserving the panel of CAR induced pro-inflammatory cytokines. We here revealed that T-cell activation by a CD28-ζ signaling CAR induced IL-10 secretion, which compromises T cell based immunity, along with the release of pro-inflammatory IFN-γ and IL-2. T cells stimulated by a ζ CAR without costimulation did not secrete IL-2 or IL-10; the latter, however, could be induced by supplementation with IL-2. Abrogation of CD28-ζ CAR induced IL-2 release by CD28 mutation did not reduce IL-10 secretion indicating that IL-10 can be induced by both a CD28 and an IL-2 mediated pathway. In contrast to the CD28-ζ CAR, a CAR with OX40 (CD134) costimulation did not induce IL-10. OX40 cosignaling by a 3rd generation CD28-ζ-OX40 CAR repressed CD28 induced IL-10 secretion but did not affect the secretion of pro-inflammatory cytokines, T-cell amplification or T-cell mediated cytolysis. IL-2 induced IL-10 was also repressed by OX40 co-signaling. OX40 moreover repressed IL-10 secretion by regulatory T cells which are strong IL-10 producers upon activation. Taken together OX40 cosignaling in CAR redirected T cell activation effectively represses IL-10 secretion which contributes to counteract self-repression and provides a rationale to explore OX40 co-signaling CARs in order to prolong a redirected T cell response.

Antibody-drug conjugates: an evolving approach for melanoma treatment

Melanoma continues to be an aggressive and deadly form of skin cancer while therapeutic options are continuously developing in an effort to provide long-term solutions for patients. Immunotherapeutic strategies incorporating antibody-drug conjugates (ADCs) have seen varied levels of success across tumor types and represent a promising approach for melanoma. This review will explore the successes of FDA-approved ADCs to date compared to the ongoing efforts of melanoma-targeting ADCs. The challenges and opportunities for future therapeutic development are also examined to distinguish how ADCs may better impact individuals with malignancies such as melanoma.

Potential strategies against resistance to CAR T-cell therapy in haematological malignancies

Chimeric antigen receptor (CAR) T-cell therapy is a rapidly developing method for adoptive immunotherapy of tumours in recent years. CAR T-cell therapies have demonstrated unprecedented efficacy in the treatment of patients with haematological malignancies. A 90% complete response (CR) rate has been reported in patients with advanced relapse or refractory acute lymphoblastic leukaemia, while >50% CR rates have been reported in cases of chronic lymphocytic leukaemia and partial B-cell lymphoma. Despite the high CR rates, a subset of the patients with complete remission still relapse. The mechanism of development of resistance is not clearly understood. Some patients have been reported to demonstrate antigen-positive relapse, whereas others show antigen-negative relapses. Patients who relapse following CAR T-cell therapy, have very poor prognosis and novel approaches to overcome resistance are required urgently. Herein, we have reviewed current literature and research that have investigated the strategies to overcome resistance to CAR T-cell therapy.

Identification of Targets to Redirect CAR T Cells in Glioblastoma and Colorectal Cancer: An Arduous Venture

The chimeric antigen receptor (CAR) is an artificial molecule engineered to induce cytolytic T cell reactions in tumors. Generally, this molecule combines an extracellular single-chain variable fragment (scFv) able to recognize tumor-associated epitopes together with the intracellular signaling domains that are required for T cell activation. When expressed by T cells, the CAR enables the recognition and subsequent destruction of cancer cells expressing the complementary antigen on their surface. Although the clinical application for CAR T cells is currently limited to some hematological malignancies, researchers are trying to develop CAR T cell-based therapies for the treatment of solid tumors. However, while in the case of CD19, or other targets restricted to the hematopoietic compartment, the toxicity is limited and manageable, the scarcity of specific antigens expressed by solid tumors and not by healthy cells from vital organs makes the clinical development of CAR T cells in this context particularly challenging. Here we summarize relevant research and clinical trials conducted to redirect CAR T cells to surface antigens in solid tumors and cancer stem cells with a focus on colorectal cancer and glioblastoma. Finally, we will discuss current knowledge of altered glycosylation of CSCs and cancer cells and how these novel epitopes may help to target CAR T cell-based immunotherapy in the future.

The Role of Immunological Synapse in Predicting the Efficacy of Chimeric Antigen Receptor (CAR) Immunotherapy

Abstract

Chimeric Antigen Receptor (CAR) immunotherapy utilizes genetically-engineered immune cells that express a unique cell surface receptor that combines tumor antigen specificity with immune cell activation. In recent clinical trials, the adoptive transfer of CAR-modified immune cells (including CAR-T and CAR-NK cells) into patients has been remarkably successful in treating multiple refractory blood cancers. To improve safety and efficacy, and expand potential applicability to other cancer types, CARs with different target specificities and sequence modifications are being developed and tested by many laboratories. Despite the overall progress in CAR immunotherapy, conventional tools to design and evaluate the efficacy and safety of CAR immunotherapies can be inaccurate, time-consuming, costly, and labor-intensive. Furthermore, existing tools cannot always determine how responsive individual patients will be to a particular CAR immunotherapy. Recent work in our laboratory suggests that the quality of the immunological synapse (IS) can accurately predict CAR-modified cell efficacy (and toxicity) that can correlate with clinical outcomes. Here we review current efforts to develop a Synapse Predicts Efficacy (SPE) system for easy, rapid and cost-effective evaluation of CAR-modified immune cell immunotherapy. Ultimately, we hypothesize the conceptual basis and clinical application of SPE will serve as an important parameter in evaluating CAR immunotherapy and significantly advance precision cancer immunotherapy.

The Chimeric Antigen Receptor Detection Toolkit

Chimeric antigen receptor-T (CAR-T) cell therapy is a promising frontier of immunoengineering and cancer immunotherapy. Methods that detect, quantify, track, and visualize the CAR, have catalyzed the rapid advancement of CAR-T cell therapy from preclinical models to clinical adoption. For instance, CAR-staining/labeling agents have enabled flow cytometry analysis, imaging applications, cell sorting, and high-dimensional clinical profiling. Molecular assays, such as quantitative polymerase chain reaction, integration site analysis, and RNA-sequencing, have characterized CAR transduction, expression, and in vivo CAR-T cell expansion kinetics. In vitro visualization methods, including confocal and total internal reflection fluorescence microscopy, have captured the molecular details underlying CAR immunological synapse formation, signaling, and cytotoxicity. In vivo tracking methods, including two-photon microscopy, bioluminescence imaging, and positron emission tomography scanning, have monitored CAR-T cell biodistribution across blood, tissue, and tumor. Here, we review the plethora of CAR detection methods, which can operate at the genomic, transcriptomic, proteomic, and organismal levels. For each method, we discuss: (1) what it measures; (2) how it works; (3) its scientific and clinical importance; (4) relevant examples of its use; (5) specific protocols for CAR detection; and (6) its strengths and weaknesses. Finally, we consider current scientific and clinical needs in order to provide future perspectives for improved CAR detection.

"UniCAR"-modified off-the-shelf NK-92 cells for targeting of GD2-expressing tumour cells

Antigen-specific redirection of immune effector cells with chimeric antigen receptors (CARs) demonstrated high therapeutic potential for targeting cancers of different origins. Beside CAR-T cells, natural killer (NK) cells represent promising alternative effectors that can be combined with CAR technology. Unlike T cells, primary NK cells and the NK cell line NK-92 can be applied as allogeneic off-the-shelf products with a reduced risk of toxicities. We previously established a modular universal CAR (UniCAR) platform which consists of UniCAR-expressing immune cells that cannot recognize target antigens directly but are redirected by a tumour-specific target module (TM). The TM contains an antigen-binding moiety fused to a peptide epitope which is recognized by the UniCAR molecule, thereby allowing an on/off switch of CAR activity, and facilitating flexible targeting of various tumour antigens depending on the presence and specificity of the TM. Here, we provide proof of concept that it is feasible to generate a universal off-the-shelf cellular therapeutic based on UniCAR NK-92 cells targeted to tumours expressing the disialoganglioside GD2 by GD2-specific TMs that are either based on an antibody-derived single-chain fragment variable (scFv) or an IgG4 backbone. Redirected UniCAR NK-92 cells induced specific killing of GD2-expressing cells in vitro and in vivo, associated with enhanced production of interferon-γ. Analysis of radiolabelled proteins demonstrated that the IgG4-based format increased the in vivo half-life of the TM markedly in comparison to the scFv-based molecule. In summary, UniCAR NK-92 cells represent a universal off-the-shelf platform that is highly effective and flexible, allowing the use of different TM formats for specific tumour targeting.

CAR T Cell Therapy Progress and Challenges for Solid Tumors

The past two decades have marked the beginning of an unprecedented success story for cancer therapy through redirecting antitumor immunity [1]. While the mechanisms that control the initial and ongoing immune responses against tumors remain a strong research focus, the clinical development of technologies that engage the immune system to target and kill cancer cells has become a translational research priority. Early attempts documented in the late 1800s aimed at sparking immunity with cancer vaccines were difficult to interpret but demonstrated an opportunity that more than 100 years later has blossomed into the current field of cancer immunotherapy. Perhaps the most recent and greatest illustration of this is the widespread appreciation that tumors actively shut down antitumor immunity, which has led to the emergence of checkpoint pathway inhibitors that re-invigorate the body's own immune system to target cancer [2, 3]. This class of drugs, with first FDA approvals in 2011, has demonstrated impressive durable clinical responses in several cancer types, including melanoma, lung cancer, Hodgkin's lymphoma, and renal cell carcinoma, with the ongoing investigation in others. The biology and ultimate therapeutic successes of these drugs led to the 2018 Nobel Prize in Physiology or Medicine, awarded to Dr. James Allison and Dr. Tasuku Honjo for their contributions to cancer therapy [4]. In parallel to the emerging science that aided in unleashing the body's own antitumor immunity with checkpoint pathway inhibitors, researchers were also identifying ways to re-engineer antitumor immunity through adoptive cellular immunotherapy approaches. Chimeric antigen receptor (CAR)-based T cell therapy has achieved an early head start in the field, with two recent FDA approvals in 2017 for the treatment of B-cell malignancies [5]. There is an explosion of preclinical and clinical efforts to expand the therapeutic indications for CAR T cell therapies, with a specific focus on improving their clinical utility, particularly for the treatment of solid tumors. In this chapter, we will highlight the recent progress, challenges, and future perspectives surrounding the development of CAR T cell therapies for solid tumors.

Tumour associated glycans: A route to boost immunotherapy?

While the development of immunotherapies for cancer treatment offer significant promise across several cancers, still only a small subset of patients respond to immune based monotherapies. As such, attention has turned to the development of combination therapies. These use conventional cancer treatments such as chemotherapy to sensitise tumours to immunotherapy. Here, we summarise key research, highlighting the exciting potential of tumour associated glycans as therapeutic targets to sensitise tumours to immunotherapy. When cells undergo carcinogenesis they reprogram their glyco-code. Several cancer associated glycans have been identified, and therapies targeting them are under development. Proteins containing carbohydrate binding domains (lectins) are expressed by many immune cell subtypes, and upon glycan binding, transduce immune modulatory signals that regulate the tumour immune microenvironment.

Combination immunotherapies implementing adoptive T-cell transfer for advanced-stage melanoma

Immunotherapy is a promising method of treatment for a number of cancers. Many of the curative results have been seen specifically in advanced-stage melanoma. Despite this, single-agent therapies are only successful in a small percentage of patients, and relapse is very common. As chemotherapy is becoming a thing of the past for treatment of melanoma, the combination of cellular therapies with immunotherapies appears to be on the rise in in-vivo models and in clinical trials. These forms of therapies include tumor-infiltrating lymphocytes, T-cell receptor, or chimeric antigen receptor-modified T cells, cytokines [interleukin (IL-2), IL-15, IL-12, granulocyte-macrophage colony stimulating factor, tumor necrosis factor-α, interferon-α, interferon-γ], antibodies (αPD-1, αPD-L1, αTIM-3, αOX40, αCTLA-4, αLAG-3), dendritic cell-based vaccines, and chemokines (CXCR2). There are a substantial number of ongoing clinical trials using two or more of these combination therapies. Preliminary results indicate that these combination therapies are a promising area to focus on for cancer treatments, especially melanoma. The main challenges with the combination of cellular and immunotherapies are adverse events due to toxicities and autoimmunity. Identifying mechanisms for reducing or eliminating these adverse events remains a critical area of research. Many important questions still need to be elucidated in regard to combination cellular therapies and immunotherapies, but with the number of ongoing clinical trials, the future of curative melanoma therapies is promising.

The Role of Glycosphingolipids in Immune Cell Functions

Glycosphingolipids (GSLs) exhibit a variety of functions in cellular differentiation and interaction. Also, they are known to play a role as receptors in pathogen invasion. A less well-explored feature is the role of GSLs in immune cell function which is the subject of this review article. Here we summarize knowledge on GSL expression patterns in different immune cells. We review the changes in GSL expression during immune cell development and differentiation, maturation, and activation. Furthermore, we review how immune cell GSLs impact membrane organization, molecular signaling, and trans-interactions in cellular cross-talk. Another aspect covered is the role of GSLs as targets of antibody-based immunity in cancer. We expect that recent advances in analytical and genome editing technologies will help in the coming years to further our knowledge on the role of GSLs as modulators of immune cell function.

Synthetic immunology: T-cell engineering and adoptive immunotherapy

During the past decades, the rapidly-evolving cancer is hard to be thoroughly eliminated even though the radiotherapy and chemotherapy do exhibit efficacy in some degree. However, a breakthrough appeared when the adoptive cancer therapy [1] was developed, especially T cells armed with chimeric antigen receptors (CARs) showed great potential in tumor clinical trials recently. CAR-T cells successfully elevated the efficiency and specificity of cytotoxicity. In this review, we will talk about the design of CAR and CAR-included combinatory therapeutic applications in the principles of systems and synthetic immunology.

Neuroblastoma Origin and Therapeutic Targets for Immunotherapy

Neuroblastoma is a pediatric solid cancer of heterogeneous clinical behavior. The unique features of this type of cancer frequently hamper the process of determining clinical presentation and predicting therapy effectiveness. The tumor can spontaneously regress without treatment or actively develop and give rise to metastases despite aggressive multimodal therapy. In recent years, immunotherapy has become one of the most promising approaches to the treatment of neuroblastoma. Still, only one drug for targeted immunotherapy of neuroblastoma, chimeric monoclonal GD2-specific antibodies, is used in the clinic today, and its application has significant limitations. In this regard, the development of effective and safe GD2-targeted immunotherapies and analysis of other potential molecular targets for the treatment of neuroblastoma represents an important and topical task. The review summarizes biological characteristics of the origin and development of neuroblastoma and outlines molecular markers of neuroblastoma and modern immunotherapy approaches directed towards these markers.

Development of third generation anti-EGFRvIII chimeric T cells and EGFRvIII-expressing artificial antigen presenting cells for adoptive cell therapy for glioma

Glioblastoma multiforme (GBM) is the most aggressive and deadly form of adult brain cancer. Despite of many attempts to identify potential therapies for this disease, including promising cancer immunotherapy approaches, it remains incurable. To address the need of improved persistence, expansion, and optimal antitumor activity of T-cells in the glioma milieu, we have developed an EGFRvIII-specific third generation (G3-EGFRvIII) chimeric antigen receptor (CAR) that expresses both co-stimulatory factors CD28 and OX40 (MR1-CD8TM-CD28-OX40-CD3ζ). To enhance ex vivo target specific activation and optimize T-cell culturing conditions, we generated artificial antigen presenting cell lines (aAPC) expressing the extracellular and transmembrane domain of EGFRvIII (EGFRVIIIΔ654) with costimulatory molecules including CD32, CD80 and 4-1BBL (EGFRVIIIΔ654 aAPC and CD32-80-137L-EGFRVIIIΔ654 aAPC). We demonstrate that the highest cell growth was achieved when G3-EGFRvIII CAR T-cells were cocultured with both co-stimulatory aAPCs and with exposure to EGFRvIII (CD32-80-137L-EGFRVIIIΔ654 aAPCs) in culturing periods of three to six weeks. G3-EGFRvIII CAR T-cells showed an increased level of IFN-γ when cocultured with CD32-80-137L-EGFRVIIIΔ654 aAPCs. Evaluation of G3-EGFRvIII CAR T-cells in an orthotropic human glioma xenograft model demonstrated a prolonged survival of G3-EGFRvIII CAR treated mice compared to control mice. Importantly, we observed survival of G3-EGFRvIII CAR T-cells within the tumor as long as 90 days after implantation in low-dose and single administration, accompanied by a marked tumor stroma demolition. These findings suggest that G3-EGFRvIII CAR cocultured with CD32-80-137L-EGFRVIIIΔ654 aAPCs warrants itself as a potential anti-tumor therapy strategy for glioblastoma.

Glycogen synthase kinase 3 inhibition lowers PD-1 expression, promotes long-term survival and memory generation in antigen-specific CAR-T cells

Successful remission in hematological cancers by CAR-T cell immunotherapy has yet to be replicated in solid tumors like GBM. A significant impediment of CAR-T immunotherapy in solid tumors is poor exposure of T cells to tumor antigens resulting in suboptimal CAR-T cell activation, which ultimately fails to induce a robust anti-tumor immune response. Costimulatory moieties in advanced-generation CARs, along with additional IL2 therapy has been shown to be insufficient to overcome this hurdle and have its cytotoxic limitations. GSK3 is constitutively active in naïve T cells and is transiently inactivated during T cell activation resulting in rapid T cell proliferation. Pharmacologic inhibition of GSK3 in GBM-specific CAR-T cells reduced FasL expression, increased T cell proliferation and reduced exhaustion by lowering PD-1 levels resulting in the development of CAR-T effector memory phenotype. Treatment with GSK3-inhibited CAR-T cells resulted in 100% tumor elimination during the tumor-rechallenge experiment in GBM-bearing animals and increased accumulation of memory CAR-T cells in secondary lymphoid organs. These adjuvant-like effects of GSK3 inhibition on activated CAR-T cells may be a valuable adjunct to a successful implementation of CAR-T immunotherapy against GBM and other solid tumors.

Melanoma treatment in review

Melanoma represents the most aggressive and the deadliest form of skin cancer. Current therapeutic approaches include surgical resection, chemotherapy, photodynamic therapy, immunotherapy, biochemotherapy, and targeted therapy. The therapeutic strategy can include single agents or combined therapies, depending on the patient’s health, stage, and location of the tumor. The efficiency of these treatments can be decreased due to the development of diverse resistance mechanisms. New therapeutic targets have emerged from studies of the genetic profile of melanocytes and from the identification of molecular factors involved in the pathogenesis of the malignant transformation. In this review, we aim to survey therapies approved and under evaluation for melanoma treatment and relevant research on the molecular mechanisms underlying melanomagenesis.

Trivalent CAR T cells overcome interpatient antigenic variability in glioblastoma

Background

Glioblastoma (GBM) is the most common primary malignant brain cancer, and is currently incurable. Chimeric antigen receptor (CAR) T cells have shown promise in GBM treatment. While we have shown that combinatorial targeting of 2 glioma antigens offsets antigen escape and enhances T-cell effector functions, the interpatient variability in surface antigen expression between patients hinders the clinical impact of targeting 2 antigen pairs. This study addresses targeting 3 antigens using a single CAR T-cell product for broader application.

Methods

We analyzed the surface expression of 3 targetable glioma antigens (human epidermal growth factor receptor 2 [HER2], interleukin-13 receptor subunit alpha-2 [IL13Rα2], and ephrin-A2 [EphA2]) in 15 primary GBM samples. Accordingly, we created a trivalent T-cell product armed with 3 CAR molecules specific for these validated targets encoded by a single universal (U) tricistronic transgene (UCAR T cells).

Results

Our data showed that co-targeting HER2, IL13Rα2, and EphA2 could overcome interpatient variability by a tendency to capture nearly 100% of tumor cells in most tumors tested in this cohort. UCAR T cells made from GBM patients' blood uniformly expressed all 3 CAR molecules with distinct antigen specificity. UCAR T cells mediated robust immune synapses with tumor targets forming more polarized microtubule organizing centers and exhibited improved cytotoxicity and cytokine release over best monospecific and bispecific CAR T cells per patient tumor profile. Lastly, low doses of UCAR T cells controlled established autologous GBM patient derived xenografts (PDXs) and improved survival of treated animals.

Conclusion

UCAR T cells can overcome antigenic heterogeneity in GBM and lead to improved treatment outcomes.

Choice of costimulatory domains and of cytokines determines CAR T-cell activity in neuroblastoma

Chimeric antigen receptor (CAR) T-cell therapy has been shown to be dramatically effective in the treatment of B-cell malignancies. However, there are still substantial obstacles to overcome, before similar responses can be achieved in patients with solid tumors. We evaluated both in vitro and in a preclinical murine model the efficacy of different 2nd and 3rd generation CAR constructs targeting GD2, a disial-ganglioside expressed on the surface of neuroblastoma (NB) tumor cells. In order to address potential safety concerns regarding clinical application, an inducible safety switch, namely inducible Caspase-9 (iC9), was also included in the vector constructs. Our data indicate that a 3rd generation CAR incorporating CD28.4-1BB costimulatory domains is associated with improved anti-tumor efficacy as compared with a CAR incorporating the combination of CD28.OX40 domains. We demonstrate that the choice of 4-1BB signaling results into significant amelioration of several CAR T-cell characteristics, including: 1) T-cell exhaustion, 2) basal T-cell activation, 3) in vivo tumor control and 4) T-cell persistence. The fine-tuning of T-cell culture conditions obtained using IL7 and IL15 was found to be synergic with the CAR.GD2 design in increasing the anti-tumor activity of CAR T cells. We also demonstrate that activation of the suicide gene iC9, included in our construct without significantly impairing neither CAR expression nor anti-tumor activity, leads to a prompt induction of apoptosis of GD2.CAR T cells. Altogether, these findings are instrumental in optimizing the function of CAR T-cell products to be employed in the treatment of children with NB.

Chimeric Antigen Receptor T-Cells for the Treatment of B-Cell Acute Lymphoblastic Leukemia

Chimeric antigen receptor (CAR) T-cell technology has seen a rapid development over the last decade mostly due to the potential that these cells may have in treating malignant diseases. It is a generally accepted principle that very few therapeutic compounds deliver a clinical response without treatment-related toxicity, and studies have shown that CAR T-cells are not an exception to this rule. While large multinational drug companies are currently investigating the potential role of CAR T-cells in hematological oncology, the potential of such cellular therapies are being recognized worldwide as they are expected to expand in the patient to support the establishment of the immune memory, provide a continuous surveillance to prevent and/or treat a relapse, and keep the targeted malignant cell subpopulation in check. In this article, we present the possible advantages of using CAR T-cells in treating acute lymphoblastic leukemia, presenting the technology and the current knowledge in their preclinical and early clinical trial use. Thus, this article first presents the main present-day knowledge on the standard of care for acute lymphoblastic leukemia. Afterward, current knowledge is presented about the use of CAR T-cells in cancer immunotherapy, describing their design, the molecular constructs, and the preclinical data on murine models to properly explain the background for their clinical use. Last, but certainly not least, this article presents the use of CAR T-cells for the immunotherapy of B-cell acute lymphoblastic leukemia, describing both their potential clinical advantages and the possible side effects.

Anti-GD2/4-1BB chimeric antigen receptor T cell therapy for the treatment of Chinese melanoma patients

Background

Chimeric antigen receptor (CAR)-engineered T cells have demonstrated promising clinical efficacy in patients with B cell lymphoma. However, the application of CAR-T cell therapy in the treatment of other solid tumors has been limited. We incorporated 4-1BB into the anti-GD2 CAR-T cells to test their cytotoxicity in melanoma in vitro and in vivo. Moreover, we reported the expression of ganglioside GD2 in non-Caucasian melanoma populations for the first time, thus providing a basis for future clinical research.

Methods

This study included tumor samples from 288 melanoma patients at the Peking University Cancer Hospital & Institute. Clinical data were collected. Immunohistochemical assays using antibodies against ganglioside GD2 were performed on formalin-fixed, paraffin-embedded specimens. The ability of ganglioside GD2 CAR-T cells to kill ganglioside GD2⁺ melanoma cells was evaluated in vitro and in a patient-derived xenograft (PDX) model.

Results

Among the 288 samples, 49.3% of cases (142/288) demonstrated positive staining with ganglioside GD2. The median survival time in patients exhibiting ganglioside GD2 expression was significantly shorter than that in patients without ganglioside GD2 expression (31 vs. 47.1 months, P < 0.001). In the present study, CAR was constructed using a GD2-specific scFv (14.G2a), T cell receptor CD3ζ chain, and the CD137 (4-1BB) costimulatory motif. In addition, the GD2.BBζ CAR-T cells demonstrated specific lysis of ganglioside GD2-expressing melanoma cells in vitro. In two PDX models, mice that received intravenous or local intratumor injections of GD2.BBζ CAR-T cells experienced rapid tumor regression.

Conclusions

These data demonstrate that the rate of GD2 expression in Chinese patients is 49.3%. GD2.BBζ CAR-T cells can both efficiently lyse melanoma in a GD2-specific manner and release Th1 cytokines in an antigen-dependent manner in vitro and in vivo. Anti-GD2/4-1BB CAR-T cells represent a clinically appealing treatment strategy for Chinese melanoma patients exhibiting GD2 expression and provide a basis for future studies of the clinical application of immunotherapy for melanoma.

Electronic supplementary material

The online version of this article (10.1186/s13045-017-0548-2) contains supplementary material, which is available to authorized users.

A novel phosphoester-based cationic co-polymer nanocarrier delivers chimeric antigen receptor plasmid and exhibits anti-tumor effect

Chimeric antigen receptor T cells (CAR-T cells) targeting of CD19 antigen has been proven to be effective and successful in B cell acute lymphoblastic leukemia. The traditional CAR delivery systems have several problems such as poor biosafety, low loading capacity, and low transfection efficiency. Utilization of nanocarriers for CAR delivery offers new possibilities for CAR-T treatment. In the present study, an anti-CD19 CAR expression lentivirus plasmid was constructed for CAR delivery and immunotherapy. In addition, a three-segment amphiphilic co-polymer, methoxy polyethylene glycol-branched polyethyleneimine-poly(2-ethylbutyl phospholane) (mPEG-bPEI-PEBP) was synthesized via click reaction as the carrier with cationic PEI, capable of delivering the CAR and packaging plasmids to co-transfect Jurkat cells and undergo expression. The PEBP and mPEG parts of the co-polymer provide hydrophobic and hydrophilic interfaces and lead to the co-polymer self-assembly into micelles in water and encapsulation of the DNA plasmids. The mPEG-bPEI-PEBP-DNA composites with different N/P ratios were incubated with the CD19 overexpression K562 cells to identify the CAR functions. The obtained CAR-Jurkat cells had the ability to secrete interferon-γ and interleukin-2. The cytotoxic effects to CD19-K562 cells suggest that the induced CAR-Jurkat cells have an excellent targeted antitumor activity.

A three-segment amphiphilic co-polymer mPEG-bPEI-PEBP was synthesized as the nanocarrier with cationic PEI, capable of delivering the CAR and packaging plasmids into Jurkat cells to generate the CAR-T cells for anti-CD19 immunotherapy study.

Targeting tumor-associated carbohydrate antigens: a phase I study of a carbohydrate mimetic-peptide vaccine in stage IV breast cancer subjects

Tumor-associated carbohydrate antigens (TACAs) support cell survival that could be interrupted by anti-TACA antibodies. Among TACAs that mediate cell survival signals are the neolactoseries antigen Lewis Y (LeY) and the ganglioside GD2. To induce sustained immunity against both LeY and GD2, we developed a carbohydrate mimicking peptide (CMP) as a surrogate pan-immunogen that mimics both. This CMP, referred to as P10s, is the N-terminal half of a peptide vaccine named P10s-PADRE, the C-terminal half of which (PADRE) is a Pan-T-cell epitope. A Phase I dose-escalation trial of P10s-PADRE plus adjuvant MONTANIDE™ ISA 51 VG was conducted in subjects with metastatic breast cancer to test 300 and 500 μg/injection in two cohorts of 3 subjects each. Doses of the P10s-PADRE vaccine were administered to research participants subcutaneously on weeks 1, 2, 3, 7 and 19. Antibody responses to P10s, GD2, and LeY were measured by ELISA. The P10s-PADRE vaccine induced antibodies specifically reactive with P10s, LeY and GD2 in all 6 subjects. Serum antibodies displayed Caspase-3-dependent apoptotic functionality against LeY or GD2 expressing breast cancer cell lines. Immunization with the P10s-PADRE vaccine was well-tolerated and induced functional antibodies, and the data suggest potential clinical benefit.

Bevacizumab-mediated tumor vasculature remodelling improves tumor infiltration and antitumor efficacy of GD2-CAR T cells in a human neuroblastoma preclinical model

GD2-redirected chimeric antigen receptor (CAR) T lymphocytes represent a promising therapeutic option for immunotherapy of neuroblastoma (NB). However, despite the encouraging therapeutic effects observed in some hematological malignancies, clinical results of CAR T cell immunotherapy in solid tumors are still modest. Tumor driven neo-angiogenesis supports an immunosuppressive microenvironment that influences treatment responses and is amenable to targeting with antiangiogenic drugs. The latter agents promote lymphocyte tumor infiltration by transiently reprogramming tumor vasculature, and may represent a valid combinatorial approach with CAR T cell immunotherapy. In light of these considerations, we investigated the anti-NB activity of GD2-CAR T cells combined with bevacizumab (BEV) in an orthotopic xenograft model of human NB. Two weeks after tumor implantation, mice received BEV or GD2-CAR T cells or both by single intravenous administration. GD2-CAR T cells exerted a significant anti-NB activity only in combination with BEV, even at the lowest concentration tested, which per se did not inhibit tumor growth. When combined with BEV, GD2-CAR T cells massively infiltrated tumor mass where they produced interferon-γ (IFN-γ), which, in turn, induced expression of CXCL10 by NB cells. IFN-γ, and possibly other cytokines, upregulated NB cell expression of PD-L1, while tumor infiltrating GD2-CAR T cells expressed PD-1. Thus, the PD-1/PD-L1 axis can limit the anti-tumor efficacy of the GD2-CAR T cell/BEV association. This study provides a strong rationale for testing the combination of GD2-CAR T cells with BEV in a clinical trial enrolling NB patients. PD-L1 silencing or blocking strategies may further enhance the efficacy of such combination.

Adoptive Cell Therapy for Metastatic Melanoma

Adoptive cell therapy (ACT) of tumor-infiltrating lymphocytes (TILs) is a powerful form of immunotherapy by inducing durable complete responses that significantly extend the survival of melanoma patients. Mutation-derived neoantigens were recently identified as key factors for tumor recognition and rejection by TILs. The isolation of T-cell receptor (TCR) genes directed against neoantigens and their retransduction into peripheral T cells may provide a new form of ACT.Genetic modifications of T cells with chimeric antigen receptors (CARs) have demonstrated remarkable clinical results in hematologic malignancies, but are so far less effective in solid tumors. Only very limited reports exist in melanoma. Progress in CAR T-cell engineering, including neutralization of inhibitory signals or additional safety switches, may open opportunities also in melanoma.We review clinical results and latest developments of adoptive therapies with TILs, T-cell receptor, and CAR-modified T cells and discuss future directions for the treatment of melanoma.

Driving better and safer HER2-specific CARs for cancer therapy

Given the clinical efficacy of chimeric antigen receptor (CAR)-based therapy in hematological malignancies, CAR T-cell therapy for a number of solid tumors has been actively investigated. Human epidermal growth factor receptor 2 (HER2) is a well-established therapeutic target in breast, as well as other types of cancer. However, HER2 CAR T cells pose a risk of lethal toxicity including cytokine release syndrome from “on-target, off-tumor” recognition of HER2. In this review, we summarize the development of conventional HER2 CAR technology, the alternative selection of CAR hosts, the novel HER2 CAR designs, clinical studies and toxicity. Furthermore, we also discuss the main strategies for improving the safety of HER2 CAR-based cancer therapies.