Adoptive therapy with CAR redirected T cells: the challenges in targeting solid tumors

Comparative Evaluation of STEAP1 Targeting Chimeric Antigen Receptors with Different Costimulatory Domains and Spacers

We have developed a chimeric antigen receptor (CAR) against the six-transmembrane epithelial antigen of prostate-1 (STEAP1), which is expressed in prostate cancer, Ewing sarcoma, and other malignancies. In the present study, we investigated the effect of substituting costimulatory domains and spacers in this STEAP1 CAR. We cloned four CAR constructs with either CD28 or 4-1BB costimulatory domains, combined with a CD8a-spacer (sp) or a mutated IgG-spacer. The CAR T-cells were evaluated in short- and long-term in vitro T-cell assays, measuring cytokine production, tumor cell killing, and CAR T-cell expansion and phenotype. A xenograft mouse model of prostate cancer was used for in vivo comparison. All four CAR constructs conferred CD4+ and CD8+ T cells with STEAP1-specific functionality. A CD8sp_41BBz construct and an IgGsp_CD28z construct were selected for a more extensive comparison. The IgGsp_CD28z CAR gave stronger cytokine responses and killing in overnight caspase assays. However, the 41BB-containing CAR mediated more killing (IncuCyte) over one week. Upon six repeated stimulations, the CD8sp_41BBz CAR T cells showed superior expansion and lower expression of exhaustion markers (PD1, LAG3, TIGIT, TIM3, and CD25). In vivo, both the CAR T variants had comparable anti-tumor activity, but persisting CAR T-cells in tumors were only detected for the 41BBz variant. In conclusion, the CD8sp_41BBz STEAP1 CAR T cells had superior expansion and survival in vitro and in vivo, compared to the IgGsp_CD28z counterpart, and a less exhausted phenotype upon repeated antigen exposure. Such persistence may be important for clinical efficacy.

Innovative Genoceuticals in Human Gene Therapy Solutions: Challenges and Safe Clinical Trials of Orphan Gene Therapy Products

The success of gene therapy attempts is controversial and inconclusive. Currently, it is popular among the public, the scientific community, and manufacturers of Gene Therapy Medical Products. In the absence of any remedy or treatment options available for untreatable inborn metabolic orphan or genetic diseases, cancer, or brain diseases, gene therapy treatment by genoceuticals and T-cells for gene editing and recovery remains the preferred choice as the last hope. A new concept of "Genoceutical Gene Therapy" by using orphan 'nucleic acid-based therapy' aims to introduce scientific principles of treating acquired tissue damage and rare diseases. These Orphan Genoceuticals provide new scope for the 'genodrug' development and evaluation of genoceuticals and gene products for ideal 'gene therapy' use in humans with marketing authorization application (MAA). This perspective study focuses on the quality control, safety, and efficacy requirements of using 'nucleic acid-based and human cell-based new gene therapy' genoceutical products to set scientific advice on genoceutical-based 'orphan genodrug' design for clinical trials as per Western and European guidelines. The ethical Western FDA and European EMA guidelines suggest stringent legal and technical requirements on genoceutical medical products or orphan genodrug use for other countries to frame their own guidelines. The introduction section proposes lessknown 'orphan drug-like' properties of modified RNA/DNA, human cell origin gene therapy medical products, and their transgene products. The clinical trial section explores the genoceutical sources, FDA/EMA approvals for genoceutical efficacy criteria with challenges, and ethical guidelines relating to gene therapy of specific rare metabolic, cancer and neurological diseases. The safety evaluation of approved genoceuticals or orphan drugs is highlighted with basic principles and 'genovigilance' requirements (to observe any adverse effects, side effects, developed signs/symptoms) to establish their therapeutic use. Current European Union and Food and Drug Administration guidelines continuously administer fast-track regulatory legal framework from time to time, and they monitor the success of gene therapy medical product efficacy and safety. Moreover, new ethical guidelines on 'orphan drug-like genoceuticals' are updated for biodistribution of the vector, genokinetics studies of the transgene product, requirements for efficacy studies in industries for market authorization, and clinical safety endpoints with their specific concerns in clinical trials or public use.

Basics of advanced therapy medicinal product development in academic pharma and the role of a GMP simulation unit

Following successes of authorized chimeric antigen receptor T-cell products being commercially marketed in the United States and European Union, product development of T-cell-based cancer immunotherapy consisting of cell-based advanced therapy medicinal products (ATMPs) has gained further momentum. Due to their complex characteristics, pharmacological properties of living cell products are, in contrast to classical biological drugs such as small molecules, more difficult to define. Despite the availability of many new advanced technologies that facilitate ATMP manufacturing, translation from research-grade to clinical-grade manufacturing in accordance with Good Manufacturing Practices (cGMP) needs a thorough product development process in order to maintain the same product characteristics and activity of the therapeutic product after full-scale clinical GMP production as originally developed within a research setting. The same holds true for transferring a fully developed GMP-grade production process between different GMP facilities. Such product development from the research to GMP-grade manufacturing and technology transfer processes of established GMP-compliant procedures between facilities are challenging. In this review, we highlight some of the main obstacles related to the product development, manufacturing process, and product analysis, as well as how these hinder rapid access to ATMPs. We elaborate on the role of academia, also referred to as 'academic pharma', and the added value of GMP production and GMP simulation facilities to keep innovation moving by reducing the development time and to keep final production costs reasonable.

CD318 is a target of chimeric antigen receptor T cells for the treatment of colorectal cancer

Colorectal cancer (CRC) currently has a poor prognosis with a 6.9-year median survival time; to relieve this malignant cancer, we proposed to establish CRC xenografts that can be used to evaluate the cytotoxicity of adoptive chimeric antigen receptor (CAR)-T cells and accelerate the clinical translation of CAR-T cells for use against CRC. We first verified that CD318 had a higher expression level in primary human CRC tissues than in normal tissues based on hundreds of clinical samples. Then, we redirected CAR-T cells containing anti-CD318 single-chain variable fragment (anti-CD318 scFv), CD3ζ, CD28, and Toll-like receptor 2 (TLR2) domains. Next, we evaluated the function of these CAR-T cells in vitro in terms of surface phenotype changes, cytotoxicity and cytokine secretion when they encountered CD318+ CRC cells. Finally, we established two different xenograft mouse models to assess in vivo antitumor activity. The results showed that CAR318 T cells were significantly activated and exhibited strong cytotoxicity and cytokine-secreting abilities against CRC cells in vitro. Furthermore, CAR318 T cells induced CRC regression in different xenograft mouse models and suppressed tumors compared with CAR19 T cells. In summary, our work demonstrates that CAR318 T cells possess strong antitumor capabilities and represent a promising therapeutic approach for CRC.

Advances in adoptive T-cell therapy for metastatic melanoma

Adoptive T cell therapy (ACT) is a fast developing, niche area of immunotherapy (IO), which is revolutionising the therapeutic landscape of solid tumour oncology, especially metastatic melanoma (MM). Identifying tumour antigens (TAs) as potential targets, the ACT response is mediated by either Tumour Infiltrating Lymphocytes (TILs) or genetically modified T cells with specific receptors - T cell receptors (TCRs) or chimeric antigen receptors (CARs) or more prospectively, natural killer (NK) cells. Clinical trials involving ACT in MM from 2006 to present have shown promising results. Yet it is not without its drawbacks which include significant auto-immune toxicity and need for pre-conditioning lymphodepletion. Although immune-modulation is underway using various combination therapies in the hope of enhancing efficacy and reducing toxicity. Our review article explores the role of ACT in MM, including the various modalities - their safety, efficacy, risks and their development in the trial and the real world setting.

Cancer Immunotherapy: Where Next?

The fundamental problem of dealing with cancer is that cancer cells are so like normal cells that it is very hard to find differences that can be a basis for treatment without severe side effects. The key to successful cancer immunotherapy will be based on a very careful choice of cancer targets that are sufficiently cancer specific not to cause serious side effects. There are two fundamentally different ways to deploy the immune system for such cancer treatments. One is to increase the efficacy of the cancer patient's own immune system so that it attacks these differences. This has been achieved by "checkpoint blocking" which is very successful but only with a relatively small proportion of cancers. Secondly, one can produce antibodies, or T cells, whose specificity is directed against proteins expressed differentially in cancers. CART cell treatments have proved very effective for some blood cancers but not so far for common solid tumours. Humanised, unmodified monoclonal antibodies have been used extensively for the treatment of certain adenocarcinomas with modest success. However, using antibodies together with the body's own immune system to treat cancers by engineering monoclonal antibodies that are directed at both a target antigen on the cancer cell surface and also against T cells shows promise for the development of novel immunotherapies. Genes can be found which are expressed highly in some cancers but with a low or absent expression on normal tissues and so are good novel targets. It is so far, only immune-based killing that can kill bystander target negative cells, which is essential for successful treatment since hardly ever will all the cells in a cancer express any desired target. We conclude that, while there still may be many hurdles in the way, engineered bispecific T cell attracting monoclonal antibody-mediated killing of cancer cells may be the most promising approach for achieving novel effective cancer immunotherapies.

Development of a TGFβ-IL-2/15 Switch Receptor for Use in Adoptive Cell Therapy

Therapy employing T cells modified with chimeric antigen receptors (CARs) is effective in hematological malignancies but not yet in solid cancers. CAR T cell activity in solid tumors is limited by immunosuppressive factors, including transforming growth factor β (TGFβ). Here, we describe the development of a switch receptor (SwR), in which the extracellular domains of the TGFβ receptor are fused to the intracellular domains from the IL-2/15 receptor. We evaluated the SwR in tandem with two variants of a CAR that we have developed against STEAP1, a protein highly expressed in prostate cancer. The SwR-CAR T cell activity was assessed against a panel of STEAP1^+/- prostate cancer cell lines with or without over-expression of TGFβ, or with added TGFβ, by use of flow cytometry cytokine and killing assays, Luminex cytokine profiling, cell counts, and flow cytometry phenotyping. The results showed that the SwR-CAR constructs improved the functionality of CAR T cells in TGFβ-rich environments, as measured by T cell proliferation and survival, cytokine response, and cytotoxicity. In assays with four repeated target-cell stimulations, the SwR-CAR T cells developed an activated effector memory phenotype with retained STEAP1-specific activity. In conclusion, the SwR confers CAR T cells with potent and durable in vitro functionality in TGFβ-rich environments. The SwR may be used as an add-on construct for CAR T cells or other forms of adoptive cell therapy.

Reversing chemokine/chemokine receptor mismatch to enhance the antitumor efficacy of CAR-T cells

Currently, the antitumor efficacy of chimeric antigen receptor T cells in solid tumors is modest. Both chemokines and their receptors play a key role in the proliferation of cancer cells, tumor angiogenesis, organ-selective metastasis and migration of immune cells to solid tumors. Unfortunately, frequent chemokine/chemokine receptor 'mismatch' between effector cells and the tumor microenvironment results in inefficient T-cell infiltration and antitumor efficacy. Thus, reversing the 'mismatch' of chemokines and chemokine receptors appears to be a promising method for promoting T-cell infiltration into the tumor and enhancing their antitumor efficacy. In this review, we discuss functions of the chemokine/chemokine receptor axis in cancer immunity and the current understanding, challenges and prospects for improving the effect of chimeric antigen receptor T cells by reversing the mismatch between chemokines and chemokine receptors.

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.

Therapeutic potential of CAR T cell in malignancies: A scoping review

Although tremendous advancements in cancer therapy over the last several years, cancer still is a complex illness to cure. Traditional cancer treatments, including chemotherapy, radiotherapy, and surgery, have a poor therapeutic effect, emphasizing the significance of employing innovative treatments like activated cell therapy. Chimeric antigen receptor T cell is one of the most prevalent types of activated cell therapy have been developed to direct T lymphocytes toward cancers (CAR-T cells). CAR-T cells therapy has illustrated poor impact versus solid tumors despite the remarkable success in patients suffering from hematological malignancies. CAR-T cells must overcome various hurdles to obtain full responses to solid tumors, including growth, stability, trafficking, and destiny inside tumors. As a result, novel treatment methods will entail overcoming the challenges that CAR-T cells face in solid tumors. The use of CAR-T cells in combination with other therapeutic approaches such as chemotherapy, radiotherapy, immuno-checkpoint inhibitors, and oncolytic viruses can promote the effectiveness of CAR-T cell therapy for the treatment of solid tumors. However, more research is needed to determine the safety and effectiveness of these therapies. CAR-T cell treatment success rates vary by type of disease, but are predicted to reach up to 90% in patients with leukemia. However, since this kind of immunotherapy is still in its infancy, there is much to learn about its efficacy. This review provided an in-depth examination of CAR-T cell therapy and its success and failure as a cancer treatment approach. We also discuss combination therapies with CAR-T Cell.

Inhibition of post-surgery tumour recurrence via a hydrogel releasing CAR-T cells and anti-PDL1-conjugated platelets

The immunosuppressive microenvironment of solid tumours reduces the antitumour activity of chimeric antigen receptor T cells (CAR-T cells). Here, we show that the release-through the implantation of a hyaluronic acid hydrogel-of CAR-T cells targeting the human chondroitin sulfate proteoglycan 4, polymer nanoparticles encapsulating the cytokine interleukin-15 and platelets conjugated with the checkpoint inhibitor programmed death-ligand 1 into the tumour cavity of mice with a resected subcutaneous melanoma tumour inhibits the local recurrence of the tumour as well as the growth of distant tumours, through the abscopal effect. The hydrogel, which functions as a reservoir, facilitates the enhanced distribution of the CAR-T cells within the surgical bed, and the inflammatory microenvironment triggers platelet activation and the subsequent release of platelet-derived microparticles. The post-surgery local delivery of combination immunotherapy through a biocompatible hydrogel reservoir could represent a translational route for preventing the recurrence of cancers with resectable tumours.

Chemokine Receptor CCR2b Enhanced Anti-tumor Function of Chimeric Antigen Receptor T Cells Targeting Mesothelin in a Non-small-cell Lung Carcinoma Model

Chimeric antigen receptor (CAR) T cell therapy faces a number of challenges for the treatment of non-small-cell lung carcinoma (NSCLC), and efficient migration of circulating CAR T cells plays an important role in anti-tumor activity. In this study, a CAR specific for tumor antigen mesothelin (Msln-CAR) was co-expressed with cell chemokine receptors CCR2b or CCR4. Findings showed that CCR2b and CCR4 enhanced the migration of Msln-CAR T cell in vitro by transwell assay. When incubated with mesothelin-positive tumor cells, Msln-CCR2b-CAR and Msln-CCR4-CAR T cell specifically exerted potent cytotoxicity and produced high levels of proinflammatory cytokines, including IL-2, IFN-γ, and TNF-α. Furthermore, NSCLC cell line-derived xenograft (CDX) model was constructed by implanting subcutaneously modified A549 into NSG mice. Compared to conventional Msln-CAR T cells, living imaging indicated that Msln-CCR2b-CAR T cells displayed superior anti-tumor function due to enhanced migration and infiltration into tumor tissue shown by immunohistochemistry (IHC) analysis. In addition, histopathological examinations of mice organs showed that no obvious organic damages were observed. This is the first time that CAR T cell therapy combined with chemokine receptor is applied to NSCLC treatment.

The antitumor capacity of mesothelin-CAR-T cells in targeting solid tumors in mice

Since the approval of chimeric antigen receptor (CAR) T cell therapy targeting CD19 by the FDA, CAR-T cell therapy has received increasing attention as a new method for targeting tumors. Although CAR-T cell therapy has a good effect against hematological malignancies, it has been less effective against solid tumors. In the present study, we selected mesothelin (MSLN/MESO) as a target for CAR-T cells because it is highly expressed by solid tumors but only expressed at low levels by normal tissues. We engineered a third generation MSLN-CAR comprising a single-chain variable fragment (scFv) targeting MSLN (MSLN-scFv), a CD8 transmembrane domain, the costimulatory domains from CD28 and 4-1BB, and the activating domain CD3ζ. In vitro, MSLN-CAR-T cells killed various solid tumor cell lines, demonstrating that it could specifically kill MSLN-positive cells and release cytokines. In vivo, we investigated the effects of MSLN-CAR-T cell therapy against ovarian, breast, and colorectal cancer cell-line-derived xenografts (CDX) and MSLN-positive colorectal and gastric cancer patient-derived xenografts (PDX). MSLN-CAR decreased the growth of MSLN-positive tumors concomitant with significantly increased T cells and cytokine levels compared to the control group. These results indicated that modified MSLN-CAR-T cells could be a promising therapeutic approach for solid tumors.

Mechanisms of Immunosuppression in Colorectal Cancer

Simple Summary

More emerging studies are exploring immunotherapy for solid cancers, including colorectal cancer. Besides, checkpoint blockade immunotherapy and chimeric antigen receptor (CAR) -based immune cell therapy have being examined in clinical trials for colorectal cancer patients. However, immunosuppression that leads to the blockage of normal immunosurveillance often leads to cancer development and relapse. In this study, we systematically reviewed the mechanism of immunosuppression, specifically in colorectal cancer, from different perspectives, including the natural or induced immunosuppressive cells, cell surface protein, cytokines/chemokines, transcriptional factors, metabolic alteration, phosphatase, and tissue hypoxia in the tumor microenvironment. We also discussed the progress of immunotherapies in clinical trials/studies for colorectal cancer and highlighted how different strategies for cancer therapy targeted the immunosuppression reviewed above. Our review provides some timely implications for restoring immunosurveillance to improve treatment efficacy in colorectal cancer (CRC).

Abstract

CRC is the third most diagnosed cancer in the US with the second-highest mortality rate. A multi-modality approach with surgery/chemotherapy is used in patients with early stages of colon cancer. Radiation therapy is added to the armamentarium in patients with locally advanced rectal cancer. While some patients with metastatic CRC are cured, the majority remain incurable and receive palliative chemotherapy as the standard of care. Recently, immune checkpoint blockade has emerged as a promising treatment for many solid tumors, including CRC with microsatellite instability. However, it has not been effective for microsatellite stable CRC. Here, main mechanisms of immunosuppression in CRC will be discussed, aiming to provide some insights for restoring immunosurveillance to improve treatment efficacy in CRC.

Enhancement of the antitumor effect of HER2-directed CAR-T cells through blocking epithelial-mesenchymal transition in tumor cells

The efficacy of chimeric antigen receptor T (CAR-T) cell therapy in solid tumors is far from satisfactory. In this study, we investigated the influence of epithelial-mesenchymal transition (EMT) on the antitumor effect of CAR-T cells and explored the potential efficacy of combining CAR-T cells with inhibitors targeting EMT. We successfully induced EMT in tumor cells with TGF-β1, and the antitumor effect of HER2-directed CAR-T cells was significantly suppressed by EMT. Upregulation of PD-L1 was observed in tumor cells undergoing EMT, and change in PD-L1 expression during the EMT process was dependent on the MEK/ERK and PI3K/Akt pathways. Inhibition of the TGF-β1 pathway could block the EMT process in tumor cells and restore their susceptibility to HER2-directed CAR-T cells in vitro. In addition, targeting the TGF-β1 pathway significantly enhanced the antitumor effect of HER2-directed CAR-T cells in vivo. Our findings suggest that blocking EMT could potently enhance the antitumor effect of CAR-T cells, which provides a promising approach to improving the therapeutic efficacy of CAR-T cell therapy in solid tumors.

DCLK1 Monoclonal Antibody-Based CAR-T Cells as a Novel Treatment Strategy against Human Colorectal Cancers

CAR-T (chimeric antigen receptor T cells) immunotherapy is effective in many hematological cancers; however, efficacy in solid tumors is disappointing. Doublecortin-like kinase 1 (DCLK1) labels tumor stem cells (TSCs) in genetic mouse models of colorectal cancer (CRC). Here, we describe a novel CAR-T targeting DCLK1 (CBT-511; with our proprietary DCLK1 single-chain antibody variable fragment) as a treatment strategy to eradicate CRC TSCs. The cell surface expression of DCLK1 and cytotoxicity of CBT-511 were assessed in CRC cells (HT29, HCT116, and LoVo). LoVo-derived tumor xenografts in NOD Scid gamma (NSG^TM)mice were treated with CBT-511 or mock CAR-T cells. Adherent CRC cells express surface DCLK1 (two-dimensional, 2D). A 4.5-fold increase in surface DCLK1 was observed when HT29 cells were grown as spheroids (three-dimensional, 3D). CBT-511 induced cytotoxicity (2D; p < 0.0001), and increased Interferon gamma (IFN-γ) release in CRC cells (2D) compared to mock CAR-T (p < 0.0001). Moreover, an even greater increase in IFN-γ release was observed when cells were grown in 3D. CBT-511 reduced tumor growth by approximately 50 percent compared to mock CAR-T. These data suggest that CRC cells with increased clonogenic capacity express increased surface DCLK1. A DCLK1-targeted CAR-T can induce cytotoxicity in vitro and inhibit xenograft growth in vivo.

Immunotherapy for Colorectal Cancer: A Review of Current and Novel Therapeutic Approaches

Colorectal cancer (CRC) remains a leading cause of cancer-related deaths in the United States. Although immunotherapy has dramatically changed the landscape of treatment for many advanced cancers, the benefit in CRC has thus far been limited to patients with microsatellite instability high (MSI-H):DNA mismatch repair-deficient (dMMR) tumors. Recent studies in the refractory CRC setting have led to US Food and Drug Administration approvals for pembrolizumab as well as nivolumab (with or without ipilimumab) for tumors harboring an MSI-H:dMMR molecular profile. Several randomized controlled trials are underway to move immunotherapy into the frontline for metastatic cancer (with or without chemotherapy) and the adjuvant setting. Awareness of these studies is critical given the relatively low incidence (approximately 3%-5%) of MSI-H:dMMR in advanced or metastatic CRC to support study completion, because the results could be potentially practice changing. The real challenge in this disease is related to demonstrating the benefit of immunotherapy for the vast majority of patients with CRC not harboring MSI-H:dMMR. Given the rapid pace of scientific changes, this article provides a narrative review regarding the current landscape of immunotherapy for CRC. Particular attention is paid to the currently available data that inform today's clinical practice along with upcoming randomized controlled trials that may soon dramatically change the treatment landscape for CRC.

Development and Clinical Translation of Approved Gene Therapy Products for Genetic Disorders

The field of gene therapy is striving more than ever to define a path to the clinic and the market. Twenty gene therapy products have already been approved and over two thousand human gene therapy clinical trials have been reported worldwide. These advances raise great hope to treat devastating rare and inherited diseases as well as incurable illnesses. Understanding of the precise pathomechanisms of diseases as well as the development of efficient and specific gene targeting and delivery tools are revolutionizing the global market. Currently, human cancers and monogenic disorders are indications number one. The elevated prevalence of genetic disorders and cancers, clear gene manipulation guidelines and increasing financial support for gene therapy in clinical trials are major trends. Gene therapy is presently starting to become commercially profitable as a number of gene and cell-based gene therapy products have entered the market and the clinic. This article reviews the history and development of twenty approved human gene and cell-based gene therapy products that have been approved up-to-now in clinic and markets of mainly North America, Europe and Asia.

A theranostic PSMA ligand for PET imaging and retargeting of T cells expressing the universal chimeric antigen receptor UniCAR

Chimeric antigen receptor (CAR) T cells have shown impressive therapeutic potential. Due to the lack of direct control mechanisms, therapy-related adverse reactions including cytokine release- and tumor lysis syndrome can even become life-threatening. In case of target antigen expression on non-malignant cells, CAR T cells can also attack healthy tissues. To overcome such side effects, we have established a modular CAR platform termed UniCAR: UniCAR T cells per se are inert as they recognize a peptide epitope (UniCAR epitope) that is not accessible on the surface of living cells. Bifunctional adapter molecules termed target modules (TM) can cross-link UniCAR T cells with target cells. In the absence of TMs, UniCAR T cells automatically turn off. Until now, all UniCAR TMs were constructed by fusion of the UniCAR epitope to an antibody domain. To open up the wide field of low-molecular-weight compounds for retargeting of UniCAR T cells to tumor cells, and to follow in parallel the progress of UniCAR T cell therapy by PET imaging we challenged the idea to convert a PET tracer into a UniCAR-TM. For proof of concept, we selected the clinically used PET tracer PSMA-11, which binds to the prostate-specific membrane antigen overexpressed in prostate carcinoma. Here we show that fusion of the UniCAR epitope to PSMA-11 results in a low-molecular-weight theranostic compound that can be used for both retargeting of UniCAR T cells to tumor cells, and for non-invasive PET imaging and thus represents a member of a novel class of theranostics.

Immunotherapy in colorectal cancer: Available clinical evidence, challenges and novel approaches

In contrast to other tumor types, immunotherapy has not yet become a relevant part of the treatment landscape of unselected colorectal cancer. Beside the small subgroup of deficient mismatch repair or microsatellite instable tumors (about 5%) as a surrogate for high mutational burden and subsequently high neoantigen load and immunogenicity, inhibitors of programmed death 1 (PD-1), programmed death ligand 1 (PD-L1) and/or cytotoxic T lymphocyte-associated antigen-4 were not or only modestly effective in metastatic colorectal cancer. Thus, a variety of combination approaches with chemotherapy, targeted therapy, toll-like receptor agonists, local ablation or oncolytic viruses is currently being evaluated in different disease settings. Despite several encouraging single arm data already presented or published, available randomized data are unimpressive. Adding PD-1/PD-L1 inhibitors to fluoropyrimidines and bevacizumab maintenance showed no beneficial impact on delaying progression. In refractory disease, the combination of PD-1/PD-L1 and MEK inhibitor was not different from regorafenib, whereas a PD-1/PD-L1 and cytotoxic T lymphocyte-associated antigen-4 inhibitor combination demonstrated better overall survival compared to supportive care alone. Clinical trials in all disease settings applying different combination approaches are ongoing and may define the role of immunotherapy in colorectal cancer.

Hypoxia Selectively Impairs CAR-T Cells In Vitro

Hypoxia is a major characteristic of the solid tumor microenvironment. To understand how chimeric antigen receptor-T cells (CAR-T cells) function in hypoxic conditions, we characterized CD19-specific and BCMA-specific human CAR-T cells generated in atmospheric (18% oxygen) and hypoxic (1% oxygen) culture for expansion, differentiation status, and CD4:CD8 ratio. CAR-T cells expanded to a much lower extent in 1% oxygen than in 18% oxygen. Hypoxic CAR-T cells also had a less differentiated phenotype and a higher CD4:CD8 ratio than atmospheric CAR-T cells. CAR-T cells were then added to antigen-positive and antigen-negative tumor cell lines at the same or lower oxygen level and characterized for cytotoxicity, cytokine and granzyme B secretion, and PD-1 upregulation. Atmospheric and hypoxic CAR-T cells exhibited comparable cytolytic activity and PD-1 upregulation; however, cytokine production and granzyme B release were greatly decreased in 1% oxygen, even when the CAR-T cells were generated in atmospheric culture. Together, these data show that at solid tumor oxygen levels, CAR-T cells are impaired in expansion, differentiation and cytokine production. These effects may contribute to the inability of CAR-T cells to eradicate solid tumors seen in many patients.

Mesothelin is a target of chimeric antigen receptor T cells for treating gastric cancer

BACKGROUND

Gastric cancer (GC) is a common cancer in Asia and currently lacks a targeted therapy approach. Mesothelin (MSLN) has been reported to be expressed in GC tissue and could be targeted by chimeric antigen receptor (CAR) T cells. Mesothelin targeting CAR-T has been reported in mesothelioma, lung cancer, breast cancer, and pancreas cancer. However, the feasibility of using anti-MSLN CAR T cells to treat GC remains to be studied.

METHODS

We verified MSLN expression in primary human GC tissues and GC cell lines and then redirected T cells with a CAR containing the MSLN scFv (single-chain variable fragment), CD3ζ, CD28, and DAP10 intracellular signaling domain (M28z10) to target MSLN. We evaluated the function of these CAR T cells in vitro in terms of cytotoxicity, cytokine secretion, and surface phenotype changes when they encountered MSLN+ GC cells. We also established four different xenograft GC mouse models to assess in vivo antitumor activity.

RESULTS

M28z10 T cells exhibited strong cytotoxicity and cytokine-secreting ability against GC cells in vitro. In addition, cell surface phenotyping suggested significant activation of M28z10 T cells upon target cell stimulation. M28z10 T cells induced GC regression in different xenograft mouse models and prolonged the survival of these mice compared with GFP-transduced T cells in the intraperitoneal and pulmonary metastatic GC models. Importantly, peritumoral delivery strategy can lead to improved CAR-T cells infiltration into tumor tissue and significantly suppress the growth of GC in a subcutaneous GC model.

CONCLUSION

These results demonstrate that M28z10 T cells possess strong antitumor activity and represent a promising therapeutic approach to GC.

T-cells "à la CAR-T(e)" - Genetically engineering T-cell response against cancer

The last decade will be remembered as the dawn of the immunotherapy era during which we have witnessed the approval by regulatory agencies of genetically engineered CAR T-cells and of checkpoint inhibitors for cancer treatment. Understandably, T-lymphocytes represent the essential player in these approaches. These cells can mediate impressive tumor regression in terminally-ill cancer patients. Moreover, they are amenable to genetic engineering to improve their function and specificity. In the present review, we will give an overview of the most recent developments in the field of T-cell genetic engineering including TCR-gene transfer and CAR T-cells strategies. We will also elaborate on the development of other types of genetic modifications to enhance their anti-tumor immune response such as the use of co-stimulatory chimeric receptors (CCRs) and unconventional CARs built on non-antibody molecules. Finally, we will discuss recent advances in genome editing and synthetic biology applied to T-cell engineering and comment on the next challenges ahead.

Transient redirection of T cells for adoptive cell therapy with telomerase-specific T helper cell receptors isolated from long term survivors after cancer vaccination

Adoptive cell therapy (ACT) with retargeted T cells has produced remarkable clinical responses against cancer, but also serious toxicity. Telomerase is overexpressed in most cancers, but also expressed in some normal cells, raising safety concerns. We hypothesize that ACT with T-helper cell receptors may overcome tumour tolerance, mobilize host immune cells and induce epitope spreading, with limited toxicity. From long term survivors after cancer vaccination, we have isolated telomerase-specific T cell receptors (TCRs) from T-helper cells. Herein, we report the development of transient retargeting of T cells with mRNA-based TCRs. This strategy allows for safer clinical testing and meaningful dose escalation. DP4 is the most common HLA molecule. We cloned two telomerase-specific, DP4-restricted TCRs into the mRNA expression vector pCIpA102, together with the sorter/marker/suicide gene RQR8. Donor T cells were electroporated with mRNA encoding TCR_RQR8. The results showed that both TCR_RQR8 constructs were expressed in >90% of T cells. The transfected T cells specifically recognized the relevant peptide, as well as naturally processed epitopes from a 177aa telomerase protein fragment, and remained functional for six days. A polyfunctional and Th1-like cytokine profile was observed. The TCRs were functional in both CD4+and CD8+recipient T cells, even though DP4-restricted. The findings demonstrate that the cloned TCRs confer recipient T cells with the desired telomerase-specificity and functionality. Preclinical experiments may provide limited information on the efficacy and toxicity of T-helper TCRs, as these mobilize the host immune system. We therefore intend to use the mRNA-based TCRs for a first-in-man trial.

La/SSB chimeric autoantibody receptor modified NK92MI cells for targeted therapy of autoimmune disease

It has been long sought to specifically eliminate B-cell clones that generate autoreactive antibodies, while sparing the immune system when combating autoimmune disease. Although it was impossible to achieve this goal before, newly developed techniques have made it feasible today. Autoantibodies against La/SSB were involved in several autoimmune diseases. Here, we aimed to introduce La/SSB epitope-based chimeric autoantibody receptors (CAAR) into NK92MI cells enabled it to destroy the corresponding La/SSB-specific B cell receptor (BCR) -bearing lymphoma cells (LaA-BCR-Romas, LaA-BCR-Maver-1, and LaA-BCR-Jurkat cells). Such cell lines could eliminate a part of the B-cells in the blood of patients positive for anti-La/SSB antibodies. The CAAR we used in this study was constructed by fusing fragments from the nucleus protein, La/SSB, with the TCR signaling molecules, CD28, CD137, and CD3ζ. Thus, this method could specifically destroy the La/SSB autoreactive B-cell clones. Our results might provide a new strategy to combat antibody-mediated autoimmune diseases.

Engineering Hematopoietic Cells for Cancer Immunotherapy: Strategies to Address Safety and Toxicity Concerns

Advances in cancer immunotherapies utilizing engineered hematopoietic cells have recently generated significant clinical successes. Of great promise are immunotherapies based on chimeric antigen receptor-engineered T (CAR-T) cells that are targeted toward malignant cells expressing defined tumor-associated antigens. CAR-T cells harness the effector function of the adaptive arm of the immune system and redirect it against cancer cells, overcoming the major challenges of immunotherapy, such as breaking tolerance to self-antigens and beating cancer immune system-evasion mechanisms. In early clinical trials, CAR-T cell-based therapies achieved complete and durable responses in a significant proportion of patients. Despite clinical successes and given the side effect profiles of immunotherapies based on engineered cells, potential concerns with the safety and toxicity of various therapeutic modalities remain. We discuss the concerns associated with the safety and stability of the gene delivery vehicles for cell engineering and with toxicities due to off-target and on-target, off-tumor effector functions of the engineered cells. We then overview the various strategies aimed at improving the safety of and resolving toxicities associated with cell-based immunotherapies. Integrating failsafe switches based on different suicide gene therapy systems into engineered cells engenders promising strategies toward ensuring the safety of cancer immunotherapies in the clinic.

Retargeting of UniCAR T cells with an in vivo synthesized target module directed against CD19 positive tumor cells

Recent treatments of leukemias with T cells expressing chimeric antigen receptors (CARs) underline their impressive therapeutic potential but also their risk of severe side effects including cytokine release storms and tumor lysis syndrome. In case of cross-reactivities, CAR T cells may also attack healthy tissues. To overcome these limitations, we previously established a switchable CAR platform technology termed UniCAR. UniCARs are not directed against typical tumor-associated antigens (TAAs) but instead against a unique peptide epitope: Fusion of this peptide epitope to a recombinant antibody domain results in a target module (TM). TMs can cross-link UniCAR T cells with tumor cells and thereby lead to their destruction. So far, we constructed TMs with a short half-life. The fast turnover of such a TM allows to rapidly interrupt the treatment in case severe side effects occur. After elimination of most of the tumor cells, however, longer lasting TMs which have not to be applied via continous infusion would be more convenient for the patient. Here we describe and characterize a TM for retargeting UniCAR T cells to CD19 positive tumor cells. Moreover, we show that the TM can efficiently be produced in vivo from producer cells housed in a sponge-like biomimetic cryogel and, thereby, serving as an in vivo TM factory for an extended retargeting of UniCAR T cells to CD19 positive leukemic cells.

Delivering Type I Interferon to Dendritic Cells Empowers Tumor Eradication and Immune Combination Treatments

An ideal generic cancer immunotherapy should mobilize the immune system to destroy tumor cells without harming healthy cells and remain active in case of recurrence. Furthermore, it should preferably not rely on tumor-specific surface markers, as these are only available in a limited set of malignancies. Despite approval for treatment of various cancers, clinical application of cytokines is still impeded by their multiple toxic side effects. Type I IFN has a long history in the treatment of cancer, but its multifaceted activity pattern and complex side effects prevent its clinical use. Here we develop AcTakines (Activity-on-Target cytokines), optimized (mutated) immunocytokines that are up to 1,000-fold more potent on target cells, allowing specific signaling in selected cell types only. Type I IFN-derived AcTaferon (AFN)-targeting Clec9A⁺ dendritic cells (DC) displayed strong antitumor activity in murine melanoma, breast carcinoma, and lymphoma models and against human lymphoma in humanized mice without any detectable toxic side effects. Combined with immune checkpoint blockade, chemotherapy, or low-dose TNF, complete tumor regression and long-lasting tumor immunity were observed, still without adverse effects. Our findings indicate that DC-targeted AFNs provide a novel class of highly efficient, safe, and broad-spectrum off-the-shelf cancer immunotherapeutics with no need for a tumor marker.Significance: Targeted type I interferon elicits powerful antitumor efficacy, similar to wild-type IFN, but without any toxic side effects. Cancer Res; 78(2); 463-74. ©2017 AACR.

Phase I Study of Chimeric Antigen Receptor-Modified T Cells in Patients with EGFR-Positive Advanced Biliary Tract Cancers

Purpose: This study is an expanded and parallel clinical trial of EGFR-specific chimeric antigen receptor-engineered autologous T (CART) cell immunotherapy (NCT01869166) to assess the safety and activity of CART-EGFR cell therapy in EGFR-positive advanced unresectable, relapsed/metastatic biliary tract cancers (BTC).Experimental Design: Patients with EGFR-positive (>50%) advanced unresectable, relapsed/metastatic BTCs were enrolled. Well-produced CART-EGFR cells were infused in a manner of dose escalation after the conditioning treatment with nab-paclitaxel (100-250 mg/m²) and cyclophosphamide (15-35 mg/kg).Results: A total of 19 patients (14 cholangiocarcinomas and 5 gallbladder carcinomas) received one to three cycles of CART-EGFR cell infusion (median CART cell dose, 2.65 × 10⁶/kg; range, 0.8-4.1 × 10⁶/kg) within 6 months. The CART-EGFR cell infusion was tolerated, but 3 patients suffered grade ≥3 acute fever/chill. Grade 1/2 target-mediated toxicities including mucosal/cutaneous toxicities and acute pulmonary edema and grade ≥3 lymphopenia and thrombocytopenia related to the conditioning treatment were observed. Of 17 evaluable patients, 1 achieved complete response and 10 achieved stable disease. The median progression-free survival was 4 months (range, 2.5-22 months) from the first cycle of treatment. Analysis of data indicated that the enrichment of central memory T cells (Tcm) in the infused CART-EGFR cells improved the clinical outcome.Conclusions: The CART-EGFR cell immunotherapy was a safe and active strategy for EGFR-positive advanced BTCs. The enrichment of Tcm in the infused CART-EGFR cells could predict clinical response. Clin Cancer Res; 24(6); 1277-86. ©2017 AACRSee related commentary by Kalos, p. 1246.

Study protocol for THINK: a multinational open-label phase I study to assess the safety and clinical activity of multiple administrations of NKR-2 in patients with different metastatic tumour types

INTRODUCTION

NKR-2 are autologous T cells genetically modified to express a chimeric antigen receptor (CAR) comprising a fusion of the natural killer group 2D (NKG2D) receptor with the CD3ζ signalling domain, which associates with the adaptor molecule DNAX-activating protein of 10 kDa (DAP10) to provide co-stimulatory signal upon ligand binding. NKG2D binds eight different ligands expressed on the cell surface of many tumour cells and which are normally absent on non-neoplastic cells. In preclinical studies, NKR-2 demonstrated long-term antitumour activity towards a breadth of tumour indications, with maximum efficacy observed after multiple NKR-2 administrations. Importantly, NKR-2 targeted tumour cells and tumour neovasculature and the local tumour immunosuppressive microenvironment and this mechanism of action of NKR-2 was established in the absence of preconditioning.

METHODS AND ANALYSIS

This open-label phase I study will assess the safety and clinical activity of NKR-2 treatment administered three times, with a 2-week interval between each administration in different tumour types. The study will contain two consecutive segments: a dose escalation phase followed by an expansion phase. The dose escalation study involves two arms, one in solid tumours (five specific indications) and one in haematological tumours (two specific indications) and will include three dose levels in each arm: 3×10⁸, 1×10⁹ and 3×10⁹ NKR-2 per injection. On the identification of the recommended dose in the first segment, based on dose-limiting toxicity occurrences, the study will expand to seven different cohorts examining the seven different tumour types separately. Clinical responses will be determined according to standard Response Evaluation Criteria In Solid Tumors (RECIST) criteria for solid tumours or international working group response criteria in haematological tumours.

ETHICS APPROVAL AND DISSEMINATION

Ethical approval has been obtained at all sites. Written informed consent will be taken from all participants. The results of this study will be disseminated through presentation at international scientific conferences and reported in peer-reviewed scientific journals.

TRIAL REGISTRATION NUMBER

NCT03018405, EudraCT 2016-003312-12; Pre-result.

CD47-CAR-T Cells Effectively Kill Target Cancer Cells and Block Pancreatic Tumor Growth

CD47 is a glycoprotein of the immunoglobulin superfamily that is often overexpressed in different types of hematological and solid cancer tumors and plays important role in blocking phagocytosis, increased tumor survival, metastasis and angiogenesis. In the present report, we designed CAR (chimeric antigen receptor)-T cells that bind CD47 antigen. We used ScFv (single chain variable fragment) from mouse CD47 antibody to generate CD47-CAR-T cells for targeting different cancer cell lines. CD47-CAR-T cells effectively killed ovarian, pancreatic and other cancer cells and produced high level of cytokines that correlated with expression of CD47 antigen. In addition, CD47-CAR-T cells significantly blocked BxPC3 pancreatic xenograft tumor growth after intratumoral injection into NSG mice. Moreover, we humanized mouse CD47 ScFv and showed that it effectively bound CD47 antigen. The humanized CD47-CAR-T cells also specifically killed ovarian, pancreatic, and cervical cancer cell lines and produced IL-2 that correlated with expression of CD47. Thus, CD47-CAR-T cells can be used as a novel cellular therapeutic agent for treating different types of cancer.

Development of novel target modules for retargeting of UniCAR T cells to GD2 positive tumor cells

As the expression of a tumor associated antigen (TAA) is commonly not restricted to tumor cells, adoptively transferred T cells modified to express a conventional chimeric antigen receptor (CAR) might not only destroy the tumor cells but also attack target-positive healthy tissues. Furthermore, CAR T cells in patients with large tumor bulks will unpredictably proliferate and put the patients at high risk of adverse side effects including cytokine storms and tumor lysis syndrome. To overcome these problems, we previously established a modular CAR technology termed UniCAR: UniCAR T cells can repeatedly be turned on and off via dosing of a target module (TM). TMs are bispecific molecules which cross-link UniCAR T cells with target cells. After elimination of the respective TM, UniCAR T cells automatically turn off. Here we describe novel TMs against the disialoganglioside GD2 which is overexpressed in neuroectodermal but also many other tumors. In the presence of GD2-specific TMs, we see a highly efficient target-specific and -dependent activation of UniCAR T cells, secretion of pro-inflammatory cytokines, and tumor cell lysis both in vitro and experimental mice. According to PET-imaging, anti-GD2 TM enrich at the tumor site and are rapidly eliminated thus fulfilling all prerequisites of a UniCAR TM.

Genome and Epigenome Editing to Treat Disorders of the Hematopoietic System

The possibility of editing complex genomes in a targeted fashion has revolutionized basic research as well as biomedical and biotechnological applications in the last 5 years. The targeted introduction of genetic changes has allowed researchers to create smart model systems for basic research, bio-engineers to modify crops and farm animals, and translational scientists to develop novel treatment approaches for inherited and acquired disorders for which curative treatment options are not yet available. With the rapid development of genome editing tools, in particular zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and the CRISPR-Cas system, a wide range of therapeutic options have been-and will be-developed at an unprecedented speed, which will change the clinical routine of various disciplines in a revolutionary way. This review summarizes the fundamentals of genome editing and the current state of research. It particularly focuses on the advances made in employing engineered nucleases in hematopoietic stem cells for the treatment of primary immunodeficiencies and hemoglobinopathies, provides a perspective of combining gene editing with the chimeric antigen receptor T cell technology, and concludes by presenting targeted epigenome editing as a novel potential treatment option.

Phase I study of chimeric antigen receptor modified T cells in treating HER2-positive advanced biliary tract cancers and pancreatic cancers

This phase I clinical trial (NCT01935843) is to evaluate the safety, feasibility, and activity of chimeric antigen receptor-engineered T cell (CART) immunotherapy targeting human epidermal growth factor receptor 2 (HER2) in patients with advanced biliary tract cancers (BTCs) and pancreatic cancers (PCs). Eligible patients with HER2-positive (>50%) BTCs and PCs were enrolled in the trial. Well cultured CART-HER2 cells were infused following the conditioning treatment composed of nab-paclitaxel (100–200 mg/m²) and cyclophosphamide (15–35 mg/kg). CAR transgene copy number in the peripheral blood was serially measured to monitor the expansion and persistence of CART-HER2 cells in vivo. Eleven enrolled patients received 1 to 2-cycle CART-HER2 cell infusion (median CAR⁺ T cell 2.1 × 10⁶/kg). The conditioning treatment resulted in mild-to-moderate fatigue, nausea/vomiting, myalgia/arthralgia, and lymphopenia. Except one grade-3 acute febrile syndrome and one abnormal elevation of transaminase (>9 ULN), adverse events related to the infusion of CART-HER2 cells were mild-to-moderate. Post-infusion toxicities included one case of reversible severe upper gastrointestinal hemorrhage which occurred in a patient with gastric antrum invaded by metastasis 11 days after the CART-HER2 cell infusion, and 2 cases of grade 1–2 delayed fever, accompanied by the release of C-reactive protein and interleukin-6. All patients were evaluable for assessment of clinical response, among which 1 obtained a 4.5-months partial response and 5 achieved stable disease. The median progression free survival was 4.8 months (range, 1.5–8.3 months). Finally, data from this study demonstrated the safety and feasibility of CART-HER2 immunotherapy, and showed encouraging signals of clinical activity.

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.

Developing Infrastructure: Managing Patients With Cancer Undergoing CAR T-Cell Therapy

BACKGROUND

The introduction of chimeric antigen receptor (CAR) T-cell therapy has created challenges and opportunities for nurses. Clinical nurses must be educated on new treatment modalities to recognize toxicity symptoms and to support the therapy moving forward. 
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OBJECTIVES

This article will discuss nursing leadership and interventions to standardize care and ensure patient safety while receiving CAR T cells. 
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METHODS

Using evolving experience, an interprofessional team created standards of care and identified common toxicities and best practices for their management. Electronic documentation forms were designed, which led to the development of a new research infrastructure to care for patients.
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FINDINGS

The ability to safely manage patients on CAR T-cell treatments has improved. The new infrastructure supported clinicians and scientists in transforming the outcomes of diseases with bleak prognoses, which is possible only with strong nursing leadership.
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Viroimmunotherapy for Colorectal Cancer: Clinical Studies

Colorectal cancer is a leading cause of cancer incidence and death. Therapies for those with unresectable or recurrent disease are not considered curative at present. More effective and less toxic therapies are desperately needed. Historically, the immune system was thought to be an enemy to oncolytic viral therapy. Thinking that oncolysis would be the only mechanism for cell death, oncolytic virologists theorized that immune clearance was a detriment to oncolysis. Recent advances in our understanding of the tumor microenvironment, and the interplay of tumor survival and a patient's immune system have called into question our understanding of both arenas. It remains unclear what combination of restrictions or enhancements of innate and/or cell-mediated immunity can yield the highest likelihood of viral efficacy. This article reviews the variety of mechanisms explored for viruses such as immunotherapy for colorectal cancer.

The growing world of CAR T cell trials: a systematic review

In recent years, cancer treatment involving adoptive cell therapy with chimeric antigen receptor (CAR)-modified patient's immune cells has attracted growing interest. Using gene transfer techniques, the patient's T cells are modified ex vivo with a CAR which redirects the T cells toward the cancer cells through an antibody-derived binding domain. The T cells are activated by the CAR primary signaling and costimulatory domains. Such "second generation" CAR T cells induced complete remission of B cell malignancies in the long-term. In this fast-moving field with a growing number of engineered T cell products, we list about 100 currently ongoing trials here that involve CAR T cells targeting hematopoietic malignancies and solid cancer. Major challenges in the further development of the therapy are briefly discussed.

T-helper cell receptors from long-term survivors after telomerase cancer vaccination for use in adoptive cell therapy

We herein report retargeting of T-helper (Th) cells against the universal cancer antigen telomerase for use in adoptive cell therapy. The redirected Th cells may counter tumor tolerance, transform the inflammatory milieu, and induce epitope spreading and cancer senescence. We have previously conducted a series of trials evaluating vaccination with telomerase peptides. From long-term survivors, we isolated >100 CD4⁺ Th-cell clones recognizing telomerase epitopes. The clones were characterized with regard to HLA restriction, functional avidity, fine specificity, proliferative capacity, cytokine profile, and recognition of naturally processed epitopes. DP4 is the most prevalent HLA molecule worldwide. Two DP4-restricted T-cell clones with different functional avidity, C13 and D71, were selected for molecular T-cell receptor (TCR) cloning. Both clones showed a high proliferative capacity, recognition of naturally processed telomerase epitopes, and a polyfunctional and Th1-weighted cytokine profile. TCR C13 and D71 were cloned into the retroviral vector MP71 together with the compact and GMP-applicable marker/suicide gene RQR8. Both TCRs were expressed well in recipient T cells after PBMC transduction. The transduced T cells co-expressed RQR8 and acquired the desired telomerase specificity, with a polyfunctional response including production of TNFa, IFNγ, and CD107a. Interestingly, the DP4-restricted TCRs were expressed and functional both in CD4⁺ and CD8⁺ T cells. The findings demonstrate that the cloned TCRs confer recipient T cells with the desired hTERT-specificity and functionality. We hypothesize that adoptive therapy with Th cells may offer a powerful novel approach for overcoming tumor tolerance and synergize with other forms of immunotherapy.

Redirecting T Cells to Glypican-3 with 4-1BB Zeta Chimeric Antigen Receptors Results in Th1 Polarization and Potent Antitumor Activity

T cells engineered to express CD19-specific chimeric antigen receptors (CARs) have shown breakthrough clinical successes in patients with B-cell lymphoid malignancies. However, similar therapeutic efficacy of CAR T cells in solid tumors is yet to be achieved. In this study we systematically evaluated a series of CAR constructs targeting glypican-3 (GPC3), which is selectively expressed on several solid tumors. We compared GPC3-specific CARs that encoded CD3ζ (Gz) alone or with costimulatory domains derived from CD28 (G28z), 4-1BB (GBBz), or CD28 and 4-1BB (G28BBz). All GPC3-CARs rendered T cells highly cytotoxic to GPC3-positive hepatocellular carcinoma, hepatoblastoma, and malignant rhabdoid tumor cell lines in vitro. GBBz induced the preferential production of Th1 cytokines (interferon γ/granulocyte macrophage colony-stimulating factor) while G28z preferentially induced Th2 cytokines (interleukin-4/interleukin-10). Inclusion of 4-1BB in G28BBz could only partially ameliorate the Th2-polarizing effect of CD28. 4-1BB induced superior expansion of CAR T cells in vitro and in vivo. T cells expressing GPC3-CARs incorporating CD28, 4-1BB, or both induced sustained tumor regressions in two xenogeneic tumor models. Thus, GBBz CAR endows T cells with superior proliferative potential, potent antitumor activity, and a Th1-biased cytokine profile, justifying further clinical development of GBBz CAR for immunotherapy of GPC3-positive solid tumors.

Preclinical and clinical evaluation of MET functions in cancer cells and in the tumor stroma

A lot of attention has been dedicated to investigate the role of the tyrosine kinase receptor MET in tumors. The acquired notion that cancer cells from different histological origin strictly rely on the engagement of this specific oncogene for their growth and survival has certainly justified the development and the use of MET-targeted therapies in the clinic. However, the function and involvement of this pathway in the stroma (that often constitutes >50% of the global cellularity of the tumor) may offer the opportunity to conceive new patient stratification criteria, rational drug design and guided trials of new combination treatments. In this review, we will summarize and discuss the role of MET in cancer cells but especially in different stromal compartments, in light of the results showed by past and recent preclinical and clinical trials with anti-MET drugs.

Different Subsets of T Cells, Memory, Effector Functions, and CAR-T Immunotherapy

This review is focused on different subsets of T cells: CD4 and CD8, memory and effector functions, and their role in CAR-T therapy--a cellular adoptive immunotherapy with T cells expressing chimeric antigen receptor. The CAR-T cells recognize tumor antigens and induce cytotoxic activities against tumor cells. Recently, differences in T cell functions and the role of memory and effector T cells were shown to be important in CAR-T cell immunotherapy. The CD4⁺ subsets (Th1, Th2, Th9, Th17, Th22, Treg, and Tfh) and CD8⁺ memory and effector subsets differ in extra-cellular (CD25, CD45RO, CD45RA, CCR-7, L-Selectin [CD62L], etc.); intracellular markers (FOXP3); epigenetic and genetic programs; and metabolic pathways (catabolic or anabolic); and these differences can be modulated to improve CAR-T therapy. In addition, CD4⁺ Treg cells suppress the efficacy of CAR-T cell therapy, and different approaches to overcome this suppression are discussed in this review. Thus, next-generation CAR-T immunotherapy can be improved, based on our knowledge of T cell subsets functions, differentiation, proliferation, and signaling pathways to generate more active CAR-T cells against tumors.

Phase 1 clinical trial demonstrated that MUC1 positive metastatic seminal vesicle cancer can be effectively eradicated by modified Anti-MUC1 chimeric antigen receptor transduced T cells

Recent progress in chimeric antigen receptor-modified T-cell (CAR-T cell) technology in cancer therapy is extremely promising, especially in the treatment of patients with B-cell acute lymphoblastic leukemia. In contrast, due to the hostile immunosuppressive microenvironment of a solid tumor, CAR T-cell accessibility and survival continue to pose a considerable challenge, which leads to their limited therapeutic efficacy. In this study, we constructed two anti-MUC1 CAR-T cell lines. One set of CAR-T cells contained SM3 single chain variable fragment (scFv) sequence specifically targeting the MUC1 antigen and co-expressing interleukin (IL) 12 (named SM3-CAR). The other CAR-T cell line carried the SM3 scFv sequence modified to improve its binding to MUC1 antigen (named pSM3-CAR) but did not co-express IL-12. When those two types of CAR-T cells were injected intratumorally into two independent metastatic lesions of the same MUC1(+) seminal vesicle cancer patient as part of an interventional treatment strategy, the initial results indicated no side-effects of the MUC1 targeting CAR-T cell approach, and patient serum cytokines responses were positive. Further evaluation showed that pSM3-CAR effectively caused tumor necrosis, providing new options for improved CAR-T therapy in solid tumors.