Multiple cancer-specific antigens are targeted by a chimeric antigen receptor on a single cancer cell

Novel banana lectin CAR-T cells to target pancreatic tumors and tumor-associated stroma

BACKGROUND

Cell therapies for solid tumors are thwarted by the hostile tumor microenvironment (TME) and by heterogeneous expression of tumor target antigens. We address both limitations with a novel class of chimeric antigen receptors based on plant lectins, which recognize the aberrant sugar residues that are a 'hallmark' of both malignant and associated stromal cells. We have expressed in T cells a modified lectin from banana, H84T BanLec, attached to a chimeric antigen receptor (H84T-CAR) that recognizes high-mannose (asparagine residue with five to nine mannoses). Here, we tested the efficacy of our novel H84T CAR in models of pancreatic ductal adenocarcinoma (PDAC), intractable tumors with aberrant glycosylation and characterized by desmoplastic stroma largely contributed by pancreatic stellate cells (PSCs).

METHODS

We transduced human T cells with a second-generation retroviral construct expressing the H84T BanLec chimeric receptor, measured T-cell expansion, characterized T-cell phenotype, and tested their efficacy against PDAC tumor cells lines by flow cytometry quantification. In three-dimensional (3D) spheroid models, we measured H84T CAR T-cell disruption of PSC architecture, and T-cell infiltration by live imaging. We tested the activity of H84T CAR T cells against tumor xenografts derived from three PDAC cell lines. Antitumor activity was quantified by caliper measurement and bioluminescence signal and used anti-human vimentin to measure residual PSCs.

RESULTS

H84T BanLec CAR was successfully transduced and expressed by T cells which had robust expansion and retained central memory phenotype in both CD4 and CD8 compartments. H84T CAR T cells targeted and eliminated PDAC tumor cell lines. They also disrupted PSC architecture in 3D models in vitro and reduced total tumor and stroma cells in mixed co-cultures. H84T CAR T cells exhibited improved T-cell infiltration in multicellular spheroids and had potent antitumor effects in the xenograft models. We observed no adverse effects against normal tissues.

CONCLUSIONS

T cells expressing H84T CAR target malignant cells and their stroma in PDAC tumor models. The incorporation of glycan-targeting lectins within CARs thus extends their activity to include both malignant cells and their supporting stromal cells, disrupting the TME that otherwise diminishes the activity of cellular therapies against solid tumors.

Chimeric antigen receptor T cells applied to solid tumors

Chimeric antigen receptor T cell (CAR-T) therapy is novel tumor immunotherapy that enables autologous T to express synthetic receptors to specifically recognize the surface tumor-associated antigens for exerting subsequent antitumor effects, and eliminating the resistance, metastases and recurrence of cancer. Although CAR T cells have exhibited success in eradicating hematologic malignancies, their applications to solid tumors has not yet been achieved due to obstacles such as the immune-suppressor tumor microenvironment and lack of tumor specific target antigens. In this review, we presented advancements in the development of CAR T cell therapy in solid tumors, and offered a brief summary of the challenges, as well as novel engineering and pharmaceutical interventions to overcome these barriers. Looking forward, we discussed the latest studies which are expected to reach the clinicals in the next few years, including CRISPR screens-based CAR modification and CAR T cells driven from progenitor-like T cells. Collectively, this review may inspire researchers and clinicians to develop clinical available strategies of CAR T cell therapies in solid tumor.

Mining the Immunopeptidome for Antigenic Peptides in Cancer

Simple Summary

The immunopeptidome of cancer cells is a treasure trove of neoantigens bound to MHC molecules, thus a great source for mining immunopeptides for immunotherapy applications, including cancer vaccines. Immunopeptides may encompass post-translational modifications that are overlooked by genomic and transcriptomic tools. We review post-translational modifications that have been uncovered, and how this information could be harnessed for cancer vaccines.

Abstract

Although harnessing the immune system for cancer therapy has shown success, response to immunotherapy has been limited. The immunopeptidome of cancer cells presents an opportunity to discover novel antigens for immunotherapy applications. These neoantigens bind to MHC class I and class II molecules. Remarkably, the immunopeptidome encompasses protein post-translation modifications (PTMs) that may not be evident from genome or transcriptome profiling. A case in point is citrullination, which has been demonstrated to induce a strong immune response. In this review, we cover how the immunopeptidome, with a special focus on PTMs, can be utilized to identify cancer-specific antigens for immunotherapeutic applications.

CAR T cells redirected against tumor-specific antigen glycoforms: can low-sugar antigens guarantee a sweet success?

Immune-based therapies have experienced a pronounced breakthrough in the past decades as they acquired multiple US Food and Drug Administration (FDA) approvals for various indications. To date, six chimeric antigen receptor T cell (CAR-T) therapies have been permitted for the treatment of certain patients with relapsed/refractory hematologic malignancies. However, several clinical trials of solid tumor CAR-T therapies were prematurely terminated, or they reported life-threatening treatment-related damages to healthy tissues. The simultaneous expression of target antigens by healthy organs and tumor cells is partly responsible for such toxicities. Alongside targeting tumor-specific antigens, targeting the aberrantly glycosylated glycoforms of tumor-associated antigens can also minimize the off-tumor effects of CAR-T therapies. Tn, T, and sialyl-Tn antigens have been reported to be involved in tumor progression and metastasis, and their expression results from the dysregulation of a series of glycosyltransferases and the endoplasmic reticulum protein chaperone, Cosmc. Moreover, these glycoforms have been associated with various types of cancers, including prostate, breast, colon, gastric, and lung cancers. Here, we discuss how underglycosylated antigens emerge and then detail the latest advances in the development of CAR-T-based immunotherapies that target some of such antigens.

Novel antigens of CAR T cell therapy: New roads; old destination

Chimeric antigen receptor T cell (CAR-T) therapy has so far proved itself as a reliable therapeutic option for the treatment of relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL), diffuse large B-cell lymphoma (DLBCL), multiple myeloma (MM), and mantle cell lymphoma (MCL). However, this picture is not as colorful when it comes to the treatment of solid tumors mainly due to the lack of definitive tumor antigens, as well as the immunosuppressive tumor microenvironments and poor CAR-T infiltration. The recent developments in bioinformatics and cell biology, such as single-cell RNA sequencing, have offered silver linings in the subject of tumor antigen discovery. In the current review, we summarize the development of some CAR-T therapies that target novel tumor antigens, rather than the traditionally CAR-T-targeted ones, and briefly discuss the clinical antitumor achievements of those evaluated in patients, so far. Furthermore, we propose some tumor antigens that might someday be therapeutically beneficial while targeted by CAR-Ts based on the experimental evaluations of their specific monoclonal antibodies.

Recent advances and discoveries in the mechanisms and functions of CAR T cells

This Review discusses the major advances and changes made over the past 3 years to our understanding of chimeric antigen receptor (CAR) T cell efficacy and safety. Recently, the field has gained insight into how various molecular modules of the CAR influence signalling and function. We report on mechanisms of toxicity and resistance as well as novel engineering and pharmaceutical interventions to overcome these challenges. Looking forward, we discuss new targets and indications for CAR T cell therapy expected to reach the clinic in the next 1-2 years. We also consider some new studies that have implications for the future of CAR T cell therapies, including changes to manufacturing, allogeneic products and drug-regulatable CAR T cells.

Use of Cell and Genome Modification Technologies to Generate Improved "Off-the-Shelf" CAR T and CAR NK Cells

The broad success of adoptive immunotherapy to treat human cancer has resulted in a paradigm shift in modern medicine. Modification of autologous and allogenic immune cells with chimeric antigen receptors (CAR) designed to target specific antigens on tumor cells has led to production of CAR T and CAR NK cell therapies, which are ever more commonly introduced into cancer patient treatment protocols. While allogenic T cells may offer advantages such as improved anti-tumor activity, they also carry the risk of adverse reactions like graft-versus-host disease. This risk can be mitigated by use of autologous immune cells, however, the time needed for T and/or NK cell isolation, modification and expansion may be too long for some patients. Thus, there is an urgent need for strategies to robustly produce “off-the-shelf” CAR T and CAR NK cells, which could be used as a bridging therapy between cancer diagnosis or relapse and allogeneic transplantation. Advances in genome modification technologies have accelerated the generation of designer cell therapy products, including development of “off-the-shelf” CAR T cells for cancer immunotherapy. The feasibility and safety of such approaches is currently tested in clinical trials. This review will describe cell sources for CAR-based therapies, provide background of current genome editing techniques and the applicability of these approaches for generation of universal “off-the-shelf” CAR T and NK cell therapeutics.