The Third Generation Anti-HER2 Chimeric Antigen Receptor Mouse T Cells Alone or Together With Anti-PD1 Antibody Inhibits the Growth of Mouse Breast Tumor Cells Expressing HER2 in vitro and in Immune Competent Mice

Flt3 ligand augments immune responses to soluble PD1-based DNA vaccine via expansion of type 1 conventional DCs

DNA vaccines are prospective for their efficient manufacturing process, but their immunogenicity is limited as they cannot efficiently induce CD8+ T cell responses. A promising approach is to induce cross-presentation by targeting antigens to DCs. Flt3L can expand the number of type 1 conventional DCs and thereby improve cross-presentation. In this study, we first constructed a DNA vaccine expressing soluble PD1 and found that the therapeutic effect of targeting DCs with only the sPD1 vaccine was limited. When combined the vaccine with Flt3L, the anti-tumor effect was significantly enhanced. Considering the complexity of tumors and that a single method may not be able to activate a large number of effective CD8+ T cells, we combined different drugs and the vaccine with Flt3L based on the characteristics of different tumors. In 4T1 model, we reduced Tregs through cyclophosphamide. In Panc02 model, we increased activated DCs by using aCD40. Both strategies triggered strong CD8+ T cell responses and significantly improved the therapeutic effect. Our study provides important support for the clinical exploration of DC-targeted DNA vaccines in combination with Flt3L.

Dual blockade of IL-10 and PD-1 leads to control of SIV viral rebound following analytical treatment interruption

Human immunodeficiency virus (HIV) persistence during antiretroviral therapy (ART) is associated with heightened plasma interleukin-10 (IL-10) levels and PD-1 expression. We hypothesized that IL-10 and PD-1 blockade would lead to control of viral rebound following analytical treatment interruption (ATI). Twenty-eight ART-treated, simian immunodeficiency virus (SIV)mac239-infected rhesus macaques (RMs) were treated with anti-IL-10, anti-IL-10 plus anti-PD-1 (combo) or vehicle. ART was interrupted 12 weeks after introduction of immunotherapy. Durable control of viral rebound was observed in nine out of ten combo-treated RMs for >24 weeks post-ATI. Induction of inflammatory cytokines, proliferation of effector CD8+ T cells in lymph nodes and reduced expression of BCL-2 in CD4+ T cells pre-ATI predicted control of viral rebound. Twenty-four weeks post-ATI, lower viral load was associated with higher frequencies of memory T cells expressing TCF-1 and of SIV-specific CD4+ and CD8+ T cells in blood and lymph nodes of combo-treated RMs. These results map a path to achieve long-lasting control of HIV and/or SIV following discontinuation of ART.

CAR-T and CAR-NK as cellular cancer immunotherapy for solid tumors

In the past decade, chimeric antigen receptor (CAR)-T cell therapy has emerged as a promising immunotherapeutic approach for combating cancers, demonstrating remarkable efficacy in relapsed/refractory hematological malignancies in both pediatric and adult patients. CAR-natural killer (CAR-NK) cell complements CAR-T cell therapy by offering several distinct advantages. CAR-NK cells do not require HLA compatibility and exhibit low safety concerns. Moreover, CAR-NK cells are conducive to "off-the-shelf" therapeutics, providing significant logistic advantages over CAR-T cells. Both CAR-T and CAR-NK cells have shown consistent and promising results in hematological malignancies. However, their efficacy against solid tumors remains limited due to various obstacles including limited tumor trafficking and infiltration, as well as an immuno-suppressive tumor microenvironment. In this review, we discuss the recent advances and current challenges of CAR-T and CAR-NK cell immunotherapies, with a specific focus on the obstacles to their application in solid tumors. We also analyze in depth the advantages and drawbacks of CAR-NK cells compared to CAR-T cells and highlight CAR-NK CAR optimization. Finally, we explore future perspectives of these adoptive immunotherapies, highlighting the increasing contribution of cutting-edge biotechnological tools in shaping the next generation of cellular immunotherapy.

Syngeneic Mouse Models for Pre-Clinical Evaluation of CAR T Cells

Chimeric antigen receptor (CAR) T cells have revolutionized the treatment of hematological malignancies. Unfortunately, this improvement has yet to be translated into the solid tumor field. Current immunodeficient models used in pre-clinical testing often overestimate the efficacy of CAR T cell therapy as they fail to recapitulate the immunosuppressive tumor microenvironment characteristic of solid tumors. As CAR T cell monotherapy is unlikely to be curative for many solid tumors, combination therapies must be investigated, for example, stromal remodeling agents and immunomodulators. The evaluation of these combination therapies requires a fully immunocompetent mouse model in order to recapitulate the interaction between the host's immune system and the CAR T cells. This review will discuss the need for improved immunocompetent murine models for the pre-clinical evaluation of CAR T cells, the current use of such models and future directions.

Acidity-targeting transition-aided universal chimeric antigen receptor T-cell (ATT-CAR-T) therapy for the treatment of solid tumors

The use of CAR-T cells in treating solid tumors frequently faces significant challenges, mainly due to the heterogeneity of tumor antigens. This study assessed the efficacy of an acidity-targeting transition-aided universal chimeric antigen receptor T (ATT-CAR-T) cell strategy, which is facilitated by an acidity-targeted transition. Specifically, the EGFRvIII peptide was attached to the N-terminus of a pH-low insertion peptide. Triggered by the acidic conditions of the tumor microenvironment, this peptide alters its structure and selectively integrates into the membrane of solid tumor cells. The acidity-targeted transition component effectively relocated the EGFRvIII peptide across various tumor cell membranes; thus, allowing the direct destruction of these cells by EGFRvIII-specific CAR-T cells. This method was efficient even when endogenous antigens were absent. In vivo tests showed marked antigen modification within the acidic tumor microenvironment using this component. Integrating this component with CAR-T cell therapy showed high effectiveness in combating solid tumors. These results highlight the capability of ATT-CAR-T cell therapy to address the challenges presented by tumor heterogeneity and expand the utility of CAR-T cell therapy in the treatment of solid tumors.

CAR-T cell technologies that interact with the tumour microenvironment in solid tumours

INTRODUCTION

Chimeric antigen receptor (CAR) T-cells have emerged as a ground-breaking therapy for the treatment of hematological malignancies due to their capacity for rapid tumor-specific killing and long-lasting tumor immunity. However, the same success has not been observed in patients with solid tumors. Largely, this is due to the additional challenges imposed by safe and uniform target selection, inefficient CAR T-cell access to sites of disease and the presence of a hostile immunosuppressive tumor microenvironment.

AREAS COVERED

Literature was reviewed on the PubMed database from the first description of a CAR by Kuwana, Kurosawa and colleagues in December 1987 through to the present day. This literature indicates that in order to tackle solid tumors, CAR T-cells can be further engineered with additional armoring strategies that facilitate trafficking to and infiltration of malignant lesions together with reversal of suppressive immune checkpoints that operate within solid tumor lesions.

EXPERT OPINION

In this review, we describe a number of recent advances in CAR T-cell technology that set out to combat the problems imposed by solid tumors including tumor recruitment, infiltration, immunosuppression, metabolic compromise, and hypoxia.

Discovery of differentially expressed proteins for CAR-T therapy of ovarian cancers with a bioinformatics analysis

Target antigens are crucial for developing chimeric antigen receptor (CAR)-T cells, but their application to ovarian cancers is limited. This study aimed to identify potential genes as CAR-T-cell antigen candidates for ovarian cancers. A differential gene expression analysis was performed on ovarian cancer samples from four datasets obtained from the GEO datasets. Functional annotation, pathway analysis, protein localization, and gene expression analysis were conducted using various datasets and tools. An oncogenicity analysis and network analysis were also performed. In total, 153 differentially expressed genes were identified in ovarian cancer samples, with 60 differentially expressed genes expressing plasma membrane proteins suitable for CAR-T-cell antigens. Among them, 21 plasma membrane proteins were predicted to be oncogenes in ovarian cancers, with nine proteins playing crucial roles in the network. Key genes identified in the oncogenic pathways of ovarian cancers included MUC1, CXCR4, EPCAM, RACGAP1, UBE2C, PRAME, SORT1, JUP, and CLDN3, suggesting them as recommended antigens for CAR-T-cell therapy for ovarian cancers. This study sheds light on potential targets for immunotherapy in ovarian cancers.

HER2 targeted therapy in colorectal Cancer: Current landscape and future directions

Colorectal cancer (CRC) is one of the most common causes of tumor-related deaths globally. Despite recent improvements in the comprehensive therapy of malignancy, metastatic CRC continues to have a poor prognosis. Human epidermal growth factor receptor 2 (HER2) is an established oncogenic driver, which is successfully targeted for breast and gastric cancers. Approximately 5% of CRC patients carry somatic HER2 mutations or gene amplification. In 2019, the U.S. Food and Drug Administration have approved trastuzumab and pertuzumab in combination with chemotherapy for the treatment of HER2-positive metastatic CRC. This approval marked a significant milestone in the treatment of CRC, as HER2-positive patients now have access to targeted therapies that can improve their outcomes. Yet, assessment for HER2 overexpression/ amplification in CRC has not been standardized. The resistance mechanisms to anti-HER2 therapy have been not clearly investigated in CRC. Although many unknowns remain, an improved understanding of these anti-HER2 agents will be essential for advanced CRC. In this review, we provide an overview of the role of HER2 in CRC as an oncogenic driver, a prognostic and predictive biomarker, and a clinically actionable target, as well as the current progress and challenges in the field.

Current challenges and therapeutic advances of CAR-T cell therapy for solid tumors

The application of chimeric antigen receptor (CAR) T cells in the management of hematological malignancies has emerged as a noteworthy therapeutic breakthrough. Nevertheless, the utilization and effectiveness of CAR-T cell therapy in solid tumors are still limited primarily because of the absence of tumor-specific target antigen, the existence of immunosuppressive tumor microenvironment, restricted T cell invasion and proliferation, and the occurrence of severe toxicity. This review explored the history of CAR-T and its latest advancements in the management of solid tumors. According to recent studies, optimizing the design of CAR-T cells, implementing logic-gated CAR-T cells and refining the delivery methods of therapeutic agents can all enhance the efficacy of CAR-T cell therapy. Furthermore, combination therapy shows promise as a way to improve the effectiveness of CAR-T cell therapy. At present, numerous clinical trials involving CAR-T cells for solid tumors are actively in progress. In conclusion, CAR-T cell therapy has both potential and challenges when it comes to treating solid tumors. As CAR-T cell therapy continues to evolve, further innovations will be devised to surmount the challenges associated with this treatment modality, ultimately leading to enhanced therapeutic response for patients suffered solid tumors.

CAR-based immunotherapy for breast cancer: peculiarities, ongoing investigations, and future strategies

Surgery, chemotherapy, and endocrine therapy have improved the overall survival and postoperative recurrence rates of Luminal A, Luminal B, and HER2-positive breast cancers but treatment modalities for triple-negative breast cancer (TNBC) with poor prognosis remain limited. The effective application of the rapidly developing chimeric antigen receptor (CAR)-T cell therapy in hematological tumors provides new ideas for the treatment of breast cancer. Choosing suitable and specific targets is crucial for applying CAR-T therapy for breast cancer treatment. In this paper, we summarize CAR-T therapy's effective targets and potential targets in different subtypes based on the existing research progress, especially for TNBC. CAR-based immunotherapy has resulted in advancements in the treatment of breast cancer. CAR-macrophages, CAR-NK cells, and CAR-mesenchymal stem cells (MSCs) may be more effective and safer for treating solid tumors, such as breast cancer. However, the tumor microenvironment (TME) of breast tumors and the side effects of CAR-T therapy pose challenges to CAR-based immunotherapy. CAR-T cells and CAR-NK cells-derived exosomes are advantageous in tumor therapy. Exosomes carrying CAR for breast cancer immunotherapy are of immense research value and may provide a treatment modality with good treatment effects. In this review, we provide an overview of the development and challenges of CAR-based immunotherapy in treating different subtypes of breast cancer and discuss the progress of CAR-expressing exosomes for breast cancer treatment. We elaborate on the development of CAR-T cells in TNBC therapy and the prospects of using CAR-macrophages, CAR-NK cells, and CAR-MSCs for treating breast cancer.

Mucin-1-Targeted Chimeric Antigen Receptor T Cells Are Effective and Safe in Controlling Solid Tumors in Immunocompetent Host

The chimeric antigen receptor (CAR) T-cell therapy in solid epithelial tumors has been explored, however, with limited success. As much of the preclinical work has relied on xenograft models in immunocompromised animals, the immune-related efficacies and toxicities may have been missed. In this study, we engineered syngeneic murine CAR T cells targeting the tumor form of human mucin-1 (tMUC1) and tested the MUC1 CAR T cells' efficacy and toxicity in the immunocompetent human MUC1-expressing mouse models. The MUC1 CAR T cells significantly eliminated murine pancreatic and breast cancer cell lines in vitro. In vivo, MUC1 CAR T cells significantly slowed the mammary gland tumor progression in the spontaneous PyVMT×MUC1.Tg (MMT) mice, prevented lung metastasis, and prolonged survival. Most importantly, there was minimal short or long-term toxicity with acceptable levels of transient liver toxicity but no kidney toxicity. In addition, the mice did not show any signs of weight loss or other behavioral changes with the treatment. We also report that a single dose of MUC1 CAR T-cell treatment modestly reduced the pancreatic tumor burden in a syngeneic orthotopic model of pancreatic ductal adenocarcinoma given at late stage of an established tumor. Taken together, these findings suggested the further development of tMUC1-targeted CAR T cells as an effective and relatively safe treatment modality for various tMUC1-expressing solid tumors.

Clinical Impact of New Treatment Strategies for HER2-Positive Metastatic Breast Cancer Patients with Resistance to Classical Anti-HER Therapies

HER2-positive breast cancer accounts for 15-20% of all breast cancer cases. This subtype is characterized by an aggressive behavior and poor prognosis. Anti-HER2 therapies have considerably improved the natural course of the disease. Despite this, relapse still occurs in around 20% of patients due to primary or acquired treatment resistance, and metastasis remains an incurable disease. This article reviews the main mechanisms underlying resistance to anti-HER2 treatments, focusing on newer HER2-targeted therapies. The progress in anti-HER2 drugs includes the development of novel antibody-drug conjugates with improvements in the conjugation process and novel linkers and payloads. Moreover, trastuzumab deruxtecan has enhanced the efficacy of trastuzumab emtansine, and the new drug trastuzumab duocarmazine is currently undergoing clinical trials to assess its effect. The combination of anti-HER2 agents with other drugs is also being evaluated. The addition of immunotherapy checkpoint inhibitors shows some benefit in a subset of patients, indicating the need for useful biomarkers to properly stratify patients. Besides, CDK4/6 and tyrosine kinase inhibitors are also included in the design of new treatment strategies. Lapitinib, neratinib and tucatinib have been approved for HER2-positive metastasis patients, however clinical trials are currently ongoing to optimize combined strategies, to reduce toxicity, and to better define the useful setting. Clinical research should be strengthened along with the discovery and validation of new biomarkers, as well as a deeper understanding of drug resistance and action mechanisms.

Metastatic HER2-Positive Breast Cancer: Is There an Optimal Sequence of Therapy?

OPINION STATEMENT

Approximately 20% of breast cancers overexpress human epidermal growth factor receptor 2 (HER2+), conferring a particularly aggressive subtype of the disease with an increased risk for the development of systemic and brain metastases. However, the advent of trastuzumab and more recently several other HER2-targeting novel therapies has led to significant improvements in the prognosis, making the diagnosis a "double-edged sword." The current standard first-line therapy for patients with HER2+ metastatic breast cancer (MBC) is a taxane combined with trastuzumab and pertuzumab. Trastuzumab deruxtecan should be used preferentially in the second line, with the only caveat being patients with CNS involvement where the tucatinib, capecitabine, and trastuzumab regimen could be considered. In the third line setting, given the survival benefits demonstrated with the tucatinib regimen in patients with and without CNS metastases, this is the preferred strategy. In the fourth line and beyond, there is no clear standard. Options include margetuximab in combination with chemotherapy, neratinib + capecitabine, or trastuzumab + chemotherapy. There are several novel therapies under investigation reporting promising results in the late-line setting. The treatment landscape of HER2-positive advanced disease is evolving constantly, with several active therapies being moved to the early-stage setting. Accordingly, it will be critical to identify biomarkers and mechanisms of resistance to optimize therapy selection and maximize patient outcomes and quality of life. Here, we provide an overview of the current and future management of HER2-positive advanced breast cancer and address the specific scenarios which may impact treatment selection including triple-positive breast cancer and the presence of brain metastases. Finally, we highlight promising novel treatments and ongoing trials that may impact future treatment sequencing.

Current progress in chimeric antigen receptor-modified T cells for the treatment of metastatic breast cancer

Breast cancer is the leading cancer in women. Around 20-30% breast cancer patients undergo invasion or metastasis after radical surgical resection and eventually die. Number of breast cancer patients show poor sensitivity toward treatments despite the advances in chemotherapy, endocrine therapy, and molecular targeted treatments. Therapeutic resistance and tumor recurrence or metastasis develop with the ongoing treatments. Conducive treatment strategies are thus required. Chimeric antigen receptor (CAR)-modified T-cell therapy has progressed as a part of tumor immunotherapy. However, CAR-T treatment has not been effective in solid tumors because of tumor microenvironment complexity, inhibitory effects of extracellular matrix, and lacking ideal tumor antigens. Herein, the prospects of CAR-T cell therapy for metastatic breast cancer are discussed, and the targets for CAR-T therapy in breast cancer (HER-2, C-MET, MSLN, CEA, MUC1, ROR1, EGFR) at clinical level are reviewed. Moreover, solutions are proposed for the challenges of breast cancer CAR-T therapy regarding off-target effects, heterogeneous antigen expression by tumor cells and immunosuppressive tumor microenvironment. Ideas for improving the therapeutics of CAR-T cell therapy in metastatic breast cancer are suggested.

Emerging Targeted Therapies for HER2-Positive Breast Cancer

Breast cancer is the most common cancer in women and the leading cause of death. HER2 overexpression is found in approximately 20% of breast cancers and is associated with a poor prognosis and a shorter overall survival. Tratuzumab, a monoclonal antibody directed against the HER2 receptor, is the standard of care treatment. However, a third of the patients do not respond to therapy. Given the high rate of resistance, other HER2-targeted strategies have been developed, including monoclonal antibodies such as pertuzumab and margetuximab, trastuzumab-based antibody drug conjugates such as trastuzumab-emtansine (T-DM1) and trastuzumab-deruxtecan (T-DXd), and tyrosine kinase inhibitors like lapatinib and tucatinib, among others. Moreover, T-DXd has proven to be of use in the HER2-low subtype, which suggests that other HER2-targeted therapies could be successful in this recently defined new breast cancer subclassification. When patients progress to multiple strategies, there are several HER2-targeted therapies available; however, treatment options are limited, and the potential combination with other drugs, immune checkpoint inhibitors, CAR-T cells, CAR-NK, CAR-M, and vaccines is an interesting and appealing field that is still in development. In this review, we will discuss the highlights and pitfalls of the different HER2-targeted therapies and potential combinations to overcome metastatic disease and resistance to therapy.

Current advances and challenges in CAR T-Cell therapy for solid tumors: tumor-associated antigens and the tumor microenvironment

The past decade has witnessed ongoing progress in immune therapy to ameliorate human health. As an emerging technique, chimeric antigen receptor (CAR) T-cell therapy has the advantages of specific killing of cancer cells, a high remission rate of cancer-induced symptoms, rapid tumor eradication, and long-lasting tumor immunity, opening a new window for tumor treatment. However, challenges remain in CAR T-cell therapy for solid tumors due to target diversity, tumor heterogeneity, and the complex microenvironment. In this review, we have outlined the development of the CAR T-cell technique, summarized the current advances in tumor-associated antigens (TAAs), and highlighted the importance of tumor-specific antigens (TSAs) or neoantigens for solid tumors. We also addressed the challenge of the TAA binding domain in CARs to overcome off-tumor toxicity. Moreover, we illustrated the dominant tumor microenvironment (TME)-induced challenges and new strategies based on TME-associated antigens (TMAs) for solid tumor CAR T-cell therapy.

Syngeneic mouse model of human HER2+ metastatic breast cancer for the evaluation of trastuzumab emtansine combined with oncolytic rhabdovirus

Background

Established mouse models of HER2+ cancer are based on the over-expression of rodent Neu/Erbb2 homologues, which are incompatible with human HER2 (huHER2) targeted therapeutics. Additionally, the use of immune-deficient xenograft or transgenic models precludes assessment of native anti-tumour immune responses. These hurdles have been a challenge for our understanding of the immune mechanisms behind huHER2-targeting immunotherapies.

Methods

To assess the immune impacts of our huHER2-targeted combination strategy, we generated a syngeneic mouse model of huHER2+ breast cancer, using a truncated form of huHER2, HER2T. Following validation of this model, we next treated tumour-bearing with our immunotherapy strategy: oncolytic vesicular stomatitis virus (VSVΔ51) with clinically approved antibody-drug conjugate targeting huHER2, trastuzumab emtansine (T-DM1). We assessed efficacy through tumour control, survival, and immune analyses.

Results

The generated truncated HER2T construct was non-immunogenic in wildtype BALB/c mice upon expression in murine mammary carcinoma 4T1.2 cells. Treatment of 4T1.2-HER2T tumours with VSVΔ51+T-DM1 yielded robust curative efficacy compared to controls, and broad immunologic memory. Interrogation of anti-tumour immunity revealed tumour infiltration by CD4+ T cells, and activation of B, NK, and dendritic cell responses, as well as tumour-reactive serum IgG.

Conclusions

The 4T1.2-HER2T model was used to evaluate the anti-tumour immune responses following our complex pharmacoviral treatment strategy. These data demonstrate utility of the syngeneic HER2T model for assessment of huHER2-targeted therapies in an immune-competent in vivo setting. We further demonstrated that HER2T can be implemented in multiple other syngeneic tumour models, including but not limited to colorectal and ovarian models. These data also suggest that the HER2T platform may be used to assess a range of surface-HER2T targeting approaches, such as CAR-T, T-cell engagers, antibodies, or even retargeted oncolytic viruses.

Nanobody-based CAR-T cells for cancer immunotherapy

Chimeric antigen receptor T-cell (CAR-T) therapy is the result of combining genetic engineering-based cancer immunotherapy with adoptive cell therapy (ACT). CAR-T therapy has been successful in treating various types of hematological cancers. CARs are receptors made of an extracellular domain, a membrane-spanning domain, and an intracellular domain. The extracellular domain of CARs harbors an antigen-targeting domain responsible for recognizing and binding cell surface-expressed target antigens. Conventionally, the single-chain fragment variable (scFv) of a monoclonal antibody (mAb) is used as the antigen-targeting domain of CARs. However, of late, researchers have exploited nanobodies for this aim based on numerous rationales including the small size of nanobodies, their stability, specificity, and high affinity, and their easy and feasible development process. Many findings have confirmed that nanobody-based CAR-Ts can be as functional as scFv-based CAR-Ts in preclinical and clinical settings. In this review, we discuss the advantages and disadvantages of scFvs and nanobodies in regards to their application as the targeting domain of CARs. Ultimately, we discuss various CAR target antigens which have been targeted using nanobody-based CAR-T cells for the treatment of different types of malignancies.

Updates in combined approaches of radiotherapy and immune checkpoint inhibitors for the treatment of breast cancer

Breast cancer is the most prevalent non-skin cancer diagnosed in females and developing novel therapeutic strategies to improve patient outcomes is crucial. The immune system plays an integral role in the body’s response to breast cancer and modulating this immune response through immunotherapy is a promising therapeutic option. Although immune checkpoint inhibitors were recently approved for the treatment of breast cancer patients, not all patients respond to immune checkpoint inhibitors as a monotherapy, highlighting the need to better understand the biology underlying patient response. Additionally, as radiotherapy is a critical component of breast cancer treatment, understanding the interplay of radiation and immune checkpoint inhibitors will be vital as recent studies suggest that combined therapies may induce synergistic effects in preclinical models of breast cancer. This review will discuss the mechanisms supporting combined approaches with radiotherapy and immune checkpoint inhibitors for the treatment of breast cancer. Moreover, this review will analyze the current clinical trials examining combined approaches of radiotherapy, immunotherapy, chemotherapy, and targeted therapy. Finally, this review will evaluate data regarding treatment tolerance and potential biomarkers for these emerging therapies aimed at improving breast cancer outcomes.

Co-expression IL-15 receptor alpha with IL-15 reduces toxicity via limiting IL-15 systemic exposure during CAR-T immunotherapy

Background

Chimeric antigen receptor (CAR)-T cell therapy is a powerful adoptive immunotherapy against both B-cell malignancies and some types of solid tumors. Interleukin (IL) -15 is an important immune stimulator that may provide ideal long-term persistent CAR-T cells. However, higher base line or peak serum IL-15 levels are also related to severe toxicity, such as cytokine release syndrome (CRS), graft-versus-host disease (GVHD), and neurotoxicity.

Methods

We successfully constructed CD19 specific armored CAR-T cells overexpressing IL-I5 and IL-15 receptor alpha (IL-15Ra). In vitro cell differentiation and viability were monitored by flow cytometry, and an in vivo xenograft mouse models was used to evaluate the anti-tumor efficiency and liver damage of CAR-T cells.

Results

CAR-T cells overexpressing IL-15 alone demonstrated enhanced viability, retarded exhaustion in vitro and superior tumor-inhibitory effects in vivo. However, these tumor-free mice had lower survival rates, with serious liver injuries, as a possible result of toxicity. As expected, CAR-T cells overexpressing IL-15 combined with IL-15Ra had reduced CD132 expression and released fewer cytokines (IFNγ, IL-2 and IL-15) in vitro, as well as had the tendency to improve mouse survival via repressing the growth of tumor cells and keeping livers healthier compared to CAR-IL-15 T cells.

Conclusions

These results indicated the importance of IL-15 in enhancing T cells persistence and IL-15Ra in reducing the adverse effects of IL-15, with superior tumor retardation during CAR-T therapy. This study paves the way for the rapid exploitation of IL-15 in adoptive cell therapy in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03626-x.

Immunotherapy and immunoengineering for breast cancer; a comprehensive insight into CAR-T cell therapy advancements, challenges and prospects

BACKGROUND

Breast cancer (BC) is a highly prevalent solid cancer with a high-rise infiltration of immune cells, turning it into a significant candidate for tumor-specific immunotherapies. Chimeric antigen receptor (CAR)-T cells are emerging as immunotherapeutic tools with genetically engineered receptors to efficiently recognize and attack tumor cells that express specific target antigens. Technological advancements in CAR design have provided five generations of CAR-T cells applicable to a wide range of cancer patients while boosting CAR-T cell therapy safety. However, CAR-T cell therapy is ineffective against breast cancer because of the loss of specified antigens, the immunosuppressive nature of the tumor and CAR-T cell-induced toxicities. Next-generation CAR-T cells actively pass through the tumor vascular barriers, persist for extended periods and disrupt the tumor microenvironment (TME) to block immune escape.

CONCLUSION

CAR-T cell therapy embodies advanced immunotherapy for BC, but further pre-clinical and clinical assessments are recommended to achieve maximized efficiency and safety.

IFI16-dependent STING signaling is a crucial regulator of anti-HER2 immune response in HER2+ breast cancer

Relapse to anti-HER2 monoclonal antibody (mAb) therapies, such as trastuzumab in HER2⁺ breast cancer (BC), is associated with residual disease progression due to resistance to therapy. Here, we identify interferon-γ inducible protein 16 (IFI16)-dependent STING signaling as a significant determinant of trastuzumab responses in HER2⁺ BC. We show that down-regulation of immune-regulated genes (IRG) is specifically associated with poor survival of HER2⁺, but not other BC subtypes. Among IRG, IFI16 is identified as a direct target of EZH2, the underexpression of which leads to deficient STING activation and downstream CXCL10/11 expression in response to trastuzumab treatment. Dual inhibition of EZH2 and histone deacetylase (HDAC) significantly activates IFI16-dependent immune responses to trastuzumab. Notably, a combination of a novel histone methylation inhibitor with an HDAC inhibitor induces complete tumor eradication and long-term T cell memory in a HER2⁺ BC mouse model. Our findings demonstrate an epigenetic regulatory mechanism suppressing the expression of the IFI16-CXCL10/11 signaling pathway that provides a survival advantage to HER2⁺ BC to confer resistance to trastuzumab treatment.

The landscape of chimeric antigen receptor T cell therapy in breast cancer: Perspectives and outlook

Chimeric antigen receptor-T (CAR-T) cell therapy is a revolutionary adoptive cell therapy, which could modify and redirect T cells to specific tumor cells. Since CAR-T cell therapy was first approved for B cell-derived malignancies in 2017, it has yielded unprecedented progress in hematological tumors and has dramatically reshaped the landscape of cancer therapy in recent years. Currently, cumulative evidence has demonstrated that CAR-T cell therapy could be a viable therapeutic strategy for solid cancers. However, owing to the immunosuppressive tumor microenvironment (TME) and heterogenous tumor antigens, the application of CAR-T cell therapy against solid cancers requires circumventing more challenging obstacles. Breast cancer is characterized by a high degree of invasiveness, malignancy, and poor prognosis. The review highlights the underlying targets of CAR-T cell therapy in breast cancer, summarizes the challenges associated with CAR-T cell therapy, and proposes the strategies to overcome these challenges, which provides a novel approach to breast cancer treatment.

HER2 in Colorectal Cancer: The Long and Winding Road From Negative Predictive Factor to Positive Actionable Target

Human epidermal growth factor receptor 2 (HER2) is a well-known oncogenic driver in different tumors and an approved therapeutic target in breast and gastroesophageal cancer. In metastatic colorectal cancer, only 3% to 5% of patients present with HER2 alterations: somatic mutations and amplifications. HER2 was first assessed as a biomarker of resistance to anti-EGFR therapy; however, in more recent years, its role as a potential actionable target has emerged. In this article, we discuss the predictive and prognostic value of HER2 in metastatic colorectal cancer, its emerging role as an actionable therapeutic target, and its possible future developments.

Nanobody-based CAR-T cells for cancer immunotherapy

Chimeric antigen receptor T-cell (CAR-T) therapy is the result of combining genetic engineering-based cancer immunotherapy with adoptive cell therapy (ACT). CAR-T therapy has been successful in treating various types of hematological cancers. CARs are receptors made of an extracellular domain, a membrane-spanning domain, and an intracellular domain. The extracellular domain of CARs harbors an antigen-targeting domain responsible for recognizing and binding cell surface-expressed target antigens. Conventionally, the single-chain fragment variable (scFv) of a monoclonal antibody (mAb) is used as the antigen-targeting domain of CARs. However, of late, researchers have exploited nanobodies for this aim based on numerous rationales including the small size of nanobodies, their stability, specificity, and high affinity, and their easy and feasible development process. Many findings have confirmed that nanobody-based CAR-Ts can be as functional as scFv-based CAR-Ts in preclinical and clinical settings. In this review, we discuss the advantages and disadvantages of scFvs and nanobodies in regards to their application as the targeting domain of CARs. Ultimately, we discuss various CAR target antigens which have been targeted using nanobody-based CAR-T cells for the treatment of different types of malignancies.

c-Met specific CAR-T cells as a targeted therapy for non-small cell lung cancer cell A549

Non-small cell lung cancer (NSCLC) is considered to be one of the most prevalent and fatal malignancies, with a poor survival rate. Chimeric antigen receptor T cell (CAR-T) cell therapy is one of the most exciting directions in the field of Cellular immunotherapy. Therefore, CAR-T cells that target c-Met have been developed for use in NSCLC therapy and might be a potential therapeutic strategy. The anti c-Met ScFv structure was fused with the transmembrane and intracellular domains. Using a lentiviral vector to load the c-Met CAR gene, then transfected the c-Met CAR lentiviral into human T cells to obtain the second generation c-Met CAR-T expressing CARs stably. In vitro co-culture, experiments revealed that CAR-T cells have high proliferative activity and the potential to secrete cytokines (IL-2, TNF-α, and IFN-γ). c-Met CAR-T cells showed special cellular cytotoxicity in LDH release assay. A subcutaneous tumor model in nude mice was used to test the anticancer effectiveness of c-Met CAR-T cells in vivo. For c-Met positive NSCLC tissue, according to tumor volume, weight, fluorescence intensity, and immunohistochemical detection, c-Met CAR-T cells had stronger tumor growth suppression compared to untransduced T cells. HE staining revealed that c-Met CAR-T cells did not produced side effects in nude mice. Taken together, we provided useful method to generate c-Met CAR- T cells, which exhibit enhanced cytotoxicity against NSCLC cells in vitro and in vivo. Thus, providing a new therapeutic avenue for treating NSCLC clinically.

Highlights

(1) c-Met CAR-T capable of stably expressing c-Met CARs were constructed.

(2) c-Met CAR-T have strong anti-tumor ability and proliferation ability in vitro.

(3) c-Met CAR-T can effectively inhibit the growth of A549 cells subcutaneous xenografts.

Emerging Novel Combined CAR-T Cell Therapies

Simple Summary

As a result of FDA approval of CAR-T cell treatments in the last few years, this immunotherapy has provided further direction to precision medicine through its combination with other therapeutic approaches. In the past year, several review articles have been published focusing on advances in this fast-developing field, especially with respect to efforts to overcome hurdles associated with applying CAR-T cells in solid tumors. This review paper focuses on combining CAR-T cell therapy with small molecule drugs, up-to-date progress in CAR-T cell therapy research, and advances in combined CAR-T immunotherapy with other treatments targeting solid tumors.

Abstract

Chimeric antigen receptors (CAR) T cells are T cells engineered to express membrane receptors with high specificity to recognize specific target antigens presented by cancer cells and are co-stimulated with intracellular signals to increase the T cell response. CAR-T cell therapy is emerging as a novel therapeutic approach to improve T cell specificity that will lead to advances in precision medicine. CAR-T cells have had impressive outcomes in hematological malignancies. However, there continue to be significant limitations of these therapeutic responses in targeting solid malignancies such as heterogeneous antigens in solid tumors, tumor immunosuppressive microenvironment, risk of on-target/off-tumor, infiltrating CAR-T cells, immunosuppressive checkpoint molecules, and cytokines. This review paper summarizes recent approaches and innovations through combination therapies of CAR-T cells and other immunotherapy or small molecule drugs to counter the above disadvantages to potentiate the activity of CAR-T cells.

Anti-HER2 therapy in metastatic breast cancer: many choices and future directions

Metastatic HER2 + breast cancer is an expanding area of drug development and research, with three new drugs approved in 2020 alone. While first-line therapy is well-established for metastatic HER2 + breast cancer, the standard of care for second-line therapy will likely be changing soon based on the results of the DESTINY-Breast03 trial. In the third-line setting, many options are available. Considerations in choosing between regimens in the third-line include resistance to trastuzumab, the presence of brain metastases, and tolerability. High rates of resistance exist in this setting particularly due to expression of p95, a truncated form of HER2 that constitutively activates downstream signaling pathways. We suggest a tyrosine kinase inhibitor (TKI)-based regimen because of the activity of TKIs in brain metastases and in p95-expressing tumors. Attempts to overcome resistance to anti-HER2 therapies with PI3K inhibitors, mTOR inhibitors, and CDK 4/6 inhibitors are an active area of research. In the future, biomarkers are needed to help predict which therapies patients may benefit from the most. We review the many new drugs in development, including those with novel mechanisms of action.

Human epidermal growth factor receptor 2 (HER2)-specific chimeric antigen receptor (CAR) for tumor immunotherapy; recent progress

Due to the overexpression or amplification of human epidermal growth factor receptor 2 (HER2) with poor prognosis in a myriad of human tumors, recent studies have focused on HER2-targeted therapies. Deregulation in HER2 signaling pathways is accompanied by sustained tumor cells growth concomitant with their migration and also tumor angiogenesis and metastasis by stimulation of proliferation of a network of blood vessels. A large number of studies have provided clear evidence that the emerging HER2-directed treatments could be the outcome of patients suffering from HER2 positive breast and also gastric/gastroesophageal cancers. Thanks to its great anti-tumor competence, immunotherapy using HER2-specific chimeric antigen receptor (CAR) expressing immune cell has recently attracted increasing attention. Human T cells and also natural killer (NK) cells can largely be found in the tumor microenvironment, mainly contributing to the tumor immune surveillance. Such properties make them perfect candidate for genetically modification to express constructed CARs. Herein, we will describe the potential targets of the HER2 signaling in tumor cells to clarify HER2-mediated tumorigenesis and also discuss recent findings respecting the HER2-specific CAR-expressing immune cells (CAR T and CAR NK cell) for the treatment of HER2-expressing tumors.

Current and future landscape of targeted therapy in HER2-positive advanced breast cancer: redrawing the lines

BACKGROUND

Evidence to date supports continued human epidermal growth factor receptor 2 (HER2) suppression beyond progression on HER2-directed therapy for advanced HER2-positive breast cancer. Data from several phase II and III trials evaluating HER2-directed therapy following second-line T-DM1 have recently become available.

METHODS

We performed a systematic search of the published and presented literature to identify phase II and phase III trials assessing novel HER2-targeted agents as third-line therapy or beyond for HER2-positive advanced breast cancer using search terms 'breast cancer' AND 'HER2' AND 'advanced' AND ('phase II' OR 'phase III').

RESULTS

Eight clinical trials reporting efficacy outcomes on third-line or greater HER2-directed therapy for HER2-positive advanced breast cancer were identified. In phase III trials, margetuximab and neratinib combinations demonstrated significant 1.3-month (hazard ratio, HR = 0.71, p < 0.001) and 0.1-month (HR = 0.76, p = 0.006) net improvements in median progression-free survival (PFS), respectively, with no significant improvements in overall survival (OS). Tucatinib added to trastuzumab and capecitabine demonstrated a significant 2.7-month improvement in median PFS (HR = 0.57, p < 0.00001) and a 5.5-month improvement in median OS (HR = 0.73, p = 0.004) in a randomized phase II trial, including significant clinical benefit for patients with brain metastases. Finally, trastuzumab-deruxtecan, zenocutuzumab, and poziotinib demonstrated benefit in phase II trials with the most robust overall response rate (62.0%) and median duration of response (18.2 months) observed for trastuzumab-deruxtecan among heavily pretreated patients.

CONCLUSION

Tucatinib plus trastuzumab and capecitabine significantly prolongs OS, and promising preliminary response outcomes for trastuzumab-deruxtecan suggest that sequencing of these regimens following second-line therapy is reasonable.

Improving the ability of CAR-T cells to hit solid tumors: Challenges and strategies

Chimeric antigen receptor T cell (CAR-T) therapy is a late-model of immune cell therapy that has been shown to be effective in refractory/recurrent B-cell leukemia and lymphoma. Compared with the traditional anti-tumor methods, CAR-T cell therapy has the advantages of higher specificity, stronger lethality and longer-lasting efficacy. Although CAR-T cells have made significant progress in the treatment of hematologic malignancies, diverse difficulties remain in the treatment of solid tumors, including immune escape due to tumor antigen heterogeneity, preventing entry or limiting the persistence of CAR-T cells by physical or cytokine barriers and along with other immunosuppressive molecule and cells in the tumor microenvironment (TME). Otherwise, the intracellular signaling of CAR also impact on CAR-T cells persistence. Appropriate modification of intracellular costimulatory molecular signal in the structure of CAR or coexpression of CAR and cytokines can provide a way to enhance CAR-T cells activity. Additionally, CAR-T cells dysfunction due to T cell exhaustion is associated with multi-factors, especially transcription factors, such as c-Jun, NR4A. Engineering CAR-T cells to coexpress or knockout transcription factors in favor of T_CM memory CAR-T cells differentiation was proved to prolonged the survival of CAR-T cells. Finally, combination of CAR-T cells with oncolytic viruses, nanoparticles or immune checkpoint inhibitors provides an effective measure to improve CAR-T cells function. Here, we discuss all of these advances and challenges and review promising strategies for treating solid tumors. In particular, we also highlight that CAR-T cells have enormous potential to be used in combination with other immunotherapies.

Clinical and Genetic Predictive Models for the Prediction of Pathological Complete Response to Optimize the Effectiveness for Trastuzumab Based Chemotherapy

Background

Trastuzumab shows excellent benefits for HER2+ breast cancer patients, although 20% treated remain unresponsive. We conducted a retrospective cohort study to optimize neoadjuvant chemotherapy and trastuzumab treatment in HER2+ breast cancer patients.

Methods

Six hundred patients were analyzed to identify clinical characteristics of those not achieving a pathological complete response (pCR) to develop a clinical predictive model. Available RNA sequence data was also reviewed to develop a genetic model for pCR.

Results

The pCR rate was 39.8% and pCR was associated with superior disease free survival and overall survival. ER negativity and PR negativity, higher HER2 IHC scores, higher Ki-67, and trastuzumab use were associated with improved pCR. Weekly paclitaxel and carboplatin had the highest pCR rate (46.70%) and the anthracycline+taxanes regimen had the lowest rate (11.11%). Four published GEO datasets were analyzed and a 10-gene model and immune signature for pCR were developed. Non-pCR patients were ER⁺PR⁺ and had a lower immune signature and gene model score. Hormone receptor status and immune signatures were independent predictive factors of pCR.

Conclusion

Hormone receptor status and a 10-gene model could predict pCR independently and may be applied for patient selection and drug effectiveness optimization.

Chimeric Antigen Receptor T Cells Targeting Integrin αvβ6 Expressed on Cholangiocarcinoma Cells

Cholangiocarcinoma (CCA) is a lethal bile duct cancer that responds poorly to current standard treatments. A new therapeutic approach is, therefore, urgently needed. Adoptive T cell transfer using chimeric antigen receptor (CAR) T cells is a new therapeutic modality with demonstrated efficacy in hematologic malignancies. However, its efficacy against solid tumors is modest, and further intensive investigation continues. An important factor that influences the success of CAR T cell therapy is the selection of a target antigen that is highly expressed on cancer cells, but markedly less so in normal cells. Integrin αvβ6 is upregulated in several solid tumors, but is minimally expressed in normal epithelial cells, which suggests integrin αvβ6 as an attractive target antigen for CAR T cell immunotherapy in CCA. We investigated integrin αvβ6 expression in pathological tissue samples from patients with liver fluke-associated CCA. We then created CAR T cells targeting integrin αvβ6 and evaluated their anti-tumor activities against CCA cells. We found overexpression of the integrin αvβ6 protein in 23 of 30 (73.3%) CCA patient tissue samples. Significant association between high integrin αvβ6 expression and short survival time (p = 0.043) was also observed. Lentiviral constructs were engineered to encode CARs containing an integrin αvβ6-binding peptide (A20) derived from foot-and-mouth disease virus fused with a second-generation CD28/CD3ζ signaling domain (A20-2G CAR) or with a fourth-generation CD28/4-1BB/CD27/CD3ζ signaling domain (A20-4G CAR). The A20-2G and A20-4G CARs were highly expressed in primary human T cells transduced with the engineered lentiviruses, and they exhibited high levels of cytotoxicity against integrin αvβ6-positive CCA cells (p < 0.05). Interestingly, the A20-2G and A20-4G CAR T cells displayed anti-tumor function against integrin αvβ6-positive CCA tumor spheroids (p < 0.05). Upon specific antigen recognition, A20-4G CAR T cells produced a slightly lower level of IFN-γ, but exhibited higher proliferation than A20-2G CAR T cells. Thus, the A20-4G CAR T cells with lower level of cytokine production, but with higher proliferation represents a promising potential adoptive T cell therapy for integrin αvβ6-positive CCA.