Fine-Tuning Tumor Endothelial Cells to Selectively Kill Cancer

Progress on angiogenic and antiangiogenic agents in the tumor microenvironment

The development of tumors and their metastasis relies heavily on the process of angiogenesis. When the volume of a tumor expands, the resulting internal hypoxic conditions trigger the body to enhance the production of various angiogenic factors. These include vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), and transforming growth factor-α (TGF-α), all of which work together to stimulate the activation of endothelial cells and catalyze angiogenesis. Antiangiogenic therapy (AAT) aims to normalize tumor blood vessels by inhibiting these angiogenic signals. In this review, we will explore the molecular mechanisms of angiogenesis within the tumor microenvironment, discuss traditional antiangiogenic drugs along with their limitations, examine new antiangiogenic drugs and the advantages of combination therapy, and consider future research directions in the field of antiangiogenic drugs. This comprehensive overview aims to provide insights that may aid in the development of more effective anti-tumor treatments.

Construction of endothelial cell signatures for predicting the diagnosis, prognosis and immunotherapy response of bladder cancer via machine learning

We subtyped bladder cancer (BC) patients based on the expression patterns of endothelial cell (EC) -related genes and constructed a diagnostic signature and an endothelial cell prognostic index (ECPI), which are useful for diagnosing BC patients, predicting the prognosis of BC and evaluating drug sensitivity. Differentially expressed genes in ECs were obtained from the Tumour Immune Single-Cell Hub database. Subsequently, a diagnostic signature, a tumour subtyping system and an ECPI were constructed using data from The Cancer Genome Atlas and Gene Expression Omnibus. Associations between the ECPI and the tumour microenvironment, drug sensitivity and biofunctions were assessed. The hub genes in the ECPI were identified as drug candidates by molecular docking. Subtype identification indicated that high EC levels were associated with a worse prognosis and immunosuppressive effect. The diagnostic signature and ECPI were used to effectively diagnose BC and accurately assess the prognosis of BC and drug sensitivity among patients. Three hub genes in the ECPI were extracted, and the three genes had the closest affinity for doxorubicin and curcumin. There was a close relationship between EC and BC. EC-related genes can help clinicians diagnose BC, predict the prognosis of BC and select effective drugs.

Exploring the crosstalk between endothelial cells, immune cells, and immune checkpoints in the tumor microenvironment: new insights and therapeutic implications

The tumor microenvironment (TME) is a highly intricate milieu, comprising a multitude of components, including immune cells and stromal cells, that exert a profound influence on tumor initiation and progression. Within the TME, angiogenesis is predominantly orchestrated by endothelial cells (ECs), which foster the proliferation and metastasis of malignant cells. The interplay between tumor and immune cells with ECs is complex and can either bolster or hinder the immune system. Thus, a comprehensive understanding of the intricate crosstalk between ECs and immune cells is essential to advance the development of immunotherapeutic interventions. Despite recent progress, the underlying molecular mechanisms that govern the interplay between ECs and immune cells remain elusive. Nevertheless, the immunomodulatory function of ECs has emerged as a pivotal determinant of the immune response. In light of this, the study of the relationship between ECs and immune checkpoints has garnered considerable attention in the field of immunotherapy. By targeting specific molecular pathways and signaling molecules associated with ECs in the TME, novel immunotherapeutic strategies may be devised to enhance the efficacy of current treatments. In this vein, we sought to elucidate the relationship between ECs, immune cells, and immune checkpoints in the TME, with the ultimate goal of identifying novel therapeutic targets and charting new avenues for immunotherapy.

Cell Proteomic Footprinting: Advances in the Quality of Cellular and Cell-Derived Cancer Vaccines

In omics sciences, many compounds are measured simultaneously in a sample in a single run. Such analytical performance opens up prospects for improving cellular cancer vaccines and other cell-based immunotherapeutics. This article provides an overview of proteomics technology, known as cell proteomic footprinting. The molecular phenotype of cells is highly variable, and their antigenic profile is affected by many factors, including cell isolation from the tissue, cell cultivation conditions, and storage procedures. This makes the therapeutic properties of cells, including those used in vaccines, unpredictable. Cell proteomic footprinting makes it possible to obtain controlled cell products. Namely, this technology facilitates the cell authentication and quality control of cells regarding their molecular phenotype, which is directly connected with the antigenic properties of cell products. Protocols for cell proteomic footprinting with their crucial moments, footprint processing, and recommendations for the implementation of this technology are described in this paper. The provided footprints in this paper and program source code for their processing contribute to the fast implementation of this technology in the development and manufacturing of cell-based immunotherapeutics.

Tumor endothelial cell-induced CD8(+) T-cell exhaustion via GPNMB in hepatocellular carcinoma

Tumor endothelial cells (TECs) promote tumor angiogenesis and regulate cytotoxic T cells in the tumor microenvironment. However, the roles of TECs for tumor‐infiltrating T‐cell in hepatocellular carcinoma (HCC) is still unknown. Here, we aimed to investigate how TECs influenced tumor growth and immune responses of HCC focusing on CD8⁺ T‐cell infiltration and exhaustion. First, TECs were isolated from subcutaneous HCC tumors with murine HCC cell lines (BNL‐T) with magnetic selection of CD31⁺ cells, and normal endothelial cells (NECs) were isolated from normal liver. Second, immunocompetent mice were injected with BNL‐T alone, BNL‐T + NECs, or BNL‐T + TECs for tumor formation, and the functions and exhaustion of tumor‐infiltrating CD8⁺ T cells were evaluated. The mice injected with BNL‐T + TEC showed rapid tumorigenesis and a decrease in the number of infiltrating CD8⁺ T cells. In addition, the percentage of CD8⁺ T‐cell exhaustion was significantly higher in tumors from the administration of BNL‐T + TEC. Third, the next‐generation sequencing on TECs was performed to identify mRNAs that might be a novel treatment target. The molecule of glycoprotein nonmetastatic melanoma protein B (GPNMB) was identified and the functions of GPNMB was analyzed by silencing of GPNMB expression using small interfering RNAs. The silencing of GPNMB expression in TECs induced the suppression of tumor growth and T‐cell exhaustion. In conclusion, TECs induced tumor‐infiltrating T‐cell exhaustion via GPNMB expression and GPNMB might be a novel therapeutic target in HCC.

Co-culture of peripheral blood mononuclear cell (PBMC) and human coronary artery endothelial cell (HCAEC) reveals the important role of autophagy implicated in Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is a systemic vasculitis syndrome that commonly occurs in children. Autophagy has been increasingly shown to be involved in various cardiovascular diseases, including endothelial dysfunction and vascular endothelial injury. However, whether autophagy is implicated in the pathogenesis of KD remains poorly understood, and particularly, how the dysfunction of human coronary artery endothelial cells (HCAECs) is associated with autophagy in peripheral blood mononuclear cells (PBMCs) from KD patients awaits further investigation.

METHODS

Peripheral blood samples were collected from KD patients, common fever patients, and healthy controls. The PBMC samples were isolated from KD blood samples collected at three different phases: the acute phase before therapy (acute-KD), 1 week (subacute-KD), and 4 weeks (convalescent-KD) after drug administration.

RESULTS

The autophagy flux was significantly increased in the PBMCs of KD patients at acute phase. The PBMCs of acute KD patients could induce autophagy in HCAECs and promote the secretion of chemokines and pro-inflammatory factors after cocultured with HCAECs whereas 3-methyladenine (3-MA) drug could partly reverse this process.

CONCLUSIONS

Autophagy is involved in the inflammatory injury of vascular endothelial cells associated with PBMCs in KD patients, and may play a crucial role in regulating inflammation. Hence, we identify a novel regulatory mechanism of vascular injury in this disease.

Mechanistic Target of Rapamycin Inhibitors in Renal Cell Carcinoma: Potential, Limitations, and Perspectives

Several elements highlight the importance of the mechanistic target of rapamycin (mTOR) in the biology of renal cell carcinoma (RCC). mTOR signaling pathway is indeed frequently activated in RCC, inducing cancer cell proliferation and survival. In addition, mTOR promotes tumor angiogenesis and regulates the expression of hypoxia-inducible factors that play an important role in a subset of RCC. Despite mTOR protumorigenic effects, mTOR inhibitors have failed to provide long-lasting anticancer benefits in RCC patients, highlighting the need to readdress their role in the treatment of RCC. This review aims to present the rationale and limitations of targeting mTOR in RCC. Future roles of mTOR inhibitors in the treatment of RCC are also discussed, in particular in the context of immunotherapies.

Antigenic Essence: Upgrade of Cellular Cancer Vaccines

Simple Summary

Early cancer vaccines include whole-cell formulations, which operate on the principle that you should vaccinate with what you want to develop protection against. Such vaccines have been widely tested in various cancers and their advantages described but have not yet managed to pass clinical trials. Antigenic essence technology offers the possibility to revitalize the field of whole-cell-based vaccination, as the essence comprises the entire diversity of native cellular antigens. At the same time, the technology allows for precise control and purposeful change of essence composition as well as purification of essence from ballast cellular substances and also addresses issues of major histocompatibility complex restriction. Antigenic essence technology makes it possible to update many cellular vaccines that have already been developed, as well as to develop new ones, therefore introducing a new direction for anticancer vaccination research.

Abstract

The development of anticancer immunotherapy is characterized by several approaches, the most recognized of which include cellular vaccines, tumor-associated antigens (TAAs), neoantigens, and chimeric antigen receptor T cells (CAR-T). This paper presents antigenic essence technology as an effective means for the production of new antigen compositions for anticancer vaccination. This technology is developed via proteomics, cell culture technology, and immunological assays. In terms of vaccine development, it does not fit into any of the above-noted approaches and can be considered a new direction. Here we review the development of this technology, its main characteristics, comparison with existing approaches, and the features that distinguish it as a novel approach to anticancer vaccination. This review will also highlight the benefits of this technology over other approaches, such as the ability to control composition, optimize immunogenicity and similarity to target cells, and evade major histocompatibility complex restriction. The first antigenic essence products, presented under the SANTAVAC brand, are also described.

Nanobodies as Versatile Tool for Multiscale Imaging Modalities

Molecular imaging is constantly growing in different areas of preclinical biomedical research. Several imaging methods have been developed and are continuously updated for both in vivo and in vitro applications, in order to increase the information about the structure, localization and function of molecules involved in physiology and disease. Along with these progresses, there is a continuous need for improving labeling strategies. In the last decades, the single domain antigen-binding fragments nanobodies (Nbs) emerged as important molecular imaging probes. Indeed, their small size (~15 kDa), high stability, affinity and modularity represent desirable features for imaging applications, providing higher tissue penetration, rapid targeting, increased spatial resolution and fast clearance. Accordingly, several Nb-based probes have been generated and applied to a variety of imaging modalities, ranging from in vivo and in vitro preclinical imaging to super-resolution microscopy. In this review, we will provide an overview of the state-of-the-art regarding the use of Nbs in several imaging modalities, underlining their extreme versatility and their enormous potential in targeting molecules and cells of interest in both preclinical and clinical studies.

Designer nanocarriers for navigating the systemic delivery of oncolytic viruses

Nanotechnology is paving the way for new carrier systems designed to overcome the greatest challenges of oncolytic virotherapy; systemic administration and subsequent implications of immune responses and specific cell binding and entry. Systemic administration of oncolytic agents is vital for disseminated neoplasms, however transition of nanoparticles (NP) to virotherapy has yielded modest results. Their success relies on how they navigate the merry-go-round of often-contradictory phases of NP delivery: circulatory longevity, tissue permeation and cellular interaction, with many studies postulating design features optimal for each phase. This review discusses the optimal design of NPs for the transport of oncolytic viruses within these phases, to determine whether improved virotherapeutic efficacy lies in the pharmacokinetic/pharmacodynamics characteristics of the NP-oncolytic viruses complexes rather than manipulation of the virus and targeting ligands.

Tumor Endothelial Cells (TECs) as Potential Immune Directors of the Tumor Microenvironment - New Findings and Future Perspectives

The tumor microenvironment (TME) plays a central role in cancer development and progression. It represents a complex network of cancer cell (sub-)clones and a variety of stromal cell types. Recently, new technology platforms shed light on the cellular composition of the TME at very high resolution and identified a complex landscape of multi-lineage immune cells (e.g., T and B lymphocytes, myeloid cells, and dendritic cells), cancer associated fibroblasts (CAF) and tumor endothelial cells (TECs). A growing body of evidence suggests that metabolically, genetically and on their transcriptomic profile TECs exhibit unique phenotypic and functional characteristics when compared to normal endothelial cells (NECs). Furthermore, the functional role of TECs is multifaceted as they are not only relevant for promoting tumor angiogenesis but have also evolved as key mediators of immune regulation in the TME. Regulatory mechanisms are complex and profoundly impact peripheral immune cell trafficking into the tumor compartment by acting as major gatekeepers of cellular transmigration. Moreover, TECs are associated with T cell priming, activation and proliferation by acting as antigen-presenting cells themselves. TECs are also essential for the formation of tertiary lymphoid structures (TLS) within the tumor, which have recently been associated with treatment response to checkpoint antibody therapy. Further essential characteristics of TECs compared to NECs are their high proliferative potential as well as greatly altered gene expression profile (e.g., upregulation of pro-angiogenic, extracellular matrix remodeling, and stemness genes), which results in enhanced secretion of immunomodulatory cytokines and altered cell-surface receptors [e.g., major histocompatibility complex (MHC) and immune checkpoints]. The TEC phenotype may be rooted in an aggressive tumor micro-milieu based on cellular stress via hypoxia and reactive oxygen species (ROS). Vice versa TECs might modulate TME immunogenicity thereby fostering cancer-associated immune suppression. This review aims to elucidate the currently emergent pathophysiological aspects of TECs with a particular focus on their potential role as regulators of immune cell function in the TME. It is a main future challenge to deeply characterize the phenotypic and functional profile of TECs to illuminate their complex role within the TME. The ultimate goal is the identification of TEC-specific drug targets to improve cancer (immuno-)therapy.

In vitro vascularized tumor platform for modeling tumor-vasculature interactions of inflammatory breast cancer

Inflammatory breast cancer (IBC), a rare form of breast cancer associated with increased angiogenesis and metastasis, is largely driven by tumor-stromal interactions with the vasculature and the extracellular matrix (ECM). However, there is currently a lack of understanding of the role these interactions play in initiation and progression of the disease. In this study, we developed the first three-dimensional, in vitro, vascularized, microfluidic IBC platform to quantify the spatial and temporal dynamics of tumor-vasculature and tumor-ECM interactions specific to IBC. Platforms consisting of collagen type 1 ECM with an endothelialized blood vessel were cultured with IBC cells, MDA-IBC3 (HER2+) or SUM149 (triple negative), and for comparison to non-IBC cells, MDA-MB-231 (triple negative). Acellular collagen platforms with endothelialized blood vessels served as controls. SUM149 and MDA-MB-231 platforms exhibited a significantly (p < .05) higher vessel permeability and decreased endothelial coverage of the vessel lumen compared to the control. Both IBC platforms, MDA-IBC3 and SUM149, expressed higher levels of vascular endothelial growth factor (p < .05) and increased collagen ECM porosity compared to non-IBCMDA-MB-231 (p < .05) and control (p < .01) platforms. Additionally, unique to the MDA-IBC3 platform, we observed progressive sprouting of the endothelium over time resulting in viable vessels with lumen. The newly sprouted vessels encircled clusters of MDA-IBC3 cells replicating a key feature of in vivo IBC. The IBC in vitro vascularized platforms introduced in this study model well-described in vivo and clinical IBC phenotypes and provide an adaptable, high throughput tool for systematically and quantitatively investigating tumor-stromal mechanisms and dynamics of tumor progression.

A treatise on endothelial biology and exosomes: homage to Theresa Maria Listowska Whiteside

Exosomes are the current primary research focus of Dr. Theresa L. Whiteside. They are key mediators of intercellular communication in the head and neck, as well as other sites. Their effects in the tumor microenvironment are manifold and include suppression of immunity, promotion of angiogenesis, enabling of metastasis, as well as reprogramming of fibroblasts and mesenchymal stromal cells. The aim of this communication is to summarize Dr. Whiteside's contribution to the field of exosome research and details the interactions of exosomes with endothelial cells leading to recent findings on how to target endothelial cells using exosomes as a therapeutic approach.

Engineering Targeting Materials for Therapeutic Cancer Vaccines

Therapeutic cancer vaccines constitute a valuable tool to educate the immune system to fight tumors and prevent cancer relapse. Nevertheless, the number of cancer vaccines in the clinic remains very limited to date, highlighting the need for further technology development. Recently, cancer vaccines have been improved by the use of materials, which can strongly enhance their intrinsic properties and biodistribution profile. Moreover, vaccine efficacy and safety can be substantially modulated through selection of the site at which they are delivered, which fosters the engineering of materials capable of targeting cancer vaccines to specific relevant sites, such as within the tumor or within lymphoid organs, to further optimize their immunotherapeutic effects. In this review, we aim to give the reader an overview of principles and current strategies to engineer therapeutic cancer vaccines, with a particular focus on the use of site-specific targeting materials. We will first recall the goal of therapeutic cancer vaccination and the type of immune responses sought upon vaccination, before detailing key components of cancer vaccines. We will then present how materials can be engineered to enhance the vaccine's pharmacokinetic and pharmacodynamic properties. Finally, we will discuss the rationale for site-specific targeting of cancer vaccines and provide examples of current targeting technologies.

SANTAVACTM: Summary of Research and Development

SANTAVAC is an antigen composition developed via proteomics and cell culture technology that is intended for the development of cancer vaccines against various solid tumors. Its mechanism of action is based on the heterogeneity of endothelial cells, the polypeptides of which are similar to the surface antigens of tumor-vessel cells, allowing targeted destruction by vaccination. While research and development work with SANTAVAC is ongoing, the existing data provide strong evidence that allogeneic SANTAVAC is an ideal candidate for the development of cancer vaccines with significant efficacy and safety. The SANTAVAC compositions described here demonstrated the ability to inhibit the growth of tumor vessel-specific endothelial cells up to 60 fold, with minimal effect on normal vasculature. Innovation, background, description of product development, and summary of nonclinical studies with SANTAVAC to date are presented in this review.

Theranostics in immuno-oncology using nanobody derivatives

Targeted therapy and immunotherapy have become mainstream in cancer treatment. However, only patient subsets benefit from these expensive therapies, and often responses are short‐lived or coincide with side effects. A growing modality in precision oncology is the development of theranostics, as this enables patient selection, treatment and monitoring. In this approach, labeled compounds and an imaging technology are used to diagnose patients and select the best treatment option, whereas for therapy, related compounds are used to target cancer cells or the tumor stroma. In this context, nanobodies and nanobody-directed therapeutics have gained interest. This interest stems from their high antigen specificity, small size, ease of labeling and engineering, allowing specific imaging and design of therapies targeting antigens on tumor cells, immune cells as well as proteins in the tumor environment. This review provides a comprehensive overview on the state-of-the-art regarding the use of nanobodies as theranostics, and their importance in the emerging field of personalized medicine.

LPA4-Mediated Vascular Network Formation Increases the Efficacy of Anti-PD-1 Therapy against Brain Tumors

: The structure and function of tumor blood vessels profoundly affects the tumor microenvironment. Signals mediated through the lysophosphatidic acid receptor 4 (LPA4) promote vascular network formation to restore normal vascular barrier function in subcutaneous tumors and thus improve drug delivery. However, the characteristics of the vasculature vary by organ and tumor types, and how drug delivery and leukocyte trafficking are affected by modification of vascular function by LPA in different cancers is unclear. Here, we show that LPA4 activation promotes the formation of fine vascular structures in brain tumors. RhoA/ROCK signaling contributed to LPA-induced endothelial cell-cell adhesion, and RhoA/ROCK activity following LPA4 stimulation regulated expression of VCAM-1. This resulted in increased lymphocyte infiltration into the tumor. LPA improved delivery of exogenous IgG into brain tumors and enhanced the anticancer effect of anti-programmed cell death-1 antibody therapy. These results indicate the effects of LPA on vascular structure and function apply not only to chemotherapy but also to immunotherapy. SIGNIFICANCE: These findings demonstrate that lysophosphatidic acid, a lipid mediator, promotes development of a fine capillary network in brain tumors by inducing tightening of endothelial cell-to-cell adhesion, facilitating improved drug delivery, and lymphocyte penetration.

The importance of the vascular endothelial barrier in the immune-inflammatory response induced by radiotherapy

Altered by ionising radiation, the vascular network is considered as a prime target to limit normal tissue damage and improve tumour control in radiotherapy (RT). Irradiation damages and/or activates endothelial cells, which then participate in the recruitment of circulating cells, especially by overexpressing cell adhesion molecules, but also by other as yet unknown mechanisms. Radiation-induced lesions are associated with infiltration of immune-inflammatory cells from the blood and/or the lymph circulation. Damaged cells from the tissues and immune-inflammatory resident cells release factors that attract cells from the circulation, leading to the restoration of tissue balance by fighting against infection, elimination of damaged cells and healing of the injured area. In normal tissues that surround the tumours, the development of an immune-inflammatory reaction in response to radiation-induced tissue injury can turn out to be chronic and deleterious for the organ concerned, potentially leading to fibrosis and/or necrosis of the irradiated area. Similarly, tumours can elicit an immune-inflammation reaction, which can be initialised and amplified by cancer therapy such as radiotherapy, although immune checkpoints often allow many cancers to be protected by inhibiting the T-cell signal. Herein, we have explored the involvement of vascular endothelium in the fate of healthy tissues and tumours undergoing radiotherapy. This review also covers current investigations that take advantage of the radiation-induced response of the vasculature to spare healthy tissue and/or target tumours better.

Evolving Significance and Future Relevance of Anti-Angiogenic Activity of mTOR Inhibitors in Cancer Therapy

mTOR inhibitors have demonstrated remarkable anti-tumor activity in experimental models, mainly by reducing cancer cell growth and tumor angiogenesis. Their use in cancer patients as monotherapy has, however, generated only limited benefits, increasing median overall survival by only a few months. Likewise, in other targeted therapies, cancer cells develop resistance mechanisms to overcome mTOR inhibition. Hence, novel therapeutic strategies have to be designed to increase the efficacy of mTOR inhibitors in cancer. In this review, we discuss the present and future relevance of mTOR inhibitors in cancer therapy by focusing on their effects on tumor angiogenesis.