Patient-Derived Head and Neck Cancer Organoids Recapitulate EGFR Expression Levels of Respective Tissues and Are Responsive to EGFR-Targeted Photodynamic Therapy

Three-dimensional in vitro models in head and neck cancer: current trends and applications

Head and neck cancer (HNC) is the sixth most prevalent malignancy worldwide and includes a variety of upper gastrointestinal abnormalities. HNC includes oral, throat, voice box, nasal cavity, paranasal sinuses, and salivary gland cancers. Squamous cells in the mouth, nose, and throat cause HNC. Drugs, alcohol, poor diets, smoking, and genetics all contribute to this condition. Cancer research has focused on three-dimensional (3D) models in HNC biology in recent decades. An adequate microenvironmental system and cancer cell culture are the initial steps to understanding cancer cells' complicated interactions with their surroundings. New 3D models claim to bridge in vivo and in vitro investigations and erase the gap. Interdisciplinary cell biology and tissue engineering researchers are creating 3D cancer tissue models to better understand the illness and develop more accurate cancer medicines. Tissue engineering researchers, who are always exploring novel approaches to treat cancer, have been able to include the third dimension into laboratory settings and mimic cell-to-cell and cell-to-matrix interactions by recreating the tumor microenvironment using 3D models and so make research on cancer easier. This review addresses recent developments in tissue engineering with an emphasis on 3D models in HNC.

Current applications, future Perspectives and challenges of Organoid technology in oral cancer research

Oral cancer poses significant health risks with an increasing incidence annually. Despite advancements in treatment methods, their efficacy is frequently constrained by cancer heterogeneity and drug resistance, leading to minimal improvement in the 5-year survival rate. Therefore, there is a critical need for new treatment methods leaded by representative preclinical research models. Compared to other models, organoids can more precisely simulate the tissue structure, genetic characteristics, and tumor microenvironment (TME) of in vivo tumors, exhibiting high tumor specificity. This makes organoid technology a valuable tool in investigating tumor development, mechanisms of metastasis, drug screening, prediction of clinical responses, and personalized patient treatment. Moreover, integrating organoid technology with other biotechnologies could expand its applications in tissue regeneration. Although organoid technology is increasingly utilized in oral cancer research, a systematic review in this field is absent. This paper is to bridge the gap by reviewing the development and current status of organoid research, highlighting its applications, future prospects, and challenges in oral cancer. It aims to provide novel insights into the role of organoids in precision treatment and regenerative medicine for oral cancer.

Squamous cell cancers of the aero-upper digestive tract: A unified perspective on biology, genetics, and therapy

Squamous cell cancers (SCCs) of the head and neck, esophagus, and lung, referred to as aero-upper digestive SCCs, are prevalent in the United States and worldwide. Their incidence and mortality are projected to increase at alarming rates, posing diagnostic, prognostic, and therapeutic challenges. These SCCs share certain epigenetic, genomic, and genetic alterations, immunologic properties, environmental exposures, as well as lifestyle and nutritional risk factors, which may underscore common complex gene-environmental interactions across them. This review focuses upon the frequent shared epigenetic, genomic, and genetic alterations, emerging preclinical model systems, and how this collective knowledge can be leveraged into perspectives on standard of care therapies and mechanisms of resistance, nominating new potential directions in translational therapeutics.

Patient-Derived Cancer-Associated Fibroblasts Support the Colonization of Tumor Cells in Head and Neck Squamous Cell Carcinoma

Background: The crosstalk between cancer-associated fibroblasts (CAFs) and tumor cells promotes proliferation, tumor relapse, and the acquisition of a partial epithelial-to-mesenchymal (pEMT) phenotype in tumor cells. The aim of this study was to investigate the effects of patient-derived CAFs on tumor cell growth and radioresistance in head and neck squamous cell carcinoma (HNSCC). Methods: CAFs were isolated and cultured in a three-dimensional spheroid formation. SCC-25 tumor cells educated by the CAFs (SCC25-E cells) were subjected to irradiation, and the response of the CAF-stimulated tumor cells to radiotherapy was determined using an MTT assay, a clonogenic assay, and Western blotting. Tumor cell morphological changes and growth dynamics were assessed using 3D holotomographic microscopy and a live video microscope. Results: Patient-derived CAFs significantly increased the growth rate of SCC-25 cells. CAFs drove fibrosis in the tumor microenvironment (TME), functioned as a physical barrier, temporarily stopped tumor growth, and induced the p38 mitogen-activated protein kinase (MAPK) signaling pathway. Viability after irradiation at 4-8 Gy was significantly higher in SCC25-E cells than in the controls (p = 8 × 10-4 or lower). Furthermore, irradiation triggered the pEMT profile in HNSCC cells. Conclusions: CAFs' education of tumor cells and the induced p38 phosphorylation had no influence on irradiation sensitivity. SCC25-E cultures demonstrated increased tumor cell growth, viability, and stress-induced phospho-p38 activation.

Preclinical in vitro models of HNSCC and their role in drug discovery - an emphasis on the cancer microenvironment and microbiota

INTRODUCTION

Head and neck squamous cell carcinoma (HNSCC) is the seventh most common cancer worldwide. Treatment options and patient outcomes have not improved significantly over the past decades, increasing the need for better preclinical models. Holistic approaches that include an intact and functional immune compartment along with the patient's individual tumor microbiome will help improve the predictive value of novel drug efficacy.

AREAS COVERED

In this review, we describe the challenges of modeling the complex and heterogeneous tumor landscape in HNSCC and the importance of sophisticated patient-specific 3D in vitro models to pave the way for clinical trials with novel immunomodulatory drugs. We also discuss the impact of the tumor microbiome and the potential implications for prospective drug screening and validation trials.

EXPERT OPINION

The repertoire of well-characterized preclinical 3D in vitro models continues to grow. With the increasing attention to the complex cellular, immunological, molecular, and spatio-temporal characteristics of tumors, well-designed proof-of-concept studies to test novel drug efficacy are on the verge of providing valuable, practice-changing insights for clinical trials. Bringing together expertise and improving collaboration between clinicians, academics, and regulatory agencies will facilitate the translation of preclinical findings into clinically meaningful outcomes.

Engineering photodynamics for treatment, priming and imaging

Photodynamic therapy (PDT) is a photochemistry-based treatment approach that relies on the activation of photosensitizers by light to locally generate reactive oxygen species that induce cellular cytotoxicity, in particular for the treatment of tumours. The cytotoxic effects of PDT are depth-limited owing to light penetration limits in tissue. However, photodynamic priming (PDP), which inherently occurs during PDT, can prime the tissue microenvironment to adjuvant therapies beyond the direct PDT ablative zone. In this Review, we discuss the underlying mechanisms of PDT and PDP, and their application to the treatment of cancer, outlining how PDP can permeabilize the tumour vasculature, overcome biological barriers, modulate multidrug resistance, enhance immune responses, increase tumour permeability and enable the photochemical release of drugs. We further examine the molecular engineering of photosensitizers to improve their pharmacodynamic and pharmacokinetic properties, increase their molecular specificity and allow image guidance of PDT, and investigate engineered cellular models for the design and optimization of PDT and PDP. Finally, we discuss alternative activation sources, including ultrasound, X-rays and self-illuminating compounds, and outline key barriers to the clinical translation of PDT and PDP.

Targeting the Neuropilin-1 receptor with Ovatodiolide and progress in using periodontal ligament organoids for COVID-19 research and therapy

The discovery of SARS-CoV-2 RNA in the periodontal tissues of patients who tested positive for COVID-19, 24 days post the initial symptom onset, indicates the oral cavity could serve as a viral reservoir. This research aims to investigate the antiviral capabilities of Ovatodiolide, introducing a novel periodontal ligament organoid model for the study of SARS-CoV-2. We have successfully established a reliable and expandable organoid culture from the human periodontal ligament, showcasing characteristics typical of epithelial stem cells. This organoid model enables us to delve into the lesser-known aspects of dental epithelial stem cell biology and their interactions with viruses and oral tissues. We conducted a series of in vitro and ex vivo studies to examine the inhibitory impacts of Ova on SARS-CoV-2. Our findings indicate that Ovatodiolide molecules can bind effectively to the NRP1 active domain. Our study identifies potential interaction sites for Ovatodiolide (OVA) within the b1 domain of the NRP1 receptor. We generated point mutations at this site, resulting in three variants: Y25A, T44A, and a double mutation Y25A/T44A. While these mutations did not alter the binding activity of the spike protein, they did impact the concentration of OVA required for inhibition. The inhibitory concentrations for these variants are 15 μM for Y25A, 15.2 μM for T44A, and 25 μM for the double mutant Y25A/T44A. In addition, in vitro inhibition experiments demonstrate that the EC50 of Ova against the main protease (Mpro) of the SARS-CoV-2 virus is 7.316 μM. Our in vitro studies and the use of the periodontal ligament organoid model highlight Ovatodiolide's potential as a small molecule therapeutic agent that impedes the virus's ability to bind to the Neuropilin-1 receptor on host cells. The research uncovers various pathways and biochemical strategies through which Ovatodiolide may function as an effective antiviral small molecule drug.

Gastrointestinal Cancer Patient Derived Organoids at the Frontier of Personalized Medicine and Drug Screening

Cancer is a leading cause of death worldwide. Around one-third of the total global cancer incidence and mortality are related to gastrointestinal (GI) cancers. Over the past few years, rapid developments have been made in patient-derived organoid (PDO) models for gastrointestinal cancers. By closely mimicking the molecular properties of their parent tumors in vitro, PDOs have emerged as powerful tools in personalized medicine and drug discovery. Here, we review the current literature on the application of PDOs of common gastrointestinal cancers in the optimization of drug treatment strategies in the clinic and their rising importance in pre-clinical drug development. We discuss the advantages and limitations of gastrointestinal cancer PDOs and outline the microfluidics-based strategies that improve the throughput of PDO models in order to extract the maximal benefits in the personalized medicine and drug discovery process.

The potential of hydrogel-free tumoroids in head and neck squamous cell carcinoma

BACKGROUND

Head and neck malignancy, and in particular squamous cell carcinoma (SCC), is responsible for a significant disease burden globally. The lack of an optimal in vitro model system to accurately recapitulate in vivo response to therapy in HNSCC remains a challenge. The development of patient-derived three-dimensional tumour cultures, or tumoroids, has enabled improved modelling of the tumour microenvironment through simulation of important characteristics such as tumour hypoxia, cell-cell interactions and nutrient diffusion characteristics.

METHODS

We performed a comprehensive English-language literature review of current methods of tumoroid development utilising Matrigel and Cultrex Basement Membrane Extract 2 (key terms: tumour organoids, tumoroids, hydrogels, Matrigel, Cultrex, squamous cell carcinoma, head and neck)-two common proprietary murine-derived hydrogels containing extracellular matrix proteins. Nascent literature on the establishment of a novel hydrogel-free platform for tumoroid development as distinct from these existing methods was also explored.

RESULTS

Whilst useful for facilitating cell-matrix interactions and providing a scaffold for three-dimensional cell growth and organisation, murine-derived cell matrix methods were noted to have notable limitations including temperature sensitivity and the medium forming a barrier to analysis of the supernatant. A novel hydrogel-free method of establishing in vitro tumoroid cultures has been subject to experimentation in colorectal but not head and neck malignancy. The absence of a hydrogel provides for the de novo synthesis of extracellular matrix native to the tumour and self-organisation of cells within this scaffold through the use of ultralow attachment plates. This model demonstrates similar structural and physiological properties to native tissue, whilst enabling more accurate biomimicry of the tumour microenvironment for drug testing.

CONCLUSIONS

In the absence of prior experimentation on a hydrogel-free method for establishing HNSCC tumoroids, and comparisons between hydrogel and hydrogel-free models, the future development of a comparative protocol encompassing recruitment, collection, processing and analysis represents a valuable opportunity.

Building consensus on the application of organoid-based drug sensitivity testing in cancer precision medicine and drug development

Patient-derived organoids (PDOs) have emerged as a promising platform for clinical and translational studies. A strong correlation exists between clinical outcomes and the use of PDOs to predict the efficacy of chemotherapy and/or radiotherapy. To standardize interpretation and enhance scientific communication in the field of cancer precision medicine, we revisit the concept of PDO-based drug sensitivity testing (DST). We present an expert consensus-driven approach for medication selection aimed at predicting patient responses. To further standardize PDO-based DST, we propose guidelines for clarification and characterization. Additionally, we identify several major challenges in clinical prediction when utilizing PDOs.

Therapeutic targeting of thioredoxin reductase 1 causes ferroptosis while potentiating anti-PD-1 efficacy in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) faces low response rates to anti-PD-1 immunotherapies, highlighting the need for enhanced treatment strategies. Auranofin, which inhibits thioredoxin reductase (TrxR) through its gold-based composition, has shown potential in cancer treatment. It targets the TrxR system, essential for safeguarding cells from oxidative stress. The overproduction of TrxR in cancerous cells supports their proliferation. However, auranofin's interference with this system can upset the cellular redox equilibrium, boost levels of reactive oxygen species, and trigger the death of cancer cells. This study is the first to highlight TXNRD1 as a crucial factor contributing to resistance to anti-PD-1 treatment in HNSCC. In this study, we identified targetable regulators of resistance to immunotherapy-induced ferroptosis in HNSCC. We observed a link of thioredoxin reductase 1 (TXNRD1) with tumoral PD-L1 expression and ferroptosis suppression in HNSCC. Moreover, HNSCC tumors with aberrant TXNRD1 expression exhibited a lack of PD-1 response, NRF2 overexpression, and PD-L1 upregulation. TXNRD1 inhibition promoted ferroptosis in HNSCC cells with NRF2 activation and in organoid tumors derived from patients lacking a PD-1 response. Mechanistically, TXNRD1 regulated PD-L1 transcription and maintained the redox balance by binding to ribonucleotide reductase regulatory subunit M2 (RRM2). TXNRD1 expression disruption sensitized HNSCC cells to anti-PD-1-mediated Jurkat T-cell activation, promoting tumor killing through ferroptosis. Moreover, TXNRD1 inhibition through auranofin cotreatment synergized with anti-PD-1 therapy to potentiate immunotherapy-mediated ferroptosis by mediating CD8+ T-cell infiltration and downregulating PD-L1 expression. Our findings indicate that targeting TXNRD1 is a promising therapeutic strategy for improving immunotherapy outcomes in patients with HNSCC.

Molecular and functional insight into anti-EGFR nanobody: Theranostic implications for malignancies

Targeted therapy and imaging are the most popular techniques for the intervention and diagnosis of cancer. A potential therapeutic target for the treatment of cancer is the epidermal growth factor receptor (EGFR), primarily for glioblastoma, lung, and breast cancer. Over-production of ligand, transcriptional up-regulation due to autocrine/paracrine signalling, or point mutations at the genomic locus may contribute to the malfunction of EGFR in malignancies. This exploit makes use of EGFR, an established biomarker for cancer diagnostics and treatment. Despite considerable development in the last several decades in making EGFR inhibitors, they are still not free from limitations like toxicity and a short serum half-life. Nanobodies and antibodies share similar binding properties, but nanobodies have the additional advantage that they can bind to antigenic epitopes deep inside the target that conventional antibodies are unable to access. For targeted therapy, anti-EGFR nanobodies can be conjugated to various molecules such as drugs, peptides, toxins and photosensitizers. These nanobodies can be designed as novel immunoconjugates using the universal modular antibody-based platform technology (UniCAR). Furthermore, Anti-EGFR nanobodies can be expressed in neural stem cells and visualised by effective fluorescent and radioisotope labelling.

Cancer organoids: A platform in basic and translational research

An accumulation of previous work has established organoids as good preclinical models of human tumors, facilitating translation from basic research to clinical practice. They are changing the paradigm of preclinical cancer research because they can recapitulate the heterogeneity and pathophysiology of human cancers and more closely approximate the complex tissue environment and structure found in clinical tumors than in vitro cell lines and animal models. However, the potential applications of cancer organoids remain to be comprehensively summarized. In the review, we firstly describe what is currently known about cancer organoid culture and then discuss in depth the basic mechanisms, including tumorigenesis and tumor metastasis, and describe recent advances in patient-derived tumor organoids (PDOs) for drug screening and immunological studies. Finally, the present challenges faced by organoid technology in clinical practice and its prospects are discussed. This review highlights that organoids may offer a novel therapeutic strategy for cancer research.

Unlocking the potential of organoids in cancer treatment and translational research: An application of cytologic techniques

Patient-derived organoid models hold promise for advancing clinical cancer research, including diagnosis and personalized and precision medicine approaches, and cytology, in particular, plays a pivotal role in this process. These three-dimensional multicellular structures are heterogeneous, potentially maintain the cancer phenotype, and conserve the genomic, transcriptomic, and epigenomic patterns of the parental tumors. To ensure that only tumor tissue is used for organoid development, cytologic validation is necessary before initiating the process of organoid generation. Here, we explore the technology of tumor organoids and discuss the fundamental application of cytology as a simple and cost-effective approach toward organoid development. We also underscore the potential application of organoid development in drug efficacy studies for lung cancer and head and neck tumors. Additionally, we stress the importance of using fine-needle aspiration to generate tumoroids.

A Photoactive Supramolecular Complex Targeting PD-L1 Reveals a Weak Correlation between Photoactivation Efficiency and Receptor Expression Levels in Non-Small-Cell Lung Cancer Tumor Models

Photo-immunotherapy uses antibodies conjugated to photosensitizers to produce nanostructured constructs endowed with targeting properties and photo-inactivation capabilities towards tumor cells. The superficial receptor density on cancer cells is considered a determining factor for the efficacy of the photodynamic treatment. In this work, we propose the use of a photoactive conjugate that consists of the clinical grade PD-L1-binding monoclonal antibody Atezolizumab, covalently linked to either the well-known photosensitizer eosin or the fluorescent probe Alexa647. Using single-molecule localization microscopy (direct stochastic optical reconstruction microscopy, dSTORM), and an anti-PD-L1 monoclonal antibody labelled with Alexa647, we quantified the density of PD-L1 receptors exposed on the cell surface in two human non-small-cell lung cancer lines (H322 and A549) expressing PD-L1 to a different level. We then investigated if this value correlates with the effectiveness of the photodynamic treatment. The photodynamic treatment of H322 and A549 with the photo-immunoconjugate demonstrated its potential for PDT treatments, but the efficacy did not correlate with the PD-L1 expression levels. Our results provide additional evidence that receptor density does not determine a priori the level of photo-induced cell death.

Small Antibodies with Big Applications: Nanobody-Based Cancer Diagnostics and Therapeutics

Monoclonal antibodies (mAbs) have exhibited substantial potential as targeted therapeutics in cancer treatment due to their precise antigen-binding specificity. Despite their success in tumor-targeted therapies, their effectiveness is hindered by their large size and limited tissue permeability. Camelid-derived single-domain antibodies, also known as nanobodies, represent the smallest naturally occurring antibody fragments. Nanobodies offer distinct advantages over traditional mAbs, including their smaller size, high stability, lower manufacturing costs, and deeper tissue penetration capabilities. They have demonstrated significant roles as both diagnostic and therapeutic tools in cancer research and are also considered as the next generation of antibody drugs. In this review, our objective is to provide readers with insights into the development and various applications of nanobodies in the field of cancer treatment, along with an exploration of the challenges and strategies for their prospective clinical trials.

Flourishing tumor organoids: History, emerging technology, and application

Malignant tumors are one of the leading causes of death which impose an increasingly heavy burden on all countries. Therefore, the establishment of research models that closely resemble original tumor characteristics is crucial to further understanding the mechanisms of malignant tumor development, developing safer and more effective drugs, and formulating personalized treatment plans. Recently, organoids have been widely used in tumor research owing to their advantages including preserving the structure, heterogeneity, and cellular functions of the original tumor, together with the ease of manipulation. This review describes the history and characteristics of tumor organoids and the synergistic combination of three-dimensional (3D) culture approaches for tumor organoids with emerging technologies, including tissue-engineered cell scaffolds, microfluidic devices, 3D bioprinting, rotating wall vessels, and clustered regularly interspaced short palindromic repeats-CRISPR-associated protein 9 (CRISPR-Cas9). Additionally, the progress in research and the applications in basic and clinical research of tumor organoid models are summarized. This includes studies of the mechanism of tumor development, drug development and screening, precision medicine, immunotherapy, and simulation of the tumor microenvironment. Finally, the existing shortcomings of tumor organoids and possible future directions are discussed.

The role of organoids in cancer research

Organoids are established through in vitro 3D culture, and they can mimic the structure and physiological functions of organs or tissues in vivo. Organoids have attracted much attention in recent years. They can provide a reliable technology platform for cancer research and treatment and are a valuable preclinical model for academic research and personalized medicine. A number of studies have confirmed that organoids have great application prospects in new drug development, drug screening, tumour mechanism research, and precision medicine. In this review, we mainly focus on recent advances in the application of organoids in cancer research. We also discussed the opportunities and challenges facing organoids, hoping to indicate directions for the development of organoids in the future.

The applications and techniques of organoids in head and neck cancer therapy

Head and neck cancer (HNC) is one of the most common cancers on the planet, with approximately 600,000 new cases diagnosed and 300,000 deaths every year. Research into the biological basis of HNC has advanced slowly over the past decades, which has made it difficult to develop new, more effective treatments. The patient-derived organoids (PDOs) are made from patient tumor cells, resembling the features of their tumors, which are high-fidelity models for studying cancer biology and designing new precision medicine therapies. In recent years, considerable effort has been focused on improving "organoids" technologies and identifying tumor-specific medicine using head and neck samples and a variety of organoids. A review of improved techniques and conclusions reported in publications describing the application of these techniques to HNC organoids is presented here. Additionally, we discuss the potential application of organoids in head and neck cancer research as well as the limitations associated with these models. As a result of the integration of organoid models into future precision medicine research and therapeutic profiling programs, the use of organoids will be extremely significant in the future.

Patient-derived three-dimensional culture techniques model tumor heterogeneity in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) outcomes remain stagnant, in part due to a poor understanding of HNSCC biology. The importance of tumor heterogeneity as an independent predictor of outcomes and treatment failure in HNSCC has recently come to light. With this understanding, 3D culture systems, including patient derived organoids (PDO) and organotypic culture (OTC), that capture this heterogeneity may allow for modeling and manipulation of critical subpopulations, such as p-EMT, as well as interactions between cancer cells and immune and stromal cells in the microenvironment. Here, we review work that has been done using PDO and OTC models of HNSCC, which demonstrates that these 3D culture models capture in vivo tumor heterogeneity and can be used to model tumor biology and treatment response in a way that faithfully recapitulates in vivo characteristics. As such, in vitro 3D culture models represent an important bridge between 2D monolayer culture and in vivo models such as patient derived xenografts.

Head and neck cancer patient-derived tumouroid cultures: opportunities and challenges

Head and neck cancers (HNC) are the seventh most prevalent cancer type globally. Despite their common categorisation, HNCs are a heterogeneous group of malignancies arising in various anatomical sites within the head and neck region. These cancers exhibit different clinical and biological manifestations, and this heterogeneity also contributes to the high rates of treatment failure and mortality. To evaluate patients who will respond to a particular treatment, there is a need to develop in vitro model systems that replicate in vivo tumour status. Among the methods developed, patient-derived cancer organoids, also known as tumouroids, recapitulate in vivo tumour characteristics including tumour architecture. Tumouroids have been used for general disease modelling and genetic instability studies in pan-cancer research. However, a limited number of studies have thus far been conducted using tumouroid-based drug screening. Studies have concluded that tumouroids can play an essential role in bringing precision medicine for highly heterogenous cancer types such as HNC.

Establishment of a diverse head and neck squamous cancer cell bank using conditional reprogramming culture methods

Most laboratory models of head and neck squamous cell cancer (HNSCC) rely on established immortalized cell lines, which carry inherent bias due to selection and clonality. We established a robust panel of HNSCC tumor cultures using a "conditional reprogramming" (CR) method, which utilizes a rho kinase inhibitor (Y-27632) and co-culture with irradiated fibroblast (J2 strain) feeder cells to support indefinite tumor cell survival. Sixteen CR cultures were successfully generated from 19 consecutively enrolled ethnically and racially diverse patients with HNSCC at a tertiary care center in the Bronx, NY. Of the 16 CR cultures, 9/16 were derived from the oral cavity, 4/16 were derived from the oropharynx, and 3/16 were from laryngeal carcinomas. Short tandem repeat (STR) profiling was used to validate culture against patient tumor tissue DNA. All CR cultures expressed ΔNp63 and cytokeratin 5/6, which are markers of squamous identity. Human papillomavirus (HPV) testing was assessed utilizing clinical p16 staining on primary tumors, reverse transcription polymerase chain reaction (RT-PCR) of HPV16/18-specific viral oncogenes E6 and E7 in RNA extracted from tumor samples, and HPV DNA sequencing. Three of four oropharyngeal tumors were p16 and HPV-positive and maintained HPV in culture. CR cultures were able to establish three-dimensional spheroid and murine flank and orthotopic tongue models. CR methods can be readily applied to all HNSCC tumors regardless of patient characteristics, disease site, and molecular background, providing a translational research model that properly includes patient and tumor diversity.

A living biobank of matched pairs of patient-derived xenografts and organoids for cancer pharmacology

Patient-derived tumor xenograft (PDX)/organoid (PDO), driven by cancer stem cells (CSC), are considered the most predictive models for translational oncology. Large PDX collections reflective of patient populations have been created and used extensively to test various investigational therapies, including population-trials as surrogate subjects in vivo. PDOs are recognized as in vitro surrogates for patients amenable for high-throughput screening (HTS). We have built a biobank of carcinoma PDX-derived organoids (PDXOs) by converting an existing PDX library and confirmed high degree of similarities between PDXOs and parental PDXs in genomics, histopathology and pharmacology, suggesting "biological equivalence or interchangeability" between the two. Here we demonstrate the applications of PDXO biobank for HTS "matrix" screening for both lead compounds and indications, immune cell co-cultures for immune-therapies and engineering enables in vitro/in vivo imaging. This large biobank of >550 matched pairs of PDXs/PDXOs across different cancers could become powerful tools for the future cancer drug discovery.

Single-Cell and Spatial Analysis of Emergent Organoid Platforms

Organoids have emerged as a promising advancement of the two-dimensional (2D) culture systems to improve studies in organogenesis, drug discovery, precision medicine, and regenerative medicine applications. Organoids can self-organize as three-dimensional (3D) tissues derived from stem cells and patient tissues to resemble organs. This chapter presents growth strategies, molecular screening methods, and emerging issues of the organoid platforms. Single-cell and spatial analysis resolve organoid heterogeneity to obtain information about the structural and molecular cellular states. Culture media diversity and varying lab-to-lab practices have resulted in organoid-to-organoid variability in morphology and cell compositions. An essential resource is an organoid atlas that can catalog protocols and standardize data analysis for different organoid types. Molecular profiling of individual cells in organoids and data organization of the organoid landscape will impact biomedical applications from basic science to translational use.

OrBITS: label-free and time-lapse monitoring of patient derived organoids for advanced drug screening

Background

Patient-derived organoids are invaluable for fundamental and translational cancer research and holds great promise for personalized medicine. However, the shortage of available analysis methods, which are often single-time point, severely impede the potential and routine use of organoids for basic research, clinical practise, and pharmaceutical and industrial applications.

Methods

Here, we developed a high-throughput compatible and automated live-cell image analysis software that allows for kinetic monitoring of organoids, named Organoid Brightfield Identification-based Therapy Screening (OrBITS), by combining computer vision with a convolutional network machine learning approach. The OrBITS deep learning analysis approach was validated against current standard assays for kinetic imaging and automated analysis of organoids. A drug screen of standard-of-care lung and pancreatic cancer treatments was also performed with the OrBITS platform and compared to the gold standard, CellTiter-Glo 3D assay. Finally, the optimal parameters and drug response metrics were identified to improve patient stratification.

Results

OrBITS allowed for the detection and tracking of organoids in routine extracellular matrix domes, advanced Gri3D®-96 well plates, and high-throughput 384-well microplates, solely based on brightfield imaging. The obtained organoid Count, Mean Area, and Total Area had a strong correlation with the nuclear staining, Hoechst, following pairwise comparison over a broad range of sizes. By incorporating a fluorescent cell death marker, intra-well normalization for organoid death could be achieved, which was tested with a 10-point titration of cisplatin and validated against the current gold standard ATP-assay, CellTiter-Glo 3D. Using this approach with OrBITS, screening of chemotherapeutics and targeted therapies revealed further insight into the mechanistic action of the drugs, a feature not achievable with the CellTiter-Glo 3D assay. Finally, we advise the use of the growth rate-based normalised drug response metric to improve accuracy and consistency of organoid drug response quantification.

Conclusion

Our findings validate that OrBITS, as a scalable, automated live-cell image analysis software, would facilitate the use of patient-derived organoids for drug development and therapy screening. The developed wet-lab workflow and software also has broad application potential, from providing a launching point for further brightfield-based assay development to be used for fundamental research, to guiding clinical decisions for personalized medicine.

Patient-derived organoids (PDOs) and PDO-derived xenografts (PDOXs): New opportunities in establishing faithful pre-clinical cancer models

One of the major bottlenecks in advancing basic cancer research and developing novel cancer therapies is the lack of in vitro pre-clinical models that faithfully recapitulate tumor properties in the patients. Monolayer cultures of cancer cell lines usually lose the heterogeneity of the parental tumors, while patient-derived xenograft (PDX) suffers from its time- and resource-intensive nature. The emergence of organoid culture system and its application in cancer research provides a unique opportunity to develop novel in vitro cancer pre-clinical models. Here we review the recent advances in utilizing organoids culture system and other related three-dimensional culture systems in studying cancer biology, performing drug screening, and developing cancer therapies. In particular, we discuss the advantages of applying xenograft initiated from patient-derived organoids (PDOs) as a faithful cancer pre-clinical model in basic cancer research and precision medicine.

Rapid tissue prototyping with micro-organospheres

In vitro tissue models hold great promise for modeling diseases and drug responses. Here, we used emulsion microfluidics to form micro-organospheres (MOSs), which are droplet-encapsulated miniature three-dimensional (3D) tissue models that can be established rapidly from patient tissues or cells. MOSs retain key biological features and responses to chemo-, targeted, and radiation therapies compared with organoids. The small size and large surface-to-volume ratio of MOSs enable various applications including quantitative assessment of nutrient dependence, pathogen-host interaction for anti-viral drug screening, and a rapid potency assay for chimeric antigen receptor (CAR)-T therapy. An automated MOS imaging pipeline combined with machine learning overcomes plating variation, distinguishes tumorspheres from stroma, differentiates cytostatic versus cytotoxic drug effects, and captures resistant clones and heterogeneity in drug response. This pipeline is capable of robust assessments of drug response at individual-tumorsphere resolution and provides a rapid and high-throughput therapeutic profiling platform for precision medicine.

In vitro models for head and neck cancer: Current status and future perspective

The 5-year overall survival rate remains approximately 50% for head and neck (H&N) cancer patients, even though new cancer drugs have been approved for clinical use since 2016. Cancer drug studies are now moving toward the use of three-dimensional culture models for better emulating the unique tumor microenvironment (TME) and better predicting in vivo response to cancer treatments. Distinctive TME features, such as tumor geometry, heterogenous cellularity, and hypoxic cues, notably affect tissue aggressiveness and drug resistance. However, these features have not been fully incorporated into in vitro H&N cancer models. This review paper aims to provide a scholarly assessment of the designs, contributions, and limitations of in vitro models in H&N cancer drug research. We first review the TME features of H&N cancer that are most relevant to in vitro drug evaluation. We then evaluate a selection of advanced culture models, namely, spheroids, organotypic models, and microfluidic chips, in their applications for H&N cancer drug research. Lastly, we propose future opportunities of in vitro H&N cancer research in the prospects of high-throughput drug screening and patient-specific drug evaluation.

Living biobank-based cancer organoids: prospects and challenges in cancer research

Biobanks bridge the gap between basic and translational research. Traditional cancer biobanks typically contain normal and tumor tissues, and matched blood. However, biospecimens in traditional biobanks are usually nonrenewable. In recent years, increased interest has focused on establishing living biobanks, including organoid biobanks, for the collection and storage of viable and functional tissues for long periods of time. The organoid model is based on a 3D in vitro cell culture system, is highly similar to primary tissues and organs in vivo, and can recapitulate the phenotypic and genetic characteristics of target organs. Publications on cancer organoids have recently increased, and many types of cancer organoids have been used for modeling cancer processes, as well as for drug discovery and screening. On the basis of the current research status, more exploration of cancer organoids through technical advancements is required to improve reproducibility and scalability. Moreover, given the natural characteristics of organoids, greater attention must be paid to ethical considerations. Here, we summarize recent advances in cancer organoid biobanking research, encompassing rectal, gastric, pancreatic, breast, and glioblastoma cancers. Living cancer biobanks that contain cancerous tissues and matched organoids with different genetic backgrounds, subtypes, and individualized characteristics will eventually contribute to the understanding of cancer and ultimately facilitate the development of innovative treatments.

Models of head and neck squamous cell carcinoma using bioengineering approaches

The use of bioengineering methods and approaches is extremely promising for the development of experimental models of cancer, especially head and neck squamous cell carcinomas (HNSCC) that are characterized by early metastasis and rapid progression., for testing novel anticancer drugs and diagnostics. This review summarizes the most relevant HNSCC tumor models used to this day as well as future directions for improved modeling of the malignant disease. Apart from conventional 2D-cell cultivation methods and in vivo animal cancer models a number of bioengineering techniques of modeling HNSCC tumors were reported: genetic-engineering, ethanol/tobacco exposure experiment, spheroids, hydrogel-based cell culture, scaffold-based cell culture, microfluidics, bone-tumor niche cell culture, cancer and normal cells co-culture, cancer cells, and bacteria co-culture. An organized set of these models can constitute a system of HNSCC experimental modeling, which gives potential towards developing the newest approaches in the diagnosis, prevention, and treatment of HNSCC.

Patient-derived Tumour Organoids: A Bridge between Cancer Biology and Personalised Therapy

Patient-derived tumour organoids (PDOs) have revolutionised our understanding of cancer biology and the applications of personalised therapies. These advancements are principally ascribed to the ability of PDOs to consistently recapitulate and maintain the genomic, proteomic and morphological characteristics of parental tumours. Given these characteristics, PDOs (and their extended biobanks) are a representative preclinical model eminently suited to translate relevant scientific findings into personalized therapies rapidly. Here, we summarise recent advancements in PDOs from the perspective of cancer biology and clinical applications, focusing on the current challenges and opportunities of reconstructing and standardising more sophisticated PDO models. STATEMENT OF SIGNIFICANCE: Patient-derived tumour organoids (PDOs), three-dimensional (3D) self-assembled organotypic structures, have revolutionised our understanding of cancer biology and the applications of personalised therapies. These advancements are principally ascribed to the ability of PDOs to consistently recapitulate and maintain the genomic, proteomic and morphological characteristics of parental tumours. Given these characteristics, PDOs (and their extended biobanks) are a representative preclinical model eminently suited to translate relevant scientific findings into personalized therapies rapidly.

Translational and Clinical Relevance of PDX-Derived Organoid Models in Oncology Drug Discovery and Development

Patient-derived cancer disease models conserve many key features of the original human cancers, potentially allowing higher predictive power than traditional cell line models. Accordingly, in vivo patient-derived xenografts (PDX) are frequently utilized in preclinical and translational oncology studies as patient surrogates for population-based screens ("mouse clinical trials"), for which large PDX biobanks have been generated over the last decade from various cancer types. In vitro patient-derived organoids (PDO) have recently emerged as a disruptive technology, enabling early "patient in a dish" clinical trials. Like PDX, PDOs retain the histology/genomics of the original tumor and are highly predictive of the clinical response. Organoids derived from adult stem cells (ASC) in patient tissue can function as mini-organs. They have greater advantages over other 3D in vitro systems, making them highly predictive, reliable, and consistent in vitro models. Large biobanks enable the adoption of organoids in early drug screening and patient selection. PDX biobanks, as a source of human material, have been used to create 3D in vitro screens, but with limitations. However, creating organoids from the ASCs residing in PDXs has been successfully used as a rapid and cost-effective way to enable higher throughput in vitro screens and generate matched in vitro/in vivo model pairs that retain genomic, histopathological, and pharmacology profiles. This overview summarizes the generation of matched in vitro/in vivo models from patient material, the advantages over other systems, and the applications to drug discovery. © 2022 Wiley Periodicals LLC.

Protocol for drug screening of patient-derived tumor organoids using high-content fluorescent imaging

High-content imaging of tumor organoids (TOs) treated with therapeutic agents provides detailed cell viability readouts at the organoid level. In contrast, most used protocols provide one number per well. While requiring the use of inverted microscopy with an automated stage, this protocol can provide critical information about heterogeneous responses of TOs to various treatments. This protocol describes a technique for culturing and drug testing TOs using fluorescent indicators of cell viability with high reproducibility. For complete details on the use and execution of this protocol, please refer to Larsen et al. (2021).

Patient-derived micro-organospheres enable clinical precision oncology

Patient-derived xenografts (PDXs) and patient-derived organoids (PDOs) have been shown to model clinical response to cancer therapy. However, it remains challenging to use these models to guide timely clinical decisions for cancer patients. Here, we used droplet emulsion microfluidics with temperature control and dead-volume minimization to rapidly generate thousands of micro-organospheres (MOSs) from low-volume patient tissues, which serve as an ideal patient-derived model for clinical precision oncology. A clinical study of recently diagnosed metastatic colorectal cancer (CRC) patients using an MOS-based precision oncology pipeline reliably assessed tumor drug response within 14 days, a timeline suitable for guiding treatment decisions in the clinic. Furthermore, MOSs capture original stromal cells and allow T cell penetration, providing a clinical assay for testing immuno-oncology (IO) therapies such as PD-1 blockade, bispecific antibodies, and T cell therapies on patient tumors.

Precision Medicine in Head and Neck Cancers: Genomic and Preclinical Approaches

Head and neck cancers (HNCs) represent the sixth most widespread malignancy worldwide. Surgery, radiotherapy, chemotherapeutic and immunotherapeutic drugs represent the main clinical approaches for HNC patients. Moreover, HNCs are characterised by an elevated mutational load; however, specific genetic mutations or biomarkers have not yet been found. In this scenario, personalised medicine is showing its efficacy. To study the reliability and the effects of personalised treatments, preclinical research can take advantage of next-generation sequencing and innovative technologies that have been developed to obtain genomic and multi-omic profiles to drive personalised treatments. The crosstalk between malignant and healthy components, as well as interactions with extracellular matrices, are important features which are responsible for treatment failure. Preclinical research has constantly implemented in vitro and in vivo models to mimic the natural tumour microenvironment. Among them, 3D systems have been developed to reproduce the tumour mass architecture, such as biomimetic scaffolds and organoids. In addition, in vivo models have been changed over the last decades to overcome problems such as animal management complexity and time-consuming experiments. In this review, we will explore the new approaches aimed to improve preclinical tools to study and apply precision medicine as a therapeutic option for patients affected by HNCs.

Head and neck cancer organoids as a promising tool for personalized cancer therapy: A literature review

Background and Aim

Chemotherapy and targeted therapy are used in treating head and neck cancers (HNCs) either alone or in combination with surgery, especially in advanced tumors but these treatments have resulted in variable outcomes in different patients. This, along with the introduction of new therapies to improve the survival of patients makes it necessary to search for models that can predict the response to treatment among different patients. Organoids, as three‐dimensional culture models, have been studied more widely in non‐HNCs and to a lesser extent in HNCs as tools to predict treatment outcomes. We aimed to conduct a review to validate the use of organoids as a preclinical tool for the treatment of HNCs patients.

Methods

A comprehensive literature search was separately performed by both authors in PubMed and google scholar databases, using the following keywords: “organoid,” “head and neck cancer,” “personalized medicine,” “chemotherapy,” and “targeted therapy.” The articles published up to September 2021 were included in this review and selected according to a quality appraisal method.

Results

Examination of HNC‐derived organoids made in various studies showed that these organoids had the ability to recapitulate original tumor features, including histopathological properties, functional characteristics, and expression of molecular markers in almost all of the studies. Differential sensitivity to chemotherapy drugs similar to in vivo was observed in sensitivity testing. Epidermal growth factor receptor (EGFR) expression levels were different between organoids from different patients and EGFR expression level was found to correlate with the response to anti‐EGFR targeted therapy. A similar result was reported for organoids derived from salivary adenoid cystic carcinoma.

Conclusion

Since HNC‐derived organoids seem to recapitulate characteristics of original tumors and to show differential responses to different chemotherapy and targeted therapy agents, these organoids might have the potential to be used as preclinical prediction tools for the treatment of HNC patients.

3D and organoid culture in research: physiology, hereditary genetic diseases and cancer

In nature, cells reside in tissues subject to complex cell–cell interactions, signals from extracellular molecules and niche soluble and mechanical signaling. These microenvironment interactions are responsible for cellular phenotypes and functions, especially in normal settings. However, in 2D cultures, where interactions are limited to the horizontal plane, cells are exposed uniformly to factors or drugs; therefore, this model does not reconstitute the interactions of a natural microenvironment. 3D culture systems more closely resemble the architectural and functional properties of in vivo tissues. In these 3D cultures, the cells are exposed to different concentrations of nutrients, growth factors, oxygen or cytotoxic agents depending on their localization and communication. The 3D architecture also differentially alters the physiological, biochemical, and biomechanical properties that can affect cell growth, cell survival, differentiation and morphogenesis, cell migration and EMT properties, mechanical responses and therapy resistance. This latter point may, in part, explain the failure of current therapies and affect drug discovery research. Organoids are a promising 3D culture system between 2D cultures and in vivo models that allow the manipulation of signaling pathways and genome editing of cells in a body-like environment but lack the many disadvantages of a living system. In this review, we will focus on the role of stem cells in the establishment of organoids and the possible therapeutic applications of this model, especially in the field of cancer research.

Nimotuzumab shows an additive effect to inhibit cell growth of ALA-PDT treated oral cancer cells

Oral squamous cell carcinoma (OSCC) is characterized by severe functional impairment and a poor prognosis. The epidermal growth factor receptor (EGFR) is highly expressed in OSCC and is a promising target for cancer therapy. In addition, aminolevulinic acid-induced photodynamic therapy (ALA-PDT) has produced robust clinical effects and showed some advantages over radiotherapy in oral cancer. Here, an EGFR inhibitor, nimotuzumab, was administered to 2 OSCC cell lines, CAL-27 and SCC-25, treated with ALA-PDT. Cell growth, apoptosis, and reactive oxygen species (ROS) generation were used to measure the antitumor activity of the combination therapy. The in vivo effect of nimotuzumab plus ALA-PDT was done using a mouse OSCC xenograft model (SCC-25). EGFR expression was further compared by Western blotting in different groups. We observed that nimotuzumab combined with ALA-PDT could enhance inhibition of OSCC cell growth in vitro and in vivo. We also observed an enhanced effect after combination on cell apoptosis in CAL-27 and SCC-25 cells. Furthermore, combined therapy significantly reduced the protein expression levels of EGFR in vitro. However, we observed that nimotuzumab plus ALA-PDT did not increase ROS generation substantially in OSCC cells compared to the ALA-PDT group alone. These observations indicate that nimotuzumab combined with ALA-PDT has valuable applications for OSCC treatment.

Targeted photoimmunotherapy for cancer

Photodynamic therapy (PDT) is a clinically approved procedure that can exert a curative action against malignant cells. The treatment implies the administration of a photoactive molecular species that, upon absorption of visible or near infrared light, sensitizes the formation of reactive oxygen species. These species are cytotoxic and lead to tumor cell death, damage vasculature, and induce inflammation. Clinical investigations demonstrated that PDT is curative and does not compromise other treatment options. One of the major limitations of the original method was the low selectivity of the photoactive compounds for malignant over healthy tissues. The development of conjugates with antibodies has endowed photosensitizing molecules with targeting capability, so that the compounds are delivered with unprecedented precision to the site of action. Given their fluorescence emission capability, these supramolecular species are intrinsically theranostic agents.

A Photosensitized Singlet Oxygen (1O2) Toolbox for Bio-Organic Applications: Tailoring 1O2 Generation for DNA and Protein Labelling, Targeting and Biosensing

Singlet oxygen (1O2) is the excited state of ground, triplet state, molecular oxygen (O2). Photosensitized 1O2 has been extensively studied as one of the reactive oxygen species (ROS), responsible for damage of cellular components (protein, DNA, lipids). On the other hand, its generation has been exploited in organic synthesis, as well as in photodynamic therapy for the treatment of various forms of cancer. The aim of this review is to highlight the versatility of 1O2, discussing the main bioorganic applications reported over the past decades, which rely on its production. After a brief introduction on the photosensitized production of 1O2, we will describe the main aspects involving the biologically relevant damage that can accompany an uncontrolled, aspecific generation of this ROS. We then discuss in more detail a series of biological applications featuring 1O2 generation, including protein and DNA labelling, cross-linking and biosensing. Finally, we will highlight the methodologies available to tailor 1O2 generation, in order to accomplish the proposed bioorganic transformations while avoiding, at the same time, collateral damage related to an untamed production of this reactive species.

EGFR-Targeted Photodynamic Therapy

The epidermal growth factor receptor (EGFR) plays a pivotal role in the proliferation and metastatization of cancer cells. Aberrancies in the expression and activation of EGFR are hallmarks of many human malignancies. As such, EGFR-targeted therapies hold significant potential for the cure of cancers. In recent years, photodynamic therapy (PDT) has gained increased interest as a non-invasive cancer treatment. In PDT, a photosensitizer is excited by light to produce reactive oxygen species, resulting in local cytotoxicity. One of the critical aspects of PDT is to selectively transport enough photosensitizers to the tumors environment. Accordingly, an increasing number of strategies have been devised to foster EGFR-targeted PDT. Herein, we review the recent nanobiotechnological advancements that combine the promise of PDT with EGFR-targeted molecular cancer therapy. We recapitulate the chemistry of the sensitizers and their modes of action in PDT, and summarize the advantages and pitfalls of different targeting moieties, highlighting future perspectives for EGFR-targeted photodynamic treatment of cancer.

In Vitro Assessment of Binding Affinity, Selectivity, Uptake, Intracellular Degradation, and Toxicity of Nanobody-Photosensitizer Conjugates

Photosensitizers have recently been conjugated to nanobodies for targeted photodynamic therapy (PDT) to selectively kill cancer cells. The success of this approach relies on nanobody-photosensitizer conjugates that bind specifically to their targets with very high affinities (k_D in low nM range). Subsequently, upon illumination, these conjugates are very toxic and selective to cells overexpressing the target of interest (EC₅₀ in low nM range). In this chapter, protocols are described to determine the binding affinity of the nanobody-photosensitizer conjugates and assess the toxicity and selectivity of the conjugates when performing in vitro PDT studies. In addition, and because the efficacy of PDT also depends on the (subcellular) localization of the conjugates at the time of illumination, assays are described to investigate the uptake and the intracellular degradation of the nanobody-photosensitizer conjugates.

Investigation of the Therapeutic Potential of Nanobody-Targeted Photodynamic Therapy in an Orthotopic Head and Neck Cancer Model

Photodynamic therapy (PDT) has a great therapeutic potential because it induces local cellular cytotoxicity upon application of a laser light that excites a photosensitizer, leading to toxic reactive oxygen species. Nevertheless, PDT still is underutilized in the clinic, mostly because of damage induced to normal surrounding tissues. Efforts have been made to improve the specificity. Nanobody-targeted PDT is one of such approaches, in which the variable domain of heavy-chain antibodies, i.e., nanobodies, are used to target photosensitizers selectively to cancer cells. In vitro studies are certainly very valuable to evaluate the therapeutic potential of PDT approaches, but many aspects such as bio-distribution of the photosensitizers, penetration through tissues, and clearance are not taken into account. In vivo studies are therefore essential to assess the influence of such factors, in order to gain more insights into the therapeutic potential of a treatment under development. This chapter describes the development of an orthotopic model of head and neck cancer, to which nanobody-targeted PDT is applied, and the therapeutic potential is assessed by immunohistochemistry one day after PDT.

Orthotopic Breast Cancer Model to Investigate the Therapeutic Efficacy of Nanobody-Targeted Photodynamic Therapy

Photodynamic therapy (PDT) is characterized by the local application of laser light, which activates a photosensitizer to lead to the formation of singlet oxygen and other toxic reactive oxygen species, to finally kill cells. Recently, photosensitizers have been conjugated to nanobodies to render PDT more selective to cancer cells. Nanobodies are the smallest naturally derived antibody fragments from heavy-chain antibodies that exist in animals of the Camelidae family. Indeed, we have shown that nanobody-targeted PDT can lead to extensive and selective tumor damage, and thus the subsequent step is to assess whether this damage can delay or even inhibit tumor growth in vivo. To evaluate the therapeutic efficacy of PDT, mouse models are mostly employed in which human tumors are grown subcutaneously in the flank of the animals. Although very useful, it has been suggested that these tumors are further away from their natural environment and that tumors developed in the organ or tissue of origin would be closer to the natural situation. Thus, this chapter describes the development of an orthotopic model of breast cancer and the application of nanobody-targeted PDT, for the assessment of the therapeutic efficacy.

Shooting at Moving and Hidden Targets-Tumour Cell Plasticity and the Notch Signalling Pathway in Head and Neck Squamous Cell Carcinomas

Head and Neck Squamous Cell Carcinoma (HNSCC) is often aggressive, with poor response to current therapies in approximately 40-50% of the patients. Current therapies are restricted to operation and irradiation, often combined with a small number of standard-of-care chemotherapeutic drugs, preferentially for advanced tumour patients. Only very recently, newer targeted therapies have entered the clinics, including Cetuximab, which targets the EGF receptor (EGFR), and several immune checkpoint inhibitors targeting the immune receptor PD-1 and its ligand PD-L1. HNSCC tumour tissues are characterized by a high degree of intra-tumour heterogeneity (ITH), and non-genetic alterations that may affect both non-transformed cells, such as cancer-associated fibroblasts (CAFs), and transformed carcinoma cells. This very high degree of heterogeneity likely contributes to acquired drug resistance, tumour dormancy, relapse, and distant or lymph node metastasis. ITH, in turn, is likely promoted by pronounced tumour cell plasticity, which manifests in highly dynamic and reversible phenomena such as of partial or hybrid forms of epithelial-to-mesenchymal transition (EMT), and enhanced tumour stemness. Stemness and tumour cell plasticity are strongly promoted by Notch signalling, which remains poorly understood especially in HNSCC. Here, we aim to elucidate how Notch signal may act both as a tumour suppressor and proto-oncogenic, probably during different stages of tumour cell initiation and progression. Notch signalling also interacts with numerous other signalling pathways, that may also have a decisive impact on tumour cell plasticity, acquired radio/chemoresistance, and metastatic progression of HNSCC. We outline the current stage of research related to Notch signalling, and how this pathway may be intricately interconnected with other, druggable targets and signalling mechanisms in HNSCC.

Tumor organoids: synergistic applications, current challenges, and future prospects in cancer therapy

Patient-derived cancer cells (PDCs) and patient-derived xenografts (PDXs) are often used as tumor models, but have many shortcomings. PDCs not only lack diversity in terms of cell type, spatial organization, and microenvironment but also have adverse effects in stem cell cultures, whereas PDX are expensive with a low transplantation success rate and require a long culture time. In recent years, advances in three-dimensional (3D) organoid culture technology have led to the development of novel physiological systems that model the tissues of origin more precisely than traditional culture methods. Patient-derived cancer organoids bridge the conventional gaps in PDC and PDX models and closely reflect the pathophysiological features of natural tumorigenesis and metastasis, and have led to new patient-specific drug screening techniques, development of individualized treatment regimens, and discovery of prognostic biomarkers and mechanisms of resistance. Synergistic combinations of cancer organoids with other technologies, for example, organ-on-a-chip, 3D bio-printing, and CRISPR-Cas9-mediated homology-independent organoid transgenesis, and with treatments, such as immunotherapy, have been useful in overcoming their limitations and led to the development of more suitable model systems that recapitulate the complex stroma of cancer, inter-organ and intra-organ communications, and potentially multiorgan metastasis. In this review, we discuss various methods for the creation of organ-specific cancer organoids and summarize organ-specific advances and applications, synergistic technologies, and treatments as well as current limitations and future prospects for cancer organoids. Further advances will bring this novel 3D organoid culture technique closer to clinical practice in the future.

Nanobody-targeted photodynamic therapy for the treatment of feline oral carcinoma: a step towards translation to the veterinary clinic

Nanobody-targeted photodynamic therapy (NB-PDT) has been developed as a potent and tumor-selective treatment, using nanobodies (NBs) to deliver a photosensitizer (PS) specifically to cancer cells. Upon local light application, reactive oxygen species are formed and consequent cell death occurs. NB-PDT has preclinically shown evident success and we next aim to treat cats with oral squamous cell carcinoma (OSCC), which has very limited therapeutic options and is regarded as a natural model of human head and neck SCC. Immunohistochemistry of feline OSCC tissue confirmed that the epidermal growth factor receptor (EGFR) is a relevant target with expression in cancer cells and not in the surrounding stroma. Three feline OSCC cell lines were employed together with a well-characterized human cancer cell line (HeLa), all with similar EGFR expression, and a low EGFR-expressing human cell line (MCF7), mirroring the EGFR expression level in the surrounding mucosal stroma. NB_A was identified as a NB binding human and feline EGFR with comparable high affinity. This NB was developed into NiBh, a NB-PS conjugate with high PS payload able to effectively kill feline OSCC and HeLa cell lines, after illumination. Importantly, the specificity of NB-PDT was confirmed in co-cultures where only the feline OSCC cells were killed while surrounding MCF7 cells were unaffected. Altogether, NiBh can be used for NB-PDT to treat feline OSCC and further advance NB-PDT towards the human clinic.

Anti-EGFR Binding Nanobody Delivery System to Improve the Diagnosis and Treatment of Solid Tumours

BACKGROUND

Epidermal Growth Factor Receptor (EGFR) and members of its homologous protein family mediate transmembrane signal transduction by binding to a specific ligand, which leads to regulated cell growth, differentiation, proliferation and metastasis. With the development and application of Genetically Engineered Antibodies (GEAs), Nanobodies (Nbs) constitute a new research hot spot in many diseases. A Nb is characterized by its low molecular weight, deep tissue penetration, good solubility and high antigen-binding affinity, the anti-EGFR Nbs are of significance for the diagnosis and treatment of EGFR-positive tumours.

OBJECTIVE

This review aims to provide a comprehensive overview of the information about the molecular structure of EGFR and its transmembrane signal transduction mechanism, and discuss the anti-EGFR-Nbs influence on the diagnosis and treatment of solid tumours.

METHODS

Data were obtained from PubMed, Embase and Web of Science. All patents are searched from the following websites: the World Intellectual Property Organization (WIPO®), the United States Patent Trademark Office (USPTO®) and Google Patents.

RESULTS

EGFR is a key target for regulating transmembrane signaling. The anti-EGFR-Nbs for targeted drugs could effectively improve the diagnosis and treatment of solid tumours.

CONCLUSION

EGFR plays a role in transmembrane signal transduction. The Nbs, especially anti- EGFR-Nbs, have shown effectiveness in the diagnosis and treatment of solid tumours. How to increase the affinity of Nb and reduce its immunogenicity remain a great challenge.