The development of a liquid biopsy for head and neck cancers

The Role of ctDNA and Liquid Biopsy in the Diagnosis and Monitoring of Head and Neck Cancer: Towards Precision Medicine

Recent data have shown a continued rise in the worldwide annual incidence and mortality rates of head and neck cancers. The present standard for diagnosis and monitoring for disease recurrence or progression involves clinical examination, imaging, and invasive biopsy techniques of lesions suspected of being malignant. In addition to limitations relating to cost, time, and patient discomfort, these methodologies have inherent inaccuracies for detecting recurrence. In view of these limitations, the analysis of patient bodily fluid samples via liquid biopsy proposes a cost-effective and convenient alternative, which provides insight on the biogenetic and biomolecular underpinnings of oncologic disease processes. The monitoring of biomarkers for head and neck cancer via liquid biopsy, including circulating tumor DNA, circulating tumor cells, and circulating cell-free RNA, has shown clinical utility in the screening, diagnosis, prognostication, and monitoring of patients with various forms of head and neck cancer. The present review will provide an update on the current literature examining the use of liquid biopsy in head and neck cancer care and the clinical applicability of potential biomarkers, with a focus on viral and non-viral circulating tumor DNA. Possible future avenues for research to address specific shortcomings of liquid biopsy will be discussed.

A comparison between mutational profiles in tumour tissue DNA and circulating tumour DNA in head and neck squamous cell carcinoma - A systematic review

BACKGROUND

Head and neck cancer is the seventh most common malignancy globally. Head and neck squamous cell carcinoma (HNSCC) originates from squamous cells and 90% of HNC are HNSCC. The gold standard for diagnosing HNSCC is tissue biopsy. However, given tumour heterogeneity, biopsies may miss important cancer-associated molecular signatures, and more importantly, after the tumour is excised, there is no means of tracking response to treatment in patients. Captured under liquid biopsy, circulating tumour DNA (ctDNA), may identify in vivo molecular genotypes and complements tumour tissue analysis in cancer management. A systematic search was conducted in PubMed, Embase, Scopus and the Cochran Library between 2012 to early 2023 on ctDNA in HNSCC using publications written in English. We summarise 20 studies that compared mutational profiles between tumour tissue DNA (tDNA) and ctDNA, using a cohort of 631 HNSCC patients and 139 controls. Among these studies, the concordance rates varied greatly and the most mutated and the most concordant gene was TP53, followed by PIK3CA, CDKN2A, NOTCH1 and FAT1. Concordant variants were mainly found in Stage IV tumours, and the mutation type is mostly single nucleotide variants (SNV). We conclude that, as a biomarker for HNSCC, ctDNA demonstrates great promise as it recapitulates tumour genotypes, however additional multi-central trials are needed.

Circulating tumour DNA alterations: emerging biomarker in head and neck squamous cell carcinoma

Head and Neck cancers (HNC) are a heterogeneous group of upper aero-digestive tract cancer and account for 931,922 new cases and 467,125 deaths worldwide. About 90% of these cancers are of squamous cell origin (HNSCC). HNSCC is associated with excessive tobacco and alcohol consumption and infection with oncogenic viruses. Genotyping tumour tissue to guide clinical decision-making is becoming common practice in modern oncology, but in the management of patients with HNSCC, cytopathology or histopathology of tumour tissue remains the mainstream for diagnosis and treatment planning. Due to tumour heterogeneity and the lack of access to tumour due to its anatomical location, alternative methods to evaluate tumour activities are urgently needed. Liquid biopsy approaches can overcome issues such as tumour heterogeneity, which is associated with the analysis of small tissue biopsy. In addition, liquid biopsy offers repeat biopsy sampling, even for patients with tumours with access limitations. Liquid biopsy refers to biomarkers found in body fluids, traditionally blood, that can be sampled to provide clinically valuable information on both the patient and their underlying malignancy. To date, the majority of liquid biopsy research has focused on blood-based biomarkers, such as circulating tumour DNA (ctDNA), circulating tumour cells (CTCs), and circulating microRNA. In this review, we will focus on ctDNA as a biomarker in HNSCC because of its robustness, its presence in many body fluids, adaptability to existing clinical laboratory-based technology platforms, and ease of collection and transportation. We will discuss mechanisms of ctDNA release into circulation, technological advances in the analysis of ctDNA, ctDNA as a biomarker in HNSCC management, and some of the challenges associated with translating ctDNA into clinical and future perspectives. ctDNA provides a minimally invasive method for HNSCC prognosis and disease surveillance and will pave the way in the future for personalized medicine, thereby significantly improving outcomes and reducing healthcare costs.

Identification of Somatic Mutations in Plasma Cell-Free DNA from Patients with Metastatic Oral Squamous Cell Carcinoma

The accurate diagnosis and treatment of oral squamous cell carcinoma (OSCC) requires an understanding of its genomic alterations. Liquid biopsies, especially cell-free DNA (cfDNA) analysis, are a minimally invasive technique used for genomic profiling. We conducted comprehensive whole-exome sequencing (WES) of 50 paired OSCC cell-free plasma with whole blood samples using multiple mutation calling pipelines and filtering criteria. Integrative Genomics Viewer (IGV) was used to validate somatic mutations. Mutation burden and mutant genes were correlated to clinico-pathological parameters. The plasma mutation burden of cfDNA was significantly associated with clinical staging and distant metastasis status. The genes TTN, PLEC, SYNE1, and USH2A were most frequently mutated in OSCC, and known driver genes, including KMT2D, LRP1B, TRRAP, and FLNA, were also significantly and frequently mutated. Additionally, the novel mutated genes CCDC168, HMCN2, STARD9, and CRAMP1 were significantly and frequently present in patients with OSCC. The mutated genes most frequently found in patients with metastatic OSCC were RORC, SLC49A3, and NUMBL. Further analysis revealed that branched-chain amino acid (BCAA) catabolism, extracellular matrix-receptor interaction, and the hypoxia-related pathway were associated with OSCC prognosis. Choline metabolism in cancer, O-glycan biosynthesis, and protein processing in the endoplasmic reticulum pathway were associated with distant metastatic status. About 20% of tumors carried at least one aberrant event in BCAA catabolism signaling that could possibly be targeted by an approved therapeutic agent. We identified molecular-level OSCC that were correlated with etiology and prognosis while defining the landscape of major altered events of the OSCC plasma genome. These findings will be useful in the design of clinical trials for targeted therapies and the stratification of patients with OSCC according to therapeutic efficacy.

Unsupervised Hierarchical Clustering of Head and Neck Cancer Patients by Pre-Treatment Plasma Metabolomics Creates Prognostic Metabolic Subtypes

There is growing evidence that the metabolism is deeply intertwined with head and neck squamous cell carcinoma (HNSCC) progression and survival but little is known about circulating metabolite patterns and their clinical potential. We performed unsupervised hierarchical clustering of 209 HNSCC patients via pre-treatment plasma metabolomics to identify metabolic subtypes. We annotated the subtypes via pathway enrichment analysis and investigated their association with overall and progression-free survival. We stratified the survival analyses by smoking history. High-resolution metabolomics extracted 186 laboratory-confirmed metabolites. The optimal model created two patient clusters, of subtypes A and B, corresponding to 41% and 59% of the study population, respectively. Fatty acid biosynthesis, acetyl-CoA transport, arginine and proline, as well as the galactose metabolism pathways differentiated the subtypes. Relative to subtype B, subtype A patients experienced significantly worse overall and progression-free survival but only among ever-smokers. The estimated three-year overall survival was 61% for subtype A and 86% for subtype B; log-rank p = 0.001. The association with survival was independent of HPV status and other HNSCC risk factors (adjusted hazard ratio = 3.58, 95% CI: 1.46, 8.78). Our findings suggest that a non-invasive metabolomic biomarker would add crucial information to clinical risk stratification and raise translational research questions about testing such a biomarker in clinical trials.

Circulating Tumor DNA in Head and Neck Squamous Cell Carcinoma

Tumors shed cell-free DNA (cfDNA) into the plasma. "Liquid biopsies" are a diagnostic test to analyze cfDNA in order to detect minimal residual cancer, profile the genomic tumor landscape, and monitor cancers non-invasively over time. This technique may be useful in patients with head and neck squamous cell carcinoma (HNSCC) due to genetic tumor heterogeneity and limitations in imaging sensitivity. However, there are technical challenges that need to be overcome for the widespread use of liquid biopsy in the clinical management of these patients. In this review, we discuss our current understanding of HNSCC genetics and the role of cfDNA genomic analyses as an emerging precision diagnostic tool.

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.

Head and neck cancer N-glycome traits are cell line and HPV status–dependent

Glycosylation is the most common post-translational modification of proteins, and glycosylation changes at cell surfaces are frequently associated with malignant epithelia including head and neck squamous cell carcinoma (HNSCC). In HNSCC, 5-year survival remains poor, averaging around 50% globally: this is partly related to late diagnosis. Specific protein glycosylation signatures on malignant keratinocytes have promise as diagnostic and prognostic biomarkers and as therapeutic targets. Nevertheless, HNSCC-specific glycome is to date largely unknown. Herein, we tested six established HNSCC cell lines to capture the qualitative and semi-quantitative N-glycome using porous graphitized carbon liquid chromatography coupled to electrospray ionisation tandem mass spectrometry. Oligomannose-type N-glycans were the predominant features in all HNSCC cell lines analysed (57.5–70%). The levels of sialylated N-glycans showed considerable cell line-dependent differences ranging from 24 to 35%. Importantly, α2-6 linked sialylated N-glycans were dominant across most HNSCC cell lines except in SCC-9 cells where similar levels of α2-6 and α2-3 sialylated N-glycans were observed. Furthermore, we found that HPV-positive cell lines contained higher levels of phosphorylated oligomannose N-glycans, which hint towards an upregulation of lysosomal pathways. Almost all fucose-type N-glycans carried core-fucose residues with just minor levels (< 4%) of Lewis-type fucosylation identified. We also observed paucimannose-type N-glycans (2–5.5%), though in low levels. Finally, we identified oligomannose N-glycans carrying core-fucose residues and confirmed their structure by tandem mass spectrometry. This first systematic mapping of the N-glycome revealed diverse and specific glycosylation features in HNSCC, paving the way for further studies aimed at assessing their possible diagnostic relevance.

Exosomes at the crossroad between therapeutic targets and therapy resistance in head and neck squamous cell carcinoma

Head and neck squamous cell carcinomas (HNSCCs) are aggressive and clinically challenging tumours that require a multidisciplinary management approach. Despite significant therapy improvements, HNSCC patients have a poor prognosis with a 5-year survival rate of about 65%. As recently recognised key players in cancer, exosomes are extracellular vesicles (EVs) with a diameter of nearly 50-120 nm which transport information from one cell to another. Exosomes are actively involved in various aspects of tumour initiation, development, metastasis, immune regulation, therapy resistance, and therapeutic applications. However, current knowledge of the role of exosomes in the pathophysiological processes of HNSCC is still in its infancy, and additional studies are needed. In this review, we summarise and discuss the relevance of exosomes in mediating local immunosuppression and therapy resistance of HNSCC. We also review the most recent studies that have explored the therapeutic potential of exosomes as cancer vaccines, drug carriers or tools to reverse the drug resistance of HNSCC.

Application of circulating tumour cells to predict response to treatment in head and neck cancer

Background

Local recurrence and metastasis remain the major causes of death in head and neck cancer (HNC) patients. Circulating tumour cells (CTCs) are shed from primary and metastatic sites into the circulation system and have been reported to play critical roles in the metastasis and recurrence of HNC. Here, we explored the use of CTCs to predict the response to treatment and disease progression in HNC patients.

Methods

Blood samples were collected at diagnosis from HNC patients (n = 119). CTCs were isolated using a spiral microfluidic device and were identified using immunofluorescence staining. Correlation of baseline CTC numbers to 13-week PET-CT data and multidisciplinary team consensus data were conducted.

Results

CTCs were detected in 60/119 (50.4%) of treatment naïve HNC patients at diagnosis. Baseline CTC numbers were higher in stage III vs. stage I-II p16-positive oropharyngeal cancers (OPCs) and other HNCs (p = 0.0143 and 0.032, respectively). In addition, we found that baseline CTC numbers may serve as independent predictors of treatment response, even after adjusting for other conventional prognostic factors. CTCs were detected in 10 out of 11 patients exhibiting incomplete treatment responses.

Conclusions

We found that baseline CTC numbers are correlated with treatment response in patients with HNC. The expression level of cell-surface vimentin (CSV) on CTCs was significantly higher in patients with persistent or progressive disease, thus providing additional prognostic information for stratifying the risk at diagnosis in HNC patients. The ability to detect CTCs at diagnosis allows more accurate risk stratification, which in the future may be translated into better patient selection for treatment intensification and/or de-intensification strategies.

Supplementary information

The online version contains supplementary material available at 10.1007/s13402-022-00681-w.

Alcohol and Head and Neck Cancer: Updates on the Role of Oxidative Stress, Genetic, Epigenetics, Oral Microbiota, Antioxidants, and Alkylating Agents

Head and neck cancer (HNC) concerns more than 890,000 patients worldwide annually and is associated with the advanced stage at presentation and heavy outcomes. Alcohol drinking, together with tobacco smoking, and human papillomavirus infection are the main recognized risk factors. The tumorigenesis of HNC represents an intricate sequential process that implicates a gradual acquisition of genetic and epigenetics alterations targeting crucial pathways regulating cell growth, motility, and stromal interactions. Tumor microenvironment and growth factors also play a major role in HNC. Alcohol toxicity is caused both directly by ethanol and indirectly by its metabolic products, with the involvement of the oral microbiota and oxidative stress; alcohol might enhance the exposure of epithelial cells to carcinogens, causing epigenetic modifications, DNA damage, and inaccurate DNA repair with the formation of DNA adducts. Long-term markers of alcohol consumption, especially those detected in the hair, may provide crucial information on the real alcohol drinking of HNC patients. Strategies for prevention could include food supplements as polyphenols, and alkylating drugs as therapy that play a key role in HNC management. Indeed, polyphenols throughout their antioxidant and anti-inflammatory actions may counteract or limit the toxic effect of alcohol whereas alkylating agents inhibiting cancer cells' growth could reduce the carcinogenic damage induced by alcohol. Despite the established association between alcohol and HNC, a concerning pattern of alcohol consumption in survivors of HNC has been shown. It is of primary importance to increase the awareness of cancer risks associated with alcohol consumption, both in oncologic patients and the general population, to provide advice for reducing HNC prevalence and complications.

The analysis of metabolomics and transcriptomics data in head and neck squamous cell carcinoma

OBJECTIVE

Studies have shown that cancer progression of head and neck squamous cell carcinoma (HNSCC) is related with metabolic alterations. The aim of this study is to identify the clinical roles of metabolic alterations in HNSCC.

MATERIALS AND METHODS

Metabolism-related genes associated with HNSCC were searched in public databases. A predictive and efficacious LASSO model was fabricated to optimize the diagnosis that was based on these genes. Meantime, Ultra-Performance Liquid Chromatography-Quadrupole/Orbitrap High Resolution Mass Spectrometry (UHPLC-Q-Orbitrap HRMS) was used to compare patients with HNSCC (n=73) with healthy controls (HC) (n=51) for serum metabolites. Potential biomarkers and alterations in serum metabolites were analysed and evaluated using t-test analysis, principal component analysis and orthogonal partial least square discrimination analysis (OPLS-DA).

RESULTS

Overall, 21 differential metabolites were probed in serum, of which 8 metabolites had potential for clinical uses. Transcriptome analysis showed that 4 genes in the constructed LASSO model were found to be associated with 7 differential metabolites. Metabolic pathway analysis by MetaboAnalyst showed that the biomarkers that were related with HNSCC were closely related to 4 metabolism pathways (p<0.05).

CONCLUSION

To conclude, future research on HNSCC should be directed toward multi-omics to provide treatment, intervention, or diagnosis of the disease.

Precise Identification of Recurrent Somatic Mutations in Oral Cancer Through Whole-Exome Sequencing Using Multiple Mutation Calling Pipelines

Understanding the genomic alterations in oral carcinogenesis remains crucial for the appropriate diagnosis and treatment of oral squamous cell carcinoma (OSCC). To unveil the mutational spectrum, in this study, we conducted whole-exome sequencing (WES), using six mutation calling pipelines and multiple filtering criteria applied to 50 paired OSCC samples. The tumor mutation burden extracted from the data set of somatic variations was significantly associated with age, tumor staging, and survival. Several genes (MUC16, MUC19, KMT2D, TTN, HERC2) with a high frequency of false positive mutations were identified. Moreover, known (TP53, FAT1, EPHA2, NOTCH1, CASP8, and PIK3CA) and novel (HYDIN, ALPK3, ASXL1, USP9X, SKOR2, CPLANE1, STARD9, and NSD2) genes have been found to be significantly and frequently mutated in OSCC. Further analysis of gene alteration status with clinical parameters revealed that canonical pathways, including clathrin-mediated endocytotic signaling, NFκB signaling, PEDF signaling, and calcium signaling were associated with OSCC prognosis. Defining a catalog of targetable genomic alterations showed that 58% of the tumors carried at least one aberrant event that may potentially be targeted by approved therapeutic agents. We found molecular OSCC subgroups which were correlated with etiology and prognosis while defining the landscape of major altered events in the coding regions of OSCC genomes. These findings provide information that will be helpful in the design of clinical trials on targeted therapies and in the stratification of patients with OSCC according to therapeutic efficacy.

Gene Mutations in Circulating Tumour DNA as a Diagnostic and Prognostic Marker in Head and Neck Cancer-A Systematic Review

(1) Background: Head and Neck Squamous Cell Carcinoma (HNSCC) is one of the most common malignancies globally. An early diagnosis of this disease is crucial, and the detection of gene mutations in circulating tumour DNA (ctDNA) through a liquid biopsy is a promising non-invasive diagnostic method. This review aims to provide an overview of ctDNA mutations in HNSCC patients and discuss the potential use of this tool in diagnosis and prognosis. (2) Methods: A systematic search for articles published in the English language between January 2000 and April 2021 in the Medline and Scopus databases was conducted. (3) Results: A total of 10 studies published in nine publications were selected and analysed. Altogether, 390 samples were obtained from HNSCC patients, and 79 control samples were evaluated. The most often explored gene mutation in ctDNA was TP53. (4) Conclusions: The examination of a larger group of gene mutations and the use of a combination of multiple detection methods contribute to a higher detection rate of mutated ctDNA. More studies are necessary to verify these conclusions and to translate them into clinical practice.

Droplet digital polymerase chain reaction for detection and quantification of cell-free DNA TP53 target somatic mutations in oral cancer

BACKGROUND:

TP53 mutation is a driver mutation of oral carcinogenesis. This study investigated cancerous and cell-free DNA (cfDNA) in patients with oral squamous cell carcinoma (OSCC) to detect the target hotspot somatic mutation of TP53.

OBJECTIVE:

TP53 target hotspot mutations were determined in surgically resected primary tumor samples from 107 OSCC patients.

METHODS:

Cancerous and cfDNA samples were examined for mutations through droplet digital polymerase chain reaction (ddPCR) by using mutation-specific assays. The ddPCR results were evaluated alongside clinicopathological data.

RESULTS:

In total, 23 cases had target TP53 mutations in varying degrees. We found that OSCC had relatively low cfDNA shedding, and mutations were at low allele frequencies. Of these 23 cases, 13 had target TP53 mutations in their corresponding cfDNA. Target somatic mutations in cancerous DNA and cfDNA are related to cervical lymph node metastasis. The cfDNA concentration is related to primary tumor size, lymph node metastasis, and OSCC stage.

CONCLUSIONS:

Our results show that the detection of TP53 target somatic mutations in OSCC patients by using ddPCR is technically feasible. Low levels of cfDNA may produce different results between cancerous tissue and cfDNA analyses. Future research on cfDNA may quantify diagnostic biomarkers in the surveillance of OSCC patients.

Emerging immune checkpoint inhibitors for the treatment of head and neck cancers

Introduction: The benefits of immune checkpoint inhibitors (ICIs) in recurrent and/or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) have been demonstrated through multiple studies to improve overall survival (OS) with decreased side effects when compared to the standard of care (SOC) treatment regimens in place for decades, leading to the approval of two ICIs, nivolumab and pembrolizumab. There has been a subsequent influx in the development of novel immunotherapy agents for the treatment of HNSCC. Areas covered: Data for anti-programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1) and anti-cytotoxic T-lymphocyte associated protein 4 (CTLA-4) antibodies in treatment of R/M HNSCC will be reviewed. Emerging immune checkpoint inhibitors as well as combined therapies in HNSCC will be discussed. The role of predictive biomarkers, HPV-status, PD-L1 expression, and challenges related to treating patients with ICIs will be summarized. Expert opinion: A shift toward ICIs as SOC for the treatment of R/M HNSCC will continue as emerging immune checkpoints and combination therapies are evaluated. Response rates are variable in this patient population underlying the importance of identifying predictive biomarkers to aid in patient selection for ICI treatment.

[Liquid biopsy-a possible key player in immuno-oncology]

BACKGROUND

Clinical application of immune checkpoint inhibitors (ICI), whether as monotherapy or in combination with established methods, is revolutionizing treatment of head and neck cancer. However, this change in therapeutic concepts requires reevaluation and further development of predictive and prognostic markers, since the survival rates for advanced and particularly human papillomavirus (HPV)-negative disease remain poor.

MATERIALS AND METHODS

A selective literature review was performed in PubMed. Literature found with the keywords "cytodiagnostics, circulating tumor cells, liquid biopsy, cfDNA, exosomes" in combination with "head and neck cancer" and/or "immune checkpoint inhibitor therapy" published until March 2020 was included. The articles were selected for their relevance for the current study by the authors.

RESULTS

This work provides a review of the current literature and indicates possible applications in the field of head and neck cancers. Liquid biopsy refers to the analysis of circulating tumor cells or of tumor genetic material in body fluids. This minimally invasive analysis can support therapeutic decisions and enable a personalized approach to treating head and neck cancer.

DISCUSSION

Before any of these approaches can be established in clinical routine, long-term data and standardization of the methods for isolating and analyzing the markers are needed.

Protein glycosylation in head and neck cancers: From diagnosis to treatment

Glycosylation is the most common post-translational modification (PTM) of proteins. Malignant tumour cells frequently undergo an alteration in surface protein glycosylation. This phenomenon is also common in cancers of the head and neck, most of which are squamous cell carcinomas (HNSCC). It affects cell functions, including proliferation, motility and invasiveness, thus increasing the propensity to metastasise. HNSCC represents the sixth most frequent malignancy worldwide. These neoplasms, which arise from the mucous membranes of the various anatomical subsites of the upper aero-digestive tract, are heterogeneous in terms of aetiology and clinico-pathologic features. With current treatments, only about 50% of HNSCC patients survive beyond 5-years. Therefore, there is the pressing need to dissect NHSCC heterogeneity to inform treatment choices. In particular, reliable biomarkers of predictive and prognostic value are eagerly needed. This review describes the current state of the art and bio-pathological meaning of glycosylation signatures associated with HNSCC and explores the possible role of tumour specific glycoproteins as potential biomarkers and attractive therapeutic targets. We have also compiled data relating to altered glycosylation and the nature of glycoproteins as tools for the identification of circulating tumour cells (CTCs) in the new era of liquid biopsy.

Review of emerging biomarkers in head and neck squamous cell carcinoma in the era of immunotherapy and targeted therapy

BACKGROUND

Biomarkers in head and neck squamous cell carcinoma (HNSCC) emerge rapidly in recent years, especially for new targeted therapies and immunotherapies.

METHODS

Recent, relevant peer-reviewed evidence were critically reviewed and summarized.

RESULTS

This review article briefly introduces essential biomarker concepts, including purposes and classifications (predictive, prognostic, and diagnostic markers), and the phases of biomarker development. We summarize current biomarkers in order of clinical utility; p16 and human papillomavirus status remain the most important and validated biomarkers in HNSCC. The rationale for biomarker study design continues to evolve with technological advances, especially whole-exome or whole-genomic sequencing. Noninvasive body fluid and liquid biopsy biomarkers appear to hold strong potential for development as tools for early cancer detection, cancer diagnosis, monitoring of disease recurrence, and outcome prediction. In light of discrepancies among different technologies, standardized approaches are needed.

CONCLUSION

Biomarkers from cancer tissue or blood in HNSCC could direct new anticancer therapies.

An update: circulating tumor cells in head and neck cancer

Introduction: Local and distant metastatic disease occurs in approximately half of head and neck squamous cell carcinoma (HNSCC) patients, representing an ongoing cause for treatment failure. Circulating tumor cells (CTCs) are transient cancer cells which have the capacity to metastasize to distant sites such as the lungs and liver in HNSCC. When metastatic disease is radiographically evident, the patient prognosis is often poor. Therefore, methodologies to assess micrometastatic disease are needed to (1) identify patients likely to develop metastatic disease and (2) treat and monitor these patients more aggressively. Whilst CTCs are well documented in other tumor streams such as breast, colorectal cancer and prostate cancers, the data and clinical utility in HNSCC remains limited.Areas covered: Here we summarize the recent advances of CTCs and applications in HNSCC.Expert opinion: CTC enumeration can be prognostic in HNSCC; further studies are warranted to investigate the role of CTC clusters in HNSCC; CTC culture (in vivo/ex vivo) may present a possibility to expand these rare cells to a critical mass for functional testing; PD-L1 expression of HNSCC CTCs may present a means by which to determine patients likely to respond to therapy; a HNSCC CTC-specific marker is warranted.

Plasma circulating tumor DNA as a potential tool for disease monitoring in head and neck cancer

BACKGROUND

Recommendations for perioperative therapy in head and neck cancer are not explicit and recurrence occurs frequently. Circulating tumor DNA is an emerging cancer biomarker, but has not been extensively explored for detection of recurrence in head and neck cancer.

METHODS

Patients diagnosed with head and neck squamous cell carcinoma were recruited into the study protocol. Tumors were sequenced to identify patient-specific mutations. Mutations were then identified in plasma circulating tumor DNA from pre-treatment blood samples and longitudinally during standard follow-up. Circulating tumor DNA status during follow-up was correlated to disease recurrence.

RESULTS

Samples were taken from eight patients. Tumor mutations were verified in seven patients. Baseline circulating tumor DNA was positive in six patients. Recurrence occurred in four patients, two of whom had detectable circulating tumor DNA prior to recurrence.

CONCLUSION

Circulating tumor DNA is a potential tool for disease and recurrence monitoring following curative therapy in head and neck cancer, allowing for better prognostication, and/or modification of treatment strategies.

The role of extracellular vesicles from different origin in the microenvironment of head and neck cancers

The proliferation and metastasis ability of tumors are mediate by the "mutual dialogue" between cells in the tumor microenvironment (TME). Extracellular vesicles (EVs), mainly exosomes and microvesicles, play an important role in achieving intercellular substance transport and information transfer in the TME. Initially considered "garbage dumpsters" and later referred to as "signal boxes", EVs carry "cargo" (proteins, lipids, or nucleic acids) that can redirect the function of a recipient cell. Currently, the molecular mechanisms and clinical applications of EVs in head and neck cancers (HNCs) are still at an early stage and need to be further investigate. In this review, we provide insight into the TME of HNCs, classifying and summarizing EVs derived from different cell types and illuminating their complex signaling networks involved in mediating tumor proliferation, invasion and metastasis, vascular angiogenesis and cancer drug resistance. In addition, we highlight the application of EVs in HNCs, underlining the special pathological and physiological environment of HNCs. The application of tumor heterogeneous EVs in saliva and circulating blood diagnostics will provide a new perspective for the early screening, real-time monitoring and prognostic risk assessment of HNCs. Given the concept of precise and individual therapy, nanostructured EVs are equipped with superior characteristics of biocompatibility, low immunogenicity, loadability and modification ability, making these molecules one of the new strategies for HNCs treatment.

A Pilot Study to Non-Invasively Track PIK3CA Mutation in Head and Neck Cancer

Background: PIK3CA pathways are the most frequently mutated oncogenic pathway in head and neck squamous cell carcinoma (HNSCC), including virally driven HNCs. PIK3CA is involved in the PI3K-PTEN-mTOR signalling pathway. PIK3CA has been implicated in HNSCC progression and PIK3CA mutations may serve as predictive biomarkers for therapy selection. Circulating tumour DNA (ctDNA) derived from necrotic and apoptotic tumour cells are thought to harbour tumour-specific genetic alterations. As such, the detection of PIK3CA alterations detected by ctDNA holds promise as a potential biomarker in HNSCC. Methods: Blood samples from treatment naïve HNSCC patients (n = 29) were interrogated for a commonly mutated PIK3CA hotspot mutation using low cost allele-specific Plex-PCR^TM technology. Results: In this pilot, cross sectional study, PIK3CA E545K mutation was detected in the plasma samples of 9/29 HNSCC patients using the Plex-PCR^TM technology. Conclusion: The results of this pilot study support the notion of using allele-specific technologies for cost-effective testing of ctDNA, and further assert the potential utility of ctDNA in HNSCC.

Increased Plasma Circulating Cell-Free DNA Could Be a Potential Marker for Oral Cancer

Background: Oral squamous cell carcinoma (OSCC) is a disease that affects patients worldwide. DNA of dead cells is released into the blood stream and may be isolated from plasma or serum samples. This DNA is termed cell-free DNA (cfDNA). cfDNA is increased in several types of malignancies. We investigated if there was a correlation between cfDNA levels and the progression of OSCC. Methods: Using quantitative spectrometry, we measured plasma cfDNA in 121 patients with OSCC and 50 matched controls. Mann Whitney and Wilcoxon tests were used to compare differences among various clinical variants. Receiver operating characteristic (ROC) analysis was used to obtain levels suitable for the separation of the clinical subsets. Kaplan-Meier analysis was used to assess correlation with survival. Results: Plasma cfDNA was significantly elevated in patients with OSCC relative to controls. Plasma cfDNA levels correlated with larger tumor size, cervical lymph node metastasis and late stage. Higher plasma cfDNA levels were associated with a poor prognosis of OSCC, which is a new finding. Conclusion: Plasma cfDNA could serve as a novel and easily accessible biomarker in OSCC, providing diagnostic and prognostic value.

Circulating cell-free DNA: A potential biomarker to differentiate inflammation and infection during radiochemotherapy

BACKGROUND AND PURPOSE

Radiochemotherapy is a standard treatment option for patients with head and neck cancer (HNSCC). During radiation, local toxicities are common and need to be differentiated from infections. As levels of circulating cell-free DNA (cfDNA) are known to be elevated during infections, cfDNA might complement clinical parameters. The aim of the study was to investigate the dynamics of cfDNA during radiochemotherapy.

MATERIAL AND METHODS

In total, 78 blood samples of 20 patients with HNSCC were analysed in this prospective biomarker study. Blood samples were taken before and during treatment. CfDNA levels were quantified fluorometrically and results were compared to laboratory and clinical parameters.

RESULTS

Elevated cfDNA levels were associated with the pre-treatment volumes of lymph node metastases (p = 0.0002), gastrostomy tube placement (20.23 ng/ml vs. 9.04 ng/ml (median), p = 0.025), the application of antibiotics (16.47 ng/ml vs. 9.04 ng/ml, p = 0.006) and manifest infections (16.81 ng/ml vs. 9.04 ng/ml, p = 0.010). Furthermore, a significant difference between moderate inflammation (radiation-induced toxicity RTOG grade 2-3) and manifest infections could be observed (8.97 ng/ml vs. 16.81 ng/ml, p = 0.014), allowing for a more pronounced differentiation than by CRP levels (p = 0.119). There might be an association between the application of G-CSF and elevated cfDNA levels.

CONCLUSION

CfDNA levels are correlated with infections during radiochemotherapy and could represent an informative complemental biomarker to drive therapeutic decision-making. Estimated levels of circulating cell-free tumour DNA (ctDNA) in plasma should be interpreted cautiously when monitoring tumour outcome by next-generation-sequencing, as confounders like infections or drug application might influence the fraction of ctDNA in total cfDNA.

Circulating tumor DNA as a biomarker and liquid biopsy in head and neck squamous cell carcinoma

The use of circulating biochemical molecular markers in head and neck cancer holds the promise of improved diagnostics, treatment planning, and posttreatment surveillance. In this review, we provide an introduction for the head and neck surgeon of the basic science, current evidence, and future applications of circulating tumor DNA (ctDNA) as a biomarker and liquid biopsy to detect tumor genetic heterogeneity in patients with head and neck squamous cell carcinoma (HNSCC).

Cell-Free Plasma DNA for Disease Stratification and Prognosis in Head and Neck Cancer

BACKGROUND

Clinicians face many challenges in disease stratification and outcome prediction in head and neck squamous cancer cell (HNSCC) patients. Given the limitations of currently used clinical scoring, repetitive biopsies, and imaging techniques, liquid biopsy approaches may provide valuable additional diagnostic and prognostic information.

METHODS

A noninterventional, single-center observational study was performed with clinical data and plasma samples from HNSCC patients. Cell-free tumor DNA-derived copy number aberrations (CNAs) were determined in 116 patients by low-coverage next-generation sequencing (NGS). Significant CNAs were combined in a genome-wide copy number instability score (CNI), which was evaluated with respect to conventional clinical staging and patient outcome.

RESULTS

Receiver-operating characteristic (ROC) curve analysis comparing the presurgery CNI in patients (n = 103) with that in tumor-free controls (n = 142) yielded an area under the ROC curve of 87.2% (95% CI, 79.4%-93.3%). At a specificity of 95%, the sensitivity to detect tumors varied between 46% (pT1) and 94% (pT4). A CNI above the median (i.e., >72) had a positive predictive value of 90% (95% CI, 79%-96%) for lymph node involvement (LNI), while the negative predictive value was 57% (95% CI, 43%-70%). For a CNI >72, overall survival (OS) was worse (hazard ratio, 4.89; 95% CI, 1.39-17.17; P = 0.01) with 62% and 90% survivors 3 years after surgery for a CNI >72 and ≤72, respectively. In multivariable models, the CNI was a superior predictor of OS compared to established disease features, including LNI.

CONCLUSIONS

The CNI may assist in predicting LNI and prognosis in HNSCC with direct therapeutic implications concerning the need for neck dissection or more aggressive treatment.

Prognostic value of circulating biomarker score in advanced-stage head and neck squamous cell carcinoma

BACKGROUND

Circulating biomarker (CB) is a convenient, emerging predictive tool for treatment response and outcomes in human cancers. Therefore, we examined the prognostic value of pre-treatment and early post-treatment CBs and their summated scores in patients with head and neck squamous cell carcinoma (HNSCC).

METHODS

This study prospectively included 310 consecutive patients who underwent definitive treatment for previously untreated advanced-stage HNSCC between 2010 and 2015. The CB score was determined by complete blood counts (CBCs) and blood chemistry before and 2 months after the treatment, and the number of abnormal CB was counted from 0 to 10. Univariate and multivariate analyses with Cox proportional hazards models were used to find factors associated with disease-free survival (DFS) and overall survival (OS).

RESULTS

Most CBC profiles were significantly changed at 2-months post-treatment compared with those at pre-treatment. Univariate analyses showed that hypoalbuminemia, leucocytosis, C-reactive protein, high CB scores (≥6), age, performance status and comorbidity and tumour site were significantly associated with DFS and OS (all P < 0.05). Both pre- and post-treatment CB scores were independent factors predictive of DFS and OS outcomes in the multivariate analyses (P < 0.05). High CB scores at pre-treatment were associated with 7-10-fold increased risk of unfavourable DFS and OS outcomes, and those at 2-months post-treatment were associated with 2 to 4-fold increased risk of poor survival outcomes (all P < 0.05).

CONCLUSIONS

CB scores at pre-treatment and early post-treatment are useful for predicting survival outcomes in patients with advanced-stage HNSCC.

A Collective Route to Head and Neck Cancer Metastasis

Distant metastasis (DM) from head and neck cancers (HNC) portends a poor patient prognosis. Despite its important biological role, little is known about the cells which seed these DM. Circulating tumour cells (CTCs) represent a transient cancer cell population, which circulate in HNC patients’ peripheral blood and seed at distant sites. Capture and analysis of CTCs offers insights into tumour metastasis and can facilitate treatment strategies. Whilst the data on singular CTCs have shown clinical significance, the role of CTC clusters in metastasis remains limited. In this pilot study, we assessed 60 treatment naïve HNC patients for CTCs with disease ranging from early to advanced stages, for CTC clusters utilizing spiral CTC enrichment technology. Single CTCs were isolated in 18/60–30% (Ranging from Stage I-IV), CTC clusters in 15/60–25% (exclusively Stage IV) with 3/15–20% of CTC clusters also containing leukocytes. The presence of CTC clusters associated with the development of distant metastatic disease(P = 0.0313). This study demonstrates that CTC clusters are found in locally advanced patients, and this may be an important prognostic marker. In vivo and in vitro studies are warranted to determine the role of these CTC clusters, in particular, whether leukocyte involvement in CTC clusters has clinical relevance.

Liquid Biopsy for Investigation of Cancer DNA in Esophageal Adenocarcinoma: Cell-Free Plasma DNA and Exosome-Associated DNA

Liquid biopsy of cancers is an area of increasing interest in medical practice for the surveillance, management, and potential detection of malignant cells, using minimally invasive collection of body fluids. A liquid biopsy is particularly useful for metastatic cancers, which may be difficult to be sampled by core biopsy, due to difficulty of access or an occult location. Access to DNA shed from esophageal adenocarcinoma can enable the detection of mutations confirming the presence of malignant cells or the evolution of clonal lines with altered treatment response profiles. In this chapter, we detail a method for the isolation of cell-free DNA from blood plasma and DNA associated with exosomes in blood from patients with esophageal adenocarcinoma.

Salivary miRNA panel to detect HPV-positive and HPV-negative head and neck cancer patients

Head and neck squamous cell carcinomas (HNSCC) are a heterogeneous group of tumours that originate predominantly from the oral cavity, pharynx and larynx. Our aim was to determine whether salivary miRNA expression levels can diagnose these cancer subtypes. Saliva samples were collected from healthy controls (n=113, smoker and non-smokers), HPV-positive (n=54) and HPV-negative (n=47) HNSCC patients. The miRNA expression levels in saliva was quantified using qPCR. The potential of salivary miRNAs to discriminate these groups of patients was evaluated using multiple logistic regression with ROC analysis and a 10-fold cross-validation analysis. Salivary miRNA-9, -127, -134, -191, -222 and -455 were shown to discriminate a control group from a HPV-negative HNSCC patient group with a sensitivity of 60% and a specificity of 94%; whilst salivary miRNA-9,-134, -196b, -210, and -455 were the most parsimonious subset discriminating a control group from a HPV-positive HNSCC group, with a sensitivity of 65% and a specificity of 95%. Furthermore, miRNA-9, -134, -196b, -210 and -455 as a panel, was the most parsimonious subset to discriminate HPV-positive HNSCC patients from HPV-negative HNSCC patients. In addition, the expression levels of miRNA-9, -127, -196a, -196b, -210, -222 and -455 were significantly increased in the saliva collected from early stage HNSCC patients compared to controls. A future multi-centre confirmatory study is warranted to test the diagnostic performance of these salivary miRNA prior to clinical implementation.

Circulating tumour cell PD-L1 test for head and neck cancers

Immune checkpoint inhibitors have gained traction over the last few years in the treatment of metastatic/recurrent head and neck squamous cell carcinoma (HNSCC) patients. Monoclonal antibodies that block the programmed death 1 (PD-1) receptor and its major ligand, PD-L1, have shown durable responses and low toxicity profiles. There are currently no validated predictive biomarkers to select patients likely to respond to anti-PD-1/PD-L1 therapy to avoid unwanted side effects and to reduce healthcare expenditure. A circulating tumour cell (CTC) PD-L1 assay could be developed as a companion diagnostic tool to potentially predict the efficacy of immune checkpoint blockade treatments.

Tumour-derived plasma cell-free DNA in patients with head and neck cancer: A short review

Head and neck squamous cell carcinoma is one of the leading causes of cancer mortality worldwide. The prognosis for patients with head and neck squamous cell carcinoma has not substantially improved during the last decades, despite numerous advancements in treatment options. Reliable markers for early tumour detection and treatment response, which complement clinical examinations, imaging techniques, and biopsies would be extremely useful. One fairly new and promising method is the analysis of tumour-derived cell-free DNA (ctDNA) in the plasma of cancer patients. First data indicate that this method may assist, in the future, in the early detection of head and neck squamous cell carcinoma, the real-time monitoring of the disease course, the therapy response, and the prediction of prognosis with direct therapeutic implications by determining the best therapeutic modality for patient care.

Early detection of squamous cell carcinoma in carcinogen induced oral cancer rodent model by ratiometric activatable cell penetrating peptides

OBJECTIVES

Ratiometric cell-penetrating-peptides (RACPP) are hairpin-shaped molecules that undergo cleavage by tumor-associated proteases resulting in measurable Cy5:Cy7 fluorescence ratiometric change to label cancer in vivo. We evaluated an MMP cleavable RACPP for use in the early detection of malignant lesions in a carcinogen-induced rodent tumor model.

METHODS

Wild-type immune-competent mice were given 4-nitroquinoline-oxide (4NQO) for 16weeks. Oral cavities from live mice that had been intravenously administered MMP cleavable PLGC(Me)AG-RACPP were serially imaged from week 11 through week 21 using white-light reflectance and Cy5:Cy7 ratiometric fluorescence.

RESULTS

In an initial study we found that at week 21 nearly all mice (13/14) had oral cavity lesions, of which 90% were high-grade dysplasia or invasive carcinoma. These high-grade lesions were identifiable with white light reflectance and RACPP Cy5:Cy7 ratiometric fluorescence with similar detectability, Area Under Curve (AUC) for RACPP detection was 0.97 (95% Confidence interval (CI)=0.92-1.02, p<0.001), sensitivity=89%, specificity=100%. In a follow up study, oral cavity lesions generated by 4NQO were imaged and histologically analyzed at weeks 16, 18 and 21. In this study we showed that RACPP-fluorescence detection positively identified 15 squamous cell carcinomas (in 6 separate mice) that were poorly visible or undetectable by white light reflectance.

CONCLUSIONS

RACPP ratiometric fluorescence can be used to accurately detect carcinogen-induced carcinoma in immunocompetent mice that are poorly visible or undetectable by white light reflectance.

PD-L1 expressing circulating tumour cells in head and neck cancers

BACKGROUND

Blockade of the PD-1/PD-L1 immune checkpoint pathway is emerging as a promising immunotherapeutic approach for the management and treatment of head and neck cancer patients who do not respond to 1st/2nd line therapy. However, as checkpoint inhibitors are cost intensive, identifying patients who would most likely benefit from anti PD-L1 therapy is required. Developing a non-invasive technique would be of major benefit to the patient and to the health care system.

CASE PRESENTATION

We report the case of a 56 year old man affected by a supraglottic squamous cell carcinoma (SCC). A CT scan showed a 20 mm right jugulodigastric node and suspicious lung lesions. The lung lesion was biopsied and confirmed to be consistent with SCC. The patient was offered palliative chemotherapy. At the time of presentation, a blood sample was taken for circulating tumour cell (CTC) analysis. The dissemination of cancer was confirmed by the detection of CTCs in the peripheral blood of the patient, measured by the CellSearch System (Janssen Diagnostics). Using marker-independent, low-shear spiral microfluidic technology combined with immunocytochemistry, CTC clusters were found in this patient at the same time point, expressing PD-L1.

CONCLUSION

This report highlights the potential use of CTCs to identify patients which might respond to anti PD-L1 therapy.