Diverse tumorigenic consequences of human papillomavirus integration in primary oropharyngeal cancers

Circulating tumor DNA to monitor treatment response in solid tumors and advance precision oncology

Circulating tumor DNA (ctDNA) has emerged as a dynamic biomarker in cancer, as evidenced by its increasing integration into clinical practice. Carrying tumor specific characteristics, ctDNA can be used to inform treatment selection, monitor response, and identify drug resistance. In this review, we provide a comprehensive, up-to-date summary of ctDNA in monitoring treatment response with a focus on lung, colorectal, and breast cancers, and discuss current challenges and future directions.

Development and Validation of an Assay to Quantify Plasma Circulating Tumor Human Papillomavirus DNA for 13 High-Risk Types that Cause 98% of HPV-Positive Cancers

PURPOSE

Plasma circulating tumor HPV DNA (ctHPVDNA) persistence after curative-intent treatment may identify patients with HPV-positive cancers at risk for recurrence. Technical validation is required for use as an integral biomarker in a prospective clinical trial.

METHODS

Development and analytical validation of a digital droplet PCR assay for detection and quantification of 13 high-risk HPV types (i.e., Cell-Free 13) was performed with oligonucleotides/plasmids encoding type-specific E6/E7 coding regions. Clinical performance, determinants of detection/quantification, and associations of pre-treatment ctHPVDNA with progression-free survival (PFS) were also evaluated in a prospective cohort of 272 head and neck cancer patients.

RESULTS

Limit of detection, limit of quantification, and linear range of quantification were 5, 16 and 16-200,000 virus copies for all 13 high-risk HPV types. No cross-reactivity was detected across all 13 HPV types. At 10,000 copies, inter-assay coefficients of variation ranged from 0.3 to 4.6%. Multiplexing, DNA purification method, input plasma volume, total input cell-free (< 1800 ng) or genomic (< 700 ng) DNA did not affect HPV detection or quantification. The assay had a sensitivity of 91.7% (95%CI 87.3-94.9%) and specificity of 97.7% (95%CI 87.7-99.9%) for ctHPVDNA detection in the setting of newly diagnosed HPV-positive oropharyngeal cancer. Tumor and nodal stage categories, tumor viral load (ρ = 0.41, p < 0.05), and HPV integration status were associated with ctHPVDNA quantitative level. Pre-treatment ctHPVDNA greater than the median (231 copies/ml) was associated with worse PFS (HR = 2.14, 95%CI 1.16-3.97, p = 0.0156) in univariate analysis. However, this was no longer significant after adjustment for clinical covariates (HRadj = 1.81, 95%CI 0.97-3.37, p = 0.0635).

CONCLUSION

Cell-Free 13 demonstrated excellent analytical performance and clinical sensitivity/specificity in HPV-positive oropharyngeal cancer. Pre-treatment ctHPVDNA may be associated with oncologic outcomes.

Virusplot: a web server for viral integration analysis and visualization

The integration of viral DNA into the human genome is a critical event in the pathogenesis of various cancers. This process leads to genomic instability, disrupts cellular regulatory mechanisms, and activates oncogenes or inactivates tumor suppressor genes. Despite significant advancements in genome sequencing technologies, there remains a notable lack of computational tools, particularly web-based applications, specifically designed for viral integration analysis and visualization. To address this gap, we present virusPlot, a web server with the following functional modules: (i) automatic retrieval of virus genome sequences and their annotation; (ii) visualization of virus integration locations and read counts through a graphical representation that links viral and host genome integration sites, facilitating the interpretation of integration patterns; (iii) analysis of virus integration hotspots using Fisher's exact test; and (iv) integration of various functions into an interactive web platform via shinyapp. VirusPlot efficiently processes and visualizes integration data from viruses and host genomes, providing researchers with an intuitive and user-friendly analytical tool that simplifies the complexity of virus integration analysis.

Genome Instability Precedes Viral Integration in Human Papillomavirus-Transformed Tonsillar Keratinocytes

Approximately 70% of oropharyngeal squamous carcinomas (OPSCC) are associated with human papillomavirus (HPV). Although patients with HPV-positive (HPV+) tumors generally have better outcomes than those with HPV-negative tumors, a subset of HPV+ positive patients do have poor outcomes. Our previous work suggested that tumors with integrated virus exhibit significantly greater genome-wide genomic instability than those with only episomal viral genomes, and patients with HPV+ OPSCC with episomal viral genomes had better outcomes. To explore the causal relation between viral integration and genomic instability, we have examined the time course of viral integration and genetic instability in tonsillar keratinocytes transformed with HPV16. HPV-infected human tonsil keratinocyte cell lines were continuously passaged, and every fifth passage, some cells were retained for genomic analysis. Whole-genome sequencing and optical genomic mapping confirmed that virus integrated in five of six cell lines while remaining episomal in the sixth. In all lines, genome instability occurred during early passages but essentially ceased following viral integration; however, it continued to occur in later passages in the episomal line. To test tumorigenicity of the cell lines, cells were injected subcutaneously into the flanks of nude mice. A cell line with the integrated virus induced tumors following injection in the nude mouse whereas that with the episomal virus did not. Implications: Genomic instability in HPV OPSCC tumors is not the result of viral integration but likely promotes integration. Moreover, transformants with episomal virus seem to be less tumorigenic than those with integrated virus.

Multiple DNA Viruses and HPV Integration in Inverted Papilloma and Associated Sinonasal Carcinoma

OBJECTIVES

Sinonasal inverted papilloma (IP) has a locally destructive growth pattern, can relapse, and can undergo malignant transformation (IP-associated sinonasal squamous cell carcinoma (IP-SNSCC)). Human papillomaviruses (HPV)-6 and -16 are frequently detected in IPs. To clarify the possible roles of other DNA viruses in IPs, we explored viruses not studied in this context before. With the setting of pre- and post-malignant transformation samples, we investigated HPV genomes in depth to assess the integration of HPV into the human genome and the presence of minor intratypic variants.

MATERIALS AND METHODS

We analyzed 35 IP samples representing 28 individuals, of which six had IP-SNSCC. For virus screening, we applied qPCR to detect 16 different DNA viruses in three virus families, comprising herpesviruses, parvoviruses, and polyomaviruses. In addition, targeted next generation sequencing (NGS) was used for detailed HPV analysis.

RESULTS

We detected herpes-, parvo-, and polyomaviruses in 13/28 (46%) patients, with codetections of multiple viruses in six (21%) patients. NGS revealed HPV16 DNA in 2/6 IP-SNSCC and in their respective earlier benign IP samples, as well as in a plasma sample from one of these patients. HPV6 was detected in two IP samples without subsequent malignant transformation. We identified sequence reads containing junctions of HPV6 and HPV16 and host genome suggestive of viral integration. HPV6 and HPV16 minor intratypic variants were present across pre- and post-malignant transformation, with mostly nonsynonymous mutations.

CONCLUSIONS

Multiple DNA viruses were present in IPs. HPV16 was detected only in IP-SNSCCs or in tumors that later underwent malignant transformation.

LEVEL OF EVIDENCE

3 Laryngoscope, 135:677-686, 2025.

Intratumor heterogeneity of HPV integration in HPV-associated head and neck cancer

Integration of human papillomavirus (HPV) into the host genome drives HPV-positive head and neck squamous cell carcinoma (HPV+ HNSCC). Whole-genome sequencing of 51 tumors revealed intratumor heterogeneity of HPV integration, with 44% of breakpoints subclonal, and a biased distribution of integration breakpoints across the HPV genome. Four HPV physical states were identified, with at least 49% of tumors progressing without integration. HPV integration was associated with APOBEC-induced broad genomic instability and focal genomic instability, including structural variants at integration sites. HPV+ HNSCCs exhibited almost no smoking-induced mutational signatures. Heterozygous loss of ataxia-telangiectasia mutated (ATM) was observed in 67% of tumors, with its downregulation confirmed by single-cell RNA sequencing and immunohistochemistry, suggesting ATM haploinsufficiency contributes to carcinogenesis. PI3K activation was the major oncogenic mutation, with JAK-STAT activation in tumors with clonal integration and NF-kappa B activation in those without. These findings provide valuable insights into HPV integration in HPV+ HNSCC.

Risk Stratification in HPV-Associated Oropharyngeal Cancer: Limitations of Current Approaches and the Search for Better Solutions

The rising incidence of human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) necessitates advancements in risk stratification to optimize treatment outcomes and improve the quality of life for patients. Despite its favorable prognosis compared to HPV-negative OPSCC, current clinical staging and biomarkers, such as p16 status, are limited in their ability to distinguish between high- and low-risk patients within HPV-associated OPSCC. This limitation results in the overtreatment of low-risk patients, exposing them to unnecessary toxicity, and the undertreatment of high-risk patients who require more aggressive interventions. This review critically evaluates current stratification methods, including clinical assessments, de-escalation trials, and candidate molecular biomarkers for risk stratification. Emerging approaches such as immune markers, viral genomic integration patterns, and other molecular markers offer promising avenues for enhanced prognostic accuracy. By integrating advanced risk stratification methods, tailored treatment approaches may one day be developed to balance oncologic efficacy with reduced treatment-related morbidity. This review underscores the need for continued research into predictive biomarkers and adaptive treatment strategies to better address the diverse risk profiles of HPV-associated OPSCC patients.

HPV integration in head and neck cancer: downstream splicing events and expression ratios linked with poor outcomes

HPV integration (HPVint) is associated with carcinogenesis and tumor progression in HPV-associated cancers, including head and neck squamous cell carcinomas (HNSCC). While its impact on human DNA has been well characterized, its relationship with clinical outcomes remains unconfirmed. Here we investigate the consequences of HPVint both with respect to human and HPV characteristics by analyzing 261 HPV-associated HNSCC bulk and single-cell RNA-seq samples from five cohorts, and DNA HPVint events from 102 HPV+ participants in two of the cohorts. By leveraging this large meta-cohort, we first reveal an oncogenic network based on the recurrent HPV integration locations in HNSCC. We then classify HPVint-positive (HPVint(+)) participants by HPV RNA features, specifically based on spliced HPV-human fusion transcripts and ratios of HPV gene transcripts, showing that subsets of participants have worse clinical outcomes. Our analyses, focused mainly on RNA instead of DNA, expand our understanding of the carcinogenic mechanisms of HPVint, partially addressing the conflicting findings of whether HPVint is associated with aggressive phenotypes and worse clinical consequences, and provide potential biomarkers to advance precision oncology in HPV-associated HNSCC.

The Clinical Utility of a Next-Generation Sequencing-Based Approach to Detecting Circulating HPV DNA in Patients with Advanced Anal Cancer

BACKGROUND

To extend the practicality of liquid biopsy beyond the historical HPV circulating tumor DNA (ctDNA) assays, we evaluated the clinical relevance of a novel next-generation sequencing HPV ctDNA assay in patients with locally advanced and metastatic squamous cell cancer of the anal canal (mSCCA).

METHODS

ctDNA isolated from the plasma of patients with mSCCA was sequenced using a 1.4 Mb hybrid-capture target-enrichment panel covering the whole genome sequences of all 193 HPV types. The HPV type, copy number (CN), and integration sites were determined using a bioinformatic pipeline.

RESULTS

A total of 77 plasma samples from 28 patients with HPV-related SCCA were retrospectively analyzed. HPV ctDNA was detected in 26 cases (93%) (including uncommon subtypes). The median HPV CN was higher in metastatic versus locally recurrent/unresectable SCCA (p = 0.043). Changes in the HPV CN were concordant with the radiographic response (p = 0.027). An integration event was detected in 23 patients (82%), with presumed episomal HPV DNA present in the remaining patients. Higher HPV integration (a mean of ≥1 integration across samples) was associated with a worse overall survival from the start of immunotherapy (13.6 months versus 36.0 months; p = 0.003).

CONCLUSIONS

Using HPV-informed next-generation sequencing of the ctDNA, we found changes in the HPV CN correlated with the treatment response and that HPV integration detected in the ctDNA is an unfavorable prognostic biomarker.

Fibroblast Growth Factor Receptor (FGFR) Alterations in HPV Oropharyngeal Cancers

HPV viral E6 and E7 onco-proteins play a well-known role in carcinogenesis. Host genomic alterations also play a key role in the development of HPV-related oropharyngeal cancer and have been under-recognized. We describe a case series of 6 metastatic/locoregionally recurrent HPVOPSCC patients with FGFR alterations. HPVOPSCC presents with distinct pattern of spread both temporally and sites of recurrence compared to  non-HPV-related oropharyngeal cancer. Identification and reporting of genomic alterations in HPV are crucial to the understanding of disease biology and could aid in development of novel therapeutics for these patients. In addition, use of circulating tumor DNA may lead to early detection and supplement imaging in the follow up of these patients. Loco-regional treatments may also play a key role in the management of metastatic HPV OPSCC depending on the pattern of presentation. Our case series highlights all these novelties that could lead to better treatment outcomes.

HPV- associated sinonasal squamous cell carcinoma with FGFR3::TACC3 fusion. A rare case report

Sinonasal squamous cell carcinomas (SNSCCs) are uncommon and they are associated with adverse prognosis. HPV-associated SNSCCs and fusion-driven SNSCCs are particularly rare. A case of an HPV-associated SNSCC with a FGFR3::TACC3 fusion is thus presented; a brief review of the pertinent literature is also provided.

Proximity ligation-based sequencing for the identification of human papillomavirus genomic integration sites in formalin-fixed paraffin embedded oropharyngeal squamous cell carcinomas

Human papillomavirus (HPV) infections are an increasing cause of oropharyngeal squamous cell carcinomas (OPSCC). Integration of the viral genome into the host genome is suggested to affect carcinogenesis, however, the correlation with OPSCC patient prognosis is still unclear. Research on HPV integration is hampered by current integration detection technologies and their unsuitability for formalin-fixed paraffin-embedded (FFPE) tissues. This study aims to develop and validate a novel targeted proximity-ligation based sequencing method (targeted locus amplification/capture [TLA/TLC]) for HPV integration detection in cell lines and FFPE OPSCCs. For the identification of HPV integrations, TLA/TLC was applied to 7 cell lines and 27 FFPE OPSCCs. Following preprocessing steps, a polymerase chain reaction (PCR)-based HPV enrichment was performed on the cell lines and a capture-based HPV enrichment was performed on the FFPE tissues before paired-end sequencing. TLA was able to sequence up to hundreds of kb around the target, detecting exact HPV integration loci, structural variants, and chromosomal rearrangements. In all cell lines, one or more integration sites were identified, in accordance with detection of integrated papillomavirus sequences PCR data and the literature. TLC detected integrated HPV in 15/27 FFPE OPSCCs and identified simple and complex integration patterns. In general, TLA/TLC confirmed PCR data and detected additional integration sites. In conclusion TLA/TLC reliably and robustly detects HPV integration in cell lines and FFPE OPSCCs, enabling large, population-based studies on the clinical relevance of HPV integration. Furthermore, this approach might be valuable for clonality assessment of HPV-related tumors in clinical diagnostics.

Oral microbiome and its relationship with oral cancer

ABSTRACT

As the initial point for digestion, the balance of oral microorganisms plays an important role in maintaining local and systemic health. Oral dysbiosis, or an imbalance in the oral microbial community, may lead to the onset of various diseases. The presence or abnormal increase of microbes in the oral cavity has attracted significant attention due to its complicated relationship with oral cancer. Oral cancer can remodel microbial profiles by creating a more beneficial microenvironment for its progression. On the other hand, altered microbial profiles can promote tumorigenesis by evoking a complex inflammatory response and affecting host immunity. This review analyzes the oncogenic potential of oral microbiome alterations as a driver and biomarker. Additionally, a potentially therapeutic strategy via the reversal of the oral microbiome dysbiosis in oral cancers has been discussed.

Tumor Subtype Classification Tool for HPV-associated Head and Neck Cancers

Importance

Molecular subtypes of HPV-associated Head and Neck Squamous Cell Carcinoma (HNSCC), named IMU (immune strong) and KRT (highly keratinized), are well-recognized and have been shown to have distinct mechanisms of carcinogenesis, clinical outcomes, and potentially differing optimal treatment strategies. Currently, no standardized method exists to subtype a new HPV+ HNSCC tumor. Our paper introduces a machine learning-based classifier and webtool to reliably subtype HPV+ HNSCC tumors using the IMU/KRT paradigm and highlights the importance of subtype in HPV+ HNSCC.

Objective

To develop a robust, accurate machine learning-based classification tool that standardizes the process of subtyping HPV+ HNSCC, and to investigate the clinical, demographic, and molecular features associated with subtype in a meta-analysis of four patient cohorts.

Data Sources

We conducted RNA-seq on 67 HNSCC FFPE blocks from University of Michigan hospital. Combining this with three publicly available datasets, we utilized a total of 229 HPV+ HNSCC RNA-seq samples. All participants were HPV+ according to RNA expression. An ensemble machine learning approach with five algorithms and three different input training gene sets were developed, with final subtype determined by majority vote. Several additional steps were taken to ensure rigor and reproducibility throughout.

Study Selection

The classifier was trained and tested using 84 subtype-labeled HPV+ RNA-seq samples from two cohorts: University of Michigan (UM; n=18) and TCGA-HNC (n=66). The classifier robustness was validated with two independent cohorts: 83 samples from the HPV Virome Consortium and 62 additional samples from UM. We revealed 24 of 39 tested clinicodemographic and molecular variables significantly associated with subtype.

Results

The classifier achieved 100% accuracy in the test set. Validation on two additional cohorts demonstrated successful separation by known features of the subtypes. Investigating the relationship between subtype and 39 molecular and clinicodemographic variables revealed IMU is associated with epithelial-mesenchymal transition (p=2.25×10-4), various immune cell types, and lower radiation resistance (p=0.0050), while KRT is more highly keratinized (p=2.53×10-8), and more likely female than IMU (p=0.0082).

Conclusions and Relevance

This study provides a reliable classifier for subtyping HPV+ HNSCC tumors as either IMU or KRT based on bulk RNA-seq data, and additionally, improves our understanding of the HPV+ HNSCC subtypes.

Molecular patterns and mechanisms of tumorigenesis in HPV-associated and HPV-independent sinonasal squamous cell carcinoma

Mechanisms of tumorigenesis in sinonasal squamous cell carcinoma (SNSCC) remain poorly described due to its rare nature. A subset of SNSCC are associated with the human papillomavirus (HPV); however, it is unknown whether HPV is a driver of HPV-associated SNSCC tumorigenesis or merely a neutral bystander. We hypothesized that performing the first large high-throughput sequencing study of SNSCC would reveal molecular mechanisms of tumorigenesis driving HPV-associated and HPV-independent SNSCC and identify targetable pathways. High-throughput sequencing was performed on 64 patients with HPV-associated and HPV-independent sinonasal carcinomas. Mutation annotation, viral integration, copy number, and pathway-based analyses were performed. Analysis of HPV-associated SNSCC revealed similar mutational patterns observed in HPV-associated cervical and head and neck squamous cell carcinoma, including lack of TP53 mutations and the presence of known hotspot mutations in PI3K and FGFR3. Further similarities included enrichment of APOBEC mutational signature, viral integration at known hotspot locations, and frequent mutations in epigenetic regulators. HPV-associated SNSCC-specific recurrent mutations were also identified including KMT2C , UBXN11 , AP3S1 , MT-ND4 , and MT-ND5 . Mutations in KMT2D and FGFR3 were associated with decreased overall survival. We developed the first known HPV-associated SNSCC cell line and combinatorial small molecule inhibition of YAP/TAZ and PI3K pathways synergistically inhibited tumor cell clonogenicity. In conclusion, HPV-associated SNSCC and HPV-independent SNSCC are driven by molecularly distinct mechanisms of tumorigenesis. Combinatorial blockade of YAP/TAZ and vertical inhibition of the PI3K pathway may be useful in targeting HPV-associated SNSCC whereas targeting MYC and horizontal inhibition of RAS/PI3K pathways for HPV-independent SNSCC.

One Sentence Summary

This study solidifies HPV as a driver of HPV-associated SNSCC tumorigenesis, identifies molecular mechanisms distinguishing HPV-associated and HPV-independent SNSCC, and elucidates YAP/TAZ and PI3K blockade as key targets for HPV-associated SNSCC.

HPV oncogenes expressed from only one of multiple integrated HPV DNA copies drive clonal cell expansion in cervical cancer

The integration of HPV DNA into human chromosomes plays a pivotal role in the onset of papillomavirus-related cancers. HPV DNA integration often occurs by linearizing the viral DNA in the E1/E2 region, resulting in the loss of a critical viral early polyadenylation signal (PAS), which is essential for the polyadenylation of the E6E7 bicistronic transcripts and for the expression of the viral E6 and E7 oncogenes. Here, we provide compelling evidence that, despite the presence of numerous integrated viral DNA copies, virus-host fusion transcripts originate from only a single integrated HPV DNA in HPV16 and HPV18 cervical cancers and cervical cancer-derived cell lines. The host genomic elements neighboring the integrated HPV DNA are critical for the efficient expression of the viral oncogenes that leads to clonal cell expansion. The fusion RNAs that are produced use a host RNA polyadenylation signal downstream of the integration site, and almost all involve splicing to host sequences. In cell culture, siRNAs specifically targeting the host portion of the virus-host fusion transcripts effectively silenced viral E6 and E7 expression. This, in turn, inhibited cell growth and promoted cell senescence in HPV16+ CaSki and HPV18+ HeLa cells. Showing that HPV E6 and E7 expression from a single integration site is instrumental in clonal cell expansion sheds new light on the mechanisms of HPV-induced carcinogenesis and could be used for the development of precision medicine tailored to combat HPV-related malignancies.

IMPORTANCE

Persistent oncogenic HPV infections lead to viral DNA integration into the human genome and the development of cervical, anogenital, and oropharyngeal cancers. The expression of the viral E6 and E7 oncogenes plays a key role in cell transformation and tumorigenesis. However, how E6 and E7 could be expressed from the integrated viral DNA which often lacks a viral polyadenylation signal in the cancer cells remains unknown. By analyzing the integrated HPV DNA sites and expressed HPV RNAs in cervical cancer tissues and cell lines, we show that HPV oncogenes are expressed from only one of multiple chromosomal HPV DNA integrated copies. A host polyadenylation signal downstream of the integrated viral DNA is used for polyadenylation and stabilization of the virus-host chimeric RNAs, making the oncogenic transcripts targetable by siRNAs. This observation provides further understanding of the tumorigenic mechanism of HPV integration and suggests possible therapeutic strategies for the development of precision medicine for HPV cancers.

HPV DNA Integration at Actionable Cancer-Related Genes Loci in HPV-Associated Carcinomas

In HPV-associated carcinomas, some examples of cancer-related genes altered by viral insertion and corresponding to potential therapeutic targets have been described, but no quantitative assessment of these events, including poorly recurrent targets, has been reported to date. To document these occurrences, we built and analyzed a database comprised of 1455 cases, including HPV genotypes and tumor localizations. Host DNA sequences targeted by viral integration were classified as "non-recurrent" (one single reported case; 838 loci), "weakly recurrent" (two reported cases; 82 loci), and highly recurrent (≥3 cases; 43 loci). Whereas the overall rate of cancer-related target genes was 3.3% in the Gencode database, this rate increased to 6.5% in "non-recurrent", 11.4% in "weakly recurrent", and 40.1% in "highly recurrent" genes targeted by integration (p = 4.9 × 10-4). This rate was also significantly higher in tumors associated with high-risk HPV16/18/45 than other genotypes. Among the genes targeted by HPV insertion, 30.2% corresponded to direct or indirect druggable targets, a rate rising to 50% in "highly recurrent" targets. Using data from the literature and the DepMap 23Q4 release database, we found that genes targeted by viral insertion could be new candidates potentially involved in HPV-associated oncogenesis. A more systematic characterization of HPV/host fusion DNA sequences in HPV-associated cancers should provide a better knowledge of HPV-driven carcinogenesis and favor the development of personalize patient treatments.

De-Escalated Therapy and Early Treatment of Recurrences in HPV-Associated Head and Neck Cancer: The Potential for Biomarkers to Revolutionize Personalized Therapy

Human papillomavirus-associated (HPV+) head and neck squamous cell carcinoma (HNSCC) is the most common HPV-associated cancer in the United States, with a rapid increase in incidence over the last two decades. The burden of HPV+ HNSCC is likely to continue to rise, and given the long latency between infection and the development of HPV+ HNSCC, it is estimated that the effect of the HPV vaccine will not be reflected in HNSCC prevalence until 2060. Efforts have begun to decrease morbidity of standard therapies for this disease, and its improved characterization is being leveraged to identify and target molecular vulnerabilities. Companion biomarkers for new therapies will identify responsive tumors. A more basic understanding of two mechanisms of HPV carcinogenesis in the head and neck has identified subtypes of HPV+ HNSCC that correlate with different carcinogenic programs and that identify tumors with good or poor prognosis. Current development of biomarkers that reliably identify these two subtypes, as well as biomarkers that can detect recurrent disease at an earlier time, will have immediate clinical application.

FGFR1/2/3-rearranged carcinoma of the head and neck: expanded histological spectrum crossing path with high-risk HPV in the sinonasal tract

AIMS

Oncogenic FGFR1/2/3 rearrangements are found in various cancers. Reported cases in head and neck (HN) are mainly squamous cell carcinomas (SCCs) with FGFR3::TACC3 fusions, a subset of which also harbour high-risk human papillomavirus (HPV). However, the knowledge of the clinicopathological spectrum of FGFR-rearranged head and neck carcinomas (FHNC) is limited.

METHODS AND RESULTS

A retrospective MSK-fusion clinical sequencing cohort 2016-23 was searched to identify malignant tumours in the HN region harbouring FGFR1/2/3 fusion. FHNC were characterised by histological examination, immunohistochemistry and molecular analysis. Electronic medical records were reviewed. Three FHNC were identified. Two cases (cases 1 and 2) involved sinonasal tract and were high-grade carcinomas with squamous, basaloid, glandular and/or ductal-myoepithelial features. Case 1 arose in a 79-year-old man and harboured FGFR2::KIF1A fusion. Case 2 arose in a 58-year-old man, appeared as HPV-related multiphenotypic sinonasal carcinoma (HMSC), and was positive for FGFR2::TACC2 fusion and concurrent high-risk HPV, non-type 16/18. Case 3 was FGFR3::TACC3 fusion-positive keratinising SCCs arising in the parotid of a 60-year-old man. All three cases presented at stage T4. Clinical follow-up was available in two cases; case 1 remained disease-free for 41 months post-treatment and case 3 died of disease 2 months after the diagnosis.

CONCLUSIONS

FHNC include a morphological spectrum of carcinomas with squamous features and may occur in different HN locations, such as parotid gland and the sinonasal tract. Sinonasal cases can harbour FGFR2 rearrangement with or without associated high-risk HPV. Timely recognition of FHNC could help select patients potentially amenable to targeted therapy with FGFR inhibitors. Further studies are needed (1) to determine if FGFR2 rearranged/HPV-positive sinonasal carcinomas are biologically distinct from HMSC, and (2) to elucidate the biological and clinical significance of FGFR2 rearrangement in the context of high-risk HPV.

Mapping the landscape of HPV integration and characterising virus and host genome interactions in HPV-positive oropharyngeal squamous cell carcinoma

BACKGROUND

Human papillomavirus (HPV) integration into the host genome is an important factor in HPV(+)OPSCC carcinogenesis, in conjunction with HPV oncoproteins E6/E7. However, a well-studied investigation about virus-host interaction still needs to be completed. Our objective is to characterise HPV integration to investigate potential mechanisms of tumourigenesis independent of E6/E7 oncoproteins.

MATERIALS AND METHODS

High-throughput viral integration detection was performed on 109 HPV(+)OPSCC tumours with relevant clinicopathological information. Of these tumours, 38 tumours underwent targeted gene sequencing, 29 underwent whole exome sequencing and 26 underwent RNA sequencing.

RESULTS

HPV integration was detected in 94% of tumours (with a mean integration count of 337). Tumours occurring at the tonsil/oropharyngeal wall that exhibit higher PD-L1 expression demonstrated increased integration sites (p = .024). HPV exhibited a propensity for integration at genomic sites located within specific fragile sites (FRA19A) or genes associated with functional roles such as cell proliferation and differentiation (PTEN, AR), immune evasion (CD274) and glycoprotein biosynthesis process (FUT8). The viral oncogenes E2, E4, E6 and E7 tended to remain intact. HPV fragments displayed enrichment within host copy number variation (CNV) regions. However, insertions into genes related to altered homologous recombination repair were infrequent. Genes with integration had distinct expression levels. Fifty-nine genes whose expression level was affected by viral integration were identified, for example, EPHB1, which was reported to be involved in cellular protein metabolic process.

CONCLUSIONS

HPV can promote oncogenesis through recurrent integration into functional host genome regions, leading to subsequent genomic aberrations and gene expression disruption. This study characterises viral integrations and virus-host interactions, enhancing our understanding of HPV-related carcinogenesis mechanisms.

Most large structural variants in cancer genomes can be detected without long reads

Short-read sequencing is the workhorse of cancer genomics yet is thought to miss many structural variants (SVs), particularly large chromosomal alterations. To characterize missing SVs in short-read whole genomes, we analyzed 'loose ends'-local violations of mass balance between adjacent DNA segments. In the landscape of loose ends across 1,330 high-purity cancer whole genomes, most large (>10-kb) clonal SVs were fully resolved by short reads in the 87% of the human genome where copy number could be reliably measured. Some loose ends represent neotelomeres, which we propose as a hallmark of the alternative lengthening of telomeres phenotype. These pan-cancer findings were confirmed by long-molecule profiles of 38 breast cancer and melanoma cases. Our results indicate that aberrant homologous recombination is unlikely to drive the majority of large cancer SVs. Furthermore, analysis of mass balance in short-read whole genome data provides a surprisingly complete picture of cancer chromosomal structure.

Targeted inhibition of BET proteins in HPV-16 associated head and neck squamous cell carcinoma reveals heterogeneous transcription response

Integrated human papillomavirus (HPV-16) associated head and neck squamous cell carcinoma (HNSCC) tumors have worse survival outcomes compared to episomal HPV-16 HNSCC tumors. Therefore, there is a need to differentiate treatment for HPV-16 integrated HNSCC from other viral forms. We analyzed TCGA data and found that HPV+ HNSCC expressed higher transcript levels of the bromodomain and extra terminal domain (BET) family of transcriptional coregulators. However, the mechanism of BET protein-mediated transcription of viral-cellular genes in the integrated viral-HNSCC genomes needs to be better understood. We show that BET inhibition downregulates E6 significantly independent of the viral transcription factor, E2, and there was overall heterogeneity in the downregulation of viral transcription in response to the effects of BET inhibition across HPV-associated cell lines. Chemical BET inhibition was phenocopied with the knockdown of BRD4 and mirrored downregulation of viral E6 and E7 expression. Strikingly, there was heterogeneity in the reactivation of p53 levels despite E6 downregulation, while E7 downregulation did not alter Rb levels significantly. We identified that BET inhibition directly downregulated c-Myc and E2F expression and induced CDKN1A expression. Overall, our studies show that BET inhibition provokes a G1-cell cycle arrest with apoptotic activity and suggests that BET inhibition regulates both viral and cellular gene expression in HPV-associated HNSCC.

Clinical, morphologic and molecular heterogeneity of HPV-associated oropharyngeal cancer

The incidence of human papillomavirus-positive (HPV+) oropharyngeal squamous cell carcinoma (OPSCC) is rising rapidly and has exceeded cervical cancer to become the most common HPV-induced cancer in developed countries. Since patients with HPV + OPSCC respond very favorably to standard aggressive treatment, the emphasis has changed to reducing treatment intensity. However, recent multi-center clinical trials failed to show non-inferiority of de-escalation strategies on a population basis, highlighting the need to select low-risk patients likely to respond to de-intensified treatments. In contrast, there is a substantial proportion of patients who develop recurrent disease despite aggressive therapy. This supports that HPV + OPSCC is not a homogeneous disease, but comprises distinct subtypes with clinical and biological variations. The overall goal for this review is to identify biomarkers for HPV + OPSCC that may be relevant for patient stratification for personalized treatment. We discuss HPV + OPSCC as a heterogeneous disease from multifaceted perspectives including clinical behavior, tumor morphology, and molecular phenotype. Molecular profiling from bulk tumors as well as single-cell sequencing data are discussed as potential driving factors of heterogeneity between tumor subgroups. Finally, we evaluate key challenges that may impede in-depth investigations of HPV + OPSCC heterogeneity and outline potential future directions, including a section on racial and ethnic differences.

Whole-genome CpG-resolution DNA Methylation Profiling of HNSCC Reveals Distinct Mechanisms of Carcinogenesis for Fine-scale HPV+ Cancer Subtypes

DNA methylation is a vital early step in carcinogenesis. Most findings of aberrant DNA methylation in head and neck squamous cell carcinomas (HNSCC) are array based with limited coverage and resolution, and mainly explored by human papillomavirus (HPV) status, ignoring the high heterogeneity of this disease. In this study, we performed whole-genome bisulfite sequencing on a well-studied HNSCC cohort (n = 36) and investigated the methylation changes between fine-scaled HNSCC subtypes in relation to genomic instability, repetitive elements, gene expression, and key carcinogenic pathways. The previously observed hypermethylation phenotype in HPV-positive (HPV+) tumors compared with HPV-negative tumors was robustly present in the immune-strong (IMU) HPV+ subtype but absent in the highly keratinized (KRT) HPV+ subtype. Methylation levels of IMU tumors were significantly higher in repetitive elements, and methylation showed a significant correlation with genomic stability, consistent with the IMU subtype having more genomic stability and better prognosis. Expression quantitative trait methylation (cis-eQTM) analysis revealed extensive functionally-relevant differences, and differential methylation pathway analysis recapitulated gene expression pathway differences between subtypes. Consistent with their characteristics, KRT and HPV-negative tumors had high regulatory potential for multiple regulators of keratinocyte differentiation, which positively correlated with an expression-based keratinization score. Together, our findings revealed distinct mechanisms of carcinogenesis between subtypes in HPV+ HNSCC and uncovered previously ignored epigenomic differences and clinical implications, illustrating the importance of fine-scale subtype analysis in cancer.

Significance

This study revealed that the previously observed hypermethylation of HPV(+) HNSCC is due solely to the IMU subtype, illustrating the importance of fine-scale subtype analysis in such a heterogeneous disease. Particularly, IMU has significantly higher methylation of transposable elements, which can be tested as a prognosis biomarker in future translational studies.

Blood and saliva-derived ctDNA is a marker of residual disease after treatment and correlates with recurrence in human papillomavirus-associated head and neck cancer

BACKGROUND

There is an alarming increase in human papillomavirus-associated head and neck cancer (HNC), reaching epidemic levels. While patient prognosis is generally good, off-target treatment effects are associated with decreased quality of life. Thus, non-invasive strategies to predict treatment response and risk of recurrence could help de-escalate treatment. In this study, we tested circulating tumor (ct)DNA in liquid biopsies (blood/saliva) of HPV-positive HNC patients to assess treatment response and disease progression.

METHODS

A total of 235 blood and saliva samples were collected from 60 HPV-positive and 17 HPV-negative HNC patients (control group) before and/or after treatment. Samples were analyzed using ddPCR for HPV16/18/31/33/35/45 and correlated with imaging and pathological examination.

RESULTS

HPV-ctDNA detection was significantly higher prior to treatment (91%) than after treatment (8.0%) (χ2 p < 0.00001), with high concordance between saliva and blood (93%). In matched samples, all patients positive for ctDNA before treatment showed significant reductions in ctDNA levels post treatment (p < 0.0001). All but one patient with persistent ctDNA after treatment showed residual tumor and subsequent recurrence. Finally, fragmentomic analysis revealed shifts in cell-free DNA fragment size after treatment, suggesting a complementary biomarker for treatment response.

CONCLUSIONS

Blood and saliva were found to be good sources of HPV-ctDNA. The presence of ctDNA strongly correlated with treatment response, demonstrating clinical utility as a non-invasive biomarker to monitor tumor progression in HPV-positive HNC. Liquid biopsy based ctDNA testing could be an effective approach to predict recurrence and stratify patients for de-escalation of treatment, thereby improving quality of life.

Human papillomavirus integration transforms chromatin to drive oncogenesis

BACKGROUND

Human papillomavirus (HPV) drives almost all cervical cancers and up to 70% of head and neck cancers. Frequent integration into the host genome occurs predominantly in tumorigenic types of HPV. We hypothesize that changes in chromatin state at the location of integration can result in changes in gene expression that contribute to the tumorigenicity of HPV.

RESULTS

We find that viral integration events often occur along with changes in chromatin state and expression of genes near the integration site. We investigate whether introduction of new transcription factor binding sites due to HPV integration could invoke these changes. Some regions within the HPV genome, particularly the position of a conserved CTCF binding site, show enriched chromatin accessibility signal. ChIP-seq reveals that the conserved CTCF binding site within the HPV genome binds CTCF in 4 HPV^+ cancer cell lines. Significant changes in CTCF binding pattern and increases in chromatin accessibility occur exclusively within 100 kbp of HPV integration sites. The chromatin changes co-occur with out-sized changes in transcription and alternative splicing of local genes. Analysis of The Cancer Genome Atlas (TCGA) HPV⁺ tumors indicates that HPV integration upregulates genes which have significantly higher essentiality scores compared to randomly selected upregulated genes from the same tumors.

CONCLUSIONS

Our results suggest that introduction of a new CTCF binding site due to HPV integration reorganizes chromatin state and upregulates genes essential for tumor viability in some HPV⁺ tumors. These findings emphasize a newly recognized role of HPV integration in oncogenesis.

Human papillomavirus genomics: Understanding carcinogenicity

Human papillomavirus (HPV) causes virtually all cervical cancers and many cancers at other anatomical sites in both men and women. However, only 12 of 448 known HPV types are currently classified as carcinogens, and even the most carcinogenic type - HPV16 - only rarely leads to cancer. HPV is therefore necessary but insufficient for cervical cancer, with other contributing factors including host and viral genetics. Over the last decade, HPV whole genome sequencing has established that even fine-scale within-type HPV variation influences precancer/cancer risks, and that these risks vary by histology and host race/ethnicity. In this review, we place these findings in the context of the HPV life cycle and evolution at various levels of viral diversity: between-type, within-type, and within-host. We also discuss key concepts necessary for interpreting HPV genomic data, including features of the viral genome; events leading to carcinogenesis; the role of APOBEC3 in HPV infection and evolution; and methodologies that use deep (high-coverage) sequencing to characterize within-host variation, as opposed to relying on a single representative (consensus) sequence. Given the continued high burden of HPV-associated cancers, understanding HPV carcinogenicity remains important for better understanding, preventing, and treating cancers attributable to infection.

High-Risk Oncogenic Human Cytomegalovirus

Human cytomegalovirus (HCMV) is a herpesvirus that infects between 40% and 95% of the population worldwide, usually without symptoms. The host immune response keeps the virus in a latent stage, although HCMV can reactivate in an inflammatory context, which could result in sequential lytic/latent viral cycles during the lifetime and thereby participate in HCMV genomic diversity in humans. The high level of HCMV intra-host genomic variability could participate in the oncomodulatory role of HCMV where the virus will favor the development and spread of cancerous cells. Recently, an oncogenic role of HCMV has been highlighted in which the virus will directly transform primary cells; such HCMV strains are named high-risk (HR) HCMV strains. In light of these new findings, this review defines the criteria that characterize HR-HCMV strains and their molecular as well as the phenotypic impact on the infected cell and its tumor microenvironment.

Human papillomavirus-related neoplasia of the ocular adnexa

Human papillomaviruses (HPV) are involved in approximately 5% of solid cancers worldwide. The mucosotropic genotypes infect the stratified epithelium of various locations, where persistent infection may lead to invasive carcinomas. While the causative role of HPV in certain anogenital and head and neck carcinomas is well established, the role of HPV in carcinomas arising in the mucosal membranes of the ocular adnexal tissue (the lacrimal drainage system and the conjunctiva) has been a topic of great uncertainty. Therefore, we conducted a series of studies to assess the correlation between HPV and carcinomas arising in the mucosa of the ocular adnexal tissue and characterize the clinical, histopathological, and genomic features of the tumors in the context of HPV status in a Danish nationwide cohort. We collected clinical and histopathological data and tumor specimens from patients with carcinomas of the conjunctiva and the lacrimal drainage system, and their potential precursors, identified in Danish nationwide registries. The HPV status of the tumors was determined by the combined use of HPV DNA polymerase chain reaction (PCR), HPV E6/E7 mRNA in-situ hybridization, and p16 immunohistochemistry. The genomic profile was investigated by high-throughput DNA sequencing targeting 523 cancer-relevant genes. The literature to date on carcinomas of the lacrimal drainage system and the conjunctiva was summarized. In the Danish cohort, 67% of all carcinomas of the lacrimal drainage system and 21% of all conjunctival carcinomas were HPV-positive. HPV16 was the most frequently implicated genotype. A full-thickness expression of the viral oncogenes E6 and E7 was evident in almost all HPV DNA-positive cases. The HPV-positive carcinomas of the conjunctiva and the lacrimal drainage system shared histopathological and genomic features distinct from their HPV-negative counterparts. The HPV-positive carcinomas were characterized by a non-keratinizing morphology, p16 overexpression, high transcriptional activity of HPV E6/E7, and frequent pathogenic variants in the PI3K-AKT signaling cascade. In contrast, the HPV-negative carcinomas were characterized by a keratinizing morphology, lack of p16 and E6/E7 expression, and frequent somatic pathogenic variants in TP53, CDKN2A, and RB1. Among the patients with conjunctival tumors, HPV positivity was associated with a younger age at diagnosis and a higher risk of recurrence. In conclusion, the results support an etiological role of HPV in a subset of conjunctival and LDS carcinomas and their precursor lesions. Our investigations have shown that the HPV-positive carcinomas of the ocular adnexa share genomic and phenotypic characteristics with HPV-positive carcinomas of other anatomical locations. Therefore, these patients may be eligible for inclusion in future basket trials and future treatment regimens tailored to the more frequently occurring HPV-positive carcinomas of other locations. Future research will further elucidate the diagnostic, prognostic, and predictive role of HPV in these carcinomas.

Direct Comparison of HPV16 Viral Genomic Integration, Copy Loss, and Structural Variants in Oropharyngeal and Uterine Cervical Cancers Reveal Distinct Relationships to E2 Disruption and Somatic Alteration

Squamous cell carcinoma of the oropharynx caused by HPV type 16 (HPV16+ OPSCC) is the most common HPV-associated malignancy in the USA and has many molecular differences from uterine cervical squamous cell carcinoma (UCSCC). Our understanding of HPV oncogenesis relied on studies of UCSCC revealing a consensus model reliant on HPV integration with a loss of E2. Here, we compare patterns of HPV integration in UCSCC and OPSCC by analysis of affinity capture sequencing of the HPV16 genome in 104 OPSCC and 44 UCSCC tumors. These cohorts were contemporaneously sequenced using an identical strategy. Integration was identified using discordant read pair clustering and assembly-based approaches. Viral integration sites, structural variants, and copy losses were examined. While large-scale deep losses of HPV16 genes were common in UCSCC and were associated with E2 loss, deep copy losses of the HPV16 genome were infrequent in HPV16+ OPSCC. Similarly, structural variants within HPV16 favored E2 loss in UCSCC but not OPSCC. HPV16 integration sites were non-random, with recurrent integration hot-spots identified. OPSCC tumors had many more integration sites per tumor when compared to UCSCC and had more integration sites in genomic regions with high gene density. These data show that viral integration and E2 disruption are distinct in UCSCC and OPSCC. Our findings also add to growing literature suggesting that HPV tumorigenesis in OPSCC does not follow the model developed based on UCSCC.

Human Papillomavirus Integration Strictly Correlates with Global Genome Instability in Head and Neck Cancer

Human papillomavirus (HPV)-positive head and neck cancers, predominantly oropharyngeal squamous cell carcinoma (OPSCC), exhibit epidemiologic, clinical, and molecular characteristics distinct from those OPSCCs lacking HPV. We applied a combination of whole-genome sequencing and optical genome mapping to interrogate the genome structure of HPV-positive OPSCCs. We found that the virus had integrated in the host genome in two thirds of the tumors examined but resided solely extrachromosomally in the other third. Integration of the virus occurred at essentially random sites within the genome. Focal amplification of the virus and the genomic sequences surrounding it often occurred subsequent to integration, with the number of tandem repeats in the chromosome accounting for the increased copy number of the genome sequences flanking the site of integration. In all cases, viral integration correlated with pervasive genome-wide somatic alterations at sites distinct from that of viral integration and comprised multiple insertions, deletions, translocations, inversions, and point mutations. Few or no somatic mutations were present in tumors with only episomal HPV. Our data could be interpreted by positing that episomal HPV is captured in the host genome following an episode of global genome instability during tumor development. Viral integration correlated with higher grade tumors, which may be explained by the associated extensive mutation of the genome and suggests that HPV integration status may inform prognosis.

IMPLICATIONS

Our results indicate that HPV integration in head and neck cancer correlates with extensive pangenomic structural variation, which may have prognostic implications.

Novel Systemic Treatment Modalities Including Immunotherapy and Molecular Targeted Therapy for Recurrent and Metastatic Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinomas (HNSCCs) are the sixth most common cancers worldwide. More than half of patients with HNSCC eventually experience disease recurrence and/or metastasis, which can threaten their long-term survival. HNSCCs located in the oral cavity and larynx are usually associated with tobacco and/or alcohol use, whereas human papillomavirus (HPV) infection, particularly HPV16 infection, is increasingly recognized as a cause of oropharyngeal HNSCC. Despite clinical, histologic, and molecular differences between HPV-positive and HPV-negative HNSCCs, current treatment approaches are the same. For recurrent disease, these strategies include chemotherapy, immunotherapy with PD-1-inhibitors, or a monoclonal antibody, cetuximab, that targets epidermal growth factor; these therapies can be administered either as single agents or in combination. However, these treatment strategies carry a high risk of toxic side effects; therefore, more effective and less toxic treatments are needed. The landscape of HNSCC therapy is changing significantly; numerous clinical trials are underway to test novel therapeutic options like adaptive cellular therapy, antibody-drug conjugates, new targeted therapy agents, novel immunotherapy combinations, and therapeutic vaccines. This review helps in understanding the various developments in HNSCC therapy and sheds light on the path ahead in terms of further research in this field.

Potential multi-modal effects of provirus integration on HIV-1 persistence: lessons from other viruses

Despite antiretroviral therapy (ART), HIV-1 persists as proviruses integrated into the genomic DNA of CD4⁺ T cells. The mechanisms underlying the persistence and clonal expansion of these cells remain incompletely understood. Cases have been described in which proviral integration can alter host gene expression to drive cellular proliferation. Here, we review observations from other genome-integrating human viruses to propose additional putative modalities by which HIV-1 integration may alter cellular function to favor persistence, such as by altering susceptibility to cytotoxicity in virus-expressing cells. We propose that signals implicating such mechanisms may have been masked thus far by the preponderance of defective and/or nonreactivatable HIV-1 proviruses, but could be revealed by focusing on the integration sites of intact proviruses with expression potential.