Longitudinal measurement of HPV copy number in cell-free DNA is associated with patient outcomes in HPV-positive oropharyngeal cancer

Therapeutic options for human papillomavirus-positive tonsil and base of tongue cancer

The incidences of human papillomavirus-positive (HPV+) tonsillar and base tongue squamous cell carcinomas (TSCC and BOTSCC) have increased in recent decades. Notably, HPV+ TSCC and BOTSCC have a significantly better prognosis than their HPV-negative counterparts when treated with current surgical options, radiotherapy, or intensified chemoradiotherapy. However, a cure is not achieved in 20% of patients with HPV+ TSCC/BOTSCC. Meanwhile, cured patients often present with severe chronic side effects. This necessitates novel tailored alternatives, such as targeted therapy, immune checkpoint inhibitors (ICIs), and treatment de-escalation, together with better follow-up. Current precision medicine therefore focuses on detecting predictive and driver cancer genes to better stratify patient treatment, provide those with poor prognostic markers targeted therapy, and select those with favorable markers for de-escalated therapy. Moreover, detecting cell-free HPV DNA (cfHPV DNA) in plasma before and after treatment has been attempted to improve follow-up. In this context, this perspective discusses the significance of optimally defining HPV+ status, which requires HPV DNA and p16INKa overexpression, using prognostic markers, such as high CD8+ T-cell counts and HPV E2 mRNA expression, tumor size, and following cfHPV DNA for patient selection for specific therapies. Clinical trials with ICI with/without chemotherapy, targeted therapy with specific inhibitors-such as phosphoinositide 3-kinase and fibroblast growth factor receptor inhibitors-or immune therapy with various HPV-based vaccines for treating recurrences have yielded promising results.

A Prospective Trial of Biomarker-Guided Surveillance for HPV-Positive Oropharynx Cancer Using Plasma Tumor Tissue-Modified Viral HPV DNA

PURPOSE

Observational studies suggest circulating tumor human papillomavirus (HPV) DNA may facilitate early detection of recurrent HPV-positive oropharynx cancer. We prospectively investigated whether biomarker-guided surveillance detects recurrence earlier than the standard-of-care methods.

PATIENTS AND METHODS

We enrolled patients evaluated for HPV-positive oropharynx cancer at a single center from November, 2020, to April, 2023, undergoing curative-intent treatment in a single-arm cohort study. Pretreatment plasma and/or tumor tissue were tested for tumor tissue-modified viral (TTMV) HPV DNA from HPV subtypes 16/18/31/33/35 using a droplet digital PCR-based commercial assay. Posttreatment plasma TTMV was assessed periodically. Detectable/indeterminate tests prompted imaging. The primary outcome was the proportion of recurrences first detected by TTMV.

RESULTS

Median follow-up was 23 months, with median six posttreatment TTMV tests for 155 subjects. Fifteen subjects (9%) experienced recurrence. Among these, six [40%, 95% confidence interval (CI) = 16%-68%] were "early true-positives," for whom TTMV detection predated and prompted the imaging and clinical workup that diagnosed recurrence (median lead time = 132 days; range = 47-280). Another five subjects (33%) were "confirmatory true-positives," for whom detectable TTMV confirmed suspicious standard-of-care imaging findings. Finally, four subjects (27%) with recurrence had undetectable TTMV at diagnosis ("false-negatives"). False-negatives had low or undetectable pretreatment TTMV, and 2/4 had non-HPV16 genotypes. Finally, three subjects had prolonged detectable TTMV without disease ("false-positives"); all had immunologic comorbidities. Overall, the sensitivity of TTMV for recurrence was 73% (95% CI = 45%-92%). Among 117 subjects with HPV16 and detectable pretreatment TTMV, sensitivity was higher (91%, 95% CI = 59%-100%).

CONCLUSIONS

TTMV-guided surveillance facilitates early detection of many HPV-positive oropharynx cancer recurrences, with the highest sensitivity for HPV16 and detectable pretreatment TTMV. Clinical implementation should be carefully informed by the limitations described in this study. See related commentary by Califano, p. 1561.

Circulating tumor DNA in human papillomavirus-associated oropharyngeal cancer management: A systematic review

OBJECTIVE

Circulating tumor DNA (ctDNA) has emerged as a promising tool in the treatment of HPV-associated oropharyngeal squamous cell cancer (OPSCC). This systematic review sought to answer the question: what is the current role of ctDNA in the diagnosis, treatment, and surveillance of HPV-associated OPSCC?

DATA SOURCES

Medline (Ovid), Embase (Ovid), Scopus.

REVIEW METHODS

Original articles studying the role of ctDNA in the diagnosis or surveillance of HPV-associated OPSCC were eligible for inclusion. Two authors independently reviewed studies for inclusion and abstracted data, including study design, characterization of liquid biopsy technology, and diagnostic outcomes.

RESULTS

After a preliminary screening of 441 studies, 23 were selected for inclusion. Ten studies were conducted retrospectively, and 13 were conducted prospectively. In these studies, diagnostic testing included plasma-based droplet digital polymerase chain reaction (ddPCR, n = 13), quantitative PCR (qPCR, n = 4), digital PCR (dPCR, n = 3), next-generation sequencing (NGS) (n = 3), or a ctDNA detection kit (n = 1). Diagnostic outcomes were reported for pre-diagnosis (n = 1), pre-treatment (n = 17), during treatment (n = 6), and surveillance/recurrence (n = 11) timepoints. Test sensitivities ranged from 20.6 %-100 % pre-treatment and 72 %-100 % during surveillance, while test specificities ranged from 95 %-100 % pre-treatment and 87.2 %-100 % during surveillance.

CONCLUSION

The majority of studied ctDNA technologies allow for detection of HPV-associated OPSCC with high diagnostic accuracy. However, heterogeneity is introduced by test type and assay used. These findings highlight the utility, as well as limitations, of ctDNA in the diagnosis, treatment monitoring, and surveillance of HPV-associated OPSCC. Future studies and clinical consensus will need to address acceptable diagnostic accuracy thresholds for clinical use.

Prognostic Implications of HPV Cell-Free DNA Serial Testing During Follow-Up of p16 Positive Oropharyngeal Squamous Cell Carcinoma After Curative-Intent Treatment

INTRODUCTION

Plasma circulating HPV cell-free DNA has high sensitivity and specificity for the detection of HPV-mediated oropharyngeal squamous cell carcinoma. We investigated the clinical significance of serial testing after curative-intent treatments.

MATERIALS AND METHODS

Patients with concordant p16 positive tumour or neck node biopsy and positive high-risk HPV plasma cell-free DNA were prospectively recruited. HPV cell-free DNA were obtained using digital droplet polymerase chain reaction (ddPCR) and were collected at diagnosis and at every clinical follow-up. Three months after completion of curative-intent treatments, patients were stratified according to treatment response on computed tomography. Complete responders (CR) were followed-up clinically, partial responders (PR) underwent further imaging and surgical/medical management if appropriate, patients with progressive disease (PD) received palliative treatments.

RESULTS

A hundred and fourteen patients were included and 717 HPV cfDNA ddPCR samples were analysed during a median follow-up of 103 weeks (IQR, 40.2-147.8). Ninety (78.9%) patients were classified as CR, 18 (15.8%) as PR and all except one, who was rapidly diagnosed with PD, had negative HPV ddPCR at 12 weeks follow-up; 6 (5.3%) had PD and all except one had positive HPV ddPCR. Eleven had recurrent disease, 6 in the CR group (6.6%) and 5 among PR (27.7%). Ninety patients had consistently negative HPV ddPCR at all time points and one developed a recurrence (NPV 99%, 95% C.I., 93.2-99.8%). Eighteen patients developed positive HPV ddPCR and 10 developed recurrent disease (PPV 55%, 95% C.I., 38.6-71.4%). Ten patients had two consecutively positive HPV ddPCR and all had proven disease (PPV 100%, 95% C.I., 69.2-100%). Nine patients had transiently positive HPV ddPCR and none developed disease at that time.

CONCLUSIONS

Post-treatment HPV ddPCR reflected treatment response on imaging and serial testing had high PPV and NPV in detecting recurrent disease.

Methodology of cfHPV-DNA Detection in Head and Neck Cancer: A Systematic Review and Meta-analysis

OBJECTIVE

We aim to compare the diagnostic accuracy of the different methodologies used in the detection of cell-free human papillomavirus (HPV) DNA in HPV-associated head and neck squamous cell carcinoma detection using bivariate analysis methods.

DATA SOURCES

Pubmed, Embase, and Scopus were queried using a broad search strategy to search for relevant studies.

REVIEW METHODS

Test characteristics were extracted from 33 studies following literature screening, and underwent analyses utilizing a bivariate approach. Summary statistics were identified for each type of methodology, and forest plots and summary receiver operating characteristic curves were constructed. Bias was estimated using Deek's Funnel Plot and the QUADAS-2 tool.

RESULTS

In terms of diagnostic accuracy, digital droplet polymerase chain reaction (ddPCR) based testing exhibited the highest diagnostics odds ratio at 138 (59.5, 318), followed closely by next-generation sequencing (NGS) at 120 (39.7, 362), then by polymerase chain reaction (PCR) at 31.4 (14.4, 68.6), and quantitative PCR at 8.74 (4.63, 16.5).

CONCLUSION

NGS and ddPCR are comparable in overall diagnostic accuracy, bringing into question their relative roles in diagnosis and screening. Cost-effective ddPCR assays may serve as useful diagnostic and screening tests in the clinic with their low false positive rates and high sensitivity. However, NGS assays also offer high sensitivity and companion metrics, suggesting they may have a more precise role in disease monitoring. Importantly, assay development and benchmarking need further standardization to improve comparison between assays. Finally, saliva-based testing needs to be further investigated using NGS and ddPCR to further understand its limitations in disease detection and monitoring.

The landscape of circulating tumor HPV DNA and TTMV-HPVDNA for surveillance of HPV-oropharyngeal carcinoma: systematic review and meta-analysis

BACKGROUND

Human papilloma virus (HPV) related cancers of the oropharynx are rapidly increasing in incidence and may soon represent the majority of all head and neck cancers. Improved monitoring and surveillance methods are thus an urgent need in public health.

MAIN TEXT

The goal is to highlight the current potential and limitations of liquid biopsy through a meta analytic study on ctHPVDNA and TTMV-HPVDNA. It was performed a Literature search on articles published until December 2023 using three different databases: MEDLINE, Embase, and Cochrane Library. Studies that evaluated post-treatment ctHPVDNA and TTMV-HPVDNA in patients with HPV + OPSCC, studies reporting complete data on the diagnostic accuracy in recurrence, or in which the number of true positives, false positives, true negatives, and false negatives was extractable, and methods of detection of viral DNA clearly defined. The meta-analysis was conducted following the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) reporting guidelines. The aim of this meta-analysis was to evaluate the sensitivity, specificity, and accuracy of ctHPVDNA and TTMV by ddPCR to define its efficacy in clinical setting for the follow up of HPV-OPSCC.

CONCLUSION

The 12 studies included in the meta-analysis provided a total of 1311 patients for the analysis (398 valuated with ctHPVDNA and 913 with TTMV-HPVDNA). Pooled sensitivity and specificity were 86% (95% CI: 78%-91%) and 96% (95% CI: 91%-99%), respectively; negative and positive likelihood ratios were 0.072 (95% CI: 0.057-0.093) and 24.7 (95% CI: 6.5-93.2), respectively; pooled DOR was 371.66 (95% CI: 179.1-918). The area under the curve (AUC) was 0.81 (95% CI, 0.67-0.91). Liquid biopsy for the identification of cell free DNA might identify earlier recurrence in HPV + OPSCC patients. At the present time, liquid biopsy protocol needs to be standardized and liquid biopsy cannot yet be used in clinical setting. In the future, a multidimensional integrated approach which links multiple clinical, radiological, and laboratory data will contribute to obtain the best follow-up strategies for the follow-up of HPV-OPSCC.

Cell-free DNA analysis for recurrent respiratory papillomatosis: A case report

A 35-year-old male presented with recurrent respiratory papillomatosis. Human papillomavirus type 11 was detected from all sites of tumor tissue DNA by PCR. The pre-surgery cell-free DNA (cfDNA) viral load (3.33 × 103 copies/ng DNA) fell below the post-surgical detection limits on achieving remission, suggesting cfDNA's potential as a biomarker.

Current and Emerging Diagnostic, Prognostic, and Predictive Biomarkers in Head and Neck Cancer

Head and neck cancers (HNC) are a biologically diverse set of cancers that are responsible for over 660,000 new diagnoses each year. Current therapies for HNC require a comprehensive, multimodal approach encompassing resection, radiation therapy, and systemic therapy. With an increased understanding of the mechanisms behind HNC, there has been growing interest in more accurate prognostic indicators of disease, effective post-treatment surveillance, and individualized treatments. This chapter will highlight the commonly used and studied biomarkers in head and neck squamous cell carcinoma.

Circulating Tumor HPV DNA for Surveillance of HPV-Positive Oropharyngeal Squamous Cell Carcinoma: A Narrative Review

Importance

Human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma has an overall favorable prognosis, yet a subset of patients will experience devastating disease recurrence. Current surveillance standards for detection of recurrent disease are imperfect. There is growing interest in improving detection of recurrent disease through the use of plasma-based assays able to detect circulating tumor HPV DNA.

Observations

Although most circulating tumor HPV DNA assays remain in the research domain, the circulating tumor tissue-modified viral HPV DNA assay became commercially available in the United States in early 2020 and has been increasingly used in the clinical setting. With the rapidly increasing incidence of HPV-positive oropharyngeal squamous cell carcinoma and concomitant expansion of biomarker capabilities for this disease, it is critical to reexamine current posttreatment surveillance practices and to determine whether emerging technologies may be used to improve outcomes for a growing survivor population. However, caution is advised; it is not yet known whether biomarker-based surveillance is truly beneficial, and as is true with any intervention, it has the capacity to cause harm.

Conclusions and Relevance

Using Margaret Pepe's classic 5 phases of biomarker development for early detection of cancer as a framework, this article reviews the current state of knowledge, highlights existing knowledge gaps, and suggests research that should be prioritized to understand the association between biomarker-based surveillance and patient outcomes. Specific attention is paid to the commercially available tumor tissue-modified viral HPV DNA assay, given its increasing clinical use. This review may serve as a road map for future research and a guide for clinicians considering its adoption in practice. Enrollment of patients into clinical trials incorporating biomarker-based surveillance should be prioritized.

Liquid Biopsies with Circulating Plasma HPV-DNA Measurements-A Clinically Applicable Surveillance Tool for Patients with HPV-Positive Oropharyngeal Cancer

PURPOSE

To evaluate the accuracy of cell-free human papillomavirus-DNA (cfHPV-DNA) measurements in liquid biopsies in predicting disease in patients with HPV-positive/p16-positive (HPV+/p16+) oropharyngeal squamous cell carcinoma (OPSCC).

EXPERIMENTAL DESIGN

This was a prospective cohort study. Plasma samples were collected before treatment, serially after curative intended therapy at follow-up visits 2 weeks, and 6, 9, 12, 18, 24, and 30 months after treatment. A droplet digital PCR assay comprising eight HPV genotypes was used. HPV genotypes found in plasma and tumor tissue were compared. We correlated biopsy- or imaging-verified tumor progression to cfHPV-DNA in follow-up samples.

RESULTS

We enrolled 72 patients with HPV+/p16+ OPSCC. Baseline sensitivity for cfHPV-DNA detection was 97.2% (95% confidence interval, 90.3%-99.6%). CfHPV-DNA copy number/milliliter plasma correlated with tumor stage. We found a 100% concordance between HPV genotype in tumor tissue and plasma. Fifty-four patients were followed with serial blood samples for a median of 19.7 months (interquartile range, 13.5-25.5 months). Forty-one patients had undetectable plasma cfHPV-DNA in all follow-up samples, and none developed recurrences. Thirteen patients were classified as cfHPV-DNA-positive in a follow-up plasma sample. Of these, five patients developed a recurrence, and three had residual cancer. It was possible to detect cfHPV-DNA in plasma 97 to 166 days prior to the proven recurrence.

CONCLUSIONS

To our knowledge, to date, our study, comprising the largest study of patients with HPV+/p16+ OPSCC, using an ultrasensitive multiplex HPV gene panel, revealed a high sensitivity of cfHPV-DNA detection in the liquid biopsies. We recommend serial plasma HPV samples for clinical monitoring of patients with HPV+/p16+ OPSCC.

[ctHPV-DNA based precision oncology for patients with oropharyngeal cancer - Where are we?]

Human papillomavirus (HPV) is an established etiologic factor for cancers in the head and neck region, specifically for Oropharyngeal Squamous Cell Carcinoma (OPSCC). The comparatively good overall survival justifies the current discussion regarding therapy de-escalation for patients with a low-risk profile. In addition to the immunohistochemistry-based biomarker p16INK4a, there is still a need for diagnostic and prognostic biomarkers that allow risk stratification and monitoring during therapy and follow-up of these patients. In recent years, liquid biopsy, especially in the form of plasma samples, has gained importance and is already used to monitor viral DNA in patients with Epstein-Barr virus-associated nasopharyngeal carcinoma. Circulating DNA (ctDNA) released by the tumor into the bloodstream is particularly suitable for a high specificity in detecting virus-associated tumors. Detection of viral E6 and E7 oncogenes in HPV-positive OPSCC is predominantly performed by droplet digital/quantitative PCR as well as next generation sequencing. Detection of circulating HPV-DNA derived from tumor cells (ctHPV-DNA) at diagnosis is associated with advanced tumor stage, locoregional and distant metastases. Longitudinal studies have further demonstrated that detectable and/or increasing ctHPV-DNA levels are associated with treatment failure and disease relapse. However, a standardization of the diagnostic procedure is necessary before introducing liquid biopsy into the clinical routine. In the future, this might allow a valid reflection of disease progression in HPV-positive OPSCC.

Redefining precision radiotherapy through liquid biopsy

Precision radiotherapy refers to the ability to deliver radiation doses with sub-millimetre accuracy. It does not however consider individual variation in tumour or normal tissue response, failing to maximise tumour control and minimise toxicity. Combining precise delivery with personalised dosing, through analysis of cell-free DNA, would redefine precision in radiotherapy.

Testing for Human Papillomaviruses in Urine, Blood, and Oral Specimens: an Update for the Laboratory

Twelve high-risk alpha human papillomavirus (HPV) genotypes cause approximately 690,000 cancer cases annually, with cervical and oropharyngeal cancer being the two most prominent types. HPV testing is performed in laboratory settings for various applications of a clinical, epidemiological, and research nature using a range of clinical specimens collected by clinicians or by individuals (self-collected specimens). Here, we reflect on the importance and justification of using the right test for the right application and provide practical updates for laboratories either participating in or anticipating involvement in HPV testing in three specimen types, namely, urine, blood, and oral specimens, which are considered "alternative" specimens by many. In addition to clinician-collected cervical samples and self-collected cervicovaginal samples, first-void urine is emerging as a credible specimen for HPV-based cervical cancer screening, triage of HPV screen-positive women, monitoring HPV vaccine impact, and HPV testing in groups for which a less invasive sample is preferred. Detection of cell-free DNA (including HPV DNA) in blood has great promise for the early detection of HPV-attributable oropharyngeal cancer (HPV-AOC) and potentially other HPV-driven cancers and as an adjunct prognostic marker in long-term tumor surveillance, including treatment response. The moderate sensitivity of HPV testing in oral rinses or swabs at HPV-AOC diagnosis prevents its use in HPV-AOC secondary prevention but represents a promising prognostic tool in HPV-AOC tertiary prevention, where the HPV persistence in oral rinses throughout treatment may predict early HPV-AOC recurrences and/or the development of secondary HPV-AOC. The increasing sophistication of specific collection devices designed for alternative samples and the enhanced precision of novel molecular technologies are likely to support the evolution of this field and catalyze potential translation into routine practice.

Peripheral surrogates of tumor burden to guide chemotherapeutic and immunotherapeutic strategies for HPV-associated malignancies

With the rapid adoption of immunotherapy into clinical practice for HPV-associated malignancies, assessing tumor burden using "liquid biopsies" would further our understanding of clinical outcomes mediated by immunotherapy and allow for tailoring of treatment based on real-time tumor dynamics. In this review, we examine translational studies on peripheral surrogates of tumor burden derived from peripheral blood in HPV-associated malignancies, including levels and methylation of circulating tumor DNA (ctDNA), miRNA derived from extracellular vesicles, circulating tumor cells (CTCs), and HPV-specific antibodies and T cell responses. We review their utility as prognostic and predictive biomarkers of response to chemotherapy and radiation, with a focus on how they may inform and guide immunotherapies to treat locally advanced and metastatic HPV-associated malignancies. We also highlight unanswered questions that must be addressed to translate and integrate these peripheral tumor biomarkers into the clinic.

The Clinical Utility of Circulating HPV DNA Biomarker in Oropharyngeal, Cervical, Anal, and Skin HPV-Related Cancers: A Review

Human papillomavirus (HPV) is recognized as being related to a wide variety of known cancers: cervical, oropharyngeal, anal, vaginal, penile, and skin. For some of these cancers, rigorous algorithms for screening, therapeutical interventions, and follow-up procedures have been established. Vaccination using the nonvalent anti-HPV vaccine, which prevents infection regarding the most frequently involved high-risk HPV types (16, 18, 31, 33, 45, 52, and 58) and low-risk HPV types (6 and 11), has also extensively prevented, controlled, and even eradicated HPV infections. Still, even with all of these multidisciplinary interventions, the burden of HPV cancers is still high worldwide. The circulating DNA of HPV-induced cancers is thought to be an adequate biomarker for optimizing the control of these virus-related cancers. We analyzed the literature published in the last 5 years regarding ctDNA and four of the above-mentioned cancers. The most frequently used assay for ctDNA detection was the droplet digital PCR assay, used for the management of therapy in the late stages of cancer. ctDNA could not be used for early detection in any of the studied cancers. The OPSCCs were the most frequent cancers analyzed via ctDNA assays. Larger, properly designed cohort studies might establish the clinical utility of this biomarker.

Emerging Roles of Circulating Tumor DNA for Increased Precision and Personalization in Radiation Oncology

Recent breakthroughs in circulating tumor DNA (ctDNA) technologies present a compelling opportunity to combine this emerging liquid biopsy approach with the field of radiogenomics, the study of how tumor genomics correlate with radiotherapy response and radiotoxicity. Canonically, ctDNA levels reflect metastatic tumor burden, although newer ultrasensitive technologies can be used after curative-intent radiotherapy of localized disease to assess ctDNA for minimal residual disease (MRD) detection or for post-treatment surveillance. Furthermore, several studies have demonstrated the potential utility of ctDNA analysis across various cancer types managed with radiotherapy or chemoradiotherapy, including sarcoma and cancers of the head and neck, lung, colon, rectum, bladder, and prostate . Additionally, because peripheral blood mononuclear cells are routinely collected alongside ctDNA to filter out mutations associated with clonal hematopoiesis, these cells are also available for single nucleotide polymorphism analysis and could potentially be used to detect patients at high risk for radiotoxicity. Lastly, future ctDNA assays will be utilized to better assess locoregional MRD in order to more precisely guide adjuvant radiotherapy after surgery in cases of localized disease, and guide ablative radiotherapy in cases of oligometastatic disease.

Circulating HPV DNA in HPV-associated cancers

Human papillomavirus (HPV) infections are the primary cause of almost all cervical cancers, anal cancers, and a variable proportion of other anogenital tumors, as well as head and neck cancers. Circulating HPV DNA (cHPV-DNA) is emerging as a biomarker with extensive potential in the management of HPV-driven malignancies. There has been a rapid advancement in the development of techniques for analyzing cHPV-DNA for the detection, characterization, and monitoring of HPV-associated cancers. As clinical evidence accumulates, it is becoming evident that cHPV-DNA can be used as a diagnostic tool. By conducting clinical trials assessing the clinical utility of cHPV-DNA, the full potential of cHPV-DNA for the screening, diagnosis, and treatment of HPV-related malignancies can be corroborated. In this review, we examine the current landscape of applications for cHPV-DNA liquid biopsies throughout the cancer care continuum, highlighting future opportunities for research and integration into clinical practice.

The role of liquid biopsy in management of the neck with indeterminate response on post-treatment imaging following non-surgical management of oropharyngeal cancer

INTRODUCTION

This study aimed to determine if post-treatment HPV cell-free DNA (cfDNA) can assist in the decision-making process for salvage neck dissection in patients following non-surgical treatment of oropharyngeal squamous cell carcinoma (OPSCC) with a partial response in the neck on imaging at 12 weeks post-treatment.

METHODS

86 patients who completed treatment were prospectively recruited through the regional multidisciplinary team (MDT). Treatment response was categorised as complete response (CR), partial response (PR) or progressive disease on 12-week post-treatment imaging. Pre- and post-treatment blood samples were assessed for HPV cfDNA through droplet digital PCR (ddPCR).

RESULTS

Eight patients had an isolated partial response in the neck. One (12.5%) had detectable HPV cfDNA (22.96 copies/ml) at ∼12 weeks post-treatment with positive disease on subsequent neck dissection (positive predictive value; PPV = 100%). Of the seven patients with undetectable HPV cfDNA, two patients had evidence of regional disease recurrence at 23.9 and 27.4 months respectively (negative predictive value; NPV = 71%).

CONCLUSION

The detection of HPV cfDNA may help target salvage therapy in patients with a partial response in the neck. Follow-up studies in larger cohorts would be required to further validate the use of post-treatment HPV cfDNA in the management of OPSCC.