Circulating HPV DNA as a Prediagnostic Marker of Oropharyngeal Cancer

The incidence of HPV-driven oropharyngeal cancer (HPV-OPC), a type of head and neck cancer, is rapidly increasing in the United States (US). HPV-OPC recently surpassed cervical cancer as the most common HPV-associated malignancy. Unlike cervical cancer, there are no methods of early detection for HPV-OPC. HPV16 E6 antibody positivity has been identified as a promising early biomarker of HPV-OPC. Previous work from our group showed that HPV16 E6 antibodies are present in up to 90% of HPV-OPC patients and appear more than 10 years prior to diagnosis. However, given the long lag time between HPV16 E6 seroconversion and cancer diagnosis, HPV16 E6 seropositive individuals may need to be followed for a decade or more before the cancer is clinically diagnosable. Thus, early detection biomarkers that indicate the presence or absence of tumor are needed before considering HPV16 E6 antibody testing for clinical use. Circulating tumor (ct)HPV DNA detection is a promising marker for detection of HPV-OPC. Work from our group has demonstrated that ctHPVDNA is 98.4% sensitive and 98.6% specific for HPV-OPC at the time of diagnosis. Prior studies of ctHPVDNA have focused on the utility of ctHPVDNA for diagnosing HPV-OPC and monitoring for recurrence post-treatment. To date, the potential of ctHPVDNA for early detection of HPV-OPC has not been explored. A major barrier to evaluating ctHPVDNA in a pre-diagnostic setting is that assays developed to date require a high volume of blood (>1ml), which has precluded nested studies in prospective cohorts given that blood samples collected prior to HPV-OPC diagnosis are limited and precious. Leveraging our experience in ctDNA, we have re-optimized our droplet digital PCR (ddPCR) based assay for detecting ctHPVDNA in small volumes of archived specimen. The objective of this study is to conduct the first large study to evaluate the kinetics of ctHPVDNA prior to diagnosis and to compare this biomarker to HPV16 E6 seropositivity. A nested case-control study will be conducted within the Prostate Lung Colorectal and Ovarian (PLCO) Cancer Screening Trial, a prospective cohort study of 154,935 middle aged men and women from across the US. Prediagnostic blood samples from 81 OPC cases and 162 matched controls (1:2 ratio) will be tested for ctHPVDNA. All serial samples from ctHPVDNA positive cases will also be tested to evaluate kinetics of the marker leading up to diagnosis. We hypothesize that ctHPVDNA will be detectable prior to cancer diagnosis and that ctHPVDNA will be more sensitive than HPV16 E6 seropositivity. This proposal is innovative given the use of a novel ctHPVDNA assay specifically optimized for small volumes of archived specimen, which will allow us to conduct the first study to evaluate ctHPVDNA in a prediagnostic setting. This research may lead to better methods for early detection of HPV-OPC and directly responds to the joint Notice of Special Interest issued by the National Cancer Institute (NCI) and National Institute for Dental and Craniofacial Research (NIDCR): Advancing Head and Neck Cancer Early Detection Research (AHEAD); NOT-CA-20-031.