Abstract PO-046: Relationship of HPV16 E6 seropositivity with circulating tumor tissue modified HPV DNA before head and neck cancer diagnosis
Authors: Rettig Eleni M. , Waterboer Tim , Sim Edward S. , Faden Daniel L. , Hanna Glenn J. , Fitz Catherine Del Vecchio , Kuperwasser Charlotte , Sroussi Herve 
Published: September 2023

Abstract
Importance: Given the increased incidence of HPV-positive oropharyngeal carcinoma (OPC) in recent decades, identifying minimally invasive biomarkers for early diagnosis is essential to decreasing disease- and treatment-related morbidity. Two such biomarkers, circulating tumor HPV DNA (ctHPVDNA) and HPV16 E6 seropositivity, are highly sensitive and specific for HPV-positive OPC. We recently reported detection of tumor tissue modified viral (TTMV) HPV16 DNA – a ctHPVDNA assay designed to detect HPV DNA derived from tumors – in blood collected several years before HPV16-positive OPC diagnosis. E6 seropositivity has been demonstrated several decades before diagnosis and is under consideration as a screening biomarker in high-incidence populations. The two biomarkers have not been compared in the prediagnostic setting. Objective: Compare pre-diagnostic HPV16 early antigen seropositivity and TTMV-HPV16 DNA detection to understand their temporal relationship with respect to clinical disease manifestation. Methods: Participants in the Mass General Brigham Biobank hospital-based cohort research study with available blood samples collected ≥6 months before diagnosis were selected. Tumor and plasma TTMV-HPV DNA testing was performed by Naveris (Natick MA). Cases were included for plasma testing only if TTMV-HPV DNA from HPV types 16/18/31/33/35 was detected in tumor tissue. Plasma was tested for antibodies to HPV16 antigens E1, E2, E4, E6 and E7 using multiplex serology by the German Cancer Research Center. Results: The study population comprised of 9 cases of HPV16-positive HNCs, 7 with OPCs and 2 with lateral tongue tumors, and 45 matched controls. Most cases were male (8/9) and all were white, with median age 70 (range, 51-93). Plasma was collected median 34 months (range, 19-76 months) before diagnosis. HPV16 E6 seropositivity was observed in 6/9 HNC cases, all of which were OPCs. Two controls were HPV16 E6 seropositive. Upon updated medical record review, one of these E6 seropositive controls had been diagnosed with HPV-positive OPC in the interim between study initiation and data analysis, 18 months after control cohort selection and 63 months after blood collection. When this control subject was included as an HPV-positive OPC case, prediagnostic E6 seropositivity was observed in 7/10 HNC cases and 7/8 OPC cases. TTMV-HPV16 DNA was detected in plasma from 3/10 HNC cases, all 3 of which were OPCs that were seropositive for ≥4 HPV16 early antigens, including E6. In contrast, among the 7 cases with undetectable TTMV-HPV16 DNA, only 1 was seropositive for ≥4 antigens. Conclusion: The higher prediagnostic prevalence of HPV16 E6 seropositivity than TTMV-HPV16 DNA detection suggests that E6 seroconversion occurs before tumor DNA is shed into circulation at detectable levels. Our data suggest that TTMV-HPV16 DNA testing may be a reasonable component of investigating HPV16 E6 seropositive individuals who are at risk for HPV-positive OPC.
Citation Format: Eleni M. Rettig, Tim Waterboer, Edward S. Sim, Daniel L. Faden, Glenn J. Hanna, Catherine Del Vecchio Fitz, Charlotte Kuperwasser, Herve Sroussi. Relationship of HPV16 E6 seropositivity with circulating tumor tissue modified HPV DNA before head and neck cancer diagnosis [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Innovating through Basic, Clinical, and Translational Research; 2023 Jul 7-8; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2023;29(18_Suppl):Abstract nr PO-046.