Abstract 7069: HPV-related oropharyngeal cancer: Circulating and salivary DNA-based biomarkers for early diagnosis and recurrence monitoring

Abstract Background: The incidence of oropharyngeal squamous cell carcinoma (OPSCC) has surged worldwide in recent decades. In the Czech Republic, annual OPSCC cases have more than tripled over 30 years, with nearly 800 new cases diagnosed in 2021, surpassing cervical cancer. OPSCC is now predominantly linked to high-risk HPV infection, with about 25% of patients experiencing recurrence within five years. Liquid biopsies (plasma and saliva) are being investigated for their potential in diagnosis, treatment monitoring, and recurrence detection. These efforts focus on DNA-based biomarkers, such as circulating tumor HPV DNA (ctHPV DNA) and oral HPV DNA. Methods: HPV tumor status was assessed in newly diagnosed OPSCC patients and those in remission using high-risk HPV DNA detection in primary tumor tissue and p16 immunohistochemistry. Only cases positive for both high-risk HPV and p16 were classified as true HPV-related OPSCC. Oral HPV DNA and ctHPV DNA testing were conducted on liquid biopsies (gargle lavage, oropharyngeal swabs, and plasma) before and after treatment, with regular follow-up sampling. Results: A total of 169 OPSCC patients were enrolled in the study, with 81.8% classified as HPV-related, predominantly involving the HPV16 genotype (98% of cases). Pre-treatment detection of tumor-derived high-risk HPV genotypes in liquid biopsies demonstrated excellent sensitivity: 92% in gargle lavage, 96.3% in oropharyngeal swabs, and 96.3% for ctHPV DNA in plasma, all achieving 100% specificity across sample types. Concordance in high-risk HPV genotype detection between gargle lavage and oropharyngeal swabs reached 94.2% in pre-treatment samples. Among recurrent HPV-related OPSCC cases, ctHPV DNA was detected in 75% (3/4) of cases, with 50% (2/4) also testing positive for oral HPV DNA. Conclusion: This study aims to validate the combined use of liquid biopsy collection, oral HPV DNA detection, and ctHPV DNA detection for early diagnosis and recurrence monitoring in HPV-related OPSCC patients. Preliminary findings are encouraging, demonstrating the potential for early detection, including in early-stage OPSCC, and highlighting the clinical applicability of these methods for HPV-related OPSCC screening. This study was supported by the Internal Grant Agency of Palacky University (IGA LF UP 2024_007 and IGA LF 2024_15), the project National Institute for Cancer Research (Programme EXCELES, ID Project No. LX22NPO5102) - Funded by the European Union - Next Generation EU, EATRIS-CZ (LM2023053), MH CZ - DRO (FNOL, 00098892), and SALVAGE (811100711/37). Citation Format: Ondrej Bouska, Vladimira Koudelakova, Zuzana Horakova, Marian Hajduch. HPV-related oropharyngeal cancer: Circulating and salivary DNA-based biomarkers for early diagnosis and recurrence monitoring [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7069.