Circulating HPVDNA in patients undergoing transoral robotic surgery for oropharyngeal cancer: liquid biopsy could identify molecular residual disease

Objectives: we evaluated the hypothesis that level of ctHPVDNA on the first postoperative day (POD-1); and at 15 days (POD-15) could be associated with the need for adjuvant therapy and the presence of recurrence. Materials and methods: this is a prospective observational study on biomarkers, focusing on the longitudinal monitoring of ctHPVDNA in a cohort of HPV-OPSCC patients undergoing TORS. Blood samples were collected according to the following schema: (1) pretreatment; (2) on first postoperative day (POD 1); and (3) at 15 days (POD 15). Plasma samples were analyzed with ddPCR assay comprising E6 of HPV16, HPV 33 and HPV 35. Results: Present study was conducted on 44 OPSCC patients and revealed a ctHPVDNA sensitivity of 100% (95%CI: 89-100%) in blood samples at first diagnosis. Data demonstrated a significant different of ctHPVDNA levels at POD-1 among patients who received observation vs. adjuvant treatment and among patients who remained disease-free at the last follow-up, compared to those who experienced recurrence. In the next years, studies on larger patients' surgical cohorts focused on ctHPVDNA levels at POD-1 and continued improvements in assay methodology could allow the implementation of ctHPVDNA in routine clinical use. Conclusion: Liquid biopsy could identify residual molecular disease after surgery and guide clinicians choosing adjuvant treatment.