Circulating tumor tissue modified viral (TTMV)-HPV DNA in Recurrent, metastatic HPV-driven oropharyngeal cancer

Background: Human papillomavirus (HPV) is causally linked to oropharyngeal squamous cell carcinoma (OPSCC). Testing for plasma tumor tissue modified viral (TTMV)-HPV DNA has emerged as a biomarker strategy for post-treatment surveillance to identify recurrent disease. We aimed to understand the prognostic and predictive potential of TTMV-HPV DNA when monitoring patients who had developed recurrent or metastatic (R/M) HPV+OPSCC. Methods: This retrospective observational cohort study included 80 patients from 4 academic centers with R/M HPV+OPSCC if they had ≥ 1 plasma TTMV-HPV DNA test obtained at any point during their R/M disease course. Physician-reported clinical data and treatment history were captured in a centralized database, along with investigator-assessed response to therapy and survival. Descriptive statistics and non-parametric tests of association were employed along with survival analyses (Kaplan-Meier method). Results: Sixteen (20 %) patients had ≥ 5 test results over time. Consecutive TTMV-HPV DNA tests were performed a median of 73 days apart. Median TTMV-HPV DNA scores were higher with an increasing per-patient number of metastatic sites (<2 vs. 2+; p < 0.01). Score changes over time were influenced by R/M treatment modality and became undetectable in 67 % (12/18) of patients who achieved a complete response to R/M therapy. Patients with detectable scores at last follow-up had significantly worse survival compared with those who were undetectable (log-rank test, p < 0.01). Conclusions: TTMV-HPV DNA appears useful as a prognostic tool for monitoring response to therapy in the R/M setting. In the future, TTMV-HPV DNA could be explored as an exploratory clinical trial endpoint in the metastatic setting.