Natural history of HPV16-E6 serology among cancer-free men in a multicenter longitudinal cohort study

Abstract

Background Human papillomavirus (HPV)16-E6 seropositivity accurately predicts oropharyngeal squamous cell carcinoma (OPSCC) risk decades before diagnosis; but the biomarker’s translational potential is unknown. To inform considerations for OPSCC screening, we described HPV16-E6 seroprevalence, predictors, and kinetics among cancer-free men. Methods In a cohort study in Brazil, Mexico, and United States, we calculated HPV16-E6 seropositivity [median fluorescence intensity (MFI) units > 1,000], measured by multiplex serology, in cancer-free men. HPV16-E6 seropositivity predictors were assessed using logistic regression, adjusting for country, age, sexual orientation, and lifetime number of partners. Among HPV16-E6 seropositive men, we retrieved all available retrospective serum samples and described temporal HPV16-E6 antibody patterns. Results Of 3,997 men, 14 had HPV16-E6 antibodies detected [seroprevalence = 0.35%; 95% confidence interval (95%CI)=0.19%-0.59%] (median MFI = 2,407; interquartile range = 1,325-5,986). Older age was associated with increased odds of HPV16-E6 seropositivity (50-84 years vs 18-29 years odds ratio = 16.61; 95%CI = 2.20-417.03). Serum from 11 of the 14 seropositive men retested positive; six men had MFI > 5,000, of whom two had MFI > 10,000. Seven men had ≥3 years follow-up; all were persistently seropositive for 3 years. One man was seropositive for nine years but seroreverted at his exit visit. Oral HPV16-DNA (prevalence = 1.13%) was associated with HPV16-E6 seropositivity (odds ratio = 16.87; 95%CI = 3.35-69.55). However, oral HPV16-DNA positivity was not persistent over follow-up, even when HPV16-E6 antibodies were persistently detected. Conclusion HPV16-E6 seropositivity is rare but generally stable once detected; thus, HPV16-E6 antibodies may be an informative biomarker of HPV-driven OPSCC. Few men seroreverted following HPV16-E6 seropositivity but remained close to the seropositivity cut-off; thus, cancer risk among these men is less clear.