Salivary and serum HPV antibody levels before and after definitive treatment in patients with oropharyngeal squamous cell carcinoma

BACKGROUND: HPV-associated oropharyngeal squamous cell carcinoma (OPSCC) is increasing in incidence. Laboratory assays that identify virally-mediated disease and predict HPV clearance in OPSCC may have important prognostic implications. OBJECTIVE: Here we investigated serum, salivary HPV16 early (E) antibodies before and after definitive chemoradiotherapy (CRT) in patients with locoregionally advanced OPSCC. METHODS: We prospectively measured salivary, serum samples at the beginning of and 6-7 weeks following the completion of CRT in 44 patients. IgG antibodies targeting N- and C-terminal fragments of E2 (NE2, CE2), E6 and E7 were measured by programmable enzyme-linked immunosorbent assay. RESULTS: We observed serum antibodies directed against HPV-associated E proteins in patients with HPV-associated OPSCC. E7 directed antibodies were detected in saliva in the majority of patients, and were associated with HPV status (p = 0.03). When analyzed longitudinally, median salivary E7 antibody levels decreased significantly post-treatment (p = 0.007). CONCLUSIONS: Our results demonstrate the feasibility of measuring HPV16 E antibodies in saliva and serum. E7 antibodies, in particular, are more detectable in saliva as compared with other E protein antibodies. Measuring E7 salivary antibody levels at various time points may have utility in understanding HPV clearance and should be explored for their ability to predict the risk of recurrence.